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Methane a growing threat to Arctic's changing climate

Doug O'Harra
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Climate-changing greenhouse gases continued their unrelenting rise during 2010, with carbon dioxide averaging 389 parts per million over the year, according to the Annual Greenhouse Gas Index posted by the National Oceanic and Atmospheric Agency.

The capacity of these gases to insulate the home planet and push the rate of climate warming has increased 29 percent since 1990, and 2 percent since 2009, NOAA reports here.

"The increasing amounts of long-lived greenhouse gases in our atmosphere indicate that climate change is an issue society will be dealing with for a long time," said Jim Butler, director of the Global Monitoring Division of NOAA's Earth System Research Laboratory, in this story. "Climate warming has the potential to affect most aspects of society, including water supplies, agriculture, ecosystems and economies. NOAA will continue to monitor these gases ... to further understand the impacts on our planet."

A quick primer: the natural presence of CO2 and other gases helps keep the Earth warm enough for life to exist. After the Sun warms the planet, these gases slow the loss of heat back into space in a process that acts somewhat like glass in a greenhouse.

After thousands of years of relative stability, Earth's CO2 concentration began climbing in the 1800s and shows no sign of abating. Scientists blame the rise largely on the burning of fossil fuel by people. The Earth's CO2 level, which cycles up and down over the course of a year, busted through an unprecedented 393 parts per million during the summer, according to the latest measurements posted by the Mauna Loa Observatory in Hawaii.

Scientists say such concentrations will kick-start warming and eventually bake the planet to average temperatures not seen in millions of years -- leading to climate change on a scale not seen since the rise of human civilization.

The NOAA Greenhouse index, started in 2004, charts and analyzes the impact of CO2 and four other long-lived gases on a yearly basis. The big five are responsible for 96 percent of what the scientists call "radiative climate forcing." The research also takes into account the influences of 15 trace gases.

The bottom line? Concentrations of carbon dioxide and nitrous oxide continued to increase at the same steep rate observed over the past decades. Perhaps more alarming was a surge in the presence of atmospheric methane, which began a sudden increase in 2007 after about 10 years of stability.

While CO2 drives 80 percent of the warming caused by greenhouse gases, methane poses an outsized threat. Some scientists warn that widespread thawing of Arctic permafrost or warming of frozen hydrates on the ocean floor could trigger massive methane releases and dramatically accelerate the rate of climate change.

"Pound for pound, methane is 25 times more potent as a greenhouse gas than carbon dioxide, but there's less of it in the atmosphere," the NOAA story notes.

Contact Doug O'Harra at doug(at)alaskadispatch.com