–Industry hype and marketing
–Industry hype and marketing
–J. Nocera, “How to Extract Gas Responsibly” NYT (Feb 28, 2012)
-J. Quiggan “Timescales and timeframes” (Mar 7, 2012)
At these temperatures, a major change in the planet’s climate system become increasingly likely, and there is a high risk of positive feedbacks making it extremely difficult to control global warming.
Fig. Observed global mean temperature from 1900 to 2009 and projected future temperature under various scenarios of controlling methane + black carbon (BC) and carbon dioxide, alone and in combination. An increase to 1.5o to 2.0 o C above the 1890-1910 baseline (illustrated by the yellow bar) poses high risk of passing a tipping point and moving the Earth into an alternate state for the climate system. Source: UNEP/WMO 2011.
See also Howarth et al. 2012 background paper for the National Climate Assessment and Hanson et al 2007.
– various sources
The global warming potential or GWP, is a simple metric often used to assess how much more powerful a given greenhouse gas is when compared to carbon dioxide. Back in 1996, the Intergovernmental Panel on Climate Change estimated the GWP for methane as 21, considered over a 100-year time period following emission. As of 2007, the IPCC presented global warming potentials (GWP) for methane of 25 for a 100-year integrated time-frame and 72 for a 20-year integrated time frame after emission. Using a more recent model to better capture how methane interacts with other radiatively active substances, Shindell et al. in a 2009 paper in Science updated these factors to 33 and 105 respectively. These higher values reflect the best, most current science. The GWP for methane is less at the longer time scale simply because methane does not stay in the atmosphere for as long as carbon dioxide.