Carbon impact of land, water compared

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LONDON, June 20 (UPI) -- Marine and freshwater environments may release more carbon dioxide into the atmosphere as climate warms than their land counterparts, British researchers say.

In the largest ever analysis of rates of respiration, scientists at Queen Mary, University of London, compared temperature affects on respiration between aquatic and land ecosystems.

"In the carbon cycle, photosynthesis by plants absorbs carbon dioxide (CO2) while respiration by animals returns CO2 to the atmosphere," Gabriel Yvon-Durocher said.

"Understanding how rates of respiration of entire ecosystems respond to changes in temperature will be crucial for forecasting future climate change as the planet warms in the coming decades."

Analyzing rates of respiration in different ecosystems around the world, researchers found aquatic ecosystems had a stronger response to temperature changes than land ecosystems.

"Respiration has a higher 'activation energy' than photosynthesis, meaning that it increases more rapidly with increasing temperature. But over a longer time period, the carbon fixed by photosynthesis limits respiration on the land, Yvon-Durocher said.

"However, many aquatic ecosystems receive additional carbon from the land, which washes into lakes, rivers, estuaries and the sea from rainfall. This extra carbon means that respiration in aquatic ecosystems is not limited by photosynthesis and can have a stronger response to temperature than ecosystems on the land," he said.