18th November, 2009 - Posted by admin - Comments Off
Recent work shows that the impact of non-CO2 climate drivers, including methane and black carbon, the scientific name for soot, should be re-evaluated. Even under current impact assessments these non-CO2 drivers add up to a radiative forcing similar to that of CO2.
The paper by Shindell et al., “Improved Attribution of Climate Forcing to Emissions“, (Science 30 October 2009) argues that methane is more potent than previously realised. This is due to the interaction with black carbon. The paper gives a revised Global Warming Potential for methane measured over 100 years as 33. This is an increase of over 30% compared to the value of 21 given in the IPCC Second Assessment Report used for the Kyoto Protocol.
Some commentators feel the impact of methane is better assessed by a GWP measured over 20 years. (See Livestock and Climate Change, Robert Goodland and Jeff Anhang) Shindell et al. calculate this GWP to be 105. If this measure were used the climate impact of methane would be 5 times the value agreed at Kyoto.