ScienceDaily (Sep. 28, 2009) — Unusually high temperatures in the Arctic and heavy rains in the tropics likely drove a global increase in atmospheric methane in 2007 and 2008 after a decade of near-zero growth, according to a new study. Methane is the second most abundant greenhouse gas after carbon dioxide, albeit a distant second.
NOAA scientists and their colleagues analyzed measurements from 1983 to 2008 from air samples collected weekly at 46 surface locations around the world. Their findings will appear in the September 28 print edition of the American Geophysical Union’s Geophysical Research Letters and are available online now.
“At least three factors likely contributed to the methane increase,” said Ed Dlugokencky, a methane expert at NOAA’s Earth System Research Laboratory in Boulder, Colo. “It was very warm in the Arctic, there was some tropical forest burning, and there was increased rain in Indonesia and the Amazon.”
Dlugokencky and his colleagues from the United States and Brazil note that while climate change can trigger a process which converts trapped carbon in permafrost to methane, as well as release methane embedded in Arctic hydrates – a compound formed with water - their observations “are not consistent with sustained changes there yet.”
It appears that the methane hydrates in the ocean depths has already started releasing methane stored in hydrates, but it is not yet getting into the atmosphere. I would expect that is at least partly because some organisms metabolize (eat) methane for energy, producing carbon dioxide, and the amounts of methane being released so far are small enough for them to fully utilize it. If that is what is happening, the good thing is that methane has a much stronger greenhouse effect than CO2. The bad thing is that CO2 acidifies the ocean, which is bad for life in the oceans, especially those which produce shells from calcium carbonate.