Spill the Scarlet Rain

Source

The name - of it - is "Autumn" -

The hue - of it - is Blood - 

An Artery - upon the Hill - 

A Vein - along the Road -

Great Globules - in the Alleys - 

And Oh, the Shower of Stain - 

When Winds - upset the Basin - 

And spill the Scarlet Rain -

It sprinkles Bonnets - far below - 

It gathers ruddy Pools - 

Then - eddies like a Rose - away - 

Upon Vermilion Wheels -

~ Emily Dickinson, 1862

11/16/07

This is an autumn like no other.  Absent are the hue of blood, the scarlet rain, the vermilion wheels.  The photographs above were taken in 2007, in Ontario, Canada - and we will never see the likes of that again.  That glowing, almost divine intensity will henceforth be, like the bright riot of coral reefs, a scintillating dream receding in the memories of this last generation to have witnessed the full spectrum of life.

Even in the best case, the colors of fall are faded.  This young maple, in Wellfleet today, looks to the hopeful eye to be turning a stunning orange.

 But the colors are muted, pale, and the leaves are marred by ugly spots.

 Well before they fall off, they are crumpled from brown rot.

Not too long ago, leaves routinely turned bright colors in the fall, from Canada to Georgia...then they fell off the branches and covered the ground with their brilliance, inspiring everyone from poets to children with their outrageous, flamboyant, breathtaking beauty.

I remember raking them for my daughters, who leapt gleefully into the soft cushioned mountains in a glorious range of purple, magenta, oranges and golds and garnet red.  That vibrancy has been successively lessened for several seasons, and has now been replaced by shriveled rust - or even the most macabre black.  What's with this hideous sumac branch, outside my kitchen window?

Yet another foolish story appeared in the news this week, claiming this autumn will be a particularly good one for tourists seeking fall color, this time originating from the Southeast instead of the Northeast.

As has occurred in past accounts this year, the newspapers can't even find pictures of leaves that are smooth and unblemished.  Instead they illustrate the exact damage that is evidence of exposure to toxic air pollution...symtoms reproduced in countless fumigation experiments and documented here at Wit's End in hundreds of photos.  These two are all they could come up with!

One normally prolific and enthusiastic photographer who makes an annual journey to a favorite place in North Carolina - Grandfather Mountain - and was so perplexed by the lack of fall color yesterday that he took only one picture and titled the caption for his flickr submission:  "Scraping off the Rust".  He explained:

October 6 - "I went up to the mountains with big plans to shoot many things today (Saturday); nature decided otherwise for me. Pulling into the parking lot of Rough Ridge at o'dark thirty yielded the unmistakable fact that it was windy--very windy. Serious persistent wind. Strong gusts. And when the sky started to get a bit lighter, it was obvious that I was either too early in the season (not too much vibrant orange and red colors) or it was just a dud of a color season--or perhaps a bit of both."

October 13, 2010

Compare to samples of his images from earlier times.

October 20, 2007

Notice in the photograph below that the leaves on the ground are still golden, even in 2010.

October 18, 2010

But by last year he was already disappointed and unable to get a shot to his satisfaction, even though it was supposedly a great year.  He wrote:

October 10, 2011

"...I returned to this particular spot during some decent conditions with fog and light rain, but the wind was still causing some havoc by blurring leaves. So, while the color was quoted as some of the best in recent years, the conditions around the color were sufficiently difficult for a guy like me to easily capture it."

Clingman's Dome, August 9, 2012

What is going on?  How can conditions have deteriorated so fast, and what does that mean?  When I first realized that forests are in decline because of tropospheric ozone (2008), I expected the trees to have no leaves within a couple of years.  I underestimated how resilient they are.  They have to be - they can't pick up and leave when there is a drought, or a plague of insects.  They have to store a huge amount of energy to tide them over, like a camel storing water in the desert.  It's part of their long-lived survival strategy.  But it cannot last forever in the face of unremitting, inexorably rising levels of background pollution and so in some places, we ARE getting close to the point where there are no leaves left, more than a month prematurely.  And the important thing, the MOST important thing is, the trend is accelerating.

Wit's End, last week - formerly a bright orange maple, like this one:

11/16/07

Thanks to XRayMike's excellent blog, Collapse of Industrial Civilization (you can watch his cool video, Graffitti Philosophy here), I discovered a paper titled "Approaching a state shift in Earth's biosphere", a tantalizing title that couldn't be more apropos to the topic here at Wit's End - trees dying around the world from pollution, and the resulting collapse of the ecosystem.  Following are photos from the source in Canada from years past - and my own pictures from Wit's End last week.  It shouldn't be too hard to tell the difference.

Localized ecological systems are known to shift abruptly and irreversibly from one state to another when they are forced across critical thresholds. Here we review evidence that the global ecosystem as a whole can react in the same way and is approaching a planetary-scale critical transition as a result of human influence. The plausibility of a planetary-scale ‘tipping point’ highlights the need to improve biological forecasting by detecting early warning signs of critical transitions on global as well as local scales, and by detecting feedbacks that promote such transitions. It is also necessary to address root causes of how humans are forcing biological changes.

I could only obtain that snippet from the periodical Nature, which blocks the paper behind a paywall (grrr), so I wrote the lead author, as follows:

10/13/07

Dear Dr. Barnosky,

Would you mind sending me a pdf of your paper?  I don't have a subscription and I would like to read it.

10/07

I am sure you are familiar with the collapse of coral reefs and the implications this has for life in the oceans and ultimately on the land as well.

Very few people however are aware that forests are dying from pollution at a rapidly accelerating rate.  Eventually climate change will destroy most trees but meanwhile, ozone is the greater threat.  It is possible that we have reached a tipping point but since they're not all quite dead yet, I like to think we could buy some time if people wake up to what is occurring right in front of them and decide that the myriad services we receive from trees are more important than a consumer culture (haha.)

9/12/06

In the past few weeks, several stories have appeared in the northeast claiming the autumn leaves will be glorious this year…even though they're not.  Of course, the media is repeating what tourist-dollar hungry business wants them to say, but also, no one wants to admit that all the trees are dying - and a lack of normal bright, vibrant fall color is a strong indicator of that.

The persistent background level of tropospheric ozone - the invisible part of smog from fuel emissions - is inexorably rising.  It's toxic to just about everything, but especially plants.  Leaves are damaged when they absorb it, and cannot photosynthesize.

10/07

They look speckled, stippled, bronzed and burnt.  By the end of the growing season - now - many of them have shriveled up and turned brown.  The ground is littered with them already.

10/22/07 - still bright on the ground!

Internal injury occurs in vegetation even before visible symptoms appear on leaves.  Roots shrink, making trees more liable to blow over in storms, and more vulnerable to drought.  Compromised immunities allow for intensified attacks from fungus, insects and disease, which are what is usually blamed.

All this is denied by virtually every professional forester, because it poses an intractable problem.  The only way to fix it is to stop creating precursors - reactive nitrogen - that our entire industrial civilization is based upon, from agriculture to transport to electrical power.  No geongineering or techno fix will be sufficient to stop the loss of the earth's forests.

11/16/07

An excellent book was published in the nineties and promptly forgotten, "An Appalachian Tragedy".  That was before it became apparent that the scenes of forest death the authors described are no longer localized, and satellite advances have demonstrated that emissions are traveling around the world.

Aside from losing all the benefits of forests - fruit and nuts, shade and lumber, beauty and wildlife habitat - we cannot survive without them absorbing CO2 and producing oxygen.  The fact that our forests - and our survival - is at risk is a hidden threat on a parallel with that of ocean acidification and the collapse of the coral reefs.  Decades of studies, including controlled fumigation experiments, have shown that we are also losing significant percentages of annual agricultural yield and quality to air pollution.

10/22/07

Even though I'm not a qualified scientist, since just about everyone is neglecting this topic, I wrote a little book with links to research which is available as a free download from dropbox (and from Amazon) and I post pictures and current articles on a regular blog at Wit's End.

10/07

I hope you will send me your paper.  Please feel free to contact me if you have any questions about the ozone.  I am always hopeful that someone with expertise will undertake to outline the enormous dimensions of this trend.

Sincerely,

Gail Zawacki

Oldwick, NJ

Yellow Branch Falls, 10/28/09

Dr. Barnosky sent me a pdf of his paper, without a word of comment.  Not easily deterred, after I read it, I wrote him again.  Surely, someone who studies planetary tipping points would be interested to know that there is ample evidence we are passing a critically important threshold RIGHT NOW in the world's tree population?  Ah well.  Did you see the article today in the New York Times about Tatoosh Island at the mouth of the Strait of Juan de Fuca, where the bird population has been halved in a decade, and the shells of mussels are so soft they are crushed by waves?

During a research trip in 2000, Dr. Pfister and Dr. Wootton first began testing the pH of water samples. They found the water around Tatoosh and along nearby coastlines to be 10 times as acidic as what accepted climate change models were predicting. Even after collecting seven years of data, when they published their findings in the Proceedings of the National Academy of Sciences in 2008, their data were met with skepticism.

“People think we just don’t know how to use the instrument — I still hear that,” Dr. Pfister said. “Luckily for our reputations, I guess, this has been corroborated by a lot of other people.”

The rest of the photos are from Cape Cod, yesterday, where the views are pretty but the leaves, upon inspection, are uniformly stippled and singed.  The nice images are from North and South Carolina, from betters days in years past, labeled with their date.

Dear Dr. Barnosky,

Thank you so much for sending me your paper.  I am looking forward to following up on several of the sources you cited about ecosystem tipping points.

I think that "early warning signs" of a critical tipping point for forests are already quite evident, but unfortunately, few people recognize them (for instance as shown in photos from yesterday, (here).  I see that you reference Rockström's work about the nine boundaries.  It's quite significant that one of the boundaries he designated as having been breached is the nitrogen cycle, which of course underlies the production of ozone in the atmosphere as well as eutrophication of water.  Obviously, I think ozone pollution is another boundary that has already been breached, although he lists it as separate - an influence which is also inadequately accounted for in the Limits to Growth studies.

I am hoping this would be of particular interest for you since tropospheric ozone is a wild card in terms of the predictive value of the paleoclimatic record of past extinction events, for what is unfolding now.  Ground level ozone is almost solely a result of anthropogenic activity and so unlike CO2 which has been known to fluctuate to much higher than contemporary levels, this concentration has no real precedent in prehistory.  Just as CO2 has doubled since the industrial revolution began, so has the background level of tropospheric ozone.

Dry Falls, 10/17/10

As a proven and known potent phytotoxin, which is now ubiquitous even in remote places, it is imperative to assess its impacts when modeling the potential trajectory of climate change influence on vegetation, and yet virtually no one does.  Clearly as vegetation is diminished in sheer volume as well as nutritive quality, any species that consume it will be inevitably affected as the consequences cascade through the food chain, a result that is already evident in the numerous reports of starving animals from lemmings to caribou to birds and bears.

I did not see Karen Rice's research in your list, Acidification of Earth (which is linked to here) and recently this Scientific American publication, Invasive Fungus Wreaks Havoc on Species Worldwide is very interesting as well.  New information also comes from the Yale School of Forestry, where researchers have discovered high levels of methane emissions from trees that are dying from fungal infection, which they claim is a worldwide phenomena, and yet they cannot (in fact, don't even try to) explain WHY trees that are only at the beginning of maturity (80 to 100 years old) are dying prematurely all over the earth.  I suspect they do not appreciate the implications of their own discovery beyond the acceleration of climate change.  From SummitCountyVoice:

Sixty trees sampled at Yale Myers Forest in northeastern Connecticut contained concentrations of methane that were as high as 80,000 times ambient levels. Normal air concentrations are less than 2 parts per million, but the Yale researchers found average levels of 15,000 parts per million inside trees.

“These are flammable concentrations,” said Kristofer Covey, the study’s lead author and a Ph.D. candidate at Yale. “Because the conditions thought to be driving this process are common throughout the world’s forests, we believe we have found a globally significant new source of this potent greenhouse gas.”

Crabtree Falls, 10/17/08

“If we extrapolate these findings to forests globally, the methane produced in trees represents 10 percent of global emissions,” said Xuhui Lee, a co-author of the study and Sara Shallenberger Brown Professor of Meteorology at Yale. “We didn’t know this pathway existed.”

The trees producing methane are older—between 80 and 100 years old—and diseased. Although outwardly healthy, they are being hollowed out by a common fungal infection that slowly eats through the trunk, creating conditions favorable to methane-producing microorganisms called methanogens.

“No one until now has linked the idea that fungal rot of timber trees, a production problem in commercial forestry, might also present a problem for greenhouse gas and climate change mitigation,” said Mark Bradford, a co-author and Assistant Professor of Terrestrial Ecosystem Ecology at F&ES.

Thank you for your attention,

Gail Zawacki

Oldwick, NJ

Dr. Barnosky has not replied and apparently hasn't even checked the links I sent him, so evidently, like most of his ilk, he would rather stick to the theoretical models than examine empirical evidence.  So for posterity, I uploaded the pdf on dropbox, in case anybody wants to read it.

The paper warns:

...if critical thresholds of diminishing returns in ecosystem services were reached over large areas and at the same time global demands increased (as will happen if the population increases by 2,000,000,000 within about three decades), widespread social unrest, economic instability and loss of human life could result.

Numerous anthropogenic activities are examined for their impact on the biosphere, from habitat destruction to climate change - tropospheric ozone is not among them.  Should that matter?  Well, the paper is using the year 2100 as a benchmark for some predictions:

Roaring Fork Falls, 10/11/09

Looking towards the year 2100, models forecast that pressures on biota will continue to increase. The co-opting of resources and energy use by humans will continue to increase as the global population reaches 9,500,000,000 people (by 2050), and effects will be greatly exacerbated if per capita resource use also increases.

...and since from what I have observed we don't have anything like 88 years remaining to save the forests - oh, and ourselves - from extinction, I would say it really does matter.  Following are some more excerpts about abrupt transitions following the passing of tipping points:

Basics of state shift theory

It is now well documented that biological systems on many scales can shift rapidly from an existing state to a radically different state.

Biological ‘states’ are neither steady nor in equilibrium; rather, they are characterized by a defined range of deviations from a mean condition over a prescribed period of time. The shift from one state to another can be caused by either a ‘threshold’ or ‘sledgehammer’ effect.  State shifts resulting from threshold effects can be difficult to anticipate, because the critical threshold is reached as incremental changes accumulate and the threshold value generally is not known in advance. By contrast, a state shift caused by a sledgehammer effect—for example the clearing of a forest using a bulldozer—comes as no surprise. In both cases, the state shift is relatively abrupt and leads to new mean conditions outside the range of fluctuation evident in the previous state.

...In the context of forecasting biological change, the realization that critical transitions and state shifts can occur on the global scale, as well as on smaller scales, is of great importance. One key question is how to recognize a global-scale state shift. Another is whether global-scale state shifts are the cumulative result of many smaller-scale events that originate in local systems or instead require global-level forcings that emerge on the planetary scale and then percolate downwards to cause changes in local systems. Examining past global-scale state shifts provides useful insights into both of these issues.

For all that, the authors warn of apocalyptic change, but deflect the inescapable conclusion that it is already well underway and irreversible - not "within a few human generations"!

Guiding the biotic future

Humans have already changed the biosphere substantially, so much so that some argue for recognizing the time in which we live as a new geologic epoch, the Anthropocene. Comparison of the present extent of planetary change with that characterizing past global-scale state shifts, and the enormous global forcings we continue to exert, suggests that another global-scale state shift is highly plausible within decades to centuries, if it has not already been initiated.

Whiteside Mountain, 10/22/09

As a result, the biological resources we take for granted at present may be subject to rapid and unpredictable transformations within a few human generations.  Anticipating biological surprises on global as well as local scales, therefore, has become especially crucial to guiding the future of the global ecosystem and human societies. Guidance will require not only scientific work that foretells, and ideally helps to avoid, negative effects of critical transitions, but also society’s willingness to incorporate expectations of biological instability into strategies for maintaining human well-being.

Boone Fork Creek, 10/13/10

Diminishing the range of biological surprises resulting from bottom-up (local-to-global) and top-down (global-to-local) forcings, postponing their effects and, in the optimal case, averting a planetary-scale critical transition demands global cooperation to stem current global-scale anthropogenic forcings. This will require reducing world population growth and per-capita resource use; rapidly increasing the proportion of the world’s energy budget that is supplied by sources other than fossil fuels while also becoming more efficient in using fossil fuels when they provide the only option; increasing the efficiency of existing means of food production and distribution instead of converting new areas or relying on wild species to feed people; and enhancing efforts to manage as reservoirs of biodiversity and ecosystem services, both in the terrestrial and marine realms, the parts of Earth’s surface that are not already dominated by humans. These are admittedly huge tasks, but are vital if the goal of science and society is to steer the biosphere towards conditions we desire, rather than those that are thrust upon us unwittingly.

Linn Cove Viaduct, 10/20/07

It's a good paper - they have the essential requirements in that final paragraph - but it's too bad that studying all those theories and models and predictions has more appeal than looking at the real world outside the ivory tower.  On the other hand, I had no idea there was so much recent scholarly research about tipping points, as assembled in the references by Barnosky and his colleagues.  I haven't had time to track them all down and read them (for one thing several will require going through the same exercise of writing the lead author to get the full paper) but I will list the ones that jump out at me as being especially pertinent.

Grandfather Mountain, 10/19/08

In fact the robust number of them has led me to feel very strongly that what they discuss is the heart of the matter - we have simply crossed the threshold beyond which plants can tolerate background ozone.  In addition, there is no question that as temperatures are rising, more ozone is being created, in addition to the volume of precursors being added to the atmosphere as population and per capita emissions both rise.  Every study of ozone ever written makes this assumption overtly.  This may turn out to be as powerful an amplifying feedback as the albedo effect in melting ice, added to the fact that the impaired photosynthesis decreases absorption of CO2, leading to ever more warming.

Synergy and feedbacks

Thresholds leading to critical transitions are often crossed when forcings are magnified by the synergistic interaction of seemingly independent processes or through feedback loops. Given that several global-scale forcings are at work today, understanding how they may combine to magnify biological change is a key challenge.

Following are references from the paper most closely related to tipping points, some with short explanatory notes highlighted by the authors:

16. Rockström, J. et al. A safe operating space for humanity. Nature 461, 472–475

(2009).  This paper specifies important planetary boundaries and explains why

exceeding them would be detrimental to humanity.

3. Steffen, W. et al. The Anthropocene: from global change to planetary stewardship. AMBIO 40, 739–761 (2011). link

This paper summarizes the many ways in which humans are changing the planet, argues that the combined effect is as strong as geological forces and points to the likelihood of planetary tipping points.

It's an excellent paper, building on Rockstroms planetary boundaries and Barnosky's loss of biodiversity, and I admire the section about the grotesquely immoral land grab (a sizzling introduction to which can be found at Decline of the Empire).  But it also is basically summarized in the infuriating figure (no. 3) with a caption that lists a baker's dozen of ways in which humanity has over-extracted, over-exploited, and over-polluted.  See below.  But NOT ONE OF THEM IS OZONE!!  You can look at it at a part of the nitrogen cascade - but it should be explicitly and separately referenced, because it has very specific results.

Global-scale changes in the Earth System as a result of the dramatic increase in human activity: a atmospheric CO2 concentration, b atmospheric N2O concentration, c atmospheric CH4 concentration, d percentage total column ozone loss over Antarctica, using the average annual total column ozone, 330, as a base, e northern hemisphere average surface temperature anomalies, f natural disasters after 1900 resulting in more than 10 people killed or more than 100 people affected, g percentage of global fisheries either fully exploited,overfished or collapsed, h annual shrimp production as a proxy for coastal zone alteration, i model-calculated partitioning of the human induced nitrogen perturbation fluxes in the global coastal margin for the period since 1850, j loss of tropical rainforest and woodland, as estimated for tropical Africa, Latin America and South and Southeast Asia, k amount of land converted to pasture and cropland, and l mathematically calculated rate of extinction.

14.  Drake, J. M. & Griffen, B. D. Early warning signals of extinction in deteriorating environments. Nature 467, 456–459 (2010). link

72.  Holtgrieve, G. W. et al. A coherent signature of anthropogenic nitrogen deposition to

remote watersheds of the northern hemisphere. Science 334, 1545–1548 (2011). This paper documents how human impacts are reaching into remote ecosystems.  link

73.  Peñuelas, J., Sardans, J., Rivas-Ubach, A. & Janssens, I. A. The human-induced imbalance between C, N and P in Earth’s life system. Glob. Change Biol. 18, 3–6 (2012). link

However, there are several studies that report no significant increases or even reductions in global tree growth and global carbon sinks, despite the increase in atmospheric CO2 concentrations, and despite the general increase in N deposition (Peñuelas et al., 2011).  These results suggest that other factors have overridden the potential growth benefits of a CO2-rich world at many sites. It is thus still uncertain how this N increase affects the global C cycle. This uncertainty is linked, among other factors such as water availability, to the possible limiting role of other nutrients and their interactions (Reich et al., 2006).

Hmm, I wonder what "other factors" might have overridden the potential growth benefits of higher CO2??

20.  Hastings, A. & Wysham, D. Regime shifts in ecological systems can occur with no warning. Ecol. Lett. 13, 464–472 (2010).  This paper points out that regime shifts in complex systems need not result from saddle-node bifurcations and thus may not show the typical early warning signals.  Link

12.  Scheffer, M. et al. Early-warning signals for critical transitions. Nature 461, 53–59 (2009).

This paper presents a general approach to the detection of critical transitions and outlines the possibility of there being general indicators.  Link, and there are several earlier studies by the same authors worth following.

13. Carpenter, S. R. et al. Early warnings of regime shifts: a whole-ecosystem experiment. Science 332, 1079–1082 (2011).  Link to text

25. Barnosky, A. D. et al. Has the Earth’s sixth mass extinction already arrived? Nature

471, 51–57 (2011).  Link

Now, that seems like a no duh? paper title!  And what I want to know is, why doesn't someone do a study - "Early warning of regime shifts occur, but are roundly ignored by the scientific community, even when they are told about them"??

Delicious autumn! My very soul is wedded to it, and if I were a bird I would fly about the earth seeking the successive autumns.  ~ George Eliot

9/12/06

Thrice happy time,
Best portion of the various year, in which
Nature rejoyceth, smiling on her works
Lovely, to full perfection wrought!

~ Wendell Phillips

I photographed this splendid specimen, an Eastern Cottonwood, yesterday.  The ocean is just beyond the far hill.  Below is a photograph from September 12.  Not much difference, just thinner now.

 

It is way too tall for me to get a photo of the leaves on the branches, but here are some that had fallen on the lawn, with stippled stomates and marginal leaf burn.

The branch up high is losing bark.

And so, ominously, is the trunk.

The lichen clinging to the fence should give us a clue about why trees now are covered with lichen too - they are dead wood.

This Crimson King maple looks tiny next to the cottonwood, but it's not - that's only because the cottonwood is so enormous.

You'ld almost think it looks pretty healthy if you only glance at it.

These leaves are desiccated too.

Divinest Autumn! who may paint thee best,
Forever changeful o'er the changeful globe?
Who guess thy certain crown, thy favorite crest,
The fashion of thy many-colored robe?

~ Richard Henry Stoddard

Here they lie, crumpled, on the grass.

How many trees have to die before scientists recognize the unmistakable collapse of the entire ecosystem...not theoretical projections, not localized, or isolated, but a planetary REALITY?  I'm leaving the Cape (by way of a one-night side trip to Nantucket, having learnt all about whaling, so why not?) early tomorrow morning since Doc is feeling better and he and Nana are, debatably, more-or-less self-sufficient once again.

Some inspired resident of Wellfleet has completed their Halloween display already, and since I don't expect to be back again any time soon, the rest of the pictures are from their fabulous yard.

Perhaps no one will ever figure out about the trees if the authors of yet another report who are continually blaming forest decline on drought from climate change have anything to to about it.  These sufferers of acute tunnel-vision have devised a "Forest Drought-Stress Index" which they apply to modeling, from which they conclude:

If the vapour-pressure deficit continues increasing as projected by climate models, the mean forest drought-stress by the 2050s will exceed that of the most severe droughts in the past 1,000 years.  Collectively, the results foreshadow twenty-first-century changes in forest structures and compositions, with transition of forests in the southwestern United States, and perhaps water-limited forests globally, towards distributions unfamiliar to modern civilization.

I don't doubt that at all that there will be species "...distributions unfamiliar to modern civilization", but what is inexplicable is why they bother to run such model predictions without accounting for the well-established withering effect of ozone on root systems, making trees and other plants much more vulnerable to drought stress.  Not to mention, they're ALL going to die from ozone - whether they are in the southwest, whether they are in drought-stricken regions or not - long before we get to the 2050's if the present rate continues!

This latest research was so annoying I decided to google ozone, which I occasionally do, to see if anything new emerges.  I actually came across an ancient conversation with the enigmatic Dan and Sid, buried in the Membrane archives.  It's kind of amusing to me to read it from way back when I first started seeking answers to dying trees.  They were just about the first people to take the threat of ozone as a serious issue, and not a mere curiosity.

Since then, so much more has come to light, entire textbooks, and more and more articles.  Here's one from a 2002 interview, in which a scientist saying exactly what I had concluded myself, the heretical notion that got me banned from RealClimate for merely suggesting it -

"Air pollution is probably one of the most serious problems facing humankind in the 21st century," said Zhang, a professor in the College of Geosciences. "And certainly, much of that pollution results from human activities. But most people are not aware of the role played by chemical reactions which change substances produced by biogenic species into harmful airborne pollutants.

"Although near-ground ozone has some beneficial effects, providing excited oxygen atoms needed to produce the free OH radicals that help to bind other chemicals like sulfur and cleanse them from the atmosphere, excess ozone proves harmful to the health of humans and plants," Zhang said. "For example, too much ozone can retard tree growth or even kill trees. And if too many trees die, there will be more CO2 in the air, further trapping heat and raising the temperature of the planet."

Then he adds:  "The isoprene chain reaction is very complicated - in fact, it's been studied for over 30 years without significant results with regard to fundamental details,"  which makes me wonder if we've made any progress since then or if science has just concluded there's nothing we can do about the emissions of precursors, so why bother?

One of my perennial favorite researchers, John Reilly of MIT, co-authored this 2007 paper, "Impacts of ozone on trees and crops" which makes the astonishing but common assumption that has since proven false, that other factors - increases in CO2 and nitrogen - will magically and conveniently offset ozone's growth inhibition to trees, although not for crops.  But it does start out factually enough:

Changes in land use and in the chemical composition of both the atmosphere (increased CO2 and O3 concentrations) and precipitation (increased nitrogen concentrations) during the last century have directly affected biogeochemical cycling of vegetation and soils. Increased atmospheric CO2 levels and changing land-use patterns, such as conversion of land to agriculture, have also indirectly affected the biota through changes in climate. Besides positive CO2 and nitrogen fertilization effects and direct consequences of land-use change, air pollutants have had a significantly negative effect on vegetation productivity and crop yield since the latter half of the 20th century. Over 90% of vegetation damage may be the result of tropospheric ozone alone.

A paper published in 2009 brings home the fact that ozone is a global issue.  Research conducted in India indicates that the threshold of 40 ppb is exceeded in many places, damaging crops and vegetation:

Using surface level measurements from Pune, Beig et al. (2008) have recently calculated the AOT40 and shown that ozone levels have surpassed the “critical levels” in most parts of the year for vegetation and forest. This is the only work where detailed study about the AOT40 based on observed data has been reported over any Indian station. In the past few decades, India has been undergoing rapid industrial and economic growth with increasing emissions of trace gases and pollutants. Due to all these reasons, the tropospheric ozone level is an issue of concern in the last few decades. Necessary and effective emission reduction strategies are required to be developed in order to curb the surface level ozone pollution to protect the vegetation from further damage in

India whose economy is highly dependent on agricultural sector. Hence, more efforts are needed to understand the spatial and temporal distribution of cumulative exposure indices and threshold exceedances over the whole domain of India.

Once again this bibliography is a bottomless rabbit's hole leading to, for instance, a book, Air Pollution Effects on Crops and Forests; a Global Assessment, which has a chapter on the impact of ozone on maize in southern Africa - so much for it being confined to the Northern Hemisphere!  It was published in 2003 by APCEN - the Air Pollution Crop Effect Network, which is a new one on me...although one of the primary co-authors, Lisa Emberson, is not.  She just co-authored a study indicating that

...ozone pollution causes millions of tonnes of crop losses each year – not just in the regions where it’s emitted, but across continents: Pollutants from North America reduce wheat yields in Europe by 1.2 million tonnes each year.  On a global scale, pollution from Southeast Asia has the biggest impact, the study shows, causing the loss of 6.7 million tonnes of wheat and about 11.6 million tonnes of rice each year.

“This study highlights the need for air pollution impacts on crops to be taken more seriously as a threat to food security in the coming decades,” says Emberson. “Given the sizeable yield losses of staple crops caused by surface ozone, there should be greater coordinated international efforts focused on reducing emissions of ozone-forming gases across the globe.”

But I guess all that crop loss means nothing for trees, because neither she nor her co-authors respond to any inquiries about them.  There is a nice recent overview from some German scientists published by the Journal Agronomy in May 2010 - so just extrapolate from that what the same processes that occur with crops do to trees and other wild plantlife that is exposed season after season and perhaps the conclusion that a tipping point for perennial vegetation has been surpassed.  Almost every word in this abstract is important but I'll highlight the indispensable parts:

The concentrations of atmospheric compounds such as greenhouse gases, heavy metals and trace gas air pollutants have rapidly changed. Many of these compounds interact with agricultural systems and influence crop performance, both directly by affecting growth and quality or indirectly by altering the plant’s ability to cope with other abiotic and biotic stresses. Some atmospheric compounds have little or no discernible impact on the environment; others reach levels that exceed thresholds for damage to crops. In this review, we analyse the literature on airborne species that directly impact crop growth and health. In Europe and North America emissions of SO₂, NOx and heavy metals have declined during the past decades and are currently not considered as a major threat to crops. By contrast, air pollutant emissions have been increasing in rapidly growing regions of Asia, Africa and Latin America.

Ozone is the most phytotoxic of the common air pollutants. The widespread distribution of O₃ already presents a risk to crop growth and health in many regions of the world. It is concluded that the continuous increase in background O₃ concentrations will pose a critical threat to future world food security. Interactions with both biotic and abiotic factors must be taken into account in assessing risks of air pollutants in the field. There is evidence that these indirect effects could be more important under certain circumstances than the direct effects of air pollutants on plants.

The parallel rapid increase in atmospheric CO₂concentrations accompanied by climate change has two major implications: (1) a possible benefit to crop growth by direct stimulation of photosynthesis and by mitigation of gaseous air pollutants and water stress; and (2) a threat to crop production due to an enhancement of crop quality losses.

I don't know how more clearly it needs to  be stated that ozone is the primary instigator for a decline in vegetation, following which initial exposure other biotic (fungus, disease and insect) and abiotic (drought) attack disproportionately as an AMPLIFYING FEEDBACK, just as the initial forcing of CO2 to climate is dwarfed by amplifying feedbacks, such as the albedo effect, that accelerate change...and the acidification of the ocean also leads to rapid amplifying feedbacks as food chains and habitat (coral) collapse.

So, based on feedbacks as described above with the other feedbacks, all increasing damage from ozone (intensified violent weather from climate change that increases from dying vegetation; higher temps leading to more ozone; more trees dying from worse drought and biotic attacks), coupled with the dramatic acceleration of premature senescence this fall, I am very much tending be confident that feedbacks and synergy have led us to the tipping point and beyond.  The ecosystem is collapsing, wipe away that tear and kiss it goodbye.

Why don't people get it?  And would it matter if they did?

A baleful glare if I ever saw one.