What are the roots that clutch, what branches grow
|Out of this stony rubbish? Son of man,|
|You cannot say, or guess, for you know only|
|A heap of broken images, where the sun beats,|
|And the dead tree gives no shelter, the cricket no relief,|
|And the dry stone no sound of water. Only|
|There is shadow under this red rock,|
|(Come in under the shadow of this red rock),|
|And I will show you something different from either|
|Your shadow at morning striding behind you|
|Or your shadow at evening rising to meet you;|
|I will show you fear in a handful of dust.|
~ T.S. Eliot, The Waste Land
My last post here at Wit’s End received some thoughtful queries which deserved an answer in kind, a response I have assiduously procrastinated making - an avoidance which was made easier by a ten day trip with minimal access to the internet. Most of the photos in this post are from my journey to the UK earlier this month.
What follows is my belated reply (with apologies), especially to Michael Jensen’s question, “How has your personal mission changed, as the likelihood of your minimal longterm impact on the trajectory of global collapse has become clear?”
Most often, writing on a blog feels to have no more effect than idly dropping a pebble in the ocean, and watching the tiny ripples disappear; lately it seems that climate heating has gone exponential, and in my imagination I anticipate the moment I will hear an official NASA announcement on the radio - that it’s too late to mitigate climate change because irreversible amplifying feedbacks have taken over and there’s nothing left but to listen to the orchestra play on the deck.
For years once I realized humans have despoiled the glorious biodiversity it took millions of years of evolution to achieve, I grieved. I was angry and horrified and mostly wracked with guilt about being oblivious of my own contribution to the Endocene, including having children. I wanted to know how and why our species is so destructive, and I needed to understand why most people persist in believing humanity is ecologically sustainable when we so patently are not. So I read a lot about history, archaeology, psychology, evolution and biology.
“Humans are just like any other invasive species,” Stanford University biology professor Elizabeth Hadly said. “If we use up our resources, we will decline. It is stating the obvious, but our study shows that even over vast geographic areas such as continents, humans can consume too much, too fast.”
The researchers reconstructed the history of human population growth in South America using radiocarbon-dating data from 1,147 archaeological sites.
Our species first appeared in Africa about 200,000 years ago, then spread to Europe and Asia and eventually crossed into the Americas roughly 15,000 to 20,000 years ago using a land bridge that once connected Siberia and Alaska.
The first phase of colonization in South America coincided with the extinction of many large animals including elephant relatives, saber-toothed cats, big ground sloths, armadillos and huge flightless birds.
During this period, human populations underwent “boom-and-bust cycles” as people exhausted local plant and animal resources, Stanford anthropologist Amy Goldberg said.
Proof that the sixth mass extinction began 15,000 years ago with the hunting of megafauna on every continent and island on earth has become irrefutable to all but the resolutely religious and stubbornly WooWoo. Examine for instance the hunting of the Persian gazelle, which was driven down corridors to mass graves in decidedly NOT sustainable, respectful, non-wasteful methods, as documented in a study titled
“Role of mass-kill hunting strategies in the extirpation of Persian gazelle (Gazella subgutturosa) in the northern Levant
”. It describes how
“hunting strategies of post-Neolithic societies involving the mass killing of wild ungulates contributed to the eventual extirpation of a number of wild species.
I still grieve - but it helps to have learned, from following the latest discoveries in neurobiology, that our behavior is no more a matter of individual choice than that of a lizard. Free will is an illusion and the idea that our ancestors were once upon a time consciously in harmony within natural confines is a myth. Once humans found fire it enabled us to grow beyond any countervailing constraints and just like any species given the opportunity to expand endlessly, that’s exactly what we have done, periodically bumping up against limits that led to starvation, war and genocide. We now live in the unique moment where we have reached the end of global resources, and although a few of us can see where this will lead, most will remain in denial to the very end. It’s an unsolvable predicament. Carpe diem.
The panoramas I admired in the Lake District and Scotland’s island of Islay brought into sharp focus the impact that even very primitive humans had upon wilderness and biodiversity in a way I had not anticipated. The 866 square mile Lake District is part of the National Trust and has been assiduously preserved - there are no visible wires, no motor boats, no flashy signs and almost no traffic lights. It’s blissfully quiet.
The spectacular views draw hikers to countless trails leading to dizzying vantages from which to gaze upon the quaint villages far below in the valleys. They can contemplate the gleaming clear lakes, sweeping vistas across to the velvety folds of the mountain slopes where even the highest peaks are punctuated by artfully constructed stone walls. Sparkling waterfalls spill down every crevasse while pockets of forest dot the pastures, and acres of green bracken ferns were turning an alarmingly bright vermilion amongst the verdant grass shorn by flocks of sheep.
The vistas I saw were so exotic and unfamiliar, so entrancingly romantic, that I was mesmerized and fascinated even though I could not ignore the poor condition of the trees, which was all too familiar. It was amazing to me that when examined individually many of the leaves looked like someone had taken a flame-thrower to them...the damage was not one iota less than those I see by summer’s end at home in New Jersey.
Even the notorious nitrogen-loving lichen that is swarming over branches at home is festering across the Atlantic.
I found it incredible that everyone else seemed utterly oblivious to what looked to me unmistakably like a graveyard.
A gathering of artists painted the landscape, seemingly unaware of the brown tones of foliage, the sickly specimens and spectral corpses right next to them.
What was even more deeply disturbing was the near total absence of any wildlife whatsoever. In five days all I saw were a few crows, two little songbirds, and some mallard ducks feeding off scraps from the tourists at the ferry dock. Not one squirrel, chipmunk, no butterfly or other insects. In a land of crystalline lakes I saw not one fish jump in the water, nor one waterbird dive for food. The sterile stillness was uncanny and profoundly unsettling.
I was startled by the coincidence that the 2016 report from State of Nature by the RSPB (Royal Society for the Preservation of Birds, originally created by women to halt the decorative use of feathers in hats), a comprehensive analysis by 50 conservation organizations was released while I was pondering the depauperate countryside.
Of biodiversity intactness, the UK was rated 189 out of 218 countries assessed, 29th lowest. The blame for species that are threatened and endangered was placed squarely on agricultural practices, including overfertilization, pesticides, and decimation of marginal habitat. Here is how one article
assessed the findings:
More than one in 10 of the UK’s wildlife species are threatened with extinction and the numbers of the nation’s most endangered creatures have plummeted by two-thirds since 1970, according to a major report.
The abundance of all wildlife has also fallen, with one in six animals, birds, fish and plants having been lost, the State of Nature report found.
Together with historical deforestation and industrialisation, these trends have left the UK “among the most nature-depleted countries in the world”, with most of the country having gone past the threshold at which “ecosystems may no longer reliably meet society’s needs”.
The depletion in the UK is all the more starkly harrowing considering that the latest report
on North America, a report from Environment Canada documents:
North American skies have grown quieter over the last decades by the absent songs of 1.5 billion birds, says the latest summary of bird populations
The survey by dozens of government, university and environmental agencies across North America has also listed 86 species of birds — including once-common and much-loved songbirds such as the evening grosbeak and Canada warbler — that are threatened by plummeting populations, habitat destruction and climate change.
After a few days in the Lake District, I began to suspect that, like Iceland (you can read about that in The Reykjavik Imperative here), the entire area had been deforested.
I wondered because while most of the District is endless fields, I did see enough very large, very old trees in far-flung copses to indicate that it could be forested, absent human interference.
Not only were there very old large trees, but a great variety of species were to be found, some of them planted from Europe and America.
While it seemed that all the open space denoted a wilderness, I gradually realized the National Trust land was in fact a gigantic meticulously manicured Disneyesque stealth imitation of bucolic paradise - a time-capsule tourist mecca - where practically every inch of land was devoted to pasture for sheep and cattle, and every charming domicile a bed and breakfast. After making some inquiries I learned that indeed, the Cumbrian region and all of Scotland and the island I would soon visit had long since been denuded of trees going back to the Norse invasions following the Roman incursion, and even earlier - a horrific massacre that continues today due to the UK appetite for “sustainable biomass” energy.
There are plantations of pine trees that were planted in rows decades ago, that are spindly and weak. It seems nobody likes their ugly monotony, and it was a failed attempt at restoration. Huge swathes are being logged.
The Inner Hebrides island of Islay, which though endowed with beautiful beaches and rocky cliffs and an almost tropically turquoise ocean, was also originally forested over the entirety of its 25 mile length. This massive deforestation for agriculture and building began, astonishingly, in the Neolithic 5,000 years ago, and was accomplished with ring barking, burning, and felling all with stone axes, by the same industrious peoples who built the 13,000 stone circles scattered across the UK.
The current population on Islay of 3,400, a fraction of earlier times, is largely supported by producing copious amounts of whisky harvesting the local peat bogs, some 10,000 years old, and growing barley with which to produce it.
It’s apparent both these places can independently only support very few people, which is why most of them left long ago - and that it is only with inputs of tourist money and other imports from outside the region, of food and fuel and consumer goods, that the contemporary communities are sustained.
It astonished me that the ancient legacy of this very early ecosystem slaughter remains mutely evident on a wasteland that is successfully masquerading as nature today. Except that the original logging is now exacerbated by invisible pollution, most of it imported as well, which is poisoning the vegetation in a location so remote it should be pristine. By another remarkable coincidence, on the day I departed, I was catching up on some reading from a book chapter about ozone and plants that I have been intending to write about (and more follows below) and section 7.4 on page 142 caught my eye.
Chapter Seven of “Trees in a Changing Environment” is titled “Forest Trees under Air Pollution”.
(citations removed, emphasis added):
Many regions of the globe are currently exposed to levels of surface O3 and other air pollutants that are high enough to promote plant damage in natural ecosystems, cultivated forests and agricultural fields, also affecting human health. Reductions in crop yield, pasture and in forest productivity have important economic consequences, being responsible for losses of several billion dollars per annum in the USA, EU and East Asia. Such detrimental effects of O3 have caused countries to establish increasingly stringent air quality policies. However, due to the high mobility of air pollutants in the atmosphere, plumes of anthropogenic O3 and its precursors can be transported into the free troposphere and across country boundaries to expand over large geographical scales. Regions located very distant from the pollutant source are now suffering from enhanced O3 background levels or episodes (e.g. Ireland within the lee of North America).
Did I mention I could see Ireland from the shore of Islay?
I was directed to that book by one of its editors, Gretchen Grulke, who is a plant physiologist employed at the US Forest Department. I wrote her having discovered her work described in a seminal brochure
produced in 2010 (I recommend taking a look at it for the pictures).
Following are excerpts, and the last line, bolded and red, is precisely and pithily what I have been going on about for years (and don’t ask me how I never saw this until now):
• Chronic exposure to high levels of common air pollutants like ozone and nitrogen oxides is damaging to forest health. The effects of air pollution mimic drought and have the potential to increase fuel loads in forests, exacerbating the risk of wildfire, especially near urban centers where air pollution is more concentrated.
• When Jeffrey pine trees are stressed by drought, they send biochemical signals that may be an attractant to bark beetles. Since the signaling trees are already significantly stressed, they are easily overwhelmed by beetles, setting the stage for an outbreak. The same biochemical signaling may also happen in other important forest species.
The San Bernardino Mountains, which help define the Los Angeles Air Basin, are one of the most polluted mountain ranges in North America. The air pollution is the result of a combination of emissions from vehicles, industrial manufacturing, and agriculture production. These greenhouse gas emissions, ozone and nitrogen oxides in particular, are especially damaging to forest health. Increased ozone and nitrogen deposition change the chemical composition of individual trees and have significant impacts on fuel loads at the stand and forest level.
...Inside the leaf, ozone changes the way trees transpire, or exchange gasses. Leaves, or needles in the case of conifers, have pores called stomata. Properly functioning stomata are crucial to a tree’s ability to regulate water loss, uptake carbon dioxide, and produce energy. In the presence of high concentrations of ozone, trees lose stomatal control and the ability to manage their water and nutrition. Too much air pollution can kill a tree outright. But what’s more likely, with high but not excessive exposures to ozone, is the slow dwindling of health. Since water is lost from the tree, the results of chronic ozone uptake mimic or exacerbate tree drought stress.
Nitrogen deposition is also a problem facing forests. Some nitrogen is generally good for trees, but too much nitrogen can change the amount of growth, the timing of growth, and resource allocation within the tree that can compromise its health and ability to withstand stress. Working in concert with ozone, increased nitrogen may affect the way carbohydrates—the energy needed for growth and survival—are stored and used, and stunt root growth. These two factors can also make a stressed tree much more susceptible to drought and its follower— beetle outbreaks.
Both ozone and nitrogen deposition cause increased leaf turnover and self-pruning, which lead to more litter on the forest floor. Nitrogen deposition also acts to slow the decomposition of forest floor litter, particularly the excess branches and leaves being shed. As a result there is a potential to have more fuel in a drying forest, enhancing the potential for catastrophic wildfires.
Nancy Grulke has been studying the effects of air pollution on forest health for the past two decades for the Pacific Southwest Research Station. Her research reveals links between high doses of ozone and nitrogen to forest stress, and shows there is a compounding relationship between stressed trees, beetle outbreaks, and wildfire.
Air Pollution in the Background
Thanks in large part to regulation and education in past decades about air pollution in the Los Angeles Air Basin, sources of pollutants are now better controlled. On any given day, there is less air pollution being emitted than there was a decade ago.
The problem though is that the overall dose is steadily climbing, not only around Los Angeles, but across the globe. The current atmospheric background rate of ozone is 50 parts per billion (ppb), up from 10 to 12 ppb in preindustrial times, and it is expected to increase another 50 percent between 2020 and 2050. “We have continuously increasing ozone,” says Grulke. Pollution is worse in some places than others, for example, downwind from large urban areas. But even forests far from urban centers are showing higher levels of ozone. The Sierra Nevada, generally synonymous with clean mountain air, now has a background rate of 67 ppb during the summertime when plants grow.
“We’re dealing with completely different atmospheric chemistry,” says Grulke, “when ozone is greater than 70 ppb, stomata function very differently than they do when ozone is 50 ppb.” At some of her study sites of ponderosa pine scattered throughout the San Bernardino Mountains, the rates of summertime ozone uptake ranged from 62 to 80 ppb. The higher ranges are closer to urban Los Angeles, whereas the lower exposures are farther east, out toward the Mojave Desert...
The effect of ozone and nitrogenous pollutants are often left out of climate models, which favor measuring and predicting the rise and consequences of increased carbon. Not quantifying and including ozone and nitrogen in models, according to Grulke, may be a big oversight. Unlike some other greenhouse gasses, there is still little understanding about specific plant thresholds of ozone and what happens after that threshold is exceeded. Besides ponderosa pine, Grulke has also measured the tolerance in a handful of other plants and trees, but a wholesale cataloging of “what proportion of plants are in trouble,” she says, is still lacking.
In addition to modeling, Grulke’s research can also inform other forest management strategies, like thinning. At some study sites, she’s looking at whether stand density plays a role in buffering the effects of air pollution and how those stands deal with the subsequent stress of drought and beetles. The effect of air pollution on plant health is not just a forestry issue. In Europe, researchers are trying to figure out ozone tolerances for important agricultural products and certain types of heritage trees. “Air pollution is the one link that ties everything together,” says Grulke.
When I asked her why there wasn't more hue and cry from scientists and foresters about something so fundamentally crucial to all forms of life on earth as trees, she said (drumroll) there’s no funding.
“We are and have been [jumping up and down with hair on fire]. Research budgets have significantly dropped over the last 15 years. For example, there have been no new federally- supported research projects on the effects of air pollutants on natural vegetation since 2002...With no funding for research, we move to other things…
She also answered, in regards to the oft-cited mitigation against harm, that stomata close when exposed to moderate levels of ozone thus limiting its damaging effects
“...at higher levels of exposure, the stomata open when they are not supposed to (the O3 must be affecting the guard cell membranes directly), and more water is lost than should be. Also the stomata become sluggish – don’t open or close at the right speed … so there is a lag to any changing environmental conditions. This phenomenon is not included in any of the models. Ooops.
Probably by now everyone has noticed at least one story about toxic algae and anoxic zones in a lake or in an ocean or a canal. There seems to be a growing global incidence, and it doesn't make sense that the main reason would be warming - or warm tropical places would always have runaway algal growth. I have lately suspected that much of problem derives from deposition of atmospheric reactive nitrogen, on top of fertilizer runoff on the ground. Given the exponential growth in reactive nitrogen I would not be surprised if we haven’
t reached a classic tipping point, on land and in the water. I’
m not going to go any further about it, but for anyone unfamiliar with the severity of the nitrogen cascade, a good starting point is with the research
of James Galloway - keeping in mind that like climate change, and ozone, the impacts are even far worse and faster than generally acknowledged in the published literature. [Update: a recent news report
states "Toxic algae has shown up in more than 40 state lakes and waterways from Los Angeles to the northern reaches of California, the highest count in state history."]
There ought to be a word that expresses in a few syllables the totality of ecocide - not just the horror in recognizing the physical manifestations of looming extinction, but the ensuing pain upon realizing the futility and meaninglessness that has been wrought by human folly, hubris, stupidity and blindness. But I don’
t know what it is.
It especially seems useless to bear witness to the final countdown when headlines proliferate along the lines of
“An American tragedy
: why are millions of trees dying across the country?”
these idiots notice that trees are dying not just in America but ALL OVER THE WORLD?
And then there’s the equally myopic subtitle: “A quiet crisis playing out in US forests as huge numbers of trees succumb to drought, disease, insects and wildfire - much of it driven by climate change”.
Won’t they ever get Grulke’s statement: “Air pollution is the one link that ties everything together”. What is so hard to understand about that?
What is the dubious value of cataloguing the endless stream of stories, about how bad air pollution
is to human health and the economy; large animals dependent on healthy vegetation are dying off, like moose
, a disease is impacting the apple tree
harvest, fungus is killing banana trees
, beetles are killing avocado
trees, so many trees are dying that some scientists want to burn them
instead of coal; Seattle’
s park trees
are dying, everything from big leaf maples to cottonwoods, birches and more, (absurdly blamed on a drought in 2015 when one year of drought is not nearly enough to kill mature trees);
the ever-growing litany of injuries
and property damage
from falling, clearly rotted branches and trunks;
a “mystery disease” is killing Zimbabwe’s baobabs; there is vast dieback of mangroves in Australia; over 50 black walnuts described as “dead, damaged, split, decaying, leaning, fallen over, among other conditions” are being removed in Chico and warnings that thousand canker disease - a fungus spread by a beetle - will wipe them out along with butternuts in the Eastern US, California; the keystone hemlocks, some up to 500 years old, dying in Shenandoah;
...and then there’
s the inability of insects to forage efficiently
when pollution interferes with their ability to follow scents:
Flowers emit mixtures of scents that mediate plant-insect interactions such as attracting insect pollinators. Because of their volatile nature, however, floral scents readily react with ozone, nitrate radical, and hydroxyl radical. The result of such reactions is the degradation and the chemical modification of scent plumes downwind of floral sources...Results indicate that even moderate air pollutant levels...substantially degrade floral volatiles and alter the chemical composition of released floral scents. As a result, insect success rates of locating plumes of floral scents were reduced and foraging times increased in polluted air masses due to considerable degradation and changes in the composition of floral scents. Results also indicate that plant-pollinator interactions could be sensitive to changes in floral scent composition, especially if insects are unable to adapt to the modified scentscape. The increase in foraging time could have severe cascading and pernicious impacts on the fitness of foraging insects by reducing the time devoted to other necessary tasks.
obsessive Ozonists and Ozonistas, following are some excerpts from the afore-mentioned book
“Trees in a Changing Environment”, chapter 7, “Forest trees under Air Pollution”, by Rainer Matyssek et al.
Air pollution and climate change are inherently linked to each other. After introducing into the presently prevalent air pollutants and their relevance for forest tree and ecosystem performance, the account focuses on nitrogen deposition and troposphere ozone (O3), the latter being regarded as potentially most detrimental to vegetation, and hence, as negating carbon sink strength and storage. Mechanisms of O3 action in trees and stands are highlighted, stressing interaction with other abiotic and biotic factors, including volatile organic compounds, as a fundamental pre-requisite for understanding O3 effects. O3 is emphasized as a globally effective agent of climate change, regarding relevance for forest productivity, in particular, at hot spots of air pollution in the southern hemisphere, prognosticated for the upcoming decades. Adaptation capacities of forest trees are discussed in view of the rapidity in the progression of environmental change.
Given the paramount role O3 currently plays in air pollution at global scale, the major focus of this chapter will be on tropospheric O3 and its impact on forest trees and ecosystems.
p. 123 - At this level of ecosystem N saturation, tree mortality may increase, and the once stimulated NPP is now suppressed, as the proportions among nutrient elements gradually shifts to an imbalance dominated by nitrogen (Aber et al. 1998). However, a balanced nutrient supply is crucial for tree growth. Imbalance is indicated by lowered Ca/Al and Mg/Al ratios (reinforced by a high affinity of roots to passive Al uptake) as indicators of forest decline. A shortage in Ca can restrict radial stem growth (Lautner et al. 2007), limiting water transport capacity. In this way, the development of tree foliage may be reduced, which can lead to progressive crown transparency. In addition, leaves may become yellowish as a consequence of Mg limitation (Schulze et al. 1989). Mg is crucial for chlorophyll functionality so that shortage reduces photosynthesis and C gains and is accompanied by the loss of chlorophyll. In particular, advanced needle age classes of evergreen coniferous tree species can turn yellow, as the retranslocation of Mg from old needles to new represent a strong sink during needle growth. Further adverse effects of luxurious N availability may be an increasing attractiveness to herbivores and pathogens and an enhanced susceptibility to early and late frosts, as high specific leaf area is induced during differentiation at the expense of leaf robustness. High N supply in addition favours aboveground relative to belowground organs in whole-tree C allocation, so that trees may become susceptible to soil drought.
Air pollution is one component of climate change. Among other anthropogenic pollutants, tropospheric O3 is the ecologically most significant compound, given its toxic potential for plants and widely spread occurrence at enhanced concentrations (see Sect. 7.1). O3 impact, therefore, must be understood in concert with other factors of relevance in a changing environment (addressed in this section), because multiple interactions determine the plants’ sensitivity to stress (Mooney and Winner 1991; Ska¨rby et al. 1998; Matyssek and Innes 1999). Because of this, principles of O3 action in trees, as highlighted in Sect. 7.2, may be moderated or even masked (Matyssek and Sandermann 2003).
Still, our judgement largely relies on findings from young trees and chamber experiments, although evidence has increased recently on tree performance at advanced ontogenetic stages and under ecologically relevant field conditions (Kubiske et al. 2007; Matyssek et al. 2010a, b). Section 7.3.1 will highlight interactions of O3 with temperature, drought, and irradiance, followed by Sect. 7.3.2 on the relevance of nutrition. Sections 7.3.3 and 7.3.4 will address such interactions with VOCs and CH4, and between O3 and CO2 respectively. Biotic influences on the O3 response of trees will be highlighted in Sect. 7.3.5, comprising the significance of tree genotype and effects by competition, host-pathogen/herbivore relationships and mycorrhizospheric interactions.
One final word about the cause of forest decline and then barring some truly earth-shattering revelation, I seriously doubt I will find any reason to bring up the subject again. The drought in California that is so widely blamed for tree deaths is not considered
to have become severe, certainly not unprecedented, until 2012 - and the trees were dying long before then. What IS widely acknowledged is that deforestation causes
droughts and ultimately desertification, and this has been known throughout history, back to the story of Gilgamesh
in the third millennium BCE - and even earlier. See a “top ten
” list of examples from the past.
Consider that by poisoning trees with ozone we are, in effect, deforesting the entire world and THIS is causing the droughts, in a hellish cycle of destruction.
Here is a current example in Madagascar,
which like the rest of Africa, is logging to produce charcoal for fuel:
Charcoal — cleaner and easier to use than firewood, cheaper and more readily available than gas or electricity — has become one of the biggest engines of Africa’s informal economy. But it has also become one of the greatest threats to its environment.
...The village chief, Evomasy, 48, said he believed that the trees’ disappearance had caused the recent severe droughts.
“We cut down everything,” he said, looking at the shrub land now surrounding his village. “We used to have trees all around us.”
Another article from the New York Times explains the mechanism by which deforestation creates drought:
Humans have long settled in places where there is adequate and predictable precipitation, and large forests play a crucial role in generating dependable amounts of rainfall. Trees take up moisture from the soil and transpire it, lifting it into the atmosphere. A fully grown tree releases 1,000 liters of water vapor a day into the atmosphere: The entire Amazon rain forest sends up 20 billion tons a day.
The water vapor creates clouds, which are seeded with volatile gases like terpenes and isoprene, emitted by the trees naturally, to form rain. These water-rich banks of clouds travel long, wind-driven distances, a conveyor belt for the delivery of precipitation that scientists call flying rivers.
The sky-borne river over the Amazon carries more water than the Amazon River itself. It begins as moisture that builds over the Atlantic Ocean, and then flows westward over the emerald crown of the Amazon, where it picks up far more moisture. The laden clouds eventually bump up against the Andes and are steered south and then east, which means rain for Bolivia and Brazil.
One way forests may move water is known as “biotic pumping.” As water transpires into the atmosphere above the forest, the theory holds, it creates a low-pressure system that sucks in air surrounding it, eventually and continually pumping moisture inland from the ocean. Cutting down forests degrades these low-pressure systems, essentially turning off the pump. Large-scale deforestation is thus believed to be a major contributor to the extreme drought in Brazil. Scientists have long known that vegetation has a profound effect on weather.
In 1907, officials built a 2,000-mile-long fence across Australia to keep invasive rabbits from crossing from the wild outback into farms. On the side with native vegetation, rain clouds formed in the sky above, but the farm-field skies were clear. The “bunny-fence experiments” charted a decline in rainfall of 20 percent on the cultivated side.
Researchers are still trying to explain why, but the leading theory is that the darker native plants absorb more heat and release it into the atmosphere, along with energy and water vapor to form clouds.
Here is another example
, the Mayan civilization:
In the past few years, scientists have been gathering evidence that drought and deforestation made life in the cities unsustainable, leading to the collapse of not only Tikal but dozens of cities in the southern part of the empire.
...when the population density reached 2,000 people per square mile — similar to that of Los Angeles — the Maya were engaged in a massive clear-cutting of the surrounding forests, unintentionally amplifying drought conditions.
While the rainwater Mayan cities depended on for drinking and irrigation was becoming more and more scarce, they were also clear-cutting their forests using a
“slash-and-burn" technique similar to the one used today. The method is exactly what it sounds like: They cut down the surrounding jungle and set it ablaze to make room for crops.
...For centuries, Mayan civilization practiced environmental management successful enough to build a powerful, sophisticated, and possibly most advanced society of the precolonial Americas.
But in the end, unchecked growth hastened the demise of the empire, even before conquistadors landed.
A recent article
about India laments the trend towards desertification:
Nearly 30% of India’s land is now undergoing desertification, primarily as a result of the land degradation accompanying overcultivation, overgrazing, deforestation, and the overexploitation of water resources in dryland regions, according to a new report from the Indian Space Research Organization.
The root causes of the situation, though, are fundamentally linked to growing population levels and the inevitable growing exploitation of the land, so there are no easy, effective actions that can be taken. Any potential “solutions” are likely to be very costly, whether with regard to resources, economic systems, or society.
The findings are the result of an analysis of satellite images over an 8-year period of time.
Land degradation and desertification has been a major issue throughout the Holocene for agricultural cultures and civilizations. Land degradation through the actions of agriculture, deforestation (and triggered changes in aridity and rainfall patterns), overgrazing, and accompanying desertification are thought to have played a prominent role in the decline and fall of a great many notable cultures and civilizations.
Several stories have appeared in my local media
about an ancient beloved oak tree in nearby Basking Ridge suddenly dying. Even though it is undoubtedly, venerably old, it should have another century or two. It’
s just another heartbreaking example of the collapse of the biosphere. I wrote about
the impending demise of this particular tree six years ago, but almost no one notices such losses until far, far after the inevitability of death becomes too apparent to ignore.
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.”
~ Leonardo da Vinci
Many thanks to my fellow travelers from The Panic Room.