Surrendering Forests

tree david johnsonDavid Johnson (1827 – 1908)

by Jeff Tietz
Rolling Stone

From a tree’s perspective, excessive heat may be as deadly as lack of water.
To photosynthesize, a tree opens pores in its leaves called stomata and inhales CO2. Solar-charged chemical reactions then transform the CO2 into carbohydrates — the raw stuff of leaves and wood. During this process, a fraction of the tree’s internal water supply evaporates through its stomata, creating the negative pressure that pulls water from the soil into the tree’s roots, through its trunk and up to its canopy. But heat juices the rate at which trees lose moisture, and that rate escalates exponentially with temperature — so small temperature increases can cause a photosynthesizing tree to lose dangerous amounts of water.
“Forests notice even a one-degree increase in temperature,” says Park Williams at Los Alamos National Laboratory.

In the death scenario, the sky sucks water from the leaves faster than it can be replaced by water in the soil, and the resulting partial vacuum fatally fractures the tree’s water column. If a tree closes its stomata to avoid this, shutting down photosynthesis, it risks starvation.
Ultimately, the tree’s cellular chemistry will fail, but it will often die before that, as its defenses fall; the complexly toxic sap that repels predatory insects dries up.
Many insects can detect diminished sap levels within tree bark by scent — they smell drought stress and pheromonally broadcast news of deteriorating tree health. Other defenses – against microbes, for example — may also be compromised.
A hotter climate generally means more insects.
It also means more, and more intense, wildfires.

For decades, all over the planet, heat-aggravated drought has been killing trees: mountain acacia in Zimbabwe, Mediterranean pine in Greece, Atlas cedar in Morocco, eucalyptus and corymbia in Australia, fir in Turkey and South Korea.
In 2010 a group of ecologists published the first global overview of forest health. They described droughts whose severity was unequaled in the “last few centuries” and documented “climate-driven episodes of regional-scale forest die-off.”

Because global warming outpaces evolutionary adaptation, the question is: Can trees survive as they are?
The conifer forests of the Southwest United States, if climate projections are even minimally accurate, cannot, but what about the rest of the world’s forests?
That’s a critical question, because forests cover more than a quarter of the planet’s land, and they help stabilize the climate by pulling immense quantities of CO2 out of the air.
In August 2011, a team of scientists led by Dr. Yude Pan, a U.S. Forest Service researcher, reported that between 1990 and 2007, forests sequestered about 25 percent of all greenhouse-gas emissions — everything not in the air or seas.

Climatologists worry that if forests across the planet deteriorate, they could, on balance, begin releasing as much carbon as they absorb.
One of Pan’s collaborators, Dr. Richard Birdsey: “If the carbon sink in forests fails, a simple speculation is that global temperatures would increase proportionally to the increase of CO2 concentration, so about 25 percent above current climate projections.”
“The more forests die, the less carbon they take out of the air, the warmer it gets, the more forests die,”
says Dr. Nate McDowell at Los Alamos. “It’s a thermostat gone bad.”

The better we understand climate change, the more we seem to find that warming begets warming in unexpected and self-amplifying ways: Implacable heat engines materialize and run independently of all human effort.

There are an estimated 1 trillion metric tons of frozen carbon in the soils of the Arctic region — a century’s worth of global emissions, twice the amount stored in the global forest, another few Industrial Revolutions.
As the planet warms, permafrost thaws and decomposes, sending carbon into the air and further warming the planet. Higher temperatures also kindle increasingly intense and frequent wildfires in high-latitude forests, to quadruple effect.
And fire releases carbon directly; it burns off the insulating upper layer of vegetation, exposing more permafrost to warm air; it blackens the trees and land, which consequently absorb more solar radiation; and its soot can settle on and darken snow and ice sheets to the north, which then also absorb more solar radiation.

By the end of the century, the woodlands of the Southwest will likely be reduced to weeds and shrubs. And scientists worry that the rest of the planet may see similar effects.


Trees Cry Out

The Longevity of Trees
A Living Miracle
Du Bon Usage des Arbres

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12 CommentsLeave a comment

  1. This is so informative, and so devastating at the same time. Thank you for this keen information. It’s breathtaking and will take a bit to contemplate. One thing is for sure, folks should spend more time being informed about our planet and less time agitating over individual petty personal issues which exponentially lead to border disputes and religious unrest. Our priorities are so out of alignment.

    • Oh my god yes. I even wish I could place other important issues beneath the problems we’re causing the environment—because that is life! Our lives, and the lives of all living things in our ken—and, unfortunately for them, within our sphere of influence! —(and the sphere too. heh)
      Guns—a ridiculous privilege most people shouldn’t have– but First we need to BREATHE.
      War—bad. But we’ve sprinkled the equivalent of napalm over almost all our green things!
      Poverty—Rich people are selfish–that’s how they got to be rich—But we can’t let them reduce children to drinking poisoned water!
      People of all backgrounds and genders & gender-choices should be treated the same. OBVIOUSLY. Do we really have to keep spelling it out every time we turn around? But we are all going to have fucking miserable lives if our priority isn’t a liveable earth.
      I feel like screaming it all the time—Thank god for you guys out there. (Wish we were reaching a lot more, though)

      • Although—-When it comes to things like keeping corporations out of elections & keeping their lobbyists out of Congress—THAT has a direct effect on whether we get to try to save the world, or whether the short-sighted, greedy, crazy evil fools get to destroy us. (And their own grandchildren–who, for some reason, they don’t seem to care about)

    • (My father talked about ideas. Those people can be so alone sometimes)

      • In a way yes, but I prefer to think of it as selective. With too much clutter one fails to recognize substance and there is no room for it when it approaches you. Quality rather than quantity hones one’s appreciation for authenticity.

  2. Secret Gardner is onebof the very few worthwhile blogs out there. I have stricken most from my life and prefer to learn more and discuss positive ideas. My father always said: small minds talk about people, mediocre minds talk about events and great minds talk about ideas. There you have it.

    • Thank you, Lynn.
      –And struggling minds like mine try to figure out what the smart people have to say, and then quote them lavishly.

  3. It is terrifying to consider the world we are leaving to our grandchildren. I fear a slow and painful death.

    • And, unfortunately, we can see the dying all around us. That’s why people are finally responding.
      Maybe geniuses will come up with some ways to enhance & accelerate our efforts to do good and even bring about miraculous methods of repair—rather than merely cease adding to the destruction–which is all we’ve barely begun to accomplish

  4. beautiful drawing – and thanks for the reminder that there are bigger things to worry about than Brexit – sigh…

    • It is a beautiful drawing, isn’t it–As usual, the studies tend to appeal to me even when the artist’s finished products don’t thrill me. (I love the name ‘Luminism’, though)
      The thing that stung most about Brexit was the mention of it interfering with world-wide environmental standards—-I’m so lost when it comes to how trade agreements & the co-operation of nations are going to affect those meager efforts, so long in coming–

  5. […] Surrendering Forests […]

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