NOAA Scientists Report Sharp Rise in Carbon Dioxide and Methane in 2007
Radiative forcing, relative to 1750, of all the long-lived greenhouse gases. The NOAA Annual Greenhouse Gas Index (AGGI), which is indexed to 1 for the year 1990, is shown on the right axis. (Larger image)
Carbon dioxide (CO2) levels continued to accelerate and levels of methane, the second most abundant greenhouse gas, rose in 2007 for the first time since 1998.
Scientists from NOAA’s Earth System Research Laboratory in Boulder, CO, have released these preliminary findings in an annual update to the NOAA Annual Greenhouse Gas Index, which tracks data from 60 global sites. Rapidly growing industrialization in Asia and rising wetland emissions in the Arctic and tropics are the most likely causes of the recent methane increase.
Last year alone nearly 19 billion additional tons of CO2, the primary driver of global climate change, and 27 million tons of methane were added to the air. Methane is 25 times more potent as a greenhouse gas than CO2, but there’s far less of it in the atmosphere. When related climate effects are taken into account, methane’s overall climate impact is nearly half that of CO2.
Permafrost, or permanently frozen ground, contains vast stores of carbon. Scientists are concerned that as the Arctic continues to warm and permafrost thaws, carbon could seep into the atmosphere in the form of methane, possibly fueling temperature rise.
April 28, 2008