RUPERT DARWALL September
30, 2013
"Human
influence extremely likely to be the dominant cause of observed warming since
the middle of the last century," was the headline from Friday's release of
the first instalment of the Intergovernmental Panel on Climate Change's fifth
assessment report. "Extremely likely"—indicating a 95%-100%
likelihood—was ratcheted up one notch from the 2007 fourth assessment report's
"very likely." Yet compared to 2007, the IPCC widened its estimate of
the responsiveness of the climate system to carbon dioxide by reducing the
lower band to a 1.5°C increase from 2°C, qualifying the new estimate as only
"likely."
This is a glaring
discrepancy. How can the IPCC be more confident that more than half the
temperature rise since the mid-20th century is caused by greenhouse-gas
emissions when it is less sure of the climatic impact of carbon dioxide? The
explanation is that IPCC reports, especially the summaries for policymakers,
are primarily designed for political consumption. And as if on cue, British
Prime Minister David Cameron
commented on the IPCC report, "If someone said there is a 95% chance that
your house might burn down, even if you are in the 5% that doesn't agree with
it, you still take out the insurance."
But poke beneath
the surface of the IPCC's latest offering and the confection is revealed for
what it is. …..To Read More…..
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