Biggest, Oldest Trees Most Likely to Succumb to Global Warming; Small Plants May be Spared

Saturday, May 23, 2015
(photo: National Park Service)

Larger, older trees will hurt the most by rising global temperatures, according to a new study.


Climate change will affect plants’ ability to absorb water, researchers at Los Alamos National Laboratory found. Larger, older trees with large leaves will be affected the most. 

Researchers came to this conclusion when they applied Darcy’s law, an equation describing the flow of water through a porous medium, such as a leaf, to plants.


“Global warming is global, and all vascular plants obey Darcy’s law,” Nathan McDowell, co-author of the study, published in Nature Climate Change, told ThinkProgress.

Basically, researchers say that as the atmosphere warms, there is less water vapor in air compared to the atmosphere’s capacity for holding the vapor. Trees then expel more water into the atmosphere, causing them to dry up. The larger the tree, the more water can be expelled.


If researchers are correct and older, larger trees die off as a result of climate change, the trees’ demise will cause there to be even more carbon in the atmosphere. “It’s the big trees that store the most carbon,” McDowell said, noting that the tall trees are also those that do the most photosynthesis, pulling more carbon out of the atmosphere than small trees.


In addition, the loss of bigger trees could affect animal species that rely on them for their habitats.

-Noel Brinkerhoff, Steve Straehley


To Learn More:

Darcy’s Law Predicts Widespread Forest Mortality under Climate Warming (by Nathan G. McDowell and Craig D. Allen, Nature Climate Change)

What Global Warming Means For Old, Tall Trees (by Natasha Geiling, ThinkProgress)

Tall, Ancient and Under Pressure (by Jim Robbins, New York Times)

Half of California's Big Trees Are Gone (by Ken Broder, AllGov California)

Redwoods Faring Better than Humans in the Age of Global Warming (by Ken Broder, AllGov California)


anonamouse 9 years ago
The elephant in the room is the Holocene Climate Optimum, a warm period that occurred only six to nine thousand years ago (in other words, in relatively modern times). During the HCO, global average temps were about four to six degrees warmer than now. Somehow, the trees and coral and polar bears etc. survived this very warm spell, that is to say, they survived thousands of years of weather significantly warmer than today's and several degrees warmer than the temps predicted by the IPCC's (failed) climate models. But of course, Darcy's Law suggests this is impossible. ... Know the old saying about the difference between Theory and Practice?

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