We all know that trees pull carbon dioxide out of the atmosphere as part of their photosynthetic cycle, turning it into wood and moving it into the soil where it will stay out of the atmosphere for a long time. This is called biological sequestration and it plays a key role in maintaining the stability of the climate. Scientists have recently determined that forests pull as much as 25% of all CO2 out of the air – as much as is emitted by all the cars and trucks in the world. Therefore it is critical that forests be preserved as a key element of the effort to maintain some level of climate stability.
Recently, scientists have seen mounting evidence of the risks to forests that climate change poses, resulting in what is called a “positive feedback loop,” which sounds like a good thing but is not. Climate change produces a number of stressors that are destructive to forests, the loss of which makes the climate change occur even faster, which, in turn, stresses the forest even more, and so on…
An article by Justin Gillis in the New York Times, describes a number of these phenomena. For example, in the American West, forests are now seriously threatened by insects that used to die off in the deep freeze of winter, which controlled their populations. But now that winters are not getting as cold, a large number of these insects survive through till spring, creating far more stress on the forests in which they live, breed and feed.
Then there are the wildfires, the result of drier summers. These are wreaking havoc with forests all across the globe from California to Siberia. Trees are also dying off in huge numbers due to heat and water stress, from the Aspen forests of Colorado to the Euphorbia trees of Southern Africa, and the Eucalyptus of Australia.
Thomas W. Swetnam, an expert on forest history at the University of Arizona told the Times, “At the same time that we’re recognizing the potential great value of trees and forests in helping us deal with the excess carbon we’re generating, we’re starting to lose forests.”
When forests die, not only do they stop absorbing carbon out of the air, but they also begin releasing all the carbon they have collected as they burn or decompose, over a very short time period, exacerbating the problem even further.
Even as controversy still rages over the credibility of global warming in a few backward countries, scientists generally agree that forests need to be protected. Progress on meaningful action has been slow, not so much for ideological reasons as much as for a lack of cash.
One plan puts the burden on developed countries by requiring them to pay developing countries to not burn down their forest. Instead, they’ll be preserved for their inherent value and forest owners will be encouraged to exploit them in less destructive ways, such as eco-tourism. That program is underfunded. So is a plan in the US to thin out forest to reduce the risk of both fire and insect damage.
Meanwhile this recent phenomenon of forest die-offs continues to spread. The loss of Alaskan spruce to beetles in the 90s is now showing up in Montana, British Colombia, and Colorado where more and more mountainsides are turning ever-brown. The ravages of the Emerald Ash Borer is predicted to threaten 8 billion trees.
Direct links to global warming are clear in some cases, less obvious in others, but the impact of hotter, drier temperatures, that have been predicted as the result of greenhouse gases by scientists dating back to Arrhenius in 1894 is undeniable.
It wasn’t until the 1950s that scientists realized that a considerable portion of the carbon dioxide being produced by the burning of fossil fuels was being picked up by forests as part of the planet’s natural system of checks and balances. The ocean also takes up an equally large portion. But unfortunately, these two “sinks” as they are called, can only take up about half of the emissions being produced today. The rest finds its way into the upper atmosphere where it adds to the accumulating greenhouse gases that have increased by 40% since the start of the Industrial Revolution, where they inhibit the amount of radiant energy that the Earth is able to freely emit into space, much in the same way that adding storm windows helps to keep your house warmer in Winter.
While it is true that the increased concentration of carbon dioxide are causing some increased growth among trees, (CO2 is, after all, a major source of food for plants) in the short term, it is also putting them at risk for heat and water stress as well as insect damage in the long term.
One thing that is abundantly clear as our forests teeter over the line dividing life and death, our planet’s future teeters with them. We must do whatever we can to protect them. We must stop the illegal logging and clear-cutting that is rampant in places like Brazil and Indonesia.
This behavior is like someone deliberately damaging his kidneys, the vital organs whose jobs it is to remove toxins from the body, while at the same time, he is consuming poison. Despite doctor’s warnings, the patient refuses to listen, insisting that his behavior has nothing to do with the fact that suddenly he’s not feeling that well. Should we be surprised when we see him in the obituaries? I don’t think so.
[Image credit: CIFOR: Flickr Creative Commons]
RP Siegel is the co-author of the eco-thriller Vapor Trails, the first in a series covering the human side of various sustainability issues including energy, food, and water. Like airplanes, we all leave behind a vapor trail. And though we can easily see others’, we rarely see our own.
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