Monday, September 26, 2011

Straight from the horse's mouth: Hansen says global warming of late 20th century was NOT due CO2 or fossil fuel burning

In a paper published in PNAS in 2000, global warming religion high priest James Hansen argues that "rapid warming in recent decades has been driven mainly by non-CO2 greenhouse gases... not by the products of fossil fuel burning, CO2 and aerosols..." Furthermore, Hansen correctly points out "The growth rate of non-CO2 greenhouse gases has declined in the past decade." The summary of the paper states, 
"Non-CO2 Greenhouse Gases: These gases are probably the main cause of observed global warming, with CH4 [methane] causing the largest net climate forcing." 
Hansen appears unaware methane represents an extremely tiny 0.0000017 mole fraction of the atmosphere and contributes almost nothing to the posited 'greenhouse' effect.

H/T to Bill Wallace of Global Hot Air for this discovery

Global warming in the twenty-first century: An alternative scenario

  1. Valdar Oinas*§
  1. *National Aeronautics and Space Administration Goddard Institute for Space Studies, Center for Climate Systems Research, Columbia University Earth Institute, and §Center for Environmental Prediction, Rutgers University, 2880 Broadway, New York, NY 10025
  1. Contributed by James Hansen


A common view is that the current global warming rate will continue or accelerate. But we argue that rapid warming in recent decades has been driven mainly by non-CO2 greenhouse gases (GHGs), such as chlorofluorocarbons, CH4, and N2O, not by the products of fossil fuel burning, CO2 and aerosols, the positive and negative climate forcings of which are partially offsetting. The growth rate of non-CO2 GHGs has declined in the past decade. If sources of CH4 and Oprecursors were reduced in the future, the change in climate forcing by non-CO2 GHGs in the next 50 years could be near zero. Combined with a reduction of black carbon emissions and plausible success in slowing CO2 emissions, this reduction of non-CO2 GHGs could lead to a decline in the rate of global warming, reducing the danger of dramatic climate change. Such a focus on air pollution has practical benefits that unite the interests of developed and developing countries. However, assessment of ongoing and future climate change requires composition-specific long-term global monitoring of aerosol properties.


  1. And that isn't all:

    "These results provide evidence that relatively small solar forcing may play a significant role in century-scale NH winter climate change. This suggests that colder winter temperatures over the NH continents during portions of the 15th through the 17th centuries (sometimes called the Little Ice Age) and warmer temperatures during the 12th through 14th centuries (the putative Medieval Warm Period) may have been influenced by longterm solar variations."

    So said Michael Mann et al.

  2. MS, Beside a tiny amount of methane in the atmosphere (about 1.7ppm cf 390pmm for CO2) Hansen does not realise (or deliberately accepts false information) that methane does not burn in the atmosphere and its radiation absorption is about one fifth of CO2. The contribution of methane is practically zero. See
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