Natural shields being weaken against climate change

(Independent):The soil and ocean are being weakened as buffers against global warming, in a vicious circle with long-term implications for the climate system, say two new studies. If the seas and the land are less able to soak up or store greenhouse gases, more of these carbon emissions will enter the atmosphere, holding in even more heat from the sun. A study published in Nature said a gradual increase in atmospheric carbon dioxide (CO2) over the last half-century has accelerated the release of methane and nitrous oxide in the soil. These gases are respectively 25 and 300 times more effective at trapping radiation than CO2, the principal greenhouse gas by volume.

"This feedback to our changing atmosphere means that nature is not as efficient in slowing globalwarming as we previously thought," said Kees Jan van Groenigen, a professor at Trinity College Dublin and the paper's lead author.

Earlier studies examining how additional CO2 affects the capacity of different soils – in forests, grasslands, wetlands and agricultural fields – to either absorb or release these two gases yielded conflicting results. When van Groenigen and colleagues reviewed 49 such studies, however, two patterns emerged. More CO2 increased nitrous oxide in all soils, but soils in rice paddies and wetlands released more methane in particular.

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