Carbon dioxide is the gas most discussed in relation to manmade climate change. But there are other gases responsible for the greenhouse effect that climate scientists blame for global warming.

Scientists say the presence of one of those gases, methane, can be expected to rise rapidly, should the planet continue to warm. That's bad news, since methane -- already the third most abundant greenhouse gas -- has roughly 30 times the heat-trapping potency of CO2.


Scientists have known for some time that methane is a byproduct of biological activity in the world's freshwater ecosystems. Microorganisms in freshwater lakes, rivers, ponds, and streams produce methane as they digest organic materials.

But exactly how much methane these ecosystems were emitting -- or would emit -- remained a mystery.

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To get a better idea, Cristian Gudasz, a visiting postdoctoral research associate at Princeton, and a number of other researchers analyzed nearly 1,600 temperature and methane emissions measurements from 127 freshwater ecosystems all over the world. Using their data, the researchers modeled future methane emissions and determined that as the temperature moved from zero degrees Celsius up to 30, methane production increased 57 times.

The researchers' findings were recently detailed in the journal Nature.

Gudasz says the calculations of his and his colleagues will help scientists get a better idea on how other greenhouse gases will react to global warming.

"The freshwater systems we talk about in our paper are an important component to the climate system," Gudasz said. "There is more and more evidence that they have a contribution to the methane emissions. Methane produced from natural or manmade freshwater systems will increase with temperature."

[Nature]