[RWG] ARTICLE: Forests might not be the climate saviors we are counting on

[Park, Margaret E]

New research suggests trees in the future won't get a big growth spurt from more CO2, and will die more in wildfires, droughts and insect outbreaks.

Warren Cornwall, May 18, 2022, Anthropocene


These days, it seems like everyone wants to plant a tree. The World Economic Forum is promoting a plan to grow a trillion trees<https://www.1t.org/>. The Nature Conservancy is pushing for a billion<https://www.nature.org/en-us/get-involved/how-to-help/plant-a-billion/>. Major corporations such as Apple are pumping money into forest restoration<https://www.apple.com/newsroom/2021/04/apple-and-partners-launch-first-ever-200-million-restore-fund/>. Much of the work is meant to help counter climate change by harnessing photosynthesis to suck carbon dioxide from the atmosphere. In part, companies and governments hope it will help them make good on promises to cut their overall climate pollution to zero. But new research suggests forests might not be quite the climate saviors we hoped. That’s not to downplay the critical role trees play today in countering climate change. Forests soak up roughly a quarter of human-caused climate emissions each year. But there are uncertainties about how forests will fare in a hotter world.



The questions run from the basics of how trees grow, to continent-scale forecasts of how heat and drought could reshape the landscape. Scientists at the University of Utah tackled the issue at both levels and, in a pair of papers, delivered some sobering news last week. When it comes to basic biology, a key uncertainty has been whether tree growth is limited more by photosynthesis or by how quickly a tree can make new cells that become wood. If photosynthesis is the driver, more carbon dioxide in the atmosphere could act like fertilizer, fueling greenery that would suck up greenhouse gases. If it’s wood-building, then trees might not get a growth boost from CO2, especially if plants experience more stress due to factors such as drought.



To solve the puzzle, scientists turned to a network of sensors installed on towers in forests across North America, Europe, Japan and Australia. These sensors sniff out fluctuations in carbon dioxide levels in the nearby air, essentially seeing how the vegetation breaths. This provides a way to gauge how much photosynthesis is happening. The researchers tracked new wood being made in trees in these forests by measuring their annual growth rings. Each ring in a tree’s trunk mark its growth during a year. A thicker growth ring translates to more wood, and more carbon dioxide trapped in the tree.



Read full article here<https://www.anthropocenemagazine.org/2022/05/forests-might-not-be-the-climate-saviors-we-are-counting-on/?utm_source=rss&utm_medium=rss&utm_campaign=forests-might-not-be-the-climate-saviors-we-are-counting-on&utm_source=rss&utm_medium=rss&utm_campaign=forests-might-not-be-the-climate-saviors-we-are-counting-on>
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