By analyzing methane in the skies of Jupiter and Saturn’s moon Titan, scientists are now pinpointing what effects this global warming gas is having on Earth, a new study finds.
By Charles Q. Choi | SPACE.com
Greenhouse gases warm the planet by trapping heat from the sun. The greenhouse gas that most often makes news is the carbon dioxide generated in great amounts by the burning of fossil fuels. However, methane is an even more potent greenhouse gas, pound for pound capable of warming the planet more than 25 times more than carbon dioxide over the span of a century, according to the Intergovernmental Panel on Climate Change (IPCC).
In the new study, researchers focused on the most poorly understood aspect of the role of methane in global warming — how much short-wavelength solar radiation it absorbs. Previous estimates from the IPCC regarding the effects of increased methane emissions on global climate omitted the impact of shortwave absorption. [Photographic Proof of Climate Change: Time-Lapse Images of Retreating Glaciers]
Recent climate models are designed to account for shortwave absorption of methane. However, their accuracy is limited by uncertainties in how well methane absorbs shortwave radiation. Whereas the carbon dioxide molecule has a relatively simple linear shape, methane has a more complex tetrahedral shape, and the way it responds to light is also complicated — too much so to pin down in the lab.