A work in progress

I just started this website, so I haven't gotten around yet to making this blog current - so please click here for the most recent posts at Wit's End, until I fix it!


Bleached Bones and Jumbled Residue

For several days a stray kitty has been lurking around Wit's End.  At first I thought it was feral, and merely hungry - poaching the food I leave on the porch for my own cats.  But even after it was well fed, it started lunging frantically at the old beveled window pane in the kitchen door.

It had scrabbled up the hydrangea vine growing on a trellis and hung precariously from the mullion.
It kept falling off, and climbing up again.
It rubbed its face against the door jamb.  Please please let me in!  Finally, I relented and have been letting it stay in the warm mudroom where the two (very disgruntled) barn cats overnight in the winter.
I took pity on it, even though its behavior is frighteningly psychotic, because most of the time it is yowling voraciously, like this!
A friend who lives on a neighboring farm said she thinks that people can't afford pet food and vet bills anymore, so they are bringing their cats out to the countryside and ditching them, hoping perhaps they can fend for themselves in the wild - she had two show up last month.  I suppose that may be the explanation - an even worse story is of horses being abandoned and left to starve, all over the UK.
Montebello, Quebec, Canada
But, back to the topic of Wit's End - trees dying from air pollution.  This site, called "Health and Energy" has a section about the effect on vegetation that describes it with breathtaking simplicity, so I'm going to post their definition, before getting into some (much) more complicated recent research.  Below is a Forest Service map of tree mortality from 2007 - even though they know that exposure to ozone makes trees more vulnerable to insects and disease, they don't mention it here:
Forest Service 2007 Tree Mortality Map, Aerial Survey
"Pollution Damage to Plants - Pollutants such as sulfur dioxide, nitrogen oxides, ozone and peroxyacetyl nitrates (PANs), cause direct damage to leaves of crop plants and trees when they enter leaf pores (stomates). Chronic exposure of leaves and needles to air pollutants can also break down the waxy coating that helps prevent excessive water loss and damage from diseases, pests, drought and frost. 'In the midwestern United States crop losses of wheat, corn, soybeans, and peanuts from damage by ozone and acid deposition amount to about $5 billion a year'."
Daniel Boone National Forest, Kentucky
Rather than use my own pictures for illustration, I decided to try a google image search for "dying forest" instead.  Oh. My. God.  What is fascinating - and important - is that these images are from countries all over the world, in both hemispheres, and are identified by the photographers themselves as "dying".  Some are from hikers or tourists who just like to take pictures, others are from websites explicitly devoted to tree death...although most (but not all) of them seem unaware that it is a global, and not merely an isolated local trend.  Thus, this post is dedicated to all the condescending scientists, foresters, and regulators who have insisted that the problem of dying trees is limited, if not to my imagination, then to my own little farm, Wit's End.
Foret du Day, Africa
Here's another lucid primer, focusing on the aforementioned PAN's, which it should be noted, are particularly high in emissions derived from biofuels (oops!).  Everything that follows are extensive quotes from various linked sources, minus references.  Any comments I insert will be highlighted and if you want to skim (and who wouldn't?) - the exciting parts are in red...

Peroxyacetyl nitrate (PAN) is an organic compound found in photochemical smog. It is a secondary pollutant produced in the atmosphere by the action of sunlight on the air pollutants present in urban areas. It is a highly potent oxidant that is both toxic and irritating. Sources of pollutants that become PAN include vehicle emissions, tobacco smoke and smoke from the burning of petroleum products, such as natural gas and coal.

Foret du Day, Africa

PAN inhibits the primary process of photosynthesis in various types of plants, which can stop or reduce their growth. Pan is more toxic to plants than ozone. Affected plants exhibit discolored leaves and leaves can fall off, which further reduces photosynthesis. The plant's ability to store food, grow and reproduce is reduced, and the plants also become more vulnerable to attacks by pests and diseases. Agricultural crops and forests are affected as well as wild plants.

Ecological Systems
  • PAN is formed in urban areas where there are high levels of pollutants from vehicles and industrial sources, and the formation of PAN peaks around midday when sunlight is strongest. Because it is fairly stable, winds can carry it to rural regions and pristine areas where it can have an ecological impact well away from its origin. A 1997 study reported in the Economist found levels of peroxyacetyl nitrate at Cheeka Peak Observatory, Washington, were 100 percent above normal due to pollutants reaching the West Coast from Asia. This means pollution from one region can affect the whole planet.
Foret du Day, Africa, Hookbill

A new study, which has caused quite a stir, urges smart targeting of pollution sources to save lives and climate.  Following is a release from the University of York:

Helena National Forest, Montana

While all regions of the world would benefit, avoided warming is greatest in central and northern Asia, southern Africa and around the Mediterranean, total numbers of avoided premature deaths are greatest in Asia and Africa and the greatest total tonnage gains in crop production are estimated to occur in China, India and the US, followed by Pakistan and Brazil.  Countries in South Asia and the Sahel region of Africa could see considerable reduction in the disruption of rainfall patterns.

The research published this week in the journal Science was led by Drew Shindell of NASA's Goddard Institute for Space Studies in New York City.
Dr Johan Kuylenstierna, the Director of SEI at York, said:  "All 14 measures are based on existing technologies and can be implemented immediately, so do not require long development processes. The measures maximize climate benefits but would also have important 'win-win' benefits for human health and agriculture.”
Buenos Aires, Argentina
Dr Kevin Hicks, at SEI, added: “The motivation for taking action will vary from country to country and region to region. In some, climate change will be the main concern but in others, air quality may well take precedence.”

Black carbon, a product of the incomplete combustion of fossil fuels or biomass such as wood or agricultural crop residues, damages human health by entering the lungs and exacerbating a number of respiratory diseases. It also absorbs radiation from the sun causing the atmosphere to warm and rainfall patterns to shift and reduces the reflectivity of bright surfaces, such as ice and deserts, a process that hastens global warming. Methane is a precursor to ground-level or lower atmosphere ozone, a component of health-sapping smog, and is also a potent greenhouse gas. Ground level ozone at current levels also damages plants and reduces agricultural yields in sensitive areas.

Dr Lisa Emberson, of SEI, said: '’Ground level ozone is a particular problem in areas such as South Asia which is particularly vulnerable to food insecurity and climate change.”
Co-author of the study, Professor Martin Williams from the Environmental Research Group at King’s College London, added: "Measures taken now to reduce carbon dioxide emissions will not have any effect on the global climate for another 40-50 years. We have shown that there are things we can do to begin to mitigate the temperature increases already being seen.’’
“The combination of methane and black carbon measures along with substantial carbon dioxide emissions reductions has a high probability of limiting global mean warming to <2ºC during the next 60 years, something which neither set of emissions reductions achieves on its own.”
Prielom-Rohatka, High Tatras, Carpathians, Slovakia
Professor David Fowler, of the Centre for Ecology and Hydrology, added: “These control measures represent many win – win options with benefits for human health and climate as well as reducing waste, for example with the methane controls.”
Black carbon and methane pollutants come from a wide variety of sources and the 14 measures identified by the study have all been successfully applied in different parts of the world.
For methane, the key strategies the scientists considered in their analysis were capturing gas that would otherwise escape from coal mines and oil rigs, reducing leakage from long-distance gas pipelines, preventing methane emissions in city landfills, updating city wastewater treatment plants, aerating rice paddies more frequently, and limiting emissions on farms from manure.
Northern Rim, Grand Canyon
For black carbon, the strategies analyzed include installing particle filters in diesel vehicles, keeping high-emitting vehicles off the road, upgrading cook stoves and boilers to cleaner burning types, installing more efficient kilns for brick production, upgrading coke ovens and banning agricultural burning.
The research team used sophisticated emission, air quality and climate models (e.g. IIASA GAINS, NASA GISS and ECHAM) to estimate the impact of emissions reductions. The modelling shows that the benefits from the methane reductions would be widespread because methane is evenly distributed throughout the atmosphere.  The methane measures if fully implemented will to large global climate and agriculture benefits and relatively small human health benefits, all with high confidence and worldwide distribution.
The black carbon measures are likely to provide substantial global climate benefits, but uncertainties are much larger. There is more certainty for the black carbon measures concerning the large regional human health benefits as well as reductions in regional rainfall disruptions, ice melting in both the Arctic and the Himalayas and improvements in regional agricultural yields.
Shenandoah National Park
Apparently, the Washington Post and perhaps others have seized on this to mean there are some easy fixes to climate change (!) - so I left this comment at The Daily Impact's dissection (which is well worth reading):
Regardless of how the Post distorted the Shindell study, my take on the point of it is that the “other” greenhouse gases – ozone, black carbon, etc – while they do not pose the same sort of long term climate change effect as CO2 – are more responsible for the disproportionately faster rate of temperature increase in the Arctic… which is quite extreme compared to lower latitudes. This is leading to very dangerous feedback effects, like methane release. So they are recommending policies to address these other emissions, and make it clear this is not going to solve the CO2 problem. Not that, as you say, we’re going to do anything about any of it. Or the bees, for that matter!
I think what they are saying in a nice science-y way is that we’re kind of in an existential emergency with the albedo effect on ice and the permafrost melt.
Krkonose National Park, Czech Republic
Of course, I sent my usual letter to Dr. Emberson, one of the co-authors who seems to be the ozonista in the group:

Dear Dr. Emberson,

I am writing in regards to the impact of ozone on vegetation.  I live in New Jersey, USA, and for several years now it has been obvious to me that individual trees and indeed entire forests are universally in decline.  There has been an abrupt, dramatic, and alarming deterioration in their health, not only around where I live but many places on this continent I have visited personally, and in fact all around the world from many reports.

It's quite clear that the composition of the atmosphere is at the bottom of what is a global trend towards vegetative die-back...and that all the insects, disease, fungus, and drought from climate change usually blamed, especially by American foresters and agronomists, actually constitute secondary, opportunistic damage to plants and trees that are already fatally compromised by ozone.
Since this would appear to be an existential threat I have been trying with little success to encourage scientific experts to warn government agencies and by extension the public that we have to stop burning fuels for energy before the ecosystem collapses and there is nothing left to eat.  Unfortunately the study of ozone and climate change are so fragmented that very few if any researchers are bold enough to put the entire picture together, and mentioning the role ozone plays in diminishing crop yield and quality is practically taboo.
Hunting Island State Park, South Carolina
In particular the US Forest Service has virtually abolished any discussion of pollution impacts to forests, preferring to conveniently focus on factors we cannot, or can no longer, control.  (I've posted excerpts from their latest reports on my blog about this topic, Wit's End, in case you are interested.)
Hunting Island State Park, South Carolina
I have a couple of specific reasons for writing to you.  First, can you send me the full paper to read?  I don't have a subscription to Science.

Second, I wonder if you have any ideas about exactly why all the trees are dying so suddenly and quickly.  Although acid rain and other biotic injuries have accrued for many decades, there has definitely been a recent surge in deaths, in a very alarming trend.  Not being a scientist I can't really investigate why, but I have considered the following possibilities and would appreciate any insights or additions you may have to this list:
1.  We have reached a tipping point where the background level of ozone is intolerable, perhaps in combination with the disruption of the nitrogen cycle;

2.  Burning biofuels has significantly contributed to worse and more persistant ozone (from acetaldehyde);
Horseshoe Lake, Mammoth, California
3.  (and this is why your article is so fascinating) Models have not registered the contribution of methane in producing ozone, from several sources - including the increase in leakage from natural gas fracking, and releases from the Arctic permafrost.

I am copying Drew Shindell because he is listed as the contact for your research, although I have written him before and never received a reply.

Thank you so much for your attention.


Gail Zawacki
Oldwick, NJ
Tatra Forest, Slovakia
I have had no response from Dr. Emberson, but I did find that she had contributed to the ozone portions of this UNEP 2008 Summary, titled "Atmospheric Brown Clouds - Regional Assessment Report with an Emphasis on Asia" which is excerpted below:

In addition, elevated concentrations of ground level ozone have been found to have large effects on crop yields. Experimental evidence suggests that growing season mean ozone concentrations of 30 - 45 ppb could see crop yield losses of 10 - 40 per cent for sensitive varieties of wheat, rice and legumes. A recent study translated such impacts on yield into economic losses estimating that for four key crops (wheat, rice, corn and soybean) annual losses in the region of US$ 5 billion may occur across Japan, the Republic of Korea, and China. These studies used dose-response relationships derived from Europe and North America, recently collated scientific evidence suggests that some important Asian grown crop cultivars may actually be more sensitive to ozone than European or North American varieties.  Concern for a worsening situation in the future is highlighted by projections which suggest that the annual surface mean ozone concentrations in parts of South Asia will grow faster than anywhere else in the world and exceed 50 ppb by 2030.
Maligne Lake, Jasper National Park, Alberta, Canada
p. 29 -  The Impact of the Ground Level Ozone Component of ABC's on Agriculture

1. Ozone concentrations vary across Asia as a result of regional and local scale variations in precursor emissions and atmospheric circulation patterns. Ozone concentrations across Asia appear to follow a well-defined annual profile with two ozone peaks (during spring and autumn, when ozone concentrations commonly reach monthly mean values of 50 and 40 ppb, respectively) and a
mid-summer trough associated with the main monsoon season, when monthly mean ozone concentrations are reduced to approximately 30 ppb. However, these values vary considerably depending on geographical location and proximity to pollutant sources.
Jasper National Park, Alberta, Canada
2. There currently exist only a few unevenly distributed ozone monitoring sites across the whole of Asia, making it difficult to obtain a true picture of the current Asian ozone climate and how this varies by geographical characteristics (for example, sub-urban, rural, remote). To aid future ozone-based risk assessments, a more evenly and densely populated monitoring network should be established.
3. A large number of experimental studies using a variety of experimental techniques (fumigation, filtration, chemical protectant and transect studies) have been conducted on major crops in Asia. The studies suggest that growing season mean ozone concentrations in the range 30 - 45 ppb could see crop yield losses in the region of 10 - 40 per cent for sensitive cultivars of important Asian crops (that is, wheat, rice and legumes). In comparison, IPCC (2007) projects decreases of 2.5-10 percent in crop yield for parts of Asia in the 2020s and a 5-30 per cent decrease in the 2050s, compared with 1990 levels,
without carbon dioxide (CO2) effects.
Aspen, Kenusha Pass, CO
4. Pooling experimental data on the impact of ozone on crops in Asia allows comparison with European and North American dose-response relationships. These comparisons would suggest that Asian grown crop varieties are more sensitive to ozone. This could be due to varietal differences, predisposing
environmental conditions or pollutant exposure characteristics. However, these data should be interpreted with caution given the heterogeneity in the experimental methods used in the derivation of the Asian data.
Aroostuck County, Maine
5. Given the annual variability in ozone concentrations, it is important to consider the growing seasons and developmental stages of the main Asian crops and to identify those that are likely to be exposed
to higher ozone concentrations and therefore be more susceptible to ozone damage. For example, the sensitive grain filling period for wheat occurs during February-March across much of Asia, coinciding with periods of high ozone concentration.
Union Pass, Wyoming
6. Economic loss estimates due to ozone impacts on crops have only been recently conducted for East Asia using North American dose-response relationships. A study estimated losses of four key crops
(wheat, rice, corn and soybean) at US$ 5 billion in Japan, South Korea and China; these economic losses were attributed to percentage yield losses of up to 9 per cent for cereal crops and 23-27 per cent for soybean.
Inside Passage, Alaska
7. Global ozone projections suggest that some of the largest increases in ozone concentration will occur in South and Southeast Asia from now until 2030. Such projections would see South Asia becoming the most ozone polluted region in the world, with annual surface mean concentrations reaching 52.2 ppb.
Seven Lakes, Colorado
8. The impacts of current and projected ozone concentrations therefore need to be considered within the broader context of impacts on agriculture under climate change, as well as consideration of how climate change may influence crop sensitivity to ozone (through alterations in temperature, atmospheric humidity and soil moisture). Atmospheric brown clouds (ABCs) will also influence radiation and precipitation patterns across the region. New flux-based risk assessment methods offer an opportunity to assess the interactions of these various environmental stresses and the consequent effects on crop productivity.
9. Although many experimental studies have been conducted to assess the impacts of ozone on a variety of different crops and cultivars, these have not been performed according to common experimental protocols, making it difficult to construct dose-response relationships.  A coordinated pan-Asian experimental programme would add greatly to our understanding of the impact of ozone on crops and cultivars that are representative of the region.

Because I'm starting to suspect that the contribution of methane to ozone is underestimated, I googled around and came up with this site, Global Methane Initiative, which says:

In addition to mitigating global warming, reducing methane emissions can deliver a host of other energy, safety, and local air and water quality benefits. These benefits make reduction projects very attractive.

Methane contributes to background tropospheric ozone levels both as an ozone precursor and by contributing to global warming, which raises daytime temperatures. Studies have shown that reducing global methane emissions can lower tropospheric ozone formation and reduce associated mortalities, particularly in equatorial regions.  In addition, many of the technologies and practices that reduce methane emissions also reduce associated emissions of volatile organic compounds (VOCs), odors, and other local air pollutants.

According to Scientific Certification Systems, ozone and black carbon are swirling around the globe.  They have terrific animated videos from NASA, which I couldn't figure out how to embed, but following are screenshots.  What's even scarier is that they are from 2004 - and emissions have increased dramatically since then.  It's pretty amazing to see how far pollution travels.
Lake Arrowhead, CA
Tropospheric Ozone (TO)

Tropospheric ozone is 20,000 times more potent than carbon dioxide as a GHG on an annual time horizon basis. The heating effects from these tropospheric ozone plumes have not been addressed by current climate change policies and mitigation efforts.
Ozone Pollution is a component of smog that rises up into the troposphere (up to 12 km high) and lasts for approximately 30 days. Tropospheric ozone is such a potent GHG, that even with its short life span, it markedly affects climate change.
The image shown below represents the South American tropospheric ozone plume that may be contributing to the rapid melting of western Antarctica. Tropospheric ozone plumes are also hitting the Arctic, increasing atmospheric heat by 40 percent and potentially contributing to the rapid disappearance of Arctic Ice Sheet.

Black Carbon

When black carbon particles absorb heat in the atmosphere, they are 30,000 times more potent than CO2 on an annual time horizon basis. When these ultra-fine particles settle atop snow and ice, they turn it gray, lowering its ability to reflect sunlight and accelerating melting.
Black carbon pollution is caused by the incomplete combustion of fuel and the burning of biomass. Satellite imaging reveals distinct plumes of black carbon originating from central Asia and Russia that travel over the Arctic. The following black carbon data is from Science On a Sphere, a project of National Oceanic and Atmospheric Administration (NOAA). See their site for more information.

At the highest concentration, the brightest white, Black Carbon is 2.5 more intense compared to background heat of CO2 since the dawn of the industrial age (from 1850 until now.)

Tracking the location of black carbon plumes helps delineate sources and hot spots— regions that will be the most impacted by climate change. In addition to the Arctic, hot spots are found in Africa, South America, the Indian Sub-Continent and Asia. These hot spots are likely contributing to more violent storms and droughts in the receiving region.

Biogenic Arctic Methane

Rising concentrations of methane, a GHG 105 times more potent than CO2, have caused Arctic spring temperatures to increase by +10°C. Arctic concentrations of methane are 35-50 percent higher than those found in the tropics due to the powerful air current vortex that forms over the North Pole each winter. The surface and upper-atmospheric winds form a tight ring of air current that draws in winter tundra methane plumes. In the winter months, methane does not break down because of the lack of sunlight.
The increased Arctic temperatures are causing spring ice to thaw up to four weeks earlier than normal. This ice melt leads to earlier and more intense formation of biogenic methane, which in turn leads to more regional warming, creating a self-destructive virtual feedback loop.

Getting back to the first paper by Shindell and Emberson et al, here are excerpts from an earlier iteration, in 2008, called "Short-lived pollutants in the Arctic: their climate impact and possible mitigation strategies."


Several short-lived pollutants known to impact Arctic climate may be contributing to the accelerated rates of warming observed in this region relative to the global annually averaged temperature increase. Here, we present a summary of the short-lived pollutants that impact Arctic climate including methane, tropospheric ozone, and tropospheric aerosols. For each pollutant, we provide a description of the major sources and the mechanism of forcing. We also provide the first seasonally averaged forcing and corresponding temperature response estimates focused specifically on the Arctic. The calculations indicate that the forcings due to black carbon, methane, and tropospheric ozone lead to a positive surface temperature response indicating the need to reduce emissions of these species within and outside the Arctic. Additional aerosol species may also lead to surface warming if the aerosol is coincident with thin, low lying clouds. We suggest strategies for reducing the warming based on current knowledge and discuss directions for future research to address the large remaining uncertainties.

Fig. 1. Forcing mechanisms in the Arctic environment resulting from the poleward transport of middle latitude gas and particulate phase pollutants. Season of maximum forcing at the surface (FS) is indicated for each forcing agent. 1T indicates the surface temperature response.

Foret du Day, Tadjoura, Djibouti, East Africa
Arctic warming is primarily a manifestation of global warming, such that reducing global-average warming will reduce Arctic warming and the rate of melting.  Reductions in the atmospheric burden of CO2 are the backbone of any meaningful effort to mitigate climate forcing.

But even if swift and deep reductions were made, given the long lifetime of CO2 in the atmosphere, the reductions may not be achieved in time to delay a rapid melting of the Arctic. Hence, the goal of constraining the length of the melt season and, in particular, delaying the onset of spring melt, may best be achieved by targeting shorter-lived climate forcing agents, especially those that impose a surface forcing that may trigger regional scale climate feedbacks pertaining to sea ice melting. Addressing these species has the advantage that emission reductions will be felt immediately.

Marco Island, FL
The forcing agents included in this discussion are methane, tropospheric ozone, and tropospheric aerosols. In this article we describe the mechanisms by which these shortlived pollutants impact Arctic climate and present the first seasonally averaged forcing and temperature response estimates for the Arctic.
Lusen Mountain, Bavaria, Germany (follow this sad couple as they hike to higher elevations)

With a lifetime of about 9 years, methane is much shorter lived than CO2 but still is globally well-mixed. Methane has contributed the second largest anthropogenic radiative forcing since the pre-industrial after CO2 and, on a per molecule basis, is a more effective Greenhouse Gas (GHG). Radiative forcing by methane results directly from the absorption of longwave radiation and indirectly through chemical reactions that lead to the formation of other radiatively important gases. The latter is dominated by the formation of tropospheric ozone, also a short-lived GHG, through the oxidation of methane by the hydroxyl radical (OH) in the presence of nitrogen oxides (NOx) and sunlight.

Lusen Mountain, Bavaria, Germany
2.2 Tropospheric ozone

Both observations and modeling studies provide evidence that tropospheric ozone concentrations, which are controlled primarily by photochemical production and loss processes within the troposphere, have increased since preindustrial times due to increases in emissions of anthropogenic ozone precursors. The rapid increase in ozone concentrations during the latter half of the 20th century has been attributed to increases in economic development at middle and low latitudes. Ozone precursors include NOx, carbon monoxide, methane, and non-methane volatile organic compounds (NMVOC).

Lusen Mountain, Bavaria, Germany
Anthropogenic sources of these precursor gases include fossil fuel combustion and production, biofuel combustion, industrial processes, and anthropogenic biomass burning. Natural sources include wildfires, biogenic emissions from soils and vegetation, and lightning. In polluted air masses, ozone is formed primarily from rapid photochemical oxidation of NMVOCs in the presence of NOx. In contrast, methane, being globally well-mixed, contributes to increases in background tropospheric ozone levels.
Lusen Mountain, Bavaria, Germany
Changes in local tropospheric ozone affect Arctic climate by altering local radiation fluxes, while changes in both local and distant ozone amounts can modulate the transport of heat to the polar region. The lifetime of ozone decreases during the summer in the extratropics since photochemical destruction rates increase with increasing insolation. Hence, ozone that is produced in the northern hemisphere mid-latitudes is most efficiently transported to the Arctic in the non-summer months.  Little is known about the contribution of local production of ozone and its precursors within the Arctic relative to extrapolar sources. Local sources include marine vessel emissions. Shipping emissions in the Arctic have the potential to increase Arctic ozone levels by a factor of 2 to 3 relative to present day.
Lusen Mountain, Bavaria, Germany
Sub-Arctic and Arctic ozone precursor emissions may be increasing as boreal regions warm and forest fire frequency increases. Fires emit large quantities of CO and non-methane volatile organic carbon (NMVOC) compounds which may combine with anthropogenic emissions in the same region to produce large amounts of ozone.
Lusen Mountain, Bavaria, Germany
CO emissions from boreal fires in the spring and summer of 2003 made a substantial impact on concentrations in the Arctic. Agricultural fires may be particularly important sources to the Arctic, especially in eastern Europe and northern Asia as these are regions with very high fire frequency.
Lusen Mountain, Bavaria, Germany
Record high concentrations of ozone were measured at the Zeppelin research station in Spitsbergen (79◦N) in April and May of 2006. This severe air pollution episode was a result of the combination of unusually high temperatures in the European Arctic and large emissions from agricultural fires in Belarus, Ukraine, and Russia. The high temperatures in the Arctic reduced the temperature gradient between the source and receptor regions, making lowlevel transport of pollution into the Arctic possible. Should the warming of the Arctic continue to proceed more quickly than that of the middle latitudes, transport from highly polluted source regions may become more frequent in the future, resulting in increased tropospheric ozone concentrations and a further increase in surface temperatures.
Lusen Mountain, Bavaria, Germany
4 Seasonality and magnitude of forcing due to shortlived pollutants and surface temperature response

Forcing due to tropospheric ozone is at a maximum during spring when transport of ozone is efficient, radiation is abundant, and substantial ozone precursors persist from the winter buildup that occurs under conditions of low photochemical loss. Summertime forcing could also be significant, particularly when agricultural or boreal forest fire emissions increase ozone levels in the Arctic.

Lusen Mountain, Bavaria, Germany
p. 1732 - Ozone and black carbon – targeting source regions.

Ozone and black carbon are not globally well mixed due to their relatively short lifetimes. Hence, specific source regions must be targeted to lessen their impacts in the Arctic. On timescales of days to weeks, northern Eurasia is the strongest source region for Arctic air pollution, especially in the lower troposphere. Therefore, to decrease concentrations of ozone precursors and black carbon in the lower atmosphere, emissions in this region should be reduced. The source regions of short-lived pollutants in the upper Arctic atmosphere include northern Eurasia and also areas in North America and Asia.

Therefore, a substantial reduction of ozone and BC in the upper troposphere will require more widespread emission reductions throughout the Northern Hemisphere. The correspondence between surface temperature response in the Arctic and global and Northern Hemisphere extratropical forcings due to ozone emphasizes the need to reduce ozone on a northern hemisphere and global basis to reduce climate response in the Arctic. Finally, emissions of ozone precursors and BC within the Arctic should be kept at a minimum as these will have a disproportionately large impact on within Arctic concentrations.

Lusen Mountain, Bavaria, Germany
Ozone and black carbon – targeting sources.

Reducing methane emissions as outlined above will decrease ozone production. Reductions in NOx also will contribute but, at the same time, will decrease OH which is the major sink for methane. Hence, an ozone reduction strategy using NOx controls that benefits climate will also include methane, NMVOCs, and/or carbon monoxide reductions. Carbon monoxide forms when carbon in fuel does not burn completely. The main source of carbon monoxide is gasoline powered vehicles.

Lusen Mountain, Bavaria, Germany
Purely for amusement I'm including the chemical calculations from this paper, "Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions", not because I understand them but because I think they are indicative of what an incredibly complex hellish soup we have created in the atmosphere, from which nobody really has a grasp on the synergistic impacts on the biosphere:
Tatra Forest, Slovakia
3. Atmospheric CH4 Oxidation

This section provides a brief description of the atmospheric chemistry leading to the formation of greenhouse gases from CH4 emissions.  CH4 oxidation leads to enhanced formation of ozone
in the troposphere and lower stratosphere through a sequence of reactions involving NOx compounds. The CH3 resulting from reaction (R1) is oxidized and the reaction products are photolyzed in the presence of sunlight:

M is an air molecule (usually N2), participating in a three‐body reaction, and “hn” represents the solar photon flux. Through this cycle ozone is efficiently formed in the presence of NOx, CO and CH4. The end product of the OH and HO2 formation from CH4 is water vapor. As two H2O molecules are formed from each CH4 molecule, water vapor enhancements due to additional CH4 releases can be
important in relative terms in the dry stratosphere. Reaction (R9) yields CO2, constituting another important product from CH4 oxidation. The result of the CH4 oxidation chain is thus the formation of the three greenhouse gases O3, H2O, and CO2, which comes in addition to the enhancement of CH4 concentrations due to direct emissions.
Wielka Sowa (Owl Mountain) Poland
Wasn't that fun?  Wait, there's more!  Next comes the monumental 2010 Final Report of the UNECE (United Nations Economic Commission for Europe) "Hemispheric Transport of Air Pollution".  In case you thought it wasn't.


Figure 1.4. Pathways of intercontinental pollution transport in the Northern Hemisphere.  Shading indicates the location of the total column of a passive anthropogenic CO tracer released over the Northern Hemisphere continents after 8-10 days of transport, and averaged over 15 years. Shown are transport pathways in summer (June, July, August; upper panel), and winter (December, January, February; lower panel). Gray arrows show transport in the lower troposphere (< 3 km) and black arrows show transport in the mid- and upper troposphere (> 3 km).

Figure 1.6. Source attribution of the ozone found at a rural location in southern England during 2006. Europe-regional refers to the ozone advected directly over the local- and regional-scales to the location. North America to that formed over that continent and over the North Atlantic and east Pacific; Asia to that formed over that continent and over the western Pacific; Europe-intercontinental to that advected around latitude circles and back into Europe; Extra-continental refers to that from interhemispheric transport.
New Mexico
p. 216 5.2. Impact of Long-range Transport on Ecosystems

The doubling of tropospheric ozone (O3) in the Northern Hemisphere since the Industrial
Revolution has had significant, negative impacts on crop production, forest productivity and has been shown to cause changes in the species composition of semi-natural systems. Rapid industrialization in the Northern Hemisphere has also resulted in increases in emissions of pollutants such as SO2, NOx and BC that enhance atmospheric PM and can impact ecosystems through acidification, eutrophication and perturbations to the quality of photosynthetically active radiation. Here we make a first attempt to investigate the implications of intercontinental long-range transport (ICT) of these pollutants for ecosystems. The focus of this section is on terrestrial ecosystems, however impacts on oceans are also briefly covered.

Buckeye Knob, Marion, North Carolina
5.2.1. Evidence for effects of ozone and PM on ecosystems

The regional distribution of experimental evidence for impacts on ecosystems is predominantly driven by the historical identification of impacts related to the regional occurrence of elevated pollutant concentrations and associated deposition. Hence, most evidence has been collected from North America and Europe over the past 30 years. The relatively recent advent of rapid industrialization and associated pollutant emissions in Asia has led to a disconnect between the level of experimental evidence available and the scale of the pollutant problem by world region.

Impacts on ecosystems caused by O3

The majority of the existing experimental evidence comes from bio-monitoring and Open Top
Chamber studies that have been conducted first in North America and later in Europe under the European Open Top Chamber and UNECE ICP Vegetation Programmes; these have mainly focussed on arable crops. Over the last decade similar studies are now increasingly being conducted in Asia. The Free Air Concentration Enrichment approach has recently been used as an experimental method to assess impacts on crops:  soybean in the US; rice in China: forest trees (Aspen, Maple and birch) in Wisconsin, US; mature beech stands in Bavaria, Germany: and grasslands (alpine semi-natural grassland in the Swiss Alps.  These methods have advantages of being closer to field conditions but are limited in their ability to define impacts at or below ambient pollutant concentrations and in defining dose-response relationships which are necessary for regional scale risk assessments.

Big Cypress Swamp, Florida
p. 217 In addition to experimental studies, epidemiologic methods have also been used, initially driven by a need to overcome difficulties in extrapolating experimental studies conducted on young forest tree species in Open Top Chambers to understand effects on mature trees growing under forest stand conditions. Such studies have consistently demonstrated that O3 can negatively influence a variety of forest responses from crown condition to radial growth. More recently, similar spatially relevant studies have been extended to crop loss assessments. These studies have found that the influence of O3 can be detected in regional level production statistics and field trial data although damage estimates have been found to differ from those obtained from risk assessments performed using empirically derived dose-response relationships. This may be due to these methods being most effective in those regions characterized by higher average O3 concentrations where the O3 signal is strong enough to overcome the influence of confounding variables affecting yield.

Rising background concentrations experienced over the last few decades can particularly enhance spring and autumn O3 levels, in effect lengthening the period of elevated O3 concentrations from the existing summer peak O3 exposures; the influence of these new seasonal profiles on ecosystems needs to be understood, this can only be achieved with new experimental investigations. To date, such new investigations have used diurnal fumigation patterns that emphasize chronic rather than peak O3 exposures and investigation of species with growth periods that extend into those times of the year when ICT is a more substantial fraction of the total pollution load i.e. the spring and autumn periods.
Torres del Paine, Chile
Range of response parameters

Key impacts for agriculture include visible injury to leafy crop species; declines in arable yields  and effects on crop quality (e.g. nitrogen content of grains, tubers etc. and nutritive quality of forage crops). Importantly, impacts have been found to vary substantially according to crop species and cultivars. Prevailing climatic and meteorological conditions and agricultural management practices (e.g. irrigation) will also affect response to O3.

Routt National Forest, Colorado - ironically from a skimobile site.
For forest trees, O3 has been shown to impact visible foliar injury, accelerate leaf senescence, reduce photosynthesis, alter carbon allocation, and reduce growth and productivity; again, these effects vary by forest tree species and genotype. O3 also appears to weaken tree resilience to a range of biotic (e.g. pest and pathogen attack) and abiotic (e.g. drought, frost hardiness) stresses. The extent to which results obtained from tree seedlings/saplings can be extrapolated to mature trees under real forest condition has been severely challenged and resulted in a study conducted at Kranzberg Forest, Germany on naturally growing and late-successional, adult forest trees. This study found reductions in annual whole-stem volume increments for beech which, when scaled to stand level, supported modelling predictions that claim elevated O3 to cause substantial reduction of C sink strength in trees.

Semi-natural grasslands are genetically highly diverse multi-species communities ranging from low to high productivity depending on site conditions and management. Component species differ strongly in their sensitivity to O3 and thus community response to O3 is likely to be species-driven. However, changes in productivity and species composition in established temperate calcareous or alpine grassland are difficult to detect against a background of considerable natural spatial and temporal variability.
Inner Mongolia
Subtle changes in Cassimilation and water economy in selected component species, as inferred from shifts in stable C and O isotopic signatures, reduced leaf longevity, and altered biomass partitioning suggest that in the longer run, productivity may decline and species dominance may change in response to ICT. This is in contrast to observations in Mediterranean therophytic grasslands, where short-term effects on reproductive traits of annuals have been observed. Experimental studies in the US and Europe have also highlighted O3 impacts on nutritive quality of forage crops.

FINDING: There is evidence that O3 can cause a variety of damage responses to crops, forests and grasslands. The strength of this evidence varies with receptor type and location, with more evidence on crops than forest trees, more on trees than grasslands, and equal evidence in North America and Europe, but less in Asia.

Eastern Norway
Experimental derivation of dose-response indices

The experimental campaigns conducted in North America and Europe were instrumental in providing experimental data describing yield and growth responses for a range of crop species (and a far more limited number of forest and grassland species) that could be used to define O3 metrics and dose-response relationships. It is important to note that in Europe, the selection of the AOT (accumulated ozone concentration over a threshold over a growing season) cut-off concentration of 40 ppb was actually driven by consideration of the level of background O3 concentrations; AOT30 was as statistically robust in terms of defining crop damage but was considered to have implications for control strategies outside of Europe and hence the 40 ppb cut-off concentration was retained.

Since the background O3 level can vary considerably across different regions, and most importantly with altitude, a single cut-off value may not be suitable for risk assessments in every geographical region with important implications for use of such threshold indices for assessment of ICT.

Pine Barrens, New Jersey
In the development of these indices it was recognised that high O3 concentrations tended to co-occur with environmental conditions that restrict uptake (e.g. hot, dry sunny conditions). In Europe this has led to the development of the O3 flux metric, PODy (Phytotoxic O3 dose above a stomatal flux threshold y; formerly known as the accumulated stomatal O3 flux, AFstY).
Pine Barrens, New Jersey
Re-analysis of existing Open Top Chamber experimental data for European wheat and potato and for a number of forest trees showed PODy to more accurately predict yield or biomass loss as compare to the AOT40 index. Although the flux metrics still have a threshold, which is assumed to act as a surrogate for the internal detoxification capacity of the plant, the ambient O3 concentrations that can contribute to accumulated flux will be substantially lower than the 40 ppb cut-off concentration used in the AOT40 index under optimum environmental conditions for plant gas exchange. Hence, the flux metric is likely to be better suited to assess the implications of rising background O3 concentrations. It should also be noted that the increasing levels of background O3 concentration translate into proportionally higher risk estimates, since both AOT40 and PODy involve a threshold value. This is due to a fundamental property of any similar threshold index and effectively means that with an increasing threshold these metrics become increasingly sensitive to the exceedance of the threshold value. The sensitivity also depends on the characteristics of the frequency distribution of the data. Owing to the relatively wider distribution of stomatal fluxes, the PODy index for crops has been shown to be less sensitive to such perturbations than the corresponding AOT index.
Walnut trees, David, California
p. 219 Mechanisms of adverse effects of O3 relevant for ICT

Phenology will play an important role in determining the importance of ICT damage to ecosystems. The timing and duration of growth periods will determine species exposure to ICT. For example, early or late season crops such as oil seed rape and maize may be more at risk, similarly forests and grasslands which have appreciably longer growth periods will be more likely to experience ICT. Within life-cycle and annual growing season variability in sensitivity may also be important. For example, age dependent changes in leaf morphology were related to changes in the defence capacity against oxidative stress, with concentrations of antioxidants increasing with tree age; therefore, early season ICT O3 exposures may occur when antioxidative defence capacities are still establishing. In more remote regions with early springtime peaks in O3, together with conditions favouring high stomatal conductance, the situation may be worse as the advancement of plant development may lead to more frequent co-occurrence of sensitive stages and early-season O3 stress.

Species distribution will also affect vulnerability to ICT. For example, many forests and grassland communities extend to high altitudes where the planetary boundary is more likely to be coupled to the lower layers of the free troposphere and hence more prone to ICT influence. Forests also host understory species, which often have ephemeral growth periods in the spring before closure of the forest canopy restricts growth.

Shingletown Gap, Pennsylvania
FINDING: Concentration-based indices to assess the importance of O3 damage, especially those which use thresholds (e.g. AOT40) may not be appropriate for assessment of damage resulting from ICT. O3 flux metrics (e.g. PODy) that incorporate the effects of differences in phenology and environmental conditions in estimates of O3 damage are more suitable for assessments of the potential impact of ICT.

p. 225 FINDING: There is considerable uncertainty as to how much of the damage to ecosystems
caused by O3 is attributable to hemispheric ICT. Provisional results from HTAP model-based risk assessments using AOT40 and Mx indices indicate that emissions from one continent have the potential to influence crop productivity on other continents by affecting O3 concentrations, with the largest influence of ICT found from North American emissions impacting on European crop yields. Based on the HTAP multi-model experiments, ICT may be responsible for about 5 to 35% of the estimated crop yield losses depending on the location, crop, and response function used, subject to large uncertainties.  Oh boy, I'll bet the European farmers love hearing that!

Casco Bay Island, Maine
p. 228 O3 crop yield response functions have been used with global chemistry transport models to estimate current and future relative yield losses due to O3. Although each of these modelling studies uses different O3 models and crop production and distribution data they all make use of the range of dose-response response functions described in Box 5.1, and hence provide a reasonably standardized indication of production and economic losses associated with O3 exposures. Currently, global yield losses are predicted to range between 3% and 5% for maize, 7% and 12% for wheat, 6% and 16% for soybean, and 3% and 4% for rice, which represents an annual economic loss of $14-$26 billion. Agricultural regions in North America, Europe and Asia are identified as particularly vulnerable to O3damage. About 40% of this damage was found to occur in parts of China and India. The substantial impacts found in the Asian region may be particularly relevant given the importance of agriculture within these country economies; e.g. losses were estimated to offset a significant portion (between 20 to 80%) of the increase in GDP in the year 2000 in such economies.

Figure 5.13. Average wheat crop production losses due to O3 estimated for the year 2000 using European and North American concentration based exposure-response relationships.
Importantly, these modelling studies have relied on North American or European dose response relationships to assess the yield losses caused by O3; a recent synthesis of data strongly suggests that key Asian crops and cultivars may well be more sensitive to O3 concentrations when growing under Asian conditions suggesting that the production and subsequent economic loss estimates for this region may be underestimated.
Sherwood Forest, Edwinstowe, England
Globally, there are a number of agricultural production areas that are vulnerable to increasing O3 pollution. The “Cornbelt” in the United States produces 40% of the world's corn and soybean crops, and this region is already potentially losing 10% of its soybean production to O3. In the U.S. as a whole, agronomic crop loss to O3 is estimated to range from 5 – 15%, with an approximate cost of $3-$5 billion annually. In Europe, similar studies have identified substantial economic losses due to O3 estimated losses for 23 crops in 47 countries in Europe of €4.4 to 9.3 billion/year, around a best estimate of €6.7 billion/year for year 2000 emissions. Despite the overwhelming evidence that current O3 concentrations are causing yield losses, new O3 tolerant crop cultivars are not being developed for a future higher-O3 world. Recent successes in identifying quality trait loci associated with O3 tolerance in rice indicate the breeding for O3 tolerance in food crops is possible, yet currently, there is little if any industrial effort in this direction.
p. 229 Forest health, grasslands and biodiversity

In contrast to agriculture, little work has been done to assess the impacts of ground level O3 on important global forest biomes. Work that has been conducted has been confined to studies in Europe and North America. A Scandinavian study estimated timber yield losses due to O3 at 2.2% in Sweden over the period 1993-2003. The resulting economic loss was estimated to be a 2.6% decline, which is equivalent to €56 million based on 2004 prices for timber and pulpwood. Additionally, Muller and Mendelsohn [2009] estimated annual timber yield losses equivalent to $80 million in the U.S.

South Sister, Smith Rock State Park, Oregon
Little is therefore known of the response to O3 by forest ecosystems that cover vast swathes of
the Northern Hemisphere, even though heavily forested areas coincide with regionally high O3
concentrations in east and southeast Asia, northern Asia, and boreal North America. Recent studies in
Scandinavia have identified certain aspects of O3 exposure of the more northerly, boreal forest
ecosystems that could particularly enhance vulnerability to ICT. These include the earlier onset of the
growing season as climate changes, the extensive periods of 24 hour daylight that allow more or less
continuous gas exchange leading to a large cumulative O3 dose, and lack of recovery from oxidative
stress during darkness. In terms of tropical forests, Fowler et al. [1999] estimated that O3 concentrations in excess of 60 ppb were experienced by an area of 3 million km in 1990 (almost 20% of total tropical forest cover) with the increase particularly great in southeast Asia.  In spite of this rapid increase in exposure, our knowledge of O3 impacts on forest ecosystems of tropical biomes is extremely limited.
I'll Say!
South Sister, Smith Rock State Park, Oregon
A similar situation exists for grasslands. Projections of O3 effects on semi-natural grasslands in different regions with widely varying climatic conditions are difficult because of the diversity of this ecosystem type, substantial intra-specific differences in O3 sensitivity among populations, and a lack of experimental data for most systems. In temperate latitudes, such as northwestern Europe, grasslands are dominated by perennial C3 species, whereas in warmer climates annual species form a greater component. These latter systems may be more sensitive to O3 due to their dependence on reproductive output, which was found to respond most sensitively to elevated O3.
Dying Melaleuca forest, Queensland, Australia
Highly diverse communities with an important conservation value in regions with a warmer climate may be more vulnerable than perennial grasslands in temperate and montane habitats. This may concern regions where C3 species predominate and where typically high O3 levels are observed, such as the Mediterranean basin in Europe or in coastal parts of southern California. Grasslands dominated by C4 grasses in warmer regions such as India, southeast Asia, southern China and in much of the Southern Hemisphere may be less sensitive to O3 as the C4 photosynthetic pathway (which is capable of providing a near constant and optimum supply of CO2 for photosynthesis with relatively low stomatal conductance) will confer some protection against O3. Similarly, therophytic grasslands in arid and semi-arid regions such as northern China may be less affected with only a few percent simulated reductions in net primary production due to O3 alone.
Dead and dying birch, shore of Lake Superior, Minnesota
 FINDING: There is evidence of impacts of O3 on vulnerable and important agricultural, forest and grassland ecosystems across the Northern Hemisphere; over such ecosystems the enhancement of locally derived O3 concentrations by ICT may be particularly important.

p. 230 5.2.4. Interactions with climate change

Effect of atmospheric composition on plant physiology

Vegetation plays an important role in determining surface O3 levels, via dry deposition of O3 to the interior of leaves through stomata. As atmospheric CO2 levels rise, the stomata will not need to open as widely to allow sufficient CO2 to enter for photosynthesis. This may reduce O3 uptake, decreasing the sensitivity of the plants to O3. Such reductions in stomatal conductance of plants would result in both lower uptake rates and increased O3 concentrations in the boundary layer.

Dead and dying birch, shore of Lake Superior, Minnesota
Sanderson et al. [2007] found that surface O3 levels over parts of Europe, Asia and the Americas were 4-8 ppb larger under doubled CO2 conditions during April, May and June (the approximate growing season for crops in northern Europe). Similarly, Klingberg et al.[2011] found that despite substantially increased modelled future O3 concentrations in central and southern Europe, the flux-based risk for O3 damage to vegetation is predicted to remain unchanged or decrease at most sites, mainly as a result of projected reductions in stomatal conductance under rising CO2 concentrations although soil moisture determining stomatal O3 flux. However, the relationship between stomatal conductance and CO2 concentration may prove to be more complex and depend on O3-CO2 interactions. In addition, recent research has found that effective regulation of stomatal conductance under drought conditions was disrupted by increasing background O3 concentration.
You often see this nonsense about ozone flux being reduced thanks to higher levels of CO2 causing stomatal closure.  It just seems like a ridiculous Hail Mary pass to me.

Figure 5.14. Global assessment of the key biodiversity areas at high risk from O3 impacts; the figure shows the projected percent decrease in gross primary productivity due to O3 within the Global 200 priority conservation areas.
Hemlocks, DuPont State Forest, North Carolina
Impact of future atmospheric conditions on ecosystems

Models simulate that global mean precipitation increases with global warming. However, there are substantial spatial and seasonal variations. Increases in the amount of precipitation are very likely in high latitudes, while decreases are likely in most subtropical land region, continuing observed patterns in recent trends in observations. Precipitation is projected to decrease in many areas already suffering from water shortages [e.g., the Mediterranean and parts of Africa], which together with rising temperatures, will increase stress among plants. Reduced stomatal conductance that may occur in response to elevated CO2 may enhance water use efficiency of plants, which may help to partly alleviate the effects of reduced rainfall. The projected increase in temperatures in many parts of the world mean that yields from
crops may also be reduced. Increased water stress in a warmer climate may be expected to decrease sensitivity to O3 via reduced uptake; however O3 induced damage to stomatal functioning might confound this effect. The exact impacts of pollutants on vegetation in the future will be complicated by the differential response of plants to climate change and rising CO2 levels, whereby the latter will increase growth and might offset some of the projected yield losses from crops by the former.
A mechanistic model of plant-O3 interactions was implemented into the Hadley Centre land surface model and run with O3 scenarios from the STOCHEM chemistry transport model driven with SRES A2 emission scenario. Results suggest a large negative impact of near-surface O3 on plant productivity. These model results have been used to identify eco-regions where a significant effect on global primary productivity might be expected to occur. The results in Figure 5.14 are based on the "low sensitivity" simulation which is overlain with the G200 regions and used to assess threats of O3 deposition to biodiversity. This identifies eco-regions of south and east Asia, central Africa and Latin America as being at risk from elevated O3 levels during this century, in addition to areas of North America and Europe where the effects of O3 are better documented. However, there is almost no information available on whether the plant communities in these other regions of the world are as sensitive to O3 as those that have been used to define critical levels, and hence the real significance of these areas of potential risk to biodiversity is completely unknown.
Institute of Community Forest Governance, India 
Wood's Hole has just released a map of biomass, to provide a baseline 2000.  When will we see a comparison to the current situation?  I don't know, although I wrote them to ask...but they didn't tell me.

With all the above warning of reduced crop productivity and quality due to air pollution, I have to say, I got a bit annoyed when I received this ludicrous, delusional email from Lester Brown's Earth Policy Institute:

Bumper 2011 Grain Harvest Fails to Rebuild Global Stocks 
Janet Larsen


Earth Policy Release
Eco-Economy Indicator: Grain
January 11, 2012
The world’s farmers produced more grain in 2011 than ever before. Estimates from the U.S. Department of Agriculture show the global grain harvest coming in at 2,295 million tons, up 53 million tons from the previous record in 2009. Consumption grew by 90 million tons over the same period to 2,280 million tons. Yet with global grain production actually falling short of consumption in 7 of the past 12 years, stocks remain worryingly low, leaving the world vulnerable to food price shocks.
Hemlocks, Nantahala Mountains, North Carolina
Nearly half the calories consumed around the world come directly from grain, with grain-fed animal products making up part of the remainder. Three grains dominate the world harvest: wheat and rice, which are primarily eaten directly as food, and corn, which is largely used as a feedgrain for livestock. Wheat was the largest of the world’s grain harvests until the mid-1990s. Then corn production surged ahead in response to growing demand for grain-fed animal products and, more recently, for fuel ethanol. Despite a drop in the important U.S. harvest due mostly to high summer temperatures, global corn production hit 868 million tons in 2011, an all-time high. The harvests of wheat (689 million tons) and rice (461 million tons) were also records.  (See data at www.earth-policy.org.)
World Corn, Wheat, and Rice Production, 1960-2011
I wrote back to ask:

How can you possibly write anything about crop yield decline without mentioning:

1.  overpopulation and the need for birth control
2.  climate change causing extreme weather, and the need to drastically curtail fuel emissions and
3.  the damage done to crop yield and quality by tropospheric ozone, also a result of fuel emissions.

Here's a video about trees dying in Oregon...and a quote from Martin Luther King, which was reprinted at Our Finite World:

The tide in the affairs of men does not remain at the flood; it ebbs. We may cry out desperately for time to pause in her passage, but time is deaf to every plea and rushes on. Over the bleached bones and jumbled residue of numerous civilizations are written the pathetic words: “Too Late.”
Dr. Martin Luther King, Jr.
Riverside Church
New York City
April 4, 1967


Occupy Congress...and Chris Hedges Sues Obama!

It is a good day when Chris Hedges explains why he is suing Obama for signing the National Defense Authorization Act - and the Occupiers have some fun when they arrest Senator Carl Levin.  Thanks guys, for trying to save me from the FEMA camp...it's not my idea of a vacation!


Occupy Freedom - Martin Luther King speaks against Economic Injustice

Dr. King was such an inspirational leader that he posed a real threat to the 1%.


All But Obliterated

It's been hideous outside - grey and brown, dark and cold.  It is so ugly, it makes it harder to quell the fear of a morbid world, where tornados appear without warning in places they shouldn't, and reports pile on of species going extinct, whooping cranes, ducks and butterflies.  The sun broke through for about 45 seconds yesterday afternoon, so I ran out to take some quick pictures of the lichen forest, silently expiring behind Wit's End.  For the most part though, I've huddled inside, poring over hundreds of pages from Forest Service reports...which we'll get to eventually.  This Boston Globe article - about the impossible task to locate trees suited to survive in urban areas - contains a number of misconceptions:
“'Your basic street tree has about a 35-year . . . life expectancy in today’s urban forest,' said Peter Wild, owner of Boston Tree Preservation in Woburn. 'That might mean that some of them might live to be 70. Some of them might live to be 15.'"
"One tree that many towns and cities hoped would be hardy, the Bradford pear, has proven disappointing, Wild said. Although the trees grow densely, ideal for urban and suburban streets, the angles of their branches, and their tendency to keep their leaves into late fall, make them susceptible to damage during winter storms, he said."
"'That’s an example of a tree that was heavily overplanted two decades ago and even recently,’’ Wild said, “and it hasn’t proven to be the tree that we thought it was.'’’
"Not the tree that we thought it was"?  Perhaps the tree isn't growing in the air they thought it was!  Fifteen to seventy years is infancy for most trees.  Pears aren't just "susceptible to damage from winter storms".  That might cause heavily-laden branches to snap, but it can't account for their bark cracking and splitting, which is pretty much a universal symptom of devastating physiological damage from absorbing poisonous chemicals and gases.  Trees are dying early, because the atmosphere and rain are acid.  But it is nigh impossible to get those who are best situated to know to admit that.
Luckily for readers at Wit's End, I have no other new pictures of trees dying from air pollution, with depressing broken branches, peeling bark, cankers and weeping holes.  Instead today I'm going to post colorful photos from a wonderful gallery, of birds.  My favorite is the flamingo image above, because there is a tanker lurking ominously in the background.  The rest are just pretty.
Before we get to those voluminous Forest Service reports though, here's a link to a wonderful website called Environmental History Resources, which is maintained by a professor who, I think, is Dutch.  Among other essays, he wrote one called "The Role of Wood in World History".  It surprised me to learn, although it shouldn't have, that civilizations have over and again relied upon and then ruthlessly depleted their supply of forests, being then forced to forage elsewhere, conquering other societies to import their supplies...or collapsed.  I have always regarded forests as essential for all they provide - fruit and nuts, wildlife habitat, and most of all for their primeval beauty.  But in this broader perspective, their foundational role as a prerequisite for civilization to grow and prosper is made apparent:
"The destruction of the world's forests is a major concern in our age. According to the UN about 40 percent of Central America's forests were destroyed between 1950 and 1980 and during the same period Africa lost about 23 percent of its forests. A whole range of environmental problems is associated with deforestation, among them severe flooding, accelerated loss of soil, encroaching deserts and declining soil productivity1. Sometimes we get the impression that these problems are unique to our time, but vast areas of surface of the earth were stripped of their tree cover well before the modern period."
"Today it is hard to believe that in antiquity vast forests were growing in the Middle East. However, during the early part of the third millennium BCE, the mountain slopes of this region were covered with massive cedar forests. These forests disappeared in the millennia before Christ's birth about two thousand years ago. The destruction of the cedar forests of the Middle East is told in the oldest known, surviving written story in the world: The epic of Gilgamesh. The epic was written in Mesopotamia sometime during in the 3rd millennium BCE. The second episode of the epic is known as 'The Forest Journey' and is the story of deforestation in the Middle East2...."
"Now that we have explored the importance of wood and forests of antiquity, we make a big jump forward in time to examine the importance of wood in the rise of the West. Without the abundant availability of wood, Europe would never have been able to undertake the exploration of the world’s oceans that led to the great geographic discoveries. This development had become very difficult in the Middle East, where the ancient forests were had largely disappeared during antiquity."
I won't post the entire thing - but the site is worth a visit if you want to follow through the Greeks and Romans, to the era of coal in England, and also he has some more references to scholarly works on the topic.  It's amazing at how many forests humans have demolished, although of course in the past they did it the old-fashioned way, by chopping them down.  We moderns are chocking them from the excrement of our insatiable desire for energy.

In yet another under-appreciated aspect of forests are the findings of two Russian scientists, who connect the lack of evapotranspiration when deforestation occurs to a consequent lack of rainfall, impacting even distant places:
"Two Russian scientists, Victor Gorshkov and Anastassia Makarieva of the St. Petersburg Nuclear Physics, have published a revolutionary theory that turns modern meteorology on its head, positing that forests—and their capacity for condensation—are actually the main driver of winds rather than temperature. While this model has widespread implications for numerous sciences, none of them are larger than the importance of conserving forests, which are shown to be crucial to 'pumping' precipitation from one place to another. The theory explains, among other mysteries, why deforestation around coastal regions tends to lead to drying in the interior."
"Although the theory has garnered a wide contrast of reactions—from dismissal to accolades—it has so far been mostly ignored by the greater scientific community since first published in a small journal in 2007. A new paper in Bioscience by Douglas Sheil and Daniel Murdiyarso attempts to remedy this by introducing (or re-introducing) the theory to scientists of all fields, many of whom have probably never heard of the theory despite its radical and widespread implications."
"...it has so far been mostly ignored by the greater scientific community..."  Sound familiar?  There are gargantuan forces at play transforming the ecosphere right in front of our eyes, and meanwhile, the greater scientific community, immersed in their meticulous research, is either preoccupied, or sanctimoniously in denial.

A perfect example are the three aforementioned US government publications.  First up, the National Report on Sustainable Forests 2010.  They are excerpted out of order, because the 2010 Report is based on the other two earlier drafts, but bear with me - we will discern some disturbing trends.  Everything that follows will be direct quotes, that I won't muddle up by including the extensive references to original research (which can of course be found by clicking the link) or adding quotation marks.  Instead any comments of mine will be highlighted.  Tommy Tidwell, the head of the USDA (which is the umbrella organization for the Forest Service), states in the introduction:

One of the report’s key findings is the fact that the United States is richly endowed with forests, 751 million acres to be exact. That area has remained remarkably stable over the last 50 years, and the amount of wood in these forests is increasing.  Ha, does he mean the amount of living trees is increasing?  Or the amount of dead wood is increasing?  This may seem silly, but don't laugh.  Further on, they have declared standing dead trees to be "assets" because 1) they provide habitat and 2) they store carbon.  That's right, even as they actually are releasing carbon while they decay, as long as any part is intact carbon is sequestered...so let us not quibble when there is a potential for international carbon offsets to be had.  That's our clever Forest Service at work, never one to waste our tax dollars!
At the same time, however, forests in the United States face a number of threats, ranging from fragmentation and loss of forest integrity due to development to an alarming increase in the area and severity of forest disturbances. The report finds, for example, that the incidence of insect-induced tree mortality has increased three-fold in the last decade. In the coming years, climate change could substantially increase the damages and uncertainties associated with these threats. Not coincidentally, forests have a major role to play in helping to mitigate climate change, a fact that is well documented in the report.  Even he used that word "alarming".  That insect-induced tree mortality has "increased three-fold" is very important, especially considering (as should be kept in mind throughout) that this is all based on old data, and the trends are continuing and accelerating...Yet nowhere in this report is it mentioned that from controlled fumigation experiments it has repeatedly been demonstrated that plants and trees exposed to ozone are more likely to be attacked by insects, disease, and fungus cited as threats.  Nowhere is there evident the plain speaking to be found in this textbook about European forests, which describes some stands as being "all but obliterated" by air pollution.

Second, this report is the United States’ contribution to the set of reports produced by the 12 countries that are members of the Montréal Process Working Group (MPWG) on the Conservation and Sustainable Management of Temperate and Boreal Forests. The MPWG is a voluntary, nonlegally binding group of countries that have agreed to use a common set of criteria and indicators for tracking each country’s progress toward their shared vision of sustainable forests. Visit http://mpci.org for 
more information about the MPWG.
Right.  No need to rush over to that link.  Their latest news?  Circa 2009.  They did have a meeting in Canada last October...but Annex E and F (Summary, and Joint Draft Statement) are still "under preparation".  This is consistent with a disturbing lack of up-to-date information.
Third, this report is just one component of the reporting process that the United States is using to report on forest conditions and trends and the progress being made toward sustainability. Supporting this document are a number of more detailed subsidiary reports on the individual indicators that provide a great deal of additional information in more detail than could be included here. These supporting technical documents are available at http://www.fs.fed.us/research/sustainability.
Right.  Don't rush over there either, because all it says is:  Page Not Found.
This report identifies seven major driving forces affecting forest sustainability:

1. Climate change. 
2. Globalization.
3. Biomass energy demand.
4. Urbanization and related shifts in land use patterns.
5. Forest fragmentation and parcelization. 
6. Loss of working forests.
7. Altered disturbance patterns.
Note:  not even a glancing reference to acid rain, the Nitrogen Cascade, or ozone!
Population growth is a major determinant in total consumption. Choices about desired standard of living and lifestyle—both of which are dependent on disposable income—determine per-capita consumption. When both of these factors are combined—increased consumption per-capita and increased overall 
population growth—stresses on sustainability can be magnified. Policymakers concerned with sustainability should track trends in per-capita consumption and use available population projections to evaluate future prospects for sustainability. The MP C&I have indicators of per-capita consumption, but leave population projections to others.  With one paragraph they dispense with arguably the greatest threat to forests of all.  No surprise there.
p. I-13 Despite notable reversals in the population declines of some forest animals (wolves in the intermountain West, for example), important components of the overall diversity of forest flora and 
fauna remain threatened. Seventy-seven forest-associated plants and animals that were present in our forests when our Nation was founded are now presumed to be extinct. An additional 4,005 
species, or 27 percent of the total number of forest-associated species, are at risk of extinction.  Horrible numbers...but if all the trees die from ozone, closer to 100 percent are at risk of extinction.
The data presented for the two indicators comprising Criterion 3 clearly show that the Nation’s forests are subject to increasing levels of disturbance, such as insect infestation and fire. These disturbances result from processes we often cannot control and may not always fully understand. In particular, the incidence of insect-induced tree mortality has increased three-fold in the past decade. This fact is backed by substantial anecdotal experience and is undoubtedly the clearest red flag emerging from this report.
Do you suppose that's why they leave out air pollution - because insects and fire are disturbances we cannot control.  We CAN control air pollution of course.  But we don't want to.
p. I-16 In this regard, the increases in insect infestations, drought, and fire registered in Indicators 3.15 and 3.16 may be the partial result of climate change, but we cannot say so with any degree of certainty.

p. I-17 Moreover, forests in close proximity to heavy emission areas, such as in and around cities, can help alleviate air pollution and reduce temperature variation by providing shade in the summer and shelter from wind in the winter.  WHERE is the essential question - what happens to the forests when they "alleviate" air pollution; i.e. absorb it??  We know what happens when humans absorb it - they get cancer, emphysema, allergies, respiratory illness, heart disease, Alzheimer's, ADHD, autism, and diabetes.
p. I-25 North Carolina Report Card:  Several issues threaten western North Carolina’s forest ecosystems. These include, but are not limited to, loss of native species and natural communities; spread of invasive 
species; insect and disease infestations; air pollution; landslides: and the loss of contiguous forest land.
Wow, North Carolina recognized air pollution as a threat to forest ecosystems.  Where is it in the synthesis?  The report doesn't even list ozone in their glossary, or nitrogen.  Following is their one acknowledgment in the glossary:
air pollutants - Gases, particles, or aerosols generated from management or combustion activities (industry, transportation, agriculture, management, etc.) that are released into the atmosphere, 
transported, and deposited in human and natural ecosystems. Air pollutants may be absorbed by forest ecosystems without effects (sink) or exceed the absorption capacity and have a deleterious effect on processes or components.  They manage to avoid any elaboration on exactly what those "deleterious effects on processes or components" might be.  Purely Orwellian.
Following are excerpts from the Draft Forest Health Monitoring 2009 National Technical Report upon which the National Report was based.  The FS has been monitoring forest health, by extensive and sophisticated means, utilizing ground inventories, aerial surveys and satellite imaging.  This they do because there is a very large timber industry with vast amounts of money at stake.  Think Georgia-Pacific, acquired by Koch Brothers in 2005 - a company which has paid tens of millions in fines for illegally polluting.  Just a minor cost of doing business in the USA.

This chart measuring mortality only goes through 2008, which was the year I first noticed that every single tree had symptoms of decline.  So had they included more recent data from the last three years, when symptoms have multiplied in number and severity, that mortality would have to be incredibly worse.  Even so, this 2009 draft report has fairly extensive discussions about mortality and the link to pollution -  a connection which was almost completely dropped from the next draft in 2010, as shall be seen - and the 2010 National Report from the USDA, which was quoted above.  WHY??????
p.32  58m. acres predicted loss of 25% standing volume over the next 15 years
on mortality, p. 41:  While the percentage of affected forest land in the United States may appear relatively low, the rate at which acreage is being impacted is alarming. As predicted by risk modeling, and confirmed by site-specific observations, actual impacts at local or regional levels are often extreme.  
Overall, the indicator shows a continuing trend in forest decline. Arguably, and considering the potential for certain outbreak events to be cyclical in nature (such as mountain pine beetle in pure, unmanaged lodgepole pine stands), many affected areas will likely regenerate; however, the resulting single-species/single-age-class regeneration will not provide a sustainable forest.
Right, "will not provide a sustainable forest", because, all of the co-dependent interrelationships of various species that contribute to the complex web of life will have been irreversibly disrupted.  This is evolution 101 and government agencies who skirt this fundamental aspect of genetic adaptation are doing so deliberately.  You won't see this come up again in the USDA final summation!
Spikes in mortality during the reporting period are largely due to a combination of high stand density in unmanaged forests and drought. Cumulative impacts are occurring within previously surveyed areas and expanding into new areas. The total area with mortality and defoliation has quadrupled over recent years for select indicators (table 3.2). Regardless of whether the cause of impacts is overstocking, climate, invasive pests or a combination of all three, intervention may be necessary to restore ecosystem to health, vigor and productivity.
Intervention?  That is delusional, but still, contrast the above assessment - total area with mortality and defoliation has quadrupled - with all the happy talk in the introduction of the National Report about our "remarkably stable" 751 million acres of forest.  Below is a case study of Hawaii.  I'm including it because it's remarkable to see how comprehensive is the tragic end of paradise, where even the Forest Service uses a word like "decimating".

Hawaii is also negatively affected by invasive pathogen, plant and insect pests. Impacts of invasive species, including animals, have been profound in Hawaii and are at the root of Hawaii's biodiversity crisis (fig. 3.13). Guava rust is currently defoliating non-native forests at low elevation; there is a potential threat to native ohia, which dominates 80 percent of Hawaii’s native forests. The erythrina gall wasp threatens widespread mortality of native wili trees, a component of much of Hawaii's remaining dry forests, and has almost eliminated the introduced coral tree.
Non-native invasive plant species impacting ecosystems in Hawaii include strawberry guava, velvet tree, peacock plume, and hundreds of other plants; there are nearly as many naturalized alien plant species as native species. Hawaii is particularly vulnerable to invasive species because its native species evolved in the absence of ungulates, rodents and predators, which have since been introduced. Non-native mosquitoes carry avian malaria, decimating native birds. Invasive grasses provide fuel for fire.
p. 68:  The approach to mortality presented here seeks to detect mortality patterns that might reflect subtle changes to fundamental ecosystem processes (due to such large-scale factors as air pollution, global climate change, or fire-regime change) that transcend individual tree species-pest/pathogen interactions.  As far as I can tell, since this was written, the Forest Service has ceased to have interest in "detecting mortality patterns that reflect fundamental ecosystem processes due to such large-scale factors as air pollution"!
However, sometimes the proximate cause of mortality may be discernable. In such cases, the cause of mortality is  reported, both because it is of interest in and of itself to many readers and because understanding such proximate causes of mortality might provide insight into whether the mortality is within the range of natural variation or reflects more fundamental changes to ecological processes.
At this point a mortality baseline is still being established for most of the U.S. To discern trends in mortality rates, at least three cycles of FIA data are required. With the up to two cycles of data currently available, it is only possible to do a spatial comparison of ecoregions and identify regions of higher than average mortality (relative to growth) for further study.
p. 102, Chapter 8

Criterion 3, Indicator 16 of the Montreal Process Criteria and Indicators for the Conservation and Sustainable Management of Temperate and Boreal Forests was designed to assess the impact of abiotic agents upon forests (Montréal Process Working Group 2007). Various abiotic agents, both natural and human-induced, can change forest structure and species composition. Where such change goes beyond some critical threshold, forest ecosystem health and vitality may be significantly altered and its ability to recover from disturbance reduced or lost, often meaning a reduction or loss of benefits associated with that forest ecosystem. Monitoring the area and percent of forests affected by abiotic agents beyond reference conditions may provide information needed in the formulation of management strategies to mitigate risk. The summary of this analysis is reported in the National Report on Sustainable Forests 2010 Report (Robertson and others 2010) while the purpose of this document is to provide the detailed evidence to support the reported data.  "The summary of this analysis is reported in the National Report on Sustainable Forests 2010 Report"...oh, really??
Objectives and Methods

The original National Report on Sustainable Forests 2003 (Guldin and others 2004) and the Montréal Process Working Group (2007) identified several abiotic agents: fire, storm, land clearance, permanent flooding, salinization, specific air pollutants (e.g. sulfates, nitrate, ozone), ultraviolet B, and soil nutrient cycling. These were addressed in three separate indicators. In the National Report on Sustainable Forests 2010, these were re-organized and addressed as one indicator (Criterion 3, Indicator 16) and were grouped into five sub-indicators that have the greatest impact on forest health. These abiotic sub-indicators are: fire, weather-related damage, pollution, land use, and climate.  Specific air pollutants - nitrate, ozone...where is that again in the National Report??  here it comes, watch for the sleight of hand on p. II-45:

What has changed since 2003?
The data––The indicators in this criterion have benefited from data improvements resulting from ongoing survey efforts undertaken by the Forest Service’s Forest Health Protection program.

The indicator––The following table summarizes the revisions. Indicator reference numbers for 2003 and 2010 are provided to assist in comparisons with the previous report. A more detailed rationale for the revisions may be found at http://www.rinya.maff.go.jp/mpci/meetings/18_e.htm.

Note:  Below is a portion of where that link with the "more detailed rationale for revisions" leads - it's all in Japanese with the exception of the copyright line, and when you try to translate, it responds with an error message:

Copyright:2007 Ministry of Agriculture, Forestry and Fisheries
〒100-8952 東京都千代田区霞が関1-2-1 電話:03-3502-8111(代表)
Next is the chart, from the National Report, showing the revisions.  2003 Reference 16 indicator "area and percent of forest land subjected to levels of specific air pollutants..." has been "merged"  purged to be "area and percent of forest affected by abiotic agents (eg fire, storm, land clearance).  It's the incredibly disappearing pollution!!

Following is the only other sections that reference pollution I could find in the National Report, which is buried by the volume of references to fire, weather, insects and disease - and then dismissed:

What does the indicator show?
Of the abiotic agents that affect forested ecosystems, five were selected that have a dominant impact—fire, weather, pollution, land development, and climate change. Given the breadth of disturbance agents, it was not possible to treat any one of them in detail. Extended details are available in the supporting data report.

Pollution effects on forests are indicated by Critical Acid Loading (CAL), which incorporates SO4 and NO3 and their relationship with soil properties. From 1994 to 2000, 74 million acres, or 17 percent of U.S. forest soils exceeded their CAL by more than 98.4 equivalents per acre per year. These areas are predominately located in the Northeastern United States. Surface ozone (O3) is also an important air pollutant that affects vegetation.  No evidence exists linking Forest Health Monitoring ozone bioindicator response data to a specific tree health problem or regional decline. Nevertheless, mapped data demonstrate that concentrations of plant damaging ozone air pollution are widespread in parts of the United States.

That's it, folks!  Is that any way to report on the Nitrogen Cascade, which leads to eutrophication??
The 2009 Draft has more about pollution that was subsequently forgotten in 2010:


The Forest Health Monitoring ozone (O3) biomonitoring program uses ozone-sensitive plants to monitor air quality and the potential impacts of tropospheric O3 (smog) on forestlands. These data include both tabular regional synopses and a raster surface model using the biomonitoring site point data. The surface ozone-injured indicator plants regional summary and graph were obtained from Smith (2008).

A Critical Acid Loading (CAL) surface raster model obtained from McNulty (2007) and the forest mask were applied to create a CAL grid layer for forested areas. The data were summarized and graphed.

p. 105  Pollution

Surface ozone (O3) is an important air pollutant that affects vegetation (US EPA 1996). Ozone is routinely monitored throughout the world and data are mostly recorded as hourly or half-hourly averages. Over the last 30 years, hourly averaged data have been summarized in different ways for the purpose of assessing vegetation effects.

The development of exposure indices to characterize plant exposure and to quantify the relationship between O3 exposure and ensuing plant response has been, and continues to be, a challenge. The USDA Forest Health Monitoring program utilizes ozone-sensitive plants (bio-indicators) to assess O3 impact upon forest ecosystems. There is not yet any evidence linking Forest Health Monitoring ozone bioindicator response data to a specific tree health problems or regional declines. Nevertheless, the mapped data demonstrate that plant damaging concentrations of ozone air pollution are widespread in parts of the nation.
There is "not yet any evidence linking...ozone...to a specific tree health problems or regional declines??  They have got to be kidding.  How about all the trees that are dying from no other apparent cause?
Continued monitoring and analysis will be important when determining probable or significant ozone damage. Ozone damage is far greater in the northeastern states however the 5-year trend indicates a decline in damage, while the west coast states have experienced an increase in ozone damage (fig. 8.4).

Just TRY to get more recent biomonitoring data - this chart stops at 2006!  When I called the northeastern station this year, I was told they had stopped collecting due to "anticipated budget constraints" and when I asked what they were doing with their time (they are still being paid!) I was laughingly told they are pushing a lot of paper around their desks.
p. 109:  Concern regarding the impacts of continued nitrogen and sulfur deposition on ecosystem health has prompted the development of critical acid load (CAL) assessments for forest soils. A critical acid load is a quantitative estimate of exposure to one or more pollutants at or above which harmful acidification-related effects on sensitive elements of the environment occur. A pollutant load in excess of a critical acid load is termed exceedance. Simple mass balance equations (SMBEs) were used to estimate forest soil critical acid loads for the conterminous United States. This spatial data was acquired and masked by the forest mask and summarized. From 1994-2000, 74.2 million acres or 17 percent of the soils on forest land exceeded their CAL threshold by more than 101 equivalents per acre per year. These areas include much of New England and West Virginia with very few areas of exceedance predicted in the western United States.
I believe the emphasis on soils is a distraction.  Certainly acid rain depletes soils of nutrients and that has killed many trees, BUT, plants and trees being grown in pots with enriched soils (and being watered) have no more or less symptoms of ozone injury than plants or trees growing in the ground.  The only thing they share in common is the atmosphere.
When Charles Little wrote "The Dying of the Trees" (for which he was widely ridiculed ostracized) one of his important examples was the disappearance of dogwoods on the Eastern Seaboard.  Dogwoods once made up a significant portion of the understory of the woods.  Thirty years ago, when I hunted for morels in spring, the dazzling white dogwood bracts made what looked like a gorgeous blizzard of snow, suspended in the greening woods.  It was breathtakingly charming, the kind of sight that fills you with happiness and sheer delight just to be alive.  Let's see what the Forest Service has to say about the condition of dogwoods now: 

p. 144:  Results – Approximately 80 percent of dead trees had confirmed D. destructiva infections. As of 2006, 245 of the 294 (85 percent) flowering dogwoods in the permanent plots had died. Of the dead trees 67 percent (196 trees) died after being confirmed as positive for infection. However, of the 43 trees still alive as of 2006, 79 percent had also been confirmed as positively infected by anthracnose. Since 2000, mean crown rating for living trees has remained relatively constant. Prior to 2000 mean crown rating had declined steadily from a high of 5.0 in 1989 to a low of 2.3 in 2002. As of 2000, no trees were rated “healthy,” or a crown rating equal to five. Of surviving trees, those infected during the secondary peak infection year of 1999 were in the poorest health.

Notice, NONE of the trees were rated as healthy, even though not all of them had anthracnose.  Above graph, live dogwoods per acre in 1983-1985, below, 2000-2004.
Lately there have been a bevy of studies claiming that long-term climate change drought is causing trees to die off, now that foresters are reluctantly coming to the realization that in fact, trees ARE dying off.  It's coming up on 3.5 years since Mother Nature smacked me upside the head and shrieked with unmistakable ferocity that all the trees are dying.  I didn't know then about the terminology of PWP (Permanent Wilt Point) but as a devoted gardener I recognized that the extent to which leaves of deciduous trees in August were hanging straight down meant that they would never really recover, ever.  They will limp along until all of their stored energy is used up, or a biotic agent moves in for the kill.
"The concept was introduced in the early 1910s. Lyman Briggs and Homer LeRoy Shantz (1912) proposed the wilting coefficient, which is defined as the percentage water content of a soil when the plants growing in that soil are first reduced to a wilted condition from which they cannot recover in approximately saturated atmosphere without the addition of water to the soil."
Initially I also attributed the leaf wilt, and then the coniferous needle drops to long term drought from climate change - what else could have such universal ramifications?  That was before I realized that just because ozone is invisible, it doesn't mean the air is clean.  Not at all.  And look at the Forest Service maps.  There can certainly be made a case that areas of the US have suffered more than mild soil moisture deficit - but not the Eastern Seaboard.  In fact, that is more closely aligned to climate change predictions - dry areas will get drier, and wet areas will get wetter.  This map is moisture deficit 98-02.
Actually, since 2003, according to the map below, much of the Eastern Seaboard has had a surplus of moisture.  So why would young trees that have been planted in the last five to eight years exhibit the same symptoms of stress - singed foliage, yellowing needles, thinning crowns, oozing bark, excessive lichen cover, etc - as older trees?  Why are some of the worst impacts attributed to climate change occurring, for instance, among maple trees in New England and Canada?

The Draft 2010 has already abandoned any specific mention of ozone.

p. vii Executive Summary:

Mortality is a natural process in all forested ecosystems, but high levels of mortality at large scales may indicate that the health of forests is declining...An analysis of FIA plots from 27 states found that the highest ratios of annual mortality to gross growth occurred in ecoregion sections of the Plains States. Mortality was also high in parts of southeastern Texas and New York. Even in areas of relatively high mortality relative to growth, no mortality occurred on most sample plots. However, on the plots with mortality, larger-diameter trees exhibited higher mortality trends as compared to remaining smaller-diameter classes of surviving trees, suggesting the mortality is related to either senescence of older stands or some insect or disease issue.
Or else it's suggesting mortality of older trees is because they have been exposed to toxic pollution longer!  Senescence is just a lie, most trees can live for centuries.  This article lists 10 famous ancient trees, the oldest of which is 4,800 years old, located in Nevada!  And again, rigorous scientific studies show that trees stressed by pollution are more likely to be attacked by and succumb to insects and disease.

Results indicate that there are more than 10 billion standing dead trees in forests across the United States, most of them less than 30 cm in diameter. Forests in the Rocky Mountains and Pacific Northwest have some of the largest mean biomass of standing dead trees per unit of forest land, while Plains states had the least. More than 130 species have greater than 1 million Mg of standing dead biomass nationwide. Given the emerging role of standing dead trees in biomass/bioenergy economies and carbon cycling, continued monitoring of this resource is highly warranted.
The first paragraph of the introduction, with its "long list of threats" doesn't mention pollution either:

Forests cover a vast area of the United States, 303.1 million hectares (749 million acres) or approximately one-third of the nation’s land area (Smith and others 2004). These forests possess substantial ecological and socioeconomic importance. Both their ecological integrity and their continued capacity to provide goods and services are of concern in the face of a long list of threats, including insect and disease infestation, fragmentation, catastrophic fire, invasive species, and the effects of climate change.

Chapter 4, tree mortality:

The mission of FHM is to monitor, assess, and report on the status, changes, and long-term trends in forest ecosystem health in the U.S. (U.S. Dept. of Agriculture, Forest Health Monitoring 1994). Thus, the aim of this mortality analysis contrasts with how mortality might be approached in other reports, such as FIA State reports or State Forest Health Highlights. The approach to mortality presented here seeks to detect non-specific or multiple host mortality patterns that might reflect subtle changes to fundamental ecosystem processes (due to such large-scale factors as air pollution, global climate change, or fire-regime change) that transcend individual tree species pest/pathogen interactions or direct concern over forest resource production and availability.

At this point a mortality baseline is still being established for most of the U.S. using the first two cycles of annualized data (i.e., the first two measurements of each plot). To discern trends in mortality rates, a minimum of three cycles of FIA data are required*6. With at most two cycles of data currently available, it is only possible to do a spatial comparison of ecoregions and identify regions of higher than average mortality (relative to growth) for 
further study.
Always, further study.  Wait, why can't they present a trend in mortality that might "reflect subtle changes to fundamental ecosystem processes - due to such large-scale factors as air pollution???  Oh, they "choose not to do so":
*6 In theory, one could estimate changes or trends in mortality rates using just two cycles of data by comparing, for example, plots measured in 2000 and 2005 with those measured in 2001 and 2006, those measured in 2002 and 2007, etc.  However, we choose not to do so because estimating mortality rates independently for each panel of data reduces the effective sample intensity by a factor of five and because an analysis of mortality rates using heavily overlapping time periods will be unlikely to detect subtle changes in mortality rates.
p. 31 Methods

The MRATIO can be large if an over-mature forest is senescing and losing a cohort of older trees. If forests are not naturally senescing, a high MRATIO (> 0.6) may indicate high mortality due to some acute cause (insects or pathogens) or due to generally deteriorating forest health conditions. An MRATIO value greater than 1 indicates that mortality exceeds growth and live standing biomass is actually decreasing.
This is frightening because it is so out of date considering the dramatic and rapid deterioration of tree health since 2008:

On Page 35 is a chart broken down into which species are dying.  p. 36 says:

Green ash also represented a large portion of the mortality in ecoregions 332A-Northeastern Glaciated Great Plains (17.43 percent), 332C-Nebraska Sand Hills (10.22 percent), and 332E-South Central Great Plains (12.25 percent). The cause of this mortality is not immediately apparent. One might be tempted to suspect the invasive insect, the emerald ash borer. However, this pest has not yet been reported in or near these regions (USDA Forest Service and others, N.d.). In ecoregion 332A-Northeastern Glaciated Great Plains, the age of the dead trees (table 4.2) suggests that older, senescent stands may be dying.
I love it!  They are "tempted" to blame an insect that doesn't exist!!  So again it's older, senescent stands, since they can't find a biotic agent.  The fact is that aside from a few isolated, protected specimens located in places that have been preserved for historical or cultural reasons - like churchyards, battlefields, Colonial estates, and Ivy-league campuses - there are virtually NO senescent stands in the Eastern US, they have ALL been clearcut, some more than once (unfortunately).  The new growth is too young to be dying of natural causes.

The mortality pattern shown in these analyses does not immediately suggest large-scale forest health issues. Mortality is rather low in most of the areas for which data are available. The areas of highest mortality occur in the mostly riparian forests of several plains ecoregions. The causes of the mortality of several of the tree species experiencing high mortality in these regions (including eastern cottonwood in ecoregion 332C-Nebraska Sand Hills and balsam poplar in ecoregion 332A-Northeastern Glaciated Great Plains) are not immediately apparent. Further study of the health of these forests is probably warranted.
Further study is "probably warranted?"  I should think so since the causes of trees experiencing high mortality "are not immediately apparent" which is probably because they refuse to factor in the rising level of background ozone, or the disruption to the nitrogen cycle.  It's interesting that "The areas of highest mortality occur in the mostly riparian forests..."  What is riparian??  Let's check with our trusty Wikipedia:

"Wiki:  The word "riparian" is derived from Latin ripa, meaning river bank. The riparian is an important feature of a wetland because it allows characterization of the wetland's overall health...Research shows riparian zones are instrumental in water quality improvement for both surface runoff and water flowing into streams through subsurface or groundwater flow. Particularly the attenuation of nitrate or denitrification of the nitrates from fertilizer in this buffer zone is important. Riparian zones can play a role in lowering nitrate contamination in surface runoff from agricultural fields, which runoff would otherwise damage ecosystems and human health. The use of wetland riparian zones shows a particularly high rate of removal of nitrate entering a stream and thus has a place in agricultural management."
As usual, the emphasis is on the benefit received by having trees in riparian areas soak up nitrate contamination - and not on what happens to trees when they absorb it.  Is is any wonder that these areas have the highest mortality rate?  They are getting a double whammy from absorbing ozone in their foliage and nitrates from their roots.

Introduction to Chapter 8 p. 71

Airborne nitrogen (N) and sulfur (S) from industrial pollution and automobile exhausts have been deposited across Europe and the Northeastern US for over 70 years in the form of acid rain. Heavily polluted areas can receive over 50 kg N ha-1each year. The environmental impacts of air pollutants have been studied since N and S were first suspected to cause forest damage and decline across the region in the mid-1980s. High pollutant levels and forest mortality can lead to mobilization of soil aluminum (Al3+) and nitrate (NO3-) and subsequent increases in stream Al and NO3 concentrations. Increased Al and NO3 stream concentrations can have negative health impacts on fish populations and human water supplies. High forest soil acidity can also cause aluminum toxicity in roots, foliar nutrient imbalances, reduced tree cold tolerance, and tree freezing injury. Each of these stressors can lead to tree mortality.
"Each of these stressors can lead to tree mortality" - (never mind what they do together) and yet the National Report neglects to mention any single one of them as a cause of tree mortality??

...Acidic deposition in excess of the critical acid load is termed the acidic exceedance, and the larger the acidic exceedance, the greater the risk of ecosystem damage. This definition of critical acid load applies to a single, long-term pollutant exposure. However, a static critical acid load level may not accurately assess ecosystem risk to damage when an ecosystem is subjected to multiple, episodic environmental stresses. If multiple stress impacts (e.g., drought, insects, wildfire) are included in critical acid load assessments, the critical acid load may need to be lowered in many areas to maintain long-term ecosystem health.
Climate Change Impacts on Critical Acid Loads

Climate change is a generic term used to define a host of changing environmental conditions associated with the atmospheric increase of greenhouse gases and global warming. Climate change is characterized by both climatic shifts and increased climate variability. Both inter-decadal shifts in climate and inter-annual climate variability can influence the critical acid load of forest soils. Each of these impacts is examined below.

Short- and Long-Term Droughts

Water is one of the principle determinants of ecosystem type. Average annual precipitation in temperate forests ranges from 50 to 250 cm per year. Deserts, scrubland, and woodlands receive between 0 and 125 cm of precipitation per year. Millennia of plant competition have favored vegetative species that best adapt to limited resources (including water). Short-term (i.e., less than two years) drought can reduce ecosystem productivity, leaf longevity in deciduous species, and leaf area. These factors reduce biological demand for nitrogen which can alter soil critical acid loads. Under short-term (i.e., less than two years) extreme drought, reduced soil moisture can cause reduced nitrogen mineralization and nitrification that then result in reduced ammonium and nitrate availability. These conditions would not impact critical acid load in the short term if both nitrogen demand and supply are reduced. However,
nitrogen will continue to accumulate in the ecosystem during the drought. A nitrate pulse could occur following a drought if nitrogen mineralization and nitrification rates respond to available water before plant demand for nitrogen increases.
Long-term (i.e., greater than two years) droughts can cause additional ecosystem disruptions and therefore have the potential to significantly lower forest soil critical acid load levels. Long-term droughts have all of the characteristics of short-term drought plus the potential for tree mortality due to water stress, increased insect outbreak potential, and increased fire risk. As with short-term drought, long-term drought may reduce biological nitrogen demand and supply. Additionally, the potential for terrestrial vegetation mortality could lead to a significant decrease in biological nitrogen uptake. If tree mortality is severe, a large nitrate pulse could occur following the drought, similar to the nitrate pulse observed following forest harvesting.
A large nitrate pulse??  This looks intriguing.  It also looks like a positive amplifying feedback - trees die back (or are cut), meaning they take up less nitrogen, so there is even more nitrogen supplied to the remaining trees, overfertilizing them.

Climate change is expected to negatively impact forest ecosystems in several ways during this century. However, the exacerbation of forest soils affected by acidic deposition may not be among those negative impacts. The results of this SMBE suggest that those soils most likely to be in exceedance of their critical acid load levels (e.g., New England forests) may also be the most likely to benefit from the warming associated with climate change. Increases in both nitrogen uptake and base cation weathering are predicted in this region of the country.  The increase in weathering rates would be particularly important for increasing the region’s critical acid load capacity. This study suggests that a major reduction in the area representing the most seriously impacted forest soils could occur. While this is potentially good news for ecosystem management, other aspects of climate change are not accounted for by the simple mass balance equation approach to critical acid load determination. Potential increases
in insect outbreaks, hurricane intensity, wildfires, and changing patterns of ice storms could all reduce forest productivity and therefore nitrogen uptake. These conditions would the reduce buffering capacity of the ecosystem and make it more likely that the ecosystem would be in exceedance of its critical acid load, so caution should be used when interpreting these results.
I'm sorry, but if you parse it, this incoherent, self-contradictory paragraph reads like double-speak!  Increasing the critical load capacity??  This is so out of step with current science about disruption of the nitrogen cycle, it's just staggeringly ignorant.

p. 106

Given the ecological importance of whitebark pine as a keystone species in these ecosystems, it is imperative that genetic materials, such as seed and/or scion, are collected from these populations and placed in genetic archives for their potential use in ecosystem restoration in the future. Furthermore, the populations should be monitored regularly to determine the trajectories of their health status over time and action taken as appropriate. All options intended to reverse the decline of these populations should be considered, including the dissemination of genetically resistant materials, restoration of natural fire regimes, and maintaining and archiving the gene pools of current populations.
This prognosis is stunningly bleak.  Whitebark pine - a keystone species - is in such imminent danger of extinction that they want to collect and archive genetic materials?  Sadly, I think this is true for ALL species if we keep on filling the atmosphere with poisonous gases.  Next, check out the graph of the increase in wildfire incidents and keep in mind, it only goes to 2009.  Wait till the wildfires start tearing through the suburbs, lapping at the fringes of major cities.  It's coming.

Forest Fire Occurrences measure by MODIS
The primary keeper of the ozone monitoring data used in these reports (or not, as it appears to have been jettisoned after 2009) is Gretchen Smith, whose most recent publication, "Ambient Ozone Injury to Forest Plants in Northeast and North Central USA:  16 years of biomonitoring" is from July 2011".  Here's the Abstract, a self-immolation that explains why the FS feels justified in ignoring ozone:

"The US Forest Service administers a long-term, nationwide ozone biomonitoring program in partnership with other state and federal agencies to address national concerns about ozone impacts on forest health. Biomonitoring surveys begun in 1994 in the East and 1998 in the West provide important regional information on ozone air quality and a field-based record of ozone injury unavailable from any other data source. Surveys in the Northeast and North Central subregions cover 450 field sites in 24 states where ozone-sensitive plants are evaluated for ozone-induced foliar injury every year. Sites are typically large, undisturbed openings (>3 acres in size) close to forested areas where >3 bioindicator species are available for evaluation.

Over the 16-year sampling period, injury indices have fluctuated annually in response to seasonal ozone concentrations and site moisture conditions. Sites with and without injury occur at all ozone exposures but when ambient concentrations are relatively low, the percentage of uninjured sites is much greater than the percentage of injured sites; and regardless of ozone exposure, when drought conditions prevail, the percentage of uninjured sites is much greater than the percentage of injured sites. Results indicate a declining trend in foliar injury especially after 2002 when peak ozone concentrations declined across the entire region."
Below is a random picture I took in July of 2009 of maple leaves with marginal leaf burn.  This is utterly typical of trees the past three summers - and the biomonitoring program supposedly reveals a declining trend in foliar injury??  I. Don't. Think. So.
Notice, the abstract states that PEAK ozone concentrations declined...but neglects to mention that the background levels are inexorably increasing.  Personally, I think it's not just possible but likely that it is worse - perhaps far, far worse - for plants to absorb lower but constant levels of ozone all of the time without respite - including nighttime - than to be exposed to occasional transient high doses during daylight when there is UV radiation...because they never get a change to recover.  I called Smith a couple of years ago to ask her whether she wasn't alarmed at what the data showed, and perhaps ought to communicate that alarm to public policy makers.  She seemed to get rather irritated and responded that partly due to her work in the ozone biomonitoring program, the EPA was going to tighten ozone standards.  Well, we know how well that worked out!

I think we should get rid of power tools like mowers, hedge clippers and leaf blowers...for starters.  Also, ridiculous trips like the one filmed in this Youtube, a movie which although very cool, is unintentionally revealing of how absurd overpopulation and overconsumption have become...no matter how the Forest Service tries to define current practices sustainable.