'A Great Aridness', Bark Beetle Infestation, Climate Change, Climate Feedback Loops, Climate Tipping Points, Craig D. Allen (U.S. Geological Survey), Droughts in the U.S. Southwest, Ecological Overshoot, Environmental Collapse, Extinction of Man, Mass Die Off, Phoenix, Pinyon Pine Tree Die-Off, Shrinking Colorado River, William deBuys
As I mentioned in my previous post, Capitalism, Population Growth, & Climate Change, I’m reading a book on the present and future effects of anthropogenic global warming to the American Southwest as well as the entire world.
The Southwest drought of the early 2000’s, accompanied by the massive bark beetle infestation, killed over 2.6 million acres of mostly piñon(pinyon) pine. Pinyon pines are an interesting tree, living for up to 800 years and producing a tasty edible nut considered to be a “super food”. Studies by Craig D. Allen (U.S. Geological Survey) tell us that climate change is making droughts, historically normal occurrences in the Southwest, a killer for that region’s trees which usually can withstand such events, but not under the prolonged higher temperatures that human-induced global warming brings. These sustained higher temperatures have been identified as the “critical factor in provoking widespread tree mortality.” With a 4°C increase in temp and all other factors remaining the same, a five fold increase in pinyon tree death has been estimated by recent studies. The problem with that estimate though is that all other factors will most certainly change: less snowfall will diminish the benefits of the albedo effect, more retained heat from the sun and altered rainfall patterns will dry out the soil and increase erosion, and elevated levels of dust in the air will also factor into this vicious feedback loop to shrink mountain snowpack and increase evaporation. Fires and insect infestation will be seasonal events of ever-increasing intensity. And the demise of desert cities like Phoenix, dependent on a shrinking Colorado River, will inevitably follow.
…The team developed a Forest Drought-Stress Index that combines the amount of winter precipitation, late summer and fall temperatures, and late summer and fall precipitation into one number.
“The new ‘Forest Drought-Stress Index’ that Williams devised from seasonal precipitation and temperature-related variables matches the records of changing forest conditions in the Southwest remarkably well,” said co-author Thomas W. Swetnam, director of the UA Laboratory of Tree-Ring Research.
“Among all climate variables affecting trees and forests that have ever been studied, this new drought index has the strongest correlation with combined tree growth, tree death from drought and insects and area burned by forest fires that I have ever seen.”…
…“Atmospheric evaporative demand is primarily driven by temperature. When air is warmer, it can hold more water vapor, thus increasing the pace at which soil and plants dry out. The air literally sucks the moisture out of the soil and plants.”…
…These trends, the researchers noted, are already occurring in the Southwest, where temperatures generally have been increasing for the past century and are expected to continue to do so because of accumulating greenhouse gases in the atmosphere… – lnk
Here’s what the benchmark drought of 2001-2002, a harbinger of future hi-temp droughts in the Southwest, did to pinyon trees:
From my post ‘Climate Tipping Points: The Global Die-Off of Forests‘, we know that forests all over the planet are dying and that mass die-offs of these areas are only a matter of time. The arid regions of the world like the U.S. Southwest are the most sensitive biomes on the planet and will be the first areas to exhibit catastrophic die-off from climate change.
This excerpt from the book I’m reading should scare the hell out of you (he’s talking about the 2001-2002 U.S. Southwest drought):
Does ‘industrial-capitalist carbon man’ give a fuck about trees? Certainly not if they get in the way of profit and ‘development’.