Monday, January 9, 2012

New paper predicts less 21st century warming than IPCC

A paper published today in Geophysical Research Letters predicts less 21st century 'greenhouse' warming than the IPCC [transient climate response of 1.3-1.8C with a midpoint of 1.5C vs. IPCC's 1-3C with a midpoint of 2C].


GEOPHYSICAL RESEARCH LETTERS, VOL. 39, L01704, 5 PP., 2012
doi:10.1029/2011GL050226
Key Points
  • Estimates of TCR and 21st century warming are sensitive to the analysis period
  • Using 1851-2010 observations gives lower and less uncertain projected warming
  • The influence of GHGs, aerosols and natural forcings on temperature is detected
N. P. Gillett
Canadian Centre for Climate Modelling and Analysis, Environment Canada,, Victoria, British Columbia,, Canada
V. K. Arora
Canadian Centre for Climate Modelling and Analysis, Environment Canada,, Victoria, British Columbia,, Canada
G. M. Flato
Canadian Centre for Climate Modelling and Analysis, Environment Canada,, Victoria, British Columbia,, Canada
J. F. Scinocca
Canadian Centre for Climate Modelling and Analysis, Environment Canada,, Victoria, British Columbia,, Canada
K. von Salzen
Canadian Centre for Climate Modelling and Analysis, Environment Canada,, Victoria, British Columbia,, Canada
Projections of 21st century warming may be derived by using regression-based methods to scale a model's projected warming up or down according to whether it under- or over-predicts the response to anthropogenic forcings over the historical period. Here we apply such a method using near surface air temperature observations over the 1851–2010 period, historical simulations of the response to changing greenhouse gases, aerosols and natural forcings, and simulations of future climate change under the Representative Concentration Pathways from the second generation Canadian Earth System Model (CanESM2). Consistent with previous studies, we detect the influence of greenhouse gases, aerosols and natural forcings in the observed temperature record. Our estimate of greenhouse-gas-attributable warming is lower than that derived using only 1900–1999 observations. Our analysis also leads to a relatively low and tightly-constrained estimate of Transient Climate Response of 1.3–1.8°C, and relatively low projections of 21st-century warming under the Representative Concentration Pathways. Repeating our attribution analysis with a second model (CNRM-CM5) gives consistent results, albeit with somewhat larger uncertainties.

6 comments:

  1. Neato!

    You don't seem to get many comments here but rest assured, many of us do read the blog. We appreciate the effort you put into your blog!

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  2. Toned down nonsense. They detect nothing but their wish to keep the money flowing.
    Agree with the Aus_Physicist about your efforts for the blog.

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  3. Thanks for the encouraging comments & agree

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  4. Yes please continue your efforts in your blogging.

    I come here almost every day to read the old stuff and look for the latest one.

    I have posted a number of your blog postings at my climate forum.The Sea Level post is the latest one I have posted.

    Take care.

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  5. Thanks very much for your support!

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  6. I seriously doubt the net increase in temperature for the 21st century will be more than 1.0C.

    Oh, and...
    Please do keep on blogging!

    ReplyDelete