Remarkably high temperatures in the Arctic Zone and heavy rainfalls in the tropical zone are most likely to be the reason behind what drove a worldwide increase in atmospheric methane in 2007 and 2008 after a decade of near-zero development, according to a new study. Methane is the second most abundant greenhouse gas after carbon dioxide.  National Oceanic and Atmospheric Administration scientists and their colleagues studied measurements from 1983 to 2008 from air samples accumulated weekly at 46 surface locations around the world. Read more about Future of Emissions Trading Markets: SO2, NOX, CO2, Mercury

According to Ed Dlugokencky, a methane expert at NOAA’s Earth System Research Laboratory in Boulder, Colorado, “At the least three factors are expected to have contributed to the methane increase. It was very warm in the Arctic, there was some tropical forest burning, and there was augmented rainfall in Indonesia and the Amazon.”

Dlugokencky and his colleagues from the United States and Brazil note that while global climate change can activate a procedure which converts trapped carbon in permafrost to methane, as well as release methane implanted in Arctic hydrates – a chemical compound formed with water – their observations “are not agreeable with sustained changes there yet.”

As per the scientists, in the tropics, the increased rainfall resulted in longer periods of rainfall and larger wetland areas, allowing for microbes to produce more methane. Starting in mid-2007, scientists acknowledged La Niña circumstances beginning, declining and then escalating in early 2008. This kind of climate condition generally brings wetter-than-normal circumstances in some tropical regions and colder ocean surface temperatures in the central and eastern tropical Pacific Ocean. It can persist for as long as two years. In the United States, La Niña often signals drier-than-normal circumstances in the Southwest and Central Plains regions, and wetter fall and winter seasons in the Pacific Northwest.

Observations from satellites and ground sites indicate that biomass burning – the burning of plant and other organic material that expels carbon dioxide and methane – imparted about 20 percent, of the total methane discharged into the atmosphere in 2007.

However, during the scientists’ 2007 measurement of methane for northern wetland regions, including the Arctic Zone, temperatures for the year were the hottest on record. This temperature increase concurred with the large jump in the amount of methane measured in that area.

Methane is generally produced in oxygen-deprived environments, such as flooded wetlands, peat bogs, rice paddies, landfills, white ant colonies, and the gastrointestinal tracts of cows and other ruminant animals. The gas also escapes during fossil fuel extraction and distribution and is given out during fires.