Methane levels plateau
Atmospheric levels of methane, the second-most important greenhouse gas, appear to have stabilized, according to a report in the journal, Scientific American. This halt to the rise of methane levels may provide us with some breathing space in which to reduce CO2 emissions.
It not yet known the reasons for the plateau in methane levels, or how permanent it is. The article lists some possible causes for the plateau as:
“Leading hypotheses include: the collapse of the Soviet Union, which resulted in a decline in energy use in Russia and the other former Soviet republics; repairs to oil and gas lines to prevent leaks; decreasing emissions from coal mining; widespread drought that led to decreased emissions from natural wetlands; and a decline in rice production. “The trends of major man-made sources such as rice fields and cattle have greatly slowed down over the last two decades,” notes physicist Aslam Khalil of Portland State University. “As these–rice and cattle–were once big sources, their lack of continued increase would then cause atmospheric methane to stop increasing as well.”