Thursday, June 28, 2012

The Inferno Ignites

The ability of humans to deny the obvious seems infinite and immutable.
a tweet
In the wake of the humongous and unmitigated fail at Rio+20, the inscrutable editors at Climate Progress, in keeping with its breezy new, insouciant incarnation, attempted to wring something positive from the shambles with a post that read, in virtual vaudeville:

"The Climate and Clean Air Coalition brings together partners to apply already-existing solutions to cut short-lived climate pollutants that will cut in half the rate of global warming in the near-term. Short-lived climate pollutants (SLCPs) — such as black carbon, soot, methane, hydrofluorocarbons (HFCs), and tropospheric ozone — are shorter lived than carbon dioxide, but much more potent and account for around one-third of global warming. Some of these potent greenhouse gases are deadly: Each year millions of people die prematurely and more are diagnosed from a high incidence of dangerous respiratory disease.  They also accelerate melting of the Arctic and are responsible for extensive crop losses each year."

Naturally, even though this proposal has frequently been shunned by scientists who are generally speaking blinded to pervasive effects of ecological destruction by their obsession with CO2-driven warming, I was very glad to see ozone impacts given some credence on a climate blog, and especially pleased that somebody thought to include the fact that ozone pollution is "...responsible for extensive crop losses each year".

Specifically, the UNEP report referred to says:  

"Increasing crop yields
Feeding a growing world population has become one of the major issues of our century and we cannot afford to lose millions of tons of crops each year because of air pollution. Present day global relative yield losses due to tropospheric ozone exposure range between 7-12 percent for wheat, 6-16 percent for soybean, 3-4 percent for rice, and 3-5 percent for maize . In addition, black carbon influences the formation of clouds that have a negative effect on photosynthesis that impacts plants growth. Rapidly reducing short-lived climate pollutants, for instance through the collection of landfill gas or the recovery of methane from coal mines, has the potential to avoid the annual loss of more than 30 million tons of crops."

That last sentence is so stupid - we should reduce pollutants through the collection of landfill gas or recovery of methane from coal mines?  Surely, those sources represent such an infinitesimal drop in the bucket they're not even worth singling out for mention!  So why bother?  OH, silly moi - so we don't have to talk about what REALLY needs to happen, like a cessation of international shipping, air travel, and long commutes in single-passenger vehicles?

If we're losing 30 million tons of crops annually (which is no doubt an obscene underestimate, because by way of one example, they're only counting major staple grains, corn and soy - not annual yield from perennial sources like...artichokes, strawberries, asparagus, rhubarb, apples, peaches, pears, coconuts and pecans, etc.) then a valid question would seem to be how many tons of wild plants are we losing?  How many trees?  How long has Wit's End been predicting unprecedented, uncontrollable wildfires??  (...and landslides - but that's another story...)

I hope I will be forgiven for posting pictures of the fires, because it's been a particular fear for me ever since I noticed that trees are dying.  My little farm is surrounded by woods swiftly turning into kindling.  We may soon require a new word to describe these uncontrollable wildfires.  Pyrocide?  WildInfernos?  I suppose it shouldn't be a surprise that wildfires aren't attributed to forests dying from ozone, when we are still seeing prodigiously idiotic research published like "Reckoning Wheat Yield Trends".   This analyzes the supposed "mystery" of a decline in the increase of wheat yield, especially in places where it should be growing, which is reviewed uncritically in Environmental Research Letters by the apparently credulous David Lobell.  Don't professors at Stanford read the research from professors at Princeton?  Apparently not.  Here's his summary of the four prime "suspects" examined in the paper: 
This is a Perspective for the article 2012 Environ. Res. Lett. 7 024016
In Lewis Carroll's Through the Looking Glass, Alice finds herself running as fast as she can but not moving anywhere. The Red Queen explains to her 'Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that.'
Such is the situation in global agriculture. Global demand for agricultural products continues to rise as population grows and people get richer. As they get richer, people have fewer babies but eat more. And they use a lot more energy, which is increasingly derived from agricultural products. Crop technologies have to move incredibly fast just to keep up. Remarkably, over the past 50 years they have, with yields (production per hectare of land) for most crops more than doubling since 1960, and real prices of food falling for most of the period. In many ways we have come to take continued yield growth for granted. But, as Lin and Huybers show [1] elsewhere in this issue, there is increasing evidence that this growth has stalled in many regions. 
The question is not new—people have worried about the pace of yield growth since at least the days of Malthus [2, 3]. But Lin and Huybers [1] use updated data and bring a new rigor to identifying where stagnation is statistically significant, for example by taking care to account for year-to-year correlation in yields. They report that for slightly more than half of the regions that they inspected, it is likely (80% chance) that yield growth has already flattened out. For many of these countries, responsible for about one quarter of global wheat production, the stagnation has very likely occurred (95% chance).
Why are yields of wheat stagnating in so many areas? At least four suspects seem plausible. One narrative is that for years the real price of wheat was declining, providing little incentive for innovation. The most obvious consequence was a major decline in investment in research and development in most regions. The recent rise in prices has reversed the decline, but technologies take a long time to develop and get adopted [4]. So yield increases are in the pipeline but have not arrived yet. 
A second narrative relates to farm policy. Farmers always have an incentive to improve profits, but this does not always mean raising yields, especially if policies encourage reducing input use. In Europe, where much of the stagnation identified by Lin and Huybers [1] is found, fertilizer rates have actually declined in recent years in response to policies. One line of evidence in support of this narrative is that total factor productivity appears to be rising steadily in many regions, including Europe, even as yields have stagnated [5].
A third story relates to biophysical limits. This narrative declares that the genetic potential of crops has not improved for a long time, and most yield growth in the past two decades was related to agronomic improvements [6, 7]. But once average yields approach genetic potential, it becomes very difficult to further raise yields, and yields will be stuck regardless of price until innovation raises genetic potential [8]. If innovation is simply a function of prices, then this story folds into the first, but it could also be that returns on breeding are becoming much harder to achieve relative to the transformative effect of dwarfing genes and rust resistance that occurred in the last century.
In the fourth corner is climate change. As Lin and Huybers [1] discuss, many of their stagnating countries have experienced adverse climate trends in the past few decades. Wheat has the lowest temperature optimum of any major crop, and has been among the most affected by climate change so far [9]. So maybe the stagnation is a sign of worse things to come. Interestingly though, they find stagnation even for Northern European countries where recent warming is more likely to have helped than hurt yields [10]. 
The easy answer is that a combination of these factors is to blame. The real answer is we do not yet know which of these, if any, are the most important. The implications of each for future research and policy are quite different, and so working out a clearer picture is an important task. The efforts of Lin and Huybers [1] provide a useful fingerprint on where and when stagnation has occurred. Now it is time to figure out which of the suspect's fingerprints is a match.
It simply infuriates me that ozone wasn't even on the list!  More research is needed - Auuuuuggghhh!  It's a beautiful day and I'm stuck inside correcting people who should know way better than I do that, moving on from crops to trees, it's obvious - isn't it? - that if annual crops can have yields reduced by 17%, then the cumulative damage to trees exposed season after season must be significant, if not fatal.  Certainly enough to weaken their immunity to opportunistic attacks from insects, disease and fungus.

Wait I'm taking my laptop out to the porch...that's better.

Since I returned to New Jersey I decided to explore two local parks I have never been to before, knowing that I would be able to obtain pictures that illustrate this trend.  Sure enough both were rife  with the usual symptoms - cankers, holes, BALDing (bark atrophy lichen decline), injured foliage (and it's only June!), thin crowns, snapped or bowed trunks...and a staggering number of broken branches lying on the forest floor, crinkled leaves still attached, plus, a strange new apparition - albino leaves.

Round Mountain Preserve is an island of old-growth forest bordered on one side by the tiny village of Stanton.
The surrounding fields and hills are bucolic and to your average passer-by must look enchanting.
But a closer scrutiny of the hedgerows reveals that many of the trees have no leaves at all.
The closer you get, the more the devastation is revealed.
It's impossible to know how many completely dead trees have already been removed.
But it is accurate to note that NONE of the crowns of either deciduous or evergreen trees are full and healthy.
This is true for every single species.
This manicured property is likely meticulously pruned, but that cannot keep the lichen at bay.
Lichen coverage this complete is a certain harbinger of imminent death.
On this maple, it extends all the way up the trunk and smothers the branches.
Below is a maple tree in the park.
The bark pops off easily, where underneath insects and fungus are feasting.  Basically, there isn't a tree around here that isn't similarly decayed.
Once I started to hike up the trail in the park, I came upon this sign.  When I got home, I called the number, which turned out to belong to the Hunterdon County Parks Department (heh, just named in the top five wealthiest US counties, for what it's worth!), to ask what "Forest Management Area" meant, and why so many trees were marred with neon orange paint.
The woman on the phone became very flustered and at first averred she knew nothing about it.  Finally, she assured me several times that "nothing was going to happen there" and "that sign is going to be removed" and "something was planned with the Freeholders but now it's not".  I gave up trying to pry information from her but then, not satisfied, I looked up the number for the  Freeholders - and the lady that answered in their office was a bit more forthcoming.  She told me that a couple of years ago, there had been plans to log the preserve (why do they call it a preserve and then make plans to log it?) which had been abandoned.  In answer to a direct question - because of complaints? - she replied cryptically, yes, many.
My curiosity piqued, I thought if there were that many complaints, there must be a record somewhere so I googled it, which is why I'm writing about it now.  Everybody needs a good laugh, especially us doomers, and this report of a public hearing from the "President's Wooden Desk" of the New Jersey Forestry Association newsletter, called New Jersey Woodlands (as if there would be any left should the Forestry Association have their way) is a real howler.  By the time I got to this line in Mr. Richard Conley's hysterically funny polemic (who is, by the way, a lawyer):  "Some people insulted professional foresters as money-hungry advocates of 'logging,' using the 'L-word' as if it were connected to the potential end of civilization" I was laughing so hard that I truly regret missing that meeting.
It's full of other gems like this:  "Les Alpaugh, a former State Forester and a Director of the New Jersey Forestry Association, criticized the Freeholders in no uncertain terms for canceling the management plan they had previously approved.  Les said the plan had been approved by a qualified forester, the Freeholders adopted the plan because they knew it was appropriate, and they had acted
like typical politicians when they cancelled the contract because members of the public opposed the plan."
I'm sorry...but isn't that what politicians are elected to do?  Represent members of the public?  It was sickening but not unusual to see that one of the biggest members of Gangreen - the Audubon Society - endorsed the L-word in a white paper claiming this so-called "management":  “carefully considers the natural resources of the site and establishes a scientifically valid approach to improve the overall condition of the forest’s health, improve habitat for forest dependent wildlife, and proactively safeguard against present and future ecological stressors.” taking out the nicest, healthiest and largest trees?  I can only imagine how that would delight the bird population that nests there.  Conley finishes with a recommendation for a dvd called "A Working Forest".  The list of sponsors at the website is a handy reference for anyone who want to find some phony environmental organizations that pretend to care about wildlife habitat but really want to chop down trees, or otherwise offer up ridiculous, delusional fake hopey this article featured in Mother Nature Network, "Mining the Moon Could Reap Riches; with billionaire backers."  I kid you not! and MNN has advertisers claiming somehow that Dasani water is good for the Earth.  Oh dear - I'm digressing again.  Back to trees.

Beyond this tale of local controversy is insight into a much larger issue.  To bolster his case that forests require human intervention to thrive, Conley wrote the following:

"A well managed forest will go on forever, while a forest left to its own devices will die and become useless to anyone, as are the pines in Atlantic County where they have lost their needles and are now rotting from the infiltration of pine bark beetles."

He added: "We have recently lost thousands of acres of pine woods in South Jersey because no one had dealt adequately with the pine bark beetle which has devastated the forests in certain areas of this state."

Surely all of us Ozonists and Ozonistas remember that the pine beetle outbreak in the Rocky Mountains is being blamed on winters where subzero temperatures don't linger anymore??  But - were the winters in New Jersey EVER as cold as the Rocky Mountains?  Can temperature from climate change REALLY be the reason bark beetles are spreading or could it possibly be that trees are being attacked by droves of insects and pathogens because they are already unhealthy from absorbing pollution?

Even Wiki says bark beetle is a problem everywhere, not just places that used to be very cold: 

"Bark beetles often attack trees that are already weakened by disease, drought, smog, conspecific beetles or physical damage.  Healthy trees may put up defenses by producing resin or latex, which may contain a number of insecticidal and fungicidal compounds that can kill or injure attacking insects, or simply immobilize and suffocate them with the sticky fluid. Under outbreak conditions, the sheer number of beetles can, however, overwhelm the tree's defenses, and the results can be disastrous for the lumber industry."

That notion - that bark beetles kill healthy trees - is how we are being misled into not understanding the underlying source.  Of all the above reasons listed that underlie bark beetle outbreaks, what is the one and only one that is occurring globally?  That's right...OZONE.
That entry mentions that bark beetles have long been an issue in Bavaria, which happens to be a place long lamented for damage from acid rain and air pollution.  Here are two shocking photographs from yesterday's webcams of the Šumava Forest, where there has been a debate for years over whether to cut the dying trees or allow them to fall on their own:

Foresters who talk about bark beetle in the Rockies never mention that trees are being attacked by fungus spread by various beetles everywhere, regardless of whether conditions are drier or warmer.  That way it seems like a localized issue, not a global pollution problem.  It's exactly the same compartmentalization and specialization that leads to a false separation between the study of ozone and the nitrogen cascade and acid rain, and the brutal dismemberment of ecology as a discipline.

In January of 2010, I wrote a post titled "Scientists Are Egomaniacal Douchebags".  This was the result of extreme frustration from writing fruitless letters to one such forester about trees dying from air pollution, the very same forester who still persists in blaming the insane wildfires on climate change, heat, drought and bark beetles.  Following is a comment I left on one recent story about the conflagrations currently raging:

You won't catch the government or the park service or the forest service telling you this (mustn't spook the herd!) but we are having unprecedented fires and can expect far worse because vegetation is dying off from exposure to air pollution. Many people believe air pollution isn't a problem anymore because the visible component of smog - SOx - has been reduced. However, the background level of invisible tropospheric ozone is inexorably rising, even in rural areas, and it happens to be quite toxic to vegetation, including annual agricultural crops. Trees that have cumulative injury are more vulnerable to insects, disease and fungus.
Reproduced below is yet another article from the New York Times written by the obstinately obtuse Justin Gillis, appended to the series from last October documenting the decline of forests but never once attributing it to ozone.  Why does he refuse to consider it?  Maybe it would offend the advertisers...
A year ago, I was sitting in a room overlooking the Pacific Ocean with a man named Ralph Keeling. The son of Charles David Keeling, who had discovered the trend of rising carbon dioxide in the atmosphere in the 1950s, Ralph Keeling had become a famous climate scientist in his own right.
We had spent two days on the campus of the Scripps Institution of Oceanography talking about his father’s legacy and his own work, and I finally asked him a simple question: How did his deep knowledge of climate change affect his life? 
He started by assuring me there was nothing paralyzing about it — he managed to get up and drive to work in the morning like the rest of us. But then, with the sun setting behind him into the sea, Dr. Keeling said something that brought me to attention.
“When I go see things with my children, I let them know they might not be around when they’re older,” he said. “‘Go enjoy these beautiful forests before they disappear. Go enjoy the glaciers in these parks because they won’t be around.’ It’s basically taking note of what we have, and appreciating it, and saying goodbye to it.”
I already knew that glaciers were disappearing the world over — but forests? It was news to me, and I resolved in that moment to figure out whether Dr. Keeling was right.
The result was a long article in Saturday’s Times on what appears to be a rising trend of forest die-offs around the world. I used the American West as a case study of the problems, with its twin plagues of bark beetles and catastrophic fires, but I could just as easily have set the piece on any other forested continent.
On all of them, forests are dying, and the underlying factor seems to be water stress caused by rising heat.
Alert readers may have noticed, however, that I did not give any specific numbers for dying forests or their extent, compared with a century or two ago. That is because we simply do not have such historical numbers on a global scale.
As with many other aspects of climate science, the past history of forests is a subject plagued by imprecision. The simple reality is that we have not been watching long and closely enough to have a good handle on the issue.
Scientists are doing their best to fill in the gaps with techniques like tree-ring studies that can detect past fire histories. But only in the era of satellites, the past 40 years or so, do we have global observations that allow us to be reasonably sure of what is happening to the world’s forests. And even the satellite record is a work in progress, involving a lot of interpretation.
My colleagues Jonathan Corum and Matthew Bloch used some of those satellite observations to build an interactive graphic that shows recent forest loss, and I commend it to all readers (start by clicking on one of the continents).
They got particular help from Matthew C. Hansen of South Dakota State University, who has published a paper with some colleagues quantifying recent loss in global forest cover.
Much of that loss came at human hands, of course, as people continued to chop down forests, especially in the tropics. Aside from compiling recent losses, scientists have done a pretty good job of figuring out the boundaries of the world’s forests 8,000 years ago, at the dawn of human civilization. Mr. Corum and Mr. Bloch used that knowledge to build a layer into the graphic that allows you to visualize how much we have destroyed over the long march of time.
Aside from the satellite record, what kind of evidence do we have of recent forest loss? Mainly this: a flood of reports about forest die-offs and die-backs are appearing in the scientific literature. 
A count of such reports by Craig D. Allen of the United States Geological Survey shows a relentless increase in recent years. In principle, that could simply reflect rising interest in the subject on the part of scientists, but most of the experts I talked to suspected that it represented a change in the reality on the ground. 
“It seems to be just too widespread to ignore,” said Steven W. Running, the University of Montana scientist who showed me and a photographer, Josh Haner, around a big chunk of his state as we reported the forest story. (Here are some of Mr. Haner’s fabulous and disturbing pictures.)
“That doesn’t mean that every forest on earth is going to fall over dead,” Dr. Running continued. “But it means we’re seeing an accelerated mortality pattern that we can’t explain by the normal processes. Maybe in 20 years we’ll look back and say we overreacted — but maybe we’ll look back and say it’s good we started thinking and focusing on this when we did.” 
Dr. Allen and some of his colleagues, including Dr. Running, included 88 forest die-offs and die-backs in a paper they published last year. It includes extensive documentation and photos of forest mortality.  Dr. Allen told me that he counted again for a recent scientific conference, and the number of mortality events surpassed 100.
By calling attention to the issue, “we are trying to get people to recognize that this is an under-appreciated risk to some of the key ecosystems on this planet — the risk of rapid mortality of forests,” he said. 
The situation certainly sounds dire, but let us pause and play devil’s advocate for a moment.
For starters, it is quite clear, as I pointed out in my article, that forests over all continue to take up far more carbon dioxide than they are losing. Most of the die-backs that have gained public attention, even including the huge attack by pine bark beetles in British Columbia and in the United States, are simply too small to show up as perturbations in the global accounting of carbon.
Yude Pan, a researcher with the United States Forest Service, led a recent scientific team that compiled the world’s most comprehensive estimate of carbon fluxes in and out of forests. I mentioned some of their conclusions in my piece, including the finding that even after losses from human-caused deforestation are taken into account, forests are still absorbing a billion tons of carbon every year.
Moreover, it would certainly be a mistake to conclude there is anything novel about fire and bugs in the world’s forests. In many places, in fact, they are a crucial part of the ecology.
Some species of pines, in their mature phase, will drop seeds only after a big fire. Large outbreaks of mountain pine beetles have occurred many times in the past.
James J. Worrall, a scientist with the Forest Service who has helped analyze the decline of aspen forests in certain parts of the West, sent me a report written in 1944 that documented a large beetle outbreak in some of the same locations that are under attack by pine beetles today.

So, these types of disturbances are definitely part of the natural history of forests. Still, the rough consensus among scientists is that something important has changed.

In the case of the mountain pine beetle, for instance, the outbreak that has been going on for 15 years now is at least 10 times larger than any previously recorded. We know for a fact that the beetle has expanded its range because of warming temperatures, and that it has jumped into a new tree species, the jack pine, that could give it a path to spread all the way across the North American continent as temperatures warm further in Canada in coming decades. 
Bitterly cold winters that used to kill off the beetles have basically stopped occurring. At the same time, as snowpack melts earlier in the year, trees are coming under late-summer water stress that weakens their defenses against beetles. That same water stress also makes forests more prone to fire, of course. 
“We can fairly unequivocally state that climate change did play a major role in the expansion of the beetle range and the growth rates of the population,” Werner A. Kurz, a leading Canadian expert, told me.
(I should note that 2011 is not a year of water stress in the northern Rockies — quite the opposite. The same La Niña weather pattern that has turned Texas into an oven pushed many storm tracks to the north, and Montana and nearby states had their best snowfalls in decades this past winter. When I was there in July, I drove through 30-foot snow banks still standing along the highest mountain passes.) 
Perhaps the most disturbing thing scientists told me in my interviews is that, even as the situation in the world’s forests starts to look precarious, we do not really have the capability we need to monitor the problems. 
In my article, I mentioned the towers that now dot the planet, allowing scientists to measure fluxes of carbon in and out of forests — but we are starting to lose those in some places, including Canada, as a result of government budget cutbacks. Scientists are tracking millions of individual trees in a network of forest plots around the world, but they say this network is still far too thin, especially in the tropics and in the vast boreal forest of the north. 
Largely because of the budget woes of the United States, even our capability to observe the world from space via satellites is slowly degrading. And in any case, a lot of work on the ground is needed to be sure we can interpret the satellite records correctly.
“The sum total that’s put into on-the-ground monitoring of forests is still very small,” said Oliver L. Phillips of the University of Leeds in Britain, who helps coordinate an observation network for tropical forests.
That raises the question: If the situation in the world’s forests were to start going downhill at a faster rate, would we even know it in a timely way?

Gillis claims, based on the scientists he cites, that forests are dying off on all continents and "...the underlying factor seems to be water stress caused by rising heat".  There are all sorts of ways to refute that is the sole or even primary reason.  For one thing, leaves of ornamental plants in pots being watered - even tropical plants grown as annuals far north of their natural range - have the identical visible damage to foliage as mature trees in the ground.  The same is true for aquatic plants in water all of the time.  Furthermore, many trees have extensive ranges.  Hemlocks, for instance, have thrived from Georgia to New England, and yet there is no trend for trees at the southern end of their range to be dying off faster than those in the northern part, which are still colder and wetter than the natural climate in the southern range.
Just for fun let's look at a new study about drought.  As is well documented in the literature, the first result when trees and other plants are injured by ozone is that their root systems get shortchanged in the process of repairing damage to foliage, making the plant more vulnerable to drought.  Aside from that though, research from Texas last winter indicated that the drought there is not unprecedented within the lifetime of existing trees, and the trees survived worse in the past.  This new paper examines the Sierras by looking deep underwater and comes to the same conclusion.
This is the caption for the photograph:
"University of Nevada, Reno, researchers were joined by a Scripps Institution of Oceanography research team, spending many days on Fallen Leaf Lake to gather sonar and side-scan radar data to study earthquake faults and paleoshorelines. The low-tech boat was adorned with high-tech hardware, such as gyroscopes used on rockets, to gather high-resolution images of the lake bottom. Using standing trees they found submerged under 130 feet of water, the team confirmed and reported in their paper, a culmination of a comprehensive high-tech assessment of Fallen Leaf Lake - a small moraine-bound lake at the south end of the Lake Tahoe Basin - that stands of pre-Medieval trees in the lake suggest the region experienced severe drought at least every 650 to 1,150 years during the mid- and late-Holocene period. Credit: Photo by Mike Wolterbeek, University of Nevada, Reno.
The erratic year-to-year swings in precipitation totals in the Reno-Tahoe area conjures up the word "drought" every couple of years, and this year is no exception. The Nevada State Climate Office at the University of Nevada, Reno, in conjunction with the Nevada Drought Response Committee, just announced a Stage 1 drought (moderate) for six counties and a Stage 2 drought (severe) for 11 counties.
Reno, Lake Tahoe and the Sierra Nevada are no strangers to drought, the most famous being the Medieval megadrought lasting from 800 to 1250 A.D. when annual precipitation was less than 60 percent of normal. The Reno-Tahoe region is now about 65 percent of annual normal precipitation for the year, which doesn't seem like much, but imagine if this were the "norm" each and every year for the next 200 years. 
Research by scientists at the University of Nevada, Reno and their partners at Scripps Institution of Oceanography in San Diego indicates that there are other instances of such long-lasting, severe droughts in the western United States throughout history.
Their recent paper, a culmination of a comprehensive high-tech assessment of Fallen Leaf Lake - a small moraine-bound lake at the south end of the Lake Tahoe Basin - reports that stands of pre-Medieval trees in the lake suggest the region experienced severe drought at least every 650 to 1,150 years during the mid- and late-Holocene period.
"Using an arsenal of cutting edge sonar tools, remotely operated vehicles (ROVs), and a manned submersible, we've obtained potentially the most accurate record thus far on the instances of 200-year-long droughts in the Sierra," Graham Kent, director of the Nevada Seismological Laboratory said.
"The record from Fallen Leaf Lake confirms what was expected and is likely the most accurate record, in terms of precipitation, than obtained previously from a variety of methods throughout the Sierra."
Kent is part of the University of Nevada, Reno and Scripps research team that traced the megadroughts and dry spells of the region using tree-ring analysis, shoreline records and sediment deposition in Fallen Leaf Lake. 
Using side-scan and multibeam sonar technology developed to map underwater earthquake fault  lines such as the West Tahoe fault beneath Fallen Leaf Lake, the team also imaged standing trees up to 130 feet beneath the lake surface as well as submerged ancient shoreline structure and development.
The trees matured while the lake level was 130 to 200 feet below its modern elevation and were not deposited by a landslide as was suspected.
The team, led by John Kleppe, University of Nevada, Reno engineering professor emeritus, published a paper on this research and is presenting its findings in seminars and workshops."The lake is like a 'canary in a coal mine' for the Sierra, telling the story of precipitation very clearly," Kent said.
"Fallen Leaf Lake elevations change rapidly due to its unique ratio between catchment basin and lake surface of about 8 to 1. With analysis of the standing trees submerged in the lake, sediment cores and our sonar scanning of ancient shorelines, we can more accurately and easily trace the precipitation history of the region." 
Water balance calculations and analysis of tree-ring samples undertaken by Kleppe, Kent and Scripps scientists Danny Brothers and Neal Driscoll, along with Professor Franco Biondi of the University's College of Science, suggest annual precipitation was less than 60 percent of normal from the late 10th century to the early 13th century.
Their research was documented in a scientific paper, Duration and severity of Medieval drought in the Lake Tahoe Basin, published in the Quaternary Science Reviews in November 2011.
Tree-ring records and submerged paleoshoreline geomorphology suggest a Medieval low-lake level of Fallen Leaf Lake lasted more than 220 years. More than 80 trees were found lying on the lake floor at various elevations above the paleoshoreline. 
"Although the ancient cycle of megadroughts seems to occur every 650 to 1150 years and the last one was 750 years ago, it is uncertain when the next megadrought will occur. With climate change upon us, it will be interesting to see how carbon dioxide loading in the atmosphere will affect this cycle," Kent said.
Somehow those sequoias and redwoods that are over 1,000 years old managed to survive a megadrought 750 years ago.  But now they're dying.  Hm!  It will no doubt come as a relief to readers to learn that scientists from the UK have revealed - ta da! - that we have a little problem with "new" pollutants - ozone and nitrogen.  Who could have guessed?
UK failing to tackle new pollutantsstudy
Authors of study say a repeat of the fight against acid rain in the 1980s is required to combat nitrogen and ozone levels
The UK has been successful in tackling acid rain, but is failing to make similar progress against a new generation of pollution threats, according to a new study from the government's respected Natural Environment Research Council (NERC).
Acid rain – the scourge of the UK and other northern European countries for decades, owing to the massive increase in coal-burning for power generation and the sulphur emissions associated with it – is now largely a problem of the past, with rivers and lakes now mostly recovered from its serious effect. Acid rain caused a wide range of problems for decades until the 1980s and 1990s, from forests stripped bare of leaves in large swaths of Scandinavia to the erosion of buildings, and the pollution of waterways leaving them as inhospitable environments for fish and other wildlife.
But regulations that forced electricity generators to put scrubbing equipment on their power stations that removed the sulphur emissions gradually cleaned up the problem, so that today the affected areas in the UK are almost entirely recovered.
However, that success story has so far not been repeated in the UK's attempts to deal with new environmental threats from pollutants, according to the 30-year NERC study, and some of them may require international co-operation – just as dealing with acid rain did.
For instance, nitrogen and ozone are two growing problems. Ground-level ozone can reduce the yield from crops, while an excess of nitrogen from a variety of sources, including car exhausts, can disrupt the natural nitrogen cycle.
The NERC Review of Transboundary Air Pollution (RoTAP), the first detailed analysis in more than a decade, found that ground-level ozone has declined by nearly one-third from its peak, owing to UK and European measures, but that background ozone levels have increased because of emissions elsewhere in the northern hemisphere, potentially including the US and China. Ozone is a problem in such cases because of its effect on crops – the UK's wheat crop yield was cut by 7% in 2000 owing to the problem, according to the study.
Martin Williams, professor at King's College London, said: "Policies to control ground-level ozone have been useful in reducing peak ozone concentrations, with significant benefits for air quality. But a steady growth in background ozone, as a consequence of ozone precursor emissions throughout the northern hemisphere, has eroded these benefits, and as a result ground-level ozone remains a threat. Ozone will only be mitigated effectively through hemispheric scale controls, which are now an urgent priority."
Despite efforts to cut emissions of nitrogen oxides – for instance from car exhausts – the amount of extra nitrogen put in the atmosphere has hardly changed in the past two decades, and this could be affecting biodiversity.'
David Fowler, of the NERC Centre for Ecology and Hydrology, said: "Policies to control eutrophication by nitrogen compounds have been less effective, mainly because emissions of a major contributor to nitrogen deposition, ammonia, have not been significantly reduced, and remains a priority for control measures."
Another puzzle raised by the study is that the amount of metals deposited in the UK from the atmosphere is far larger than it should be, according to standard scientific estimates. The report found the amount of some metals in the atmosphere was 10 times what it should be, when compared with the amount of metals reported to be released into the atmosphere by business and other sources. The scientists said they could not tell where the metal originated.
In the picture below there is a giant gap in the canopy of the woods.  You can barely discern, lying on the ground, a massive fallen tree that once obscured the sky.
This wasn't the post I meant to do - I have collected a score of papers about how ozone interferes with the ripening of fruit, and also very interesting chemical processes.
But as usual I got sidetracked, this time by the wildfires.
Trees like these are dangerous tinder, as is all the other vegetation lower to the ground.  It's dying back too.
I often worry about the mountain-top removal activists, who are mostly young, and passionate, and who often sit in trees to prevent the mining companies from blasting.  Trees don't provide the trustworthy, solid, secure perches they once did, as a tragic accident in Utah, where fires are also burning, demonstrates.  A young woman was playing with her friends in a mock Hunger Games re-enactment when the branch she was sitting on snapped.  She fell to the ground and her spinal cord was broken.  She's paralyzed for life from the waist down.  Perhaps the tree she climbed looked like this one:

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