By Sid Perkins
In experiments using a rare isotope of carbon, scientists have singled out microorganisms that appear to be largely responsible for natural emissions of the greenhouse gas methane from rice paddies. The finding may lead to methods to trim this major source of planet-warming gas.
In Earth’s atmosphere, natural and industrial greenhouse gases permit sunlight to reach the planet but block heat from escaping to space. Molecule for molecule, methane traps more than 20 times as much heat as carbon dioxide does, but methane is much less prevalent in the atmosphere than carbon dioxide is and so contributes less to the current problem. However, in the past 200 years, methane’s atmospheric concentrations have doubled, outpacing increases in atmospheric carbon dioxide.