"When Vegetation Rioted the Earth and the Big Trees Were Kings"

I rarely venture outside anymore - only under duress...if I must. The contrast between the profusion of life that existed, in the vibrant world that I was born to - which was still lush with promise until fairly recently - has lately become, with the current hideous decay, almost unremittingly grim.  This is the time of year I used to pore over seed catalogs, and plot new floriferous additions to the ornamental garden.

Boxwood shrubs turning a lurid orange, and it's not because they are in a parking lot.

Now I know that's a waste of time, effort and money, because I cannot escape the evidence that trees are dying, even in winter when the leaves are gone.  The evergreens - cedars, yew, pine, boxwood - are turning dull yellow, garish coppery, or a gruesome purply bruised hue.  Other symptoms - cracking bark, leaky holes in trunks, and cankers - are insistently present as well.

This is my boxwood hedge around the house at Wit's End, situated in the middle of the woods, far from cars, salt, or pavement.

It is impossible to avoid the signal that Rachel Carson's calamitous warning is about to be realized, perhaps as soon as this spring - and so I tend to cower in my kitchen these days, reading, assiduously avoiding a look out the window at the silent deterioration that surrounds.

But, one morning this week I was asked to drive beloved first daughter to the Newark airport, so of course I happily complied.  She was returning to her winter sojourn in Florida, where she is subjecting her fabulous dressage stallion to rigorous training.

The pictures in this post (other than graphs from linked research) were taken along my journey back to Wit's End.  The felled trees I happened to notice in a fleeting glimpse, piled between the parking lot of a dentist's office, and a decrepit farm, in the tiny enclave of Liberty Corner.  I stopped and climbed through thorns to see just how many there were.

Some of them were enormous trunks and since there is no logging industry in New Jersey, they can only be the remains of trees taken from neighborhoods, trees that died or were dying...deemed hazardous, and removed by a tree service which happens to be headquartered a short distance down the road.

It was shocking that there is such an overabundance of huge logs, from valuable hardwood species, that they aren't even being used for lumber, let alone firewood...they are just tossed onto the field at the back of an old farm, and left to petrify, like bones in a open graveyard.

The trees standing around the lot where I parked to take the pictures will have to be cut down soon, too.

On the left, is a pine tree with absolutely no needles remaining, next to it a pine tree very thin, and on the right a deciduous tree losing bark, with stumpy broken branches.

Across the street, a cryptomeria is turning bronze.

The photos that follow are from a little park on the way home, called Buck Gardens.  The arboretum is nestled deep in a ravine carved out from bedrock by the southernmost tongue of a glacier, with wonderful outcroppings of granite.  A small creek runs through it, dammed into a shallow pond.

There were a few flowers blooming ridiculously early, but mostly, what follows will be evergreen leaves that are exhibiting the stippling and chlorosis typical of ozone damage.

The Hellebores were just starting to open - over a month early!

After I deposited first daughter for her flight, I began thinking about the month following her bar exam, in August 2005, when she was diagnosed with cancer.  I can remember sitting, stunned and incredulous, in front of a television shortly thereafter, mindlessly staring at the news, which was inundated with the swirling white satellite images of a menacing Hurricane Katrina.  I was so numb with horror at the thought that my daughter might die (she didn't) that the catastrophe unfolding in New Orleans seemed like a surreal and almost unsurprising backdrop to my family's own personal calamity.

Many unwelcome lessons ensued in the course of her diagnosis and treatment in the following months... lots of stupidly obvious ones like carpe diem.  But as this blog is about trees dying from air pollution, I'm going to mention just two, since they happen to be pertinent, about doctors.  Because doctors are really scientists, they are indoctrinated trained to think in certain ways - for very good reasons.  Or at least, reasons that used to be good, back in the days when science wasn't quite so essential for setting sane public policy - and things weren't changing so fast that predictions based upon meticulous gathering of data, testing in controlled experiments, and designing models, are swiftly rendered dangerously obsolete.

Lesson One.  Scientists and doctors are egomaniacal douchebags arrogant know-it-alls.  When first daughter was initially admitted to the hospital, there was uncertainty as to what was wrong with her.  First, ludicrously, it was pneumonia, a few days later, Hodgkin's Disease, then the next, non-Hodgkin's lymphoma.  Interminable minutes dragged by in agonizing ignorance.  My then-boyfriend did some googling and sent me an email, suggesting I ask her doctor whether she might possibly have "Mediastinal Large B-cell Diffuse Lymphoma".

I wrote it down because I knew I wouldn't be able to remember it all, and the next day at our morning meeting in her hospital room I read each syllable carefully from the card.  Her doctor waved his hand, as if to brush it aside.  No that's not it, he said, and reassured us that after a few more tests they would have the diagnosis and be able to begin treatment.  Which would be a good thing, since she was considered to be, by then, in an "oncological emergency".  Indeed, it turned out to be Mediastinal Large B-cell Diffuse Lymphoma after all.

I bring this up not because I think he was a bad man or a bad doctor, au contraire, he was a nice person, and went out of his way to help us.  I mention it to illustrate that doctors and scientists generally assume a layperson knows precisely nothing at all, and they give no credence to unsolicited outlier inferences.  In much the same way, virtually every scientist or other "expert" I have approached about trees dying from air pollution has dismissed the implication without ever seriously considering it, or even attempting the slightest effort to refute any of the unimpeachable evidence. Not one of them has ever bothered to explain why annuals or young saplings being watered regularly have the exact same injured foliage and corroded bark as indigenous trees anchored in the ground, which are supposedly dying from long-term climate-change drought.

At any rate, this first doctor was akin to saintly compared to the next, a researcher at Manhattan's Sloan Kettering who accepted her case, once she was finally diagnosed.  He is conducting a clinical trial, and so alienated from empathy as to be classified borderline sadistic.  He has as much compassion for his patients as he might for microbes he is studying under a microscope.  I suppose that's a prerequisite when you are dealing with people every day, who may not survive, and are traumatized.  But still.

Lesson Two.  Scientists and Doctors have tunnel vision.  They are trained to specialize but in order to do that, they become incapable of thinking outside the box, or of putting their particular research into a broader context in relation to other fields.  In many instances, they don't even want to know about other fields and the influence that might have on their own field (think how climate change physicists refuse to factor the loss of the forest carbon sink into calculations).  Case in point, early on, I asked this new doctor why he thought first daughter might have gotten the cancer.  He shot me a withering look and said, "What difference does it make?  I'm going to treat it the same way!"  Well, I would submit it makes a hell of a lot of difference, but unfortunately although there are enormous sums of money to be made in treating cancer, there is nothing to be made in figuring out what toxic soup is creating so much of it.

When I was growing up, cancer was almost unheard of.  It was a terrifying prospect, but very rare, about as likely an attack as being mauled by wolves or eaten by a shark.  I will never forget when the first mother at my children's school got breast cancer, and died.  Everyone was in complete shock that could happen to someone we knew...someone our age.  Nowadays, is there anybody who doesn't know someone in their inner circle, or maybe several, who hasn't been affected by cancer?

Similarly, when I was young, a favorite pastime was climbing trees.  They were considered to be as sturdy as stones, I never gave a thought to any danger of a branch breaking.  Now, branches break and fall constantly, it is commonplace, we are inured to it.  And still, although there are at last some (by no means all) scientists and foresters who admit trees are dying - because the evidence is incontrovertible and becoming overwhelming - it's almost always blamed on drought, or insects, or diseases or fungus or salt or wind.  Anything but the pollution that is a byproduct of our industrial lifestyle, and the consumption that is so often enabled by exploiting the poorest people in the world, as often as not at the end of a gun.

One scientist who has made the leap wrote an article for the current edition of New Scientist magazine.  Dr. William Laurance, a scientist from Australia, began "Big Trees in Trouble, How the Mighty are Falling" with a quote:


"Going up that river was like travelling back to the earliest beginnings of the world, when vegetation rioted on the earth and the big trees were kings." - Joseph Conrad, Heart of Darkness (1902)

Dr. Laurance surveyed the panoply of invasive species, logging, climate change and so forth, and investigated how those impact ancient large trees.  He cited a variety of studies, including this one from 2007 of Panama and Malaysia, "Decelerating Growth in Tropical Forest Trees".  It warns ominously:   "While the underlying cause(s) of decelerating growth is still unresolved, these patterns strongly contradict the hypothesized pantropical increase in tree growth rates caused by carbon fertilization. Decelerating tree growth will have important economic and environmental implications."

And in 2009, from Costa Rica, researchers reported:  "Tree growth in this Tropical Wet Forest was surprisingly sensitive to the current range of dry season conditions and to variations in mean annual night-time temperature of 1–2°. Our results suggest that wood production in the lowland rainforests of NE Costa Rica (and by extension in other tropical regions) may be severely reduced in future climates that are only slightly drier and/or warmer."

Yet another quote indicating "surprise":


"Long-term studies in Africa, Central America and the Amazon have shown many large trees succumbing to severe droughts. Many ecologists are surprised at just how devastating droughts can be for big trees. 'Old trees must have survived numerous droughts over the centuries, but more recent, harsh droughts are killing lots of them,' says Richard Condit of the Smithsonian Tropical Research Institute in Panama."

Exactly - they must have survived numerous droughts over the centuries!!  No wonder the ecologists are surprised they are dying - and so sensitive to drought.  I went to Costa Rica in June of 2010, and I personally saw that even on a fancy, meticulously maintained resort, where all the shrubs and trees are watered as well as of course all the ornamental flowers in pots, every plant had symptoms of exposure to ozone.  You can see pictures here - and another post about foresters reluctantly recognizing global tree death here, if you can't get your fill.  The next picture shows just how tough and resilient trees are:

Naturally I wrote Dr. Laurance my usual letter asking why ozone didn't make the cut in his litany of tree threats, and he was kind to reply:

"Thanks for your message.  That’s a very good point to make—I only wish it had occurred to me when I wrote the article.  The fact that sulfur dioxide pollution has generally declined in places like the eastern US and Europe made me think air pollution impacts on trees had waned somewhat.  But on reflection I think you are quite right, as there are many other pollutants (e.g. ozone) out there that might predispose trees to opportunistic pathogens or pests."

"I’m hoping my article will begin to sensitize people to be more aware of the potential dangers for trees, especially the big, long-lived ones."

So that was decidedly nice except that he doesn't seem prepared to actually do much of anything about it.  Perhaps he thinks the problem is limited to old-growth trees, and doesn't perceive it as an urgent existential threat to all ages of trees...because he wished me luck and ended by suggesting that I ought to "alert journalists and environmental organizations" !!! - as if there's anything else I do, day in day out!

However, in a 2009 paper, "Widespread Increase of Tree Mortality in the Western United States", the authors explicitely ruled out old age as the source, and report that young trees are dying as well.  Here are two of their graphs:

They ruled out other natural, biotic causes - insects and disease - and conclude "...our results are inconsistent with a major role for endogenous causes of increasing mortality rates. Instead, the evidence is consistent with contributions from exogenous causes, with regional warming and consequent drought stress being the most likely drivers."  They say "most likely" because 1.  they have no other explanation which is because 2.  they didn't consider ozone, even though the western US is constantly receiving increasing doses of pollution from China.

Description of the above graph:  "Locations of the 76 forest plots in the western United States and southwestern British Columbia. Red and blue symbols indicate, respectively, plots with increasing or decreasing mortality rates. Symbol size corresponds to annual fractional change in mortality rate."

Pine trees going bare.

Equally compelling is newly published research about the boreal forest in Canada, whose principal author, Dr. Peng, is from the University of Montreal.  I couldn't obtain the original paper so he generously emailed me not one, but two.

One of the reasons these papers are so fascinating is that he and his colleagues from China selected a huge number of plots, choosing only those not influenced by insects or impacted by wildfire.  Thus, they too believe the primary variable affecting the 96 forest permanent sampling plots they included to be drought from climate change.  Their sampling was based on two periods of measurements, the first census from 1963 to 1994, and the second from 1990 to 2008, so it's quite a large timeframe.

The measurement of carbon sink is important to Canada because they want to be able to use their vast forests to count in international negotiations over emission reductions.  As far as I can tell, any notion that background tropospheric ozone might be influential is not reflected in the papers, nor is there any recognition of the well-established fact that ozone leads to a reduction in root systems, which in turn leads to greater susceptibility to drought.

The first paper, published in Nature Climate Change in November 2011 is titled, "A drought-induced pervasive increase in tree mortality across Canada's boreal forests" and says:

"Our results showed that mortality rates increased significantly in 83% of the PSP's, including 91% of these plots in western Canada, and 62% of the plots in eastern Canada...Mortality rates also increased for small, medium and large trees, and at low, medium and high elevations...All four [of the most abundant species] showed increasing mortality rates, as did trees of all the remaining species."

Gawd!  How often have I been ridiculed for saying: all species of trees, of all ages, in all habitats are dying?  And yet that's exactly the trend they discovered.  Minus any insects.  Hm.

This is a magnificent old sycamore.  The trunk, sadly, is infested with cankers.  These fungal lumps are like malignant tumors that will expand wildly, girdling the tree and swiftly killing it.

The authors speculate on why the scientific community has failed to account for the loss of forests as carbon sinks in climate modeling (another observation that has embroiled me in controversy):

"...both because data on tree mortality over large areas are expensive and are therefore not widely available, and because the physiological mechanisms of drought-induced tree mortality are still poorly understood."

This is really quite astonishing when you think about it.  Clearly, if a drought is severe and prolonged enough, it will kill trees.  And yet these researchers - and the folks in New England speculating about the decline of sugar maples - simply assume, with NO EVIDENCE other than correlation, that climate change drought is killing trees...even though they really don't even know how that might work.  Yet they cling to the idea, ignoring the fact that trees are experiencing increased mortality in areas where there hasn't been drought, AND there exists abundant evidence that ozone is toxic to vegetation, plus that it makes plants more vulnerable to drought - oh, and the background levels of ozone are inexorably increasing.  Now, that is a glaring omission that is just bizarre.

Everywhere around the park there are stumps from dead and dying trees that have been cut down.

Wait you say, isn't air pollution improving?  According to this study from 2000 (and many others since, ho hum), while episodic high peaks have decreased, the constant background level is increasing.  This Harvard team doesn't get into it explicitly, but it's quite possible that chronic exposure without any period for recovery is far worse for trees than occasional, transitory highest peak levels.  The paper is titled "Increasing background ozone in surface air in the United States":

Several trees are marked with orange tape for removal.

"Ozone concentrations have decreased at  the  high end of the probability distribution (reflecting emission  controls) but  have  increased  at  the  low  end.  The  cross-over  takes place between the 30th and 50th percentiles in May-August and between the 60th  and 90th  percentiles during the rest of the year. The increase is statistically significant at a 5% level in spring and fall, when it is 3-5  ppbv. The maximum increase is in  the  Northeast.  A  possible explanation  is an increase in the O3 background transported from outside the United  States....Although  Altshuller and Lefohn [him again!] view this background as natural, there is in fact good evidence that  it  includes a major  anthropogenic component associated with intercontinental transport of pollution. The lifetime of O3 in the free troposphere is sufficiently long (several weeks) that anthropogenic  O3 pollution can circumnavigate the  globe and  enhance O3  over the  entire  northern midlatitudes belt."

Along one side of the park is the unfortunately placed freeway, Route 287.  When I first started walking in this park, 30 years ago, it was disappointing that the roar of the cars and trucks marred the tranquility of the gardens.  But the noise was the only way you would know it was so close, even in winter.  There was no hint through the thicket of trees and shrubs that a road was there.  Now, so much has died away that the straight line of the shoulder is plainly visible.

Keep in mind this paper used data up to 1998, and the background level has been continuing to increase, not just from the fuel emissions from China, but the increasing emissions of reactive nitrogen from crop fertilization, and methane, both precursors to ozone, neither of which are regulated.  Their impact on the environment and contribution to ozone formation is thus potentially grotesquely underestimated.  For example, see this amazing terrifying report about methane leaks, "The emission of methane from natural gas activities includes both purposeful venting of gas and accidental leakage.  The exact magnitude remains somewhat uncertain, but despite industry assertions, most estimates for both conventional natural gas and shale gas fall in a reasonably narrow range...any of these estimates are cause for alarm, and the lowest numbers are clearly biased, or in error..."  And that's not even considering the melting of the permafrost and release of methane in the Arctic due to climate change, which has been declared a planetary emergency.

More trees designated to meet the chainsaw.

It is ceaselessly perplexing that there is no recognition that trees exposed to ozone are more vulnerable to drought.  This can be extrapolated from the fact that their root mass shrinks.  Here's a lovely quote I had posted over on the DeadTrees...DyingForests website:  "The most curious result obtained appears to me to be that relating to the effect of a highly ozonized atmosphere upon the roots of plants." – M. Carey Lea, 1864".


Yep, that's right.  It's been known for well over a hundred years that ozone shrinks rootmass, and yet foresters studying tree decline and comparing it to temperature and drought NEVER make the connection!  Consider - there are trees on earth that have lived for over 7,000 years.  Surely they have survived many droughts over the millennia.  What hasn't been a significant influence in the atmosphere before...what's different now, in this fraught moment in geologic time when a massive, rapid die off is occurring...is tropospheric ozone.

The second version of this paper, published in January in the Proceedings of the National Academy of Science, is attributed to the same authors but edited by Steven Wofsy, a Harvard professor who fervently claims Eastern forests are "growing strong".  The same data is referenced, but the emphasis is altered.

Lichens on rocks!

Compare the title of the first:

"A drought-induced pervasive increase in tree mortality across Canada's boreal forests"

which, remember, says the following:

"Our results showed that mortality rates increased significantly in 83% of the PSP's, including 91% of these plots in western Canada, and 62% of the plots in eastern Canada...Mortality rates also increased for small, medium and large trees, and a low, medium and high elevations...All four [of the most abundant species] showed increasing mortality rates, as did trees of all the remaining species."

Whereas the later, Wofsy-edited iteration is titled:

"Regional drought-induced reduction in the biomass carbon sink of Canada's boreal forests"

and interprets the date like this:

"Our analysis shows that the rate of biomass change for all plots combined and for the western region showed significant decreasing trends, but there was no significant change for the eastern region."

Caption for this graph:  "Locations of the 96 Forest PSP's in Canada's boreal forests.  The black and red circles represent plots with decreasing and increasing mortality rates, respectively.  The circle size corresponds to the magnitude of the annual change in mortality rates."

Personally, I see an awful lot of red circles in the Eastern section, and what's more, there are simply fewer sample plots in the Eastern section, which could skew the comparison to the western area.

The above graph comparing Eastern (pink) and Western (blue) increases in mortality rates was omitted from the second paper.  What it shows is that the increase in mortality is faster in the west, however the upward trend in the East, although not as steep a trajectory, is still pronounced.  I find this anything but reassuring, and certainly not "insignificant"!  A trend is a trend.

I'm also not quite sure how "no significant change" can be reconciled with the many reports that sugar maples are dying off, supposedly from drought from climate change, because the vast majority of them are in Eastern Canada and US, and they often dominate the forests there.  In any event, it seems the trend revealed by both regions, and other places all over the Earth, is indicative of a march towards disaster.  There dataset stopped in 2008, which happens to be the year that I noticed a dramatic and abrupt decline begin, so that isn't reflected in the survey.  This lack of recent data is reminiscent of a study published by the Smithsonian Institute Research Institute in Maryland, reporting that Eastern forests are growing faster.  It took a while to extract the information, but it turned out that the data they relied upon for their assessment ceased in 2007.  There's a somewhat comical account of my attempt to do a more current followup the same forest they studied at their plot, in April 2010 (but only if you want to massively digress).

Another stump

By way of illustration of just how pig-headed this fixation on drought is (unless it's a ruthlessly deliberate attempt to withhold frightening statistics, who knows?), following are links, chosen pretty much at random, to just a few from the avalanche of studies about the damage done to annual crop yield and quality, from researchers all over the world, with their abstracts.  There is a dizzying number of others, just go to the "related articles" column on the right of any link and you will be down the rabbit's hole.

By the sheer volume of studies dating back decades, it ought to be evident that there has been a serious problem for some time, and that it is inevitably worsening as more and more precursors are emitted by a growing population living a more polluting lifestyle.  The critical question to ask, since ozone diminishes annual plants so badly, is what does it do to trees that are exposed to cumulative injury season after season, for years?  If you slog all the way to the end, there's very pretty little video that will help you forget everything you've read here!

Yes, this is a pine tree.

1982, the UK,  Effects of air pollutants on agriculture and forestry
Abstract:  Historically, studies of the effects of the main phytotoxic gases (SO₂, O₃, NOx and HF) have focused on determining the threshold for onset of visible foliar injury.  More recently, research has focused on determining the thresholds for effects on economically important yield parameters irrespective of foliar injury. The implication is that long-term seasonal or annual standards may be required to prevent yield losses particularly for the primary pollutants in diffuse-source regions and for secondary pollutants. This paper reviews the literature on thresholds for yield effects of SO₂ and O₃ and concludes that

1.(a) the current EEC standard for SO₂ is adequate to protect most crops and trees and

2.(b) more work is required to determine whether the U.S.A. threshold for O₃ effects are applicable to the climate and crops of Europe.

Recent results suggest that yield responses vary so much with climatic factors that broad regional standards may not be acceptable. In addition, the effect of one phytotoxic gas must now be assessed against the background of the other gases.

Future research on effects of SO₂ and O₃ in particular, will be increasingly influenced by the use of cost-benefit analysis in the regulating process and the consequent demand for dose-response relationships. This approach is fraught with difficulty and particular problems arise

1. when ‘hypothetical’ relationships are assumed in the absence of good data and

2. when the linearity of dose-response relationships are presumed to justify the extrapolation from effects at high concentrations to lower ambient concentrations.

The evidence for nutritional effects of low levels of SO₂ and NOx abrogates this assumption and suggests that for some gases at least, there should be a threshold below which no detrimental effects occur. This paper reviews the recent work aimed at producing dose-response relationships for economically important yield parameters.

1983, Brookhaven National Laboratory - Quantifying effects of oxidant air pollutants on agricultural crops

Abstract:  Estimating risks of air pollution damage to agricultural crops requires identifying crop location and size, likely doses, models for translating dose to response, and measures of response appropriate for economic analysis. Assessment of risk requires compatible data sets for each of these variables. Analysis of air pollution mixtures suggests that oxidant crop damage is caused by three compounds: ozone, nitrogen oxides, and peroxyacetylnitrates. The phytotoxicity of ozone, the most prevalent photochemical oxidant, has been studied more extensively than the other two oxidants, and its effects on vegetation are best understood. Response of vegetation to air pollutants was first characterized by foliar or visible injury. Subsequent research indicated that foliar injury did not translate directly into reduced plant growth or yield, which can be measured. Response to air pollutants may be influenced by physical, biological, and environmental factors. Inherent genetic resistance is probably the most important single factor affecting plant response, although environmental factors influencing stomatal aperture may also be important. For several crops open-top chamber studies and cross sectional analyses of field data provide adequate information to develop dose-response functions. All of these studies have both strengths and weaknesses. Although a number of different models exist for selected crops, there is no single biological or statistical criterion which identifies the best or most accurate model.

1986 US EPA - The Impact of Ozone on Agriculture and its Consequences

Abstract - Given its high level of phytotoxicity and distribution of elevated concentrations over broad geographic areas, O3 is considered the most critical air pollutant affecting vegetation in the United States. Diverse experimental methods have been used to assess the impacts of O3 on the crop yield. Comparisons of plant growth and yield in charcoal-filtered or unfiltered air and the use of chemical protectants show that ambient O3 levels will reduce the growth and yield of numerous plant species. Ozone studies in open-top field-exposure chambers have provided exposure-response functions needed to evaluate the economic impacts of O3 on agriculture. Exposure-response functions have been developed for a range of legume, grain, fiber and horticultural crops. Yield reductions (10%) were predicted for several crop species when the 7-hr seasonal mean concentration exceeded 0.04 to 0.05 ppm. for some sensitive cultivars of wheat, kidney bean and soybean, 10% yield reductions occurred at 7-hr mean concentrations of 0.028 to 0.033 ppm. Recent studies, using exposure-response functions developed in open-top chambers, have attempted to assess the national economic consequences of O3 effects on agriculture. These studies indicate that elevated O3 concentrations are costing U.S. agricultural producers and consumers between 1.2 and 2.4 billion dollars annually.

1987 - U CA, Air pollutant yield-loss assessment for four vegetable crops
Abstract:  Crop loss was evaluated for leaf lettuce, green onion, turnip and beet in a field chamber system using a gradient of ambient pollutants. The nine-chamber gradient had air flows adjusted to filter pollutants to 100, 90, 80, 70, 60, 50, 35, 20 and 0% of ambient or ambient plus added ozone. Dose-response functions were calculated for the four crops using both a 12-h seasonal mean dose statistic and a 0.10 μl l−1 threshold dose summary. Yield-loss functions were generated from yield equations. Crop yield-loss functions for green onion, turnips and beets were significant with 12-h seasonal mean ozone dose. Yield-loss functions based on the 0.10 μl l−1 threshold were significant for onion, lettuce and beets. Multiple regression analysis using both dose summary statistics did not produce a better predictive model of yield loss for any of the four crops examined.

The pussywillows are out!

1989, Germany - Current Knowledge of Ozone on Vegetation/Forest Effects and Emerging Issues

Abstract:  In consequence of increased emissions of nitrogen oxides and reactive hydrocarbons as precursor substances as well as in respect of phytotoxicity, range of concentration and spatial distribution, ozone is today the most important phytotoxic component among photochemical oxidants and besides sulfur dioxide probably the most important air pollutant in Europe today. While its importance to forest decline was first discovered in California 25 years ago, new impetus in effects research was caused by the appearance of novel forest decline in Europe and United States of America. Former research was emphasizing more the acute effects, especially in connection with agricultural and horticultural crops. Now, the central point of discussion are chronic effects. By this, the problem has become increasingly difficult, since other environmental stresses, such as pathogenes, soil, and climate very often mimic ozone effects under field conditions.

Given that winter neglected to arrive this year, I thought this admonition was funny!

1993, Pakistan - Air pollution and its impacts on wheat yield in the Pakistan Punjab

Abstract:  A study using open-top chambers ventilated with ambient or charcoal-filtered air in the vicinity of Lahore, Pakistan, has demonstrated a reduction of 46·7% and 34·8% in the grain yield for two cultivars of winter wheat (Triticum aestivum L.). The 6-h daily mean O3 concentrations were 25–45 nl litre−1 and on the basis of experience in North America and Europe, reductions in yield in the present study are substantially greater than might be predicted. The reasons for this discrepancy are discussed, together with implications for the suitability of a simple, relatively cheap, open-top chamber system for developing-country studies on the effects of air pollution on crops.

2000 Italy, Spain, Belgium - Evidence of ozone-induced adverse effects on crops in the Mediterranean region
Abstract:  The impacts of ambient ozone pollution on crops in the Mediterranean countries have been recorded regularly in the so-called “grey literature” of UN/ECE Workshop Reports for the Convention on Long-range Transboundary Air Pollution, and less frequently in the peer-reviewed literature. This short communication reviews such records and shows that ambient ozone episodes have been reported to cause visible injury on 24 agricultural and horticultural crops grown in commercial fields including three of the most important crops in the region (wheat, maize, and grapevine). On one occasion, the damage was so extensive that complete crop loss occurred in commercial glasshouses of Butterhead lettuce in one area of Greece. Experiments with open-top chambers have indicated that ambient ozone caused 17–39% yield loss in crops such as wheat, bean, watermelon and tomato.

2007 Wood's Hole, MIT - Impacts of ozone on trees and crops
Abstract:  In this review article, we explore how surface-level ozone affects trees and crops with special emphasis on consequences for productivity and carbon sequestration. Vegetation exposure to ozone reduces photosynthesis, growth, and other plant functions. Ozone formation in the atmosphere is a product of NO_x, which are also a source of nitrogen deposition. Reduced carbon sequestration of temperate forests resulting from ozone is likely offset by increased carbon sequestration from nitrogen fertilization. However, since fertilized croplands are generally not nitrogen-limited, capping ozone-polluting substances in the USA, Europe, and China can reduce future crop yield loss substantially.

2008 Italy, UK, Austria - The global impact of ozone on agricultural crop yields under current and future air quality legislation
Abstract in part:  Translating these assumed yield losses into total global economic damage for the four crops considered, using world market prices for the year 2000, we estimate an economic loss in the range $14–$26 billion. About 40% of this damage is occurring in China and India. Considering the recent upward trends in food prices, the ozone-induced damage to crops is expected to offset a significant portion of the GDP growth rate, especially in countries with an economy based on agricultural production.

Bees - on the first of February!

2010 Princeton U - Global crop yield reductions due to surface ozone exposure: 1. Year 2000 crop production losses and economic damage
Abstract:  Exposure to elevated concentrations of surface ozone (O₃) causes substantial reductions in the agricultural yields of many crops. As emissions of O₃ precursors rise in many parts of the world over the next few decades, yield reductions from O₃ exposure appear likely to increase the challenges of feeding a global population projected to grow from 6 to 9 billion between 2000 and 2050. This study estimates year 2000 global yield reductions of three key staple crops (soybean, maize, and wheat) due to surface ozone exposure using hourly O₃ concentrations simulated by the Model for Ozone and Related Chemical Tracers version 2.4 (MOZART-2).  Our results indicate that year 2000 O₃-induced global yield reductions ranged, depending on the metric used, from 8.5–14% for soybean, 3.9–15% for wheat, and 2.2–5.5% for maize. Global crop production losses totaled 79–121 million metric tons, worth $11–18 billion annually (USD₂₀₀₀). Our calculated yield reductions agree well with previous estimates, providing further evidence that yields of major crops across the globe are already being substantially reduced by exposure to surface ozone – a risk that will grow unless O₃-precursor emissions are curbed in the future or crop cultivars are developed and utilized that are resistant to O₃.  [note - crop cultivars developed to be resistant to ozone, even assuming it's possible to do so, will do exactly nothing to save indigenous plants and forests!]

from the contents: (uploaded to googledocs)

"Surface ozone (O3) is a major component of smog, produced in the troposphere by the catalytic reactions of nitrogen oxides (NOx NO ␣ NO2) with carbon monoxide (CO), methane (CH4), and non-methane volatile organic compounds (NMVOCs) in the presence of sunlight. In addition to having a detrimental effect on human health, field experiments in the United States, Europe, and Asia demonstrate that surface ozone causes substantial damage to many plants and agricultural crops, including increased susceptibility to disease, reduced growth and reproductive capacity, increased senescence, and reductions in crop yields. O3 penetrates leaves through the stomata, where it reacts with various compounds to yield reactive odd-oxygen species that oxidize plant tissue and result in altered gene expression, impaired photosynthesis, protein and chlorophyll degradation, and changes in metabolic activity."

"Based on the large-scale experimental studies of the National Crop Loss Assessment Network (NCLAN) conducted in the United States in the 1980s, the U.S. Environmental Protection Agency estimated that the yields of about one third of U.S. crops were reduced by 10% due to ambient O3 concentrations during this time. Results from the European Open-Top Chamber Programme in the 1990s similarly suggest that the European Union may be losing more than 5% of their wheat yield due to O3 exposure. Although comparable large-scale studies have not been conducted in developing countries, the potential risk of ambient O3 exposure to agricultural production has been documented through both small-scale field studies and modeling efforts in East Asia, the Indian subcontinent, Egypt, and South Africa."

"With over one billion people in the world currently estimated to be undernourished, the impact of O3 pollution on present-day and future global food production deserves attention. This is especially true as both population and O3-precursor emissions are projected to increase in most developing nations over the next few decades. Rising emissions of O3-precursors in these countries pose a risk to not only their national and regional food security but also to global food production as O3 and some of its precursors are sufficiently long-lived to be transported between continents."

public policy implications:

"Our study highlights the need for such a secondary O3 standard, with O3-induced agricultural losses already estimated to cost an annual $11e18 billion globally and over $3 billion in the U.S. alone. For context, these damages are 2-3 times larger than estimated global crop losses due to climate change since the 1980s ($5 billion annually). While the selection and development of crop cultivars with O3-resistance is therefore a worthwhile addition to efforts to increase crop resilience to climatic stresses, strategies aimed at mitigating global O3 concentrations would provide additional co-benefits for human health and climate change. Ozone is a noxious air pollutant in the troposphere and the third most potent greenhouse gas after carbon dioxide and methane. Reductions in CH4 in particular have been shown to decrease surface ozone concentrations globally with significant health benefits while also generating the largest net reduction in radiative forcing of all the O3-precursor species."


[note:  "Our study highlights the need for such a secondary O3 standard..." is precisely what Obama told the EPA they can't do!]

Comparison of regionally-averaged monthly mean surface ozone concentrations from monitoring sites (black diamonds) and MOZART-2 (grey squares).

Following is their companion paper, which compares models of future crop loss based on different amounts of ozone pollution.

2010 Princeton - Global crop yield reductions due to surface ozone exposure: 2. Year 2030 potential crop production losses and economic damage under two scenarios of O₃ pollution
Abstract:  ...Because our analysis uses crop data from the year 2000, which likely underestimates agricultural production in 2030 due to the need to feed a population increasing from approximately 6 to 8 billion people between 2000 and 2030, our calculations of crop production and economic losses are highly conservative. Our results suggest that O₃ pollution poses a growing threat to global food security even under an optimistic scenario of future ozone precursor emissions. Further efforts to reduce surface O₃ concentrations thus provide an excellent opportunity to increase global grain yields without the environmental degradation associated with additional fertilizer application or land cultivation.

Total crop production loss, left panels, and economic, right, under the 2030 A2 scenario

Highlights: (full text on googledocs)  ► Surface O₃ will have an increasingly detrimental impact on future crop yields. ► Yields of wheat, soybean, and maize could be reduced by up to 26% globally in 2030. ► Global losses up to 17% are possible even in an optimistic scenario of future O₃. ► Agricultural losses worldwide may be worth $17–35 billion annually by 2030.

2010 Greece - Economic damages of ozone air pollution to crops using combined air quality and GIS modelling
Abstract:  This study aims at presenting a combined air quality and GIS modelling methodological approach in order to estimate crop damages from photochemical air pollution, depict their spatial resolution and assess the order of magnitude regarding the corresponding economic damages. The analysis is conducted within the Greater Thessaloniki Area, Greece, a Mediterranean territory which is characterised by high levels of photochemical air pollution and considerable agricultural activity. Ozone concentration fields for 2002 and for specific emission reduction scenarios for the year 2010 were estimated with the Ozone Fine Structure model in the area under consideration. Total economic damage to crops turns out to be significant and estimated to be approximately 43 M€ for the reference year. Production of cotton presents the highest economic loss, which is over 16 M€, followed by table tomato (9 M€), rice (4.2 M€), wheat (4 M€) and oilseed rape (2.8 M€) cultivations. Losses are not spread uniformly among farmers and the major losses occur in areas with valuable ozone-sensitive crops. The results are very useful for highlighting the magnitude of the total economic impacts of photochemical air pollution to the area’s agricultural sector and can potentially be used for comparison with studies worldwide. Furthermore, spatial analysis of the economic damage could be of importance for governmental authorities and decision makers since it provides an indicative insight, especially if the economic instruments such as financial incentives or state subsidies to farmers are considered.

These gaping holes that leak fluid have become ubiquitous.

One of the most interesting symptoms of decline is this corrosion of bark.  It becomes uncharacteristically rough, breaks up in patches or ribbons, and ultimately falls off.  I don't know if it's from an internal process, or actually from caustic action on the surface.  The trunks look like they've had acid thrown on them.

2010 NASA - An investigation of widespread ozone damage to the soybean crop in the upper Midwest determined from ground-based and satellite measurements

Abstract:  Elevated concentrations of ground-level ozone (O3) are frequently measured over farmland regions in many parts of the world. While numerous experimental studies show that O3 can significantly decrease crop productivity, independent verifications of yield losses at current ambient O3 concentrations in rural locations are sparse. In this study, soybean crop yield data during a 5-year period over the Midwest of the United States were combined with ground and satellite O3 measurements to provide evidence that yield losses on the order of 10% could be estimated through the use of a multiple linear regression model. Yield loss trends based on both conventional ground-based instrumentation and satellite-derived tropospheric O3 measurements were statistically significant and were consistent with results obtained from open-top chamber experiments and an open-air experimental facility (SoyFACE, Soybean Free Air Concentration Enrichment) in central Illinois. Our analysis suggests that such losses are a relatively new phenomenon due to the increase in background tropospheric O3 levels over recent decades. Extrapolation of these findings supports previous studies that estimate the global economic loss to the farming community of more than $10 billion annually.

One last thing, harkening back to an earlier post about the Nitrogen Cascade, here's another graph from the review by UNEP and Woods Hole Research Center "Reactive Nitrogen in the Environment", with the description beneath, estimate the costs of pollution around the Chesapeake Bay, including to forests.

description:  "Diagram of economic nitrogen cascade, illustrating the damage costs associated with nitrogen from each source type as it cascades through the various systems in the watershed. Cost estimates in boxes are the estimated costs per tonne of nitrogen emitted by each source type for each ecosystem type. Monetarized costs include reduced recreational and residential visibility, mortality, hospitalization and work loss caused by particulate and ozone exposure, materials damage via corrosion, loss in agricultural productivity due to ozone exposure, reduced crab fisheries and impacted recreational use.  These costs are summed for each source type to provide a total economic damage estimate (in monetary terms) for each source type. In addition to the monetary damage estimates, the types of economic damage for which monetary estimates were not available are also identified, including nine such types of damage for nitrogen from energy production and seven types each for food and fibre production and wastewater."

Finally now - the sweet, happy video - as promised!