Carbon starvation

Dec 23, 2015 | written by:

Despite the good intentions and commitments established at Cop21 in Paris, probably reading this article you will think that we behaved really badly with Mother Nature and she, in turn, is really angry. Now, even run for cover and mitigate damages is difficult in spite of all the good wills. This is also highlighted by a new and troubling study, just out in Nature Climate Change and it was led by Nate McDowell of the Los Alamos National Laboratory: warming climate could trigger a “massive” dieoff of coniferous trees, such as junipers and piñon pines, in the U.S. southwest sometime this century. The study is based on both global and regional simulations, conducted over five years, and examined both an extreme warming scenario and also a more modest scenario.

The difference between the two is only a matter of time: in the first the disaster would occur in 2050, in the second in 2100. The problem is that climate change is expected to not only increase the risk of drought, but will also drive heat up in general. And this could injure trees in two ways — simply drying them out, but also leading to “carbon starvation.”

This could occur if, faced with dry conditions, tree leaves close their stomata to keep water in, but therefore cannot bring in more carbon dioxide and thus suffer from reduced or even fully halted photosynthesis.The scientists then proceeded to use regional models to examine whether they would reproduce this phenomena on a much larger scale in a warming world. The result was that 72 percent of the U.S. southwest’s needle leaf evergreen forests would “experience mortality in less than 40 years. The models might overestimate tree death, but they could also underestimate it, since the study does not consider the possibility of fires that could shorten life expectancy of conifers. Certainly, the future doesn’t appear to be bright, but if playing with colors we choose to dedicate ourselves to the green... this eventuality would move away from us very quickly!

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