Thursday, March 06, 2014

IPCC over estimates climate sensitivity

Posted over at WUWT is a link to a significant new report by Lewis and Crick examining climate sensitivity.  

Along with the report, is a foreword by Judith Curry in which she writes:
  • The sensitivity of our climate to increasing concentrations of carbon dioxide is at the heart of the scientific debate on anthropogenic climate change, and also the public debate on the appropriate policy response to increasing carbon dioxide in the atmosphere. 
  • Climate sensitivity and estimates of its uncertainty are key inputs into the economic models that drive cost-benefit analyses and estimates of the social cost of carbon.
  • This report by Nic Lewis and Marcel Crok addresses this gap between the IPCC assessments and the primary scientific literature by providing an overview of the different methods for estimating climate sensitivity and a historical perspective on IPCC’s assessments of climate sensitivity. 
  •  The report also provides an independent assessment of the different methods for estimating climate sensitivity and a critique of the IPCC AR4 and AR5 assessments of climate sensitivity.
As Lewis notes, the report is significant as it
  •  ...shows that – contrary to the impression given by the Summary for Policymakers – the observational, scientific evidence in the main IPCC AR5 report actually supports much lower estimates of how sensitive the climate system is to greenhouse gas levels, both in the long term and over the remainder of this century...
The narrative for CAGW has been loosing impetus for some time. Despite this, the data are still being juiced to imply and promote a crisis not evidenced by empirical observation.  Bottom line:
  • The GCMs overestimate future warming by 1.7–2 times relative to an estimate based on the best observational evidence.
CAGW isn't happening.  Won't be happening in the future, probably never was happening.  Climate changes as a dynamic natural system. Always has, always will.  Humans do modify both the weather and the climate, but not near to the degree that has been implied nor implicated in advocacy of the CAGW narrative.  Severe weather has always been a feature of human occupancy of the planet and there is insifficient evidence to support the contention that either the frequency nor intensity of weather events has changed in a manner inconsistent with the historical record.

Climate was and remains a proxy for a supposed scientific imperative for a set of political policies designed to suppress growth, control economic development, centralize governance and curtail globalization.  These policies reflect a particular morality and ideology that is both elitist in design and lacking on poplar support and resonance, hence the attempt to co-opt science as a mechanism to compel compliance by invoking an authority that is difficult to challenge and contradict.

After all this  (the IPCC, the Hockey Stick, the blogs, Climategate and the constant revisionism from global warming to AGW to CAGW) the central issue remains the provision of cheap energy and not climate.

And without the stigma of CAGW, what is the rationale for windmills? For solar panels? For constraint and increasing carbon taxes?  Fracking has removed the peril of an energy crisis for the West.  What is the cheap energy option for Africa?  Why is energy not dropping in price and fueling a new age of innovation and economic prosperity?

And, lastly, absent of any climate crisis, what possible purpose is there to zero-carbon as a goal?

Remove the presumption of CAGW, dismiss the narrative, and the value of pursuing zero-carbon as a goal is similarly removed.