How much longer can plants help to offset global climate change?

PLANTS HAVE BEEN HELPING TO OFFSET CLIMATE CHANGE, BUT NOW IT’S UP TO US
Carnegie Institution for Science
​Wednesday, April 05, 2017

Washington, DC—Plants are currently removing more CO2 from the air than they did 200 years ago, according to new work from Carnegie’s Joe Berry and led by J. Elliott Campbell of UC Merced. The team’s findings, which are published in Nature, affirm estimates used in models from the Intergovernmental Panel on Climate Change. 
 
Plants take up carbon dioxide as part of the process of photosynthesis—a series of cellular reactions through which they transform the Sun’s energy into chemical energy for food. This research from Campbell, Berry, and their colleagues constructs a new history of global changes in photosynthetic activity.

Just as plants in actual glass greenhouses grow faster and more profusely when provided with elevated levels of CO2, plants in natural ecosystems have been expected to grow faster as the concentration of CO2 in the global atmosphere increases. At the global scale, this effect could offer some stability to the climate system by countering increased human emissions of CO2.
 
The magnitude of this effect is currently under debate. Could it be as large at the global scale as it is in small-scale greenhouse experiments? Or are other factors limiting the global system’s response to increased greenhouse gas emissions? A long-term record, similar to what we have for CO2 and temperature, is needed to address this large uncertainty in climate change projections.
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“We’ve done something new here,” Campbell said. “Reliable measurements of photosynthesis are typically made at the leaf-level. But you can’t get the big picture that way, and we need to know what the Earth as a whole is doing and how it has responded through time.”

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