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Rising temperatures reducing ability of plants to absorb carbon, study warns
Rising temperatures in the past decade have reduced the ability of the world's plants to soak up carbon from the atmosphere, scientists said today.
Large-scale droughts have wiped out plants that would have otherwise absorbed an amount of carbon equivalent to Britain's annual man-made greenhouse gas emissions.
Scientists measure the amount of atmospheric carbon dioxide absorbed by plants and turned into biomass as a quantity known as the net primary production. NPP increased from 1982 to 1999 as temperatures rose and there was more solar radiation.
But the period from 2000 to 2009 reverses that trend–surprising some scientists. Maosheng Zhao and Steven Running of the University of Montana estimate that there has been a global reduction in NPP of 0.55 gigatonnes (Gt). In comparison, the UK's contribution to annual worldwide carbon dioxide emissions was 0.56Gt in 2007, while global aviation industry made up around 0.88Gt (3%) of the world total of 29.3Gt that year, according to UN data.
The researchers used data from the moderate resolution imaging spectroradiometer (Modis) on board Nasa's Terra satellite, combined with global climate data to measure the change in global NPP over the past decade.
"The past decade has been the warmest since instrumental measurements began, which could imply continued increases in NPP," wrote Zhao and Running in the journal Science.