Wetlands, forests and farmlands soak up large amounts of carbon dioxide but rising amounts of the gas in the atmosphere mean these carbon "sinks" could become less effective at fighting climate change.
Scientists say land ecosystems are an essential brake on the pace of climate change because plants soak up large amounts of carbon dioxide (CO2) as they grow. This also boosts the level of carbon in soils.
But in a study published in the British journal Nature on Thursday, scientists say rising levels of planet-warming CO2 will trigger an increased release of two other far more potent greenhouse gases from soils, rice paddies and wetlands.
"Our results suggest that the capacity of land ecosystems to slow climate warming has been overstated," the authors, led by Kees Jan van Groenigen of Northern Arizona University in the United States, conclude.
Scientists say many plants will grow faster as CO2 levels rise, leading to more CO2 mopped up from the atmosphere. But rising levels of nitrous oxide and methane offsets some of the benefit.
Van Groenigen and colleagues calculated that a surge in the release of greenhouse gases from soils would negate at least 16.6 percent of the previously estimated climate change fighting potential of increased carbon storage in the landscape.
This means the pace of global warming could in fact be faster than previously thought and that complex computer models that scientists use to project the impacts of climate change would need to be adjusted, van Groenigen.
Thursday 14 July 2011
As CO2 levels rise, land becomes less able to curb warming
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