Bishop Hill IPCC hides the good news
Mar 6, 2014 Climate: sensitivity From GWPF:
A new report published by the Global Warming Policy Foundation shows that the best observational evidence indicates our climate is considerably less sensitive to greenhouse gases than climate models are estimating.
The clues for this and the relevant scientific papers are all referred to in the recently published Fifth Assessment report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). However, this important conclusion was not drawn in the full IPCC report – it is only mentioned as a possibility – and is ignored in the IPCC's Summary for Policymakers (SPM).
For over thirty years climate scientists have presented a range for climate sensitivity (ECS) that has hardly changed. It was 1.5-4.5°C in 1979 and this range is still the same today in AR5. The new report suggests that the inclusion of recent evidence, reflected in AR5, justifies a lower observationally-based temperature range of 1.25–3.0°C, with a best estimate of 1.75°C, for a doubling of CO2. By contrast, the climate models used for projections in AR5 indicate a range of 2-4.5°C, with an average of 3.2°C.
This is one of the key findings of the new report Oversensitive: how the IPCC hid the good news on global warming, written by independent UK climate scientist Nic Lewis and Dutch science writer Marcel Crok. Lewis and Crok were both expert reviewers of the IPCC report, and Lewis was an author of two relevant papers cited in it.
In recent years it has become possible to make good empirical estimates of climate sensitivity from observational data such as temperature and ocean heat records. These estimates, published in leading scientific journals, point to climate sensitivity per doubling of CO2 most likely being under 2°C for long-term warming, with a best estimate of only 1.3-1.4°C for warming over a seventy year period.
“The observational evidence strongly suggest that climate models display too much sensitivity to carbon dioxide concentrations and in almost all cases exaggerate the likely path of global warming,” says Nic Lewis.
These lower, observationally-based estimates for both long-term climate sensitivity and the seventy-year response suggest that considerably less global warming and sea level rise is to be expected in the 21st century than most climate model projections currently imply.
“We estimate that on the IPCC’s second highest emissions scenario warming would still be around the international target of 2°C in 2081-2100,” Lewis says.
The full report is here.
Bishop Hill
Piers Forster has penned a response at Ed Hawkins' Climate Lab Book site.
Reader Comments (155)
Any good statistician would inform you that extrapolation too far is a few steps too far. 10 headache pills are no way 10 times as effective as 1, how do we know the shape of the response when we haven't any where near observed it?
@Monty Mar 6, 2014 at 1:04 PM
"If you knew anything about paleo reconstructions you would know that there are lots of them. Many of them use glacier length records, permafrost boreholes, deep sea sediments, ice cores, fluvial records etc. Are they ALL flawed?"
Who knows, Monty? Who can know?
In the absence of any independent contemporaneous verification (and there isn't any) it's all finger-in-the-air stuff. The "hiding the decline" fiasco said it all. In the face of facts which contradicted them the paleo guys were left floundering.
Ssat
Do you smoke or drive?
As usual those commenting on here are generally tolerant, even polite to trolls like the Fool Monty and his chums, who don't hesitate to tell us what (they allege) we believe and condescending to tell us how scientifically illiterate we all are.
I claim no scientific credentials, as an old Chartered Engineer.
But although I find the discussions on climate sensitivity interesting, the real question is, do we as a society, continue to rely on policy based evidence making. And continue to pour Billions into 'solutions' which absolutely demonstrably don't work, to 'problems' which (at best) are enormously exaggerated.
Martin,
Don't sell yourself short. As a Chartered Engineer, you were held to a high standard of efficacy and ethics. Science is not some divine mystery that only the initiated can look into.
Your work required you to do things that could be tested and had to work.
Climate science, by contrast, is pushing 'solutions' that when tested either require huge efforts in defending or adjusting (or covering up) or simply don't work.