Atmospheric Methane Concentrations

By | May 11, 2013


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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 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?