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Fred Singer: Keeping The IPCC Honest
I know it’s a tough job – but let’s just check their iconic, widely-quoted conclusion and parse its meaning:
“Most of the observed increase in globally-averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations.” [IPCC Synthesis Report, SPM, Nov 2007]. How should one interpret this ex cathedra declaration to the faithful? IPCC helpfully defines ‘very likely’ as ‘90-99% certain.’ But they don’t tell us how they reached such well-defined certainty. What remarkable unanimity! Just how many and whom did they poll?
IPCC doesn’t define the word ‘most.’ We may assume it means anything between 51 and 99%. Quite a spread. But a footnote informs us that solar forcing is less than 10% of anthropogenic [0.12/ 1.6 W/m2]; so ‘most’ must be closer to 99% than to 51%.
OK; let’s check out the data since 1958. But we don’t want to rely on contaminated surface data – which IPCC likely used – although they omitted to say so. Atmospheric data were readily available to the IPCC in the CCSP-SAP-1.1 report (Fig 3a, p.54; convening lead author John Lanzante, NOAA), with independent analyses by Hadley Centre and NOAA that agree well. And further, according to GH models, atmospheric trends should be larger than surface temperature trends.
1958 – 2005: Total warming of +0.5 C – but how much of that is anthropogenic?
1958 – 1976: Cooling
1976 – 1977: Sudden jump of +0.5 C Cannot be due to GHG
1977 – 1997: No detectable trend
1998 – 1999: El Nino spike
2000 – 2001: No detectable trend
2001 – 2003: Sudden jump of +0.3 C Cannot be due to GHG
2003 – present No trend, maybe even slight cooling
Conclusion: The IPCC’s ‘most’ is not sustained by observations; the human contribution is very likely only 10% or even less.
S. Fred Singer: Science & Environmental Policy Project (SEPP)