Summer Drought Limits the Positive Effects of CO2 and Heat On Plant Growth in Future Climate

http://www.sciencedaily.com/releases/2011/08/110823104918.htm

ScienceDaily (Aug. 27, 2011) — Although the rain this summer has been pouring down over Denmark, most scientists agree that global temperature increases will intensify periods with summer drought already in 2075. The large scale project CLIMAITE, led by Risø DTU, has published its first synthesis paper in the journal Global Change Biology, and the conclusion is perhaps a little surprising that the predicted increase in plant growth, due to more CO2 in the atmosphere is noticeably limited when combined with higher temperatures -- and especially summer droughts.

In contrast to the increased growth in plants that scientists have often seen in studies with elevated CO2, the first synthesis paper on the comprehensive CLIMAITE project shows that the combination of summer drought and potential plant growth-promoting factors such as higher temperatures and increased CO2 together limit the effect of CO2 increased plant growth significantly.

"When you've previously seen a significantly higher plant growth at elevated CO2 concentrations, it is typically because it has been controlled studies, where only the CO2 concentration was changed. We fundamentally had the theory that you have to look at the combination of the different climate variables, since the plants in the future will be exposed to multiple changes simultaneously, "explains Klaus Steenberg Larsen, who is a researcher in the Biosystems Division at Risø DTU and lead author on the scientific paper.


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