Columbia engineers demonstrate that, as temperatures rise, northern high latitude regions will not become more conducive to vegetation growth—light is still essential to end of season photosynthesis
Most projections about climate change assume that, as temperatures rise, regions in the north high latitudes may become more suitable for the growth of vegetation, turning into cropland to feed increasing populations while also fixing more carbon dioxide (CO2) and slowing down climate change. Plants require appropriate temperature, water, and light conditions for photosynthesis and growth, so it seems logical that as temperatures increase in the northern high latitudes, plant photosynthesis, which uses CO2 to release oxygen, should also increase. At the same time, plant respiration, which uses oxygen to release CO2 and is also highly dependent on temperature, is expected to increase, too. The critical question still under debate is whether autumn warming might lead to an increase in carbon uptake, i.e., the difference between photosynthesis and respiration.
A new Columbia Engineering study demonstrates that even when temperatures warm and cold stress is limited, light is still a major factor in limiting carbon uptake of northern high latitudes. The team, led by Pierre Gentine, associate professor of earth and environmental engineering, analyzed satellite observations, field measurements, and model simulations and showed that there is a prevalent radiation limitation on carbon uptake in northern ecosystems, especially in autumn. Using a new dataset, Gentine’s group developed an algorithm to map global plant photosynthesis and then developed a framework to quantify the limitation of light on photosynthesis. The study is published today in Nature Climate Change.
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