“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.”
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
In conclusion: The IPCC’s ‘most’ is not sustained by observations; the human contribution is very likely only 10% or even less.
By Fred Singer, who lives in Arlington, Virginia, and holds a B.E.E. in Electrical engineering from Ohio State University and an A.M. and PhD in Physics from Princeton University
*IPCC Synthesis Report, Summary for Policy Makers, November 2007
Photograph of Fred Singer taken in New York by Jennifer Marohasy in March 2008.
This note is from SEPP Science Editorial #17 (December 27, 08), ‘Keeping the IPCC honest’ http://www.sepp.org/