Wednesday, May 15, 2013

Review paper finds growth of atmospheric methane has significantly decreased, opposite of IPCC predictions

A new review paper from SPPI and CO2 Science finds the growth rate of atmospheric methane has significantly decreased over the past 30 years, the opposite of IPCC predictions. Separately, a new paper finds, "Warming may not release Arctic carbon – Element could stay locked in soil, 20-year study suggests."
[Illustrations, footnotes and references available in PDF version]
Atmospheric methane's contribution to anthropogenic climate forcing is estimated to be about half that of CO2 when both direct and indirect components to its forcing are summed (see Figure 1, below); and nearly all models project atmospheric methane (CH4) concentrations will increase for at least the next 3 decades, with many of the scenarios assuming a much larger increase throughout the 21st century. A quick fact-check, however, reveals that methane observations lie far below the model projections, as shown in each of the four prior Assessment Reports of the IPCC. So what has caused the IPCC to get things so wrong?

Anthony Watts reports today: Arctic methane emergency called off