Overview of The 4th Annual SORCE Meeting: Earth’s Radiative Budget – Part II

This weblog continues the posting of further excerpts from the 4th Annual SORCE Meeting: Earth’s Radiative Budget”. I was informed yesterday that most of the powerpoint slides from the talks will be available within a few weeks, and I will post when they are.

One of the most presented slide at the meeting was the 1997 Kiehl and Trenberth figure on the components of the average Earth’s energy budget (see page 16 of the 2005 National Research Council Report for an illustration of this figure). There were a number of talks that indicated the specific values within the figure need to be corrected by several Watts per meter squared. More on this subject when the powerpoint slides become available.

On the radiation budget, Bill Collins presented evidence on significant problems with the radiative parameterizations used in the global climate models. He stated that none of the IPCC models have methane and nitrous oxide [with repect to solar radiative forcing]. Also, that the largest [radiative] forcing bias occurs at the surface. His abstract reads in part,

“assessment by the Intergovernmental Panel on Climate Change (IPCC). Several lines of evidence from this evaluation indicate that there are substantial discrepancies among the AOGCMs in the ensemble and between the AOGCMs and reference line-by-line (LBL) In some cases this is because the AOGCMs neglect particular absorbers, while in others due to the methods for modeling the radiative processes. These differences have important implications for interpreting variations in forcing and response across the multi-model ensemble of AOGCM simulations assembled for the IPCC fourth assessment report (AR4). We conclude by presenting new mathematical methods for improving the accuracy of the radiative parameterizations in global models.”

Mark Weber stated that the stratosphere has become drier. In his abstract he wrote,

“After the middle 1990s, ozone levels have been increasing particularly in the northern hemisphere after a long-term downward trend.”

and that,

” Since the direct radiation impact on lower stratospheric ozone (as represented by total ozone) is rather small, solar irradiance variability must alter ozone via dynamical feedbacks as will be discussed in this talk.”

Jose Rial presented a very interesting talk that demonstrated how a slowly varying external [in his case natural] forcing can produce rapid and sudden major transitions in climate. His study will be available soon in a paper [Rial and Young 2006]. An important conclusion from his study is that the Milankovitch cycle is clearly a regional climate forcing effect, not only a global average forcing. His abstract states in part,

The modeling results further indicate that solar forcing organizes the free oscillations to form the (as yet unexplained) characteristic pattern of abrupt climate over the last ice age. No North Atlantic fresh water balance perturbations were necessary produce these model results; no external forcing other than the Milankovitch summer insolation was used.”.

Additional notes from this excellent SORCE meeting will be presented on Climate Science in upcoming posts.

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