IPCC Scientists Assess the Assessments

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The IPCC Assessment Reports are an increasing burden on the climate science community that may have reached its limits, according to the scientists who write them.


SAN FRANCISCO, CA., DEC. 10, 2013 — The IPCC Assessments Reports, such as the 5th report (5AR) that came out in September, are an increasing burden on the climate science community that has reached its limit, Thomas Stocker said at an AGU press conference this morning.

Stocker, from the University of Bern, is a co-chair on Working Group I, which assesses the scientific side of climate change. He gave some statistics that went into the 5AR:

  • 259 scientists worked, each for three and a half years
  • 9,200 peer reviewed publications were assessed
  • 2 million gigabytes of numerical data was reviewed
  • 1,200 diagrams were produced
  • over 54,000 comments were received and reviewed

Stocker said it’s too early to say if there will be a 6th AR, or what form it might take. But he did say it’s “becoming evident that they [the ARs] are an increasing burden for the scientific community” that “has become extremely large.”

Dennis Hartmann from the University of Washington briefly reviewed the main messages of the 5AR (warming is unequivocal, and the human influence on climate is clear), and presented three areas of interest for the future:

  • More analysis on “the hiatus” in surface warming (the 5AR concluded part of it was changes in forcings — the solar constant and aerosol forcing — and natural variability related to El Niños and La Niñas. How long can it be expected to persist? Can science get a better handle on short-term (decadal) variability, particularly from the oceans?
  • Sea ice trends at both poles — scientists want to better understand the role of natural variability. The Arctic is melting faster than models predict, and the puzzling Antarctic is gaining sea ice (possibly from a changing upper ocean salinity or stronger winds in the southern hemisphere).
  • Extremes weather, especially extreme precipitation. Models need better resolution (grid sizes), and tropical storms need better observations and science in order to say if a change has been observed or not, and to predict their future

Olivier Boucher, Director of Research at the French National Centre for Scientific Research (CNRS), said clouds are critical for understanding the remaining uncertainties in climate behavior, and that new instruments for measuring clouds and aerosols should help better characterize trends in cloud properties. As always though, there are challenges to be overcome, especially in sampling and in instrument calibration.

Boucher called low-level clouds the “joker” of cloud feedbacks, since they’re the wild card in the science.

Stocker was asked to comment on the NIPCC report put out by the Heartland Institute. He said, “No one can seriously believe the NIPCC is a scientific report, so I will not comment on that,” which itself is quite a comment!

One interesting thought from Olivier Boucher, in response to a question: even with a 100-fold increase in computing power, modelers would still need “some time” to make progress, which requires a better understanding of the underlying physics. Thomas Stocker noted again that the “human factor is also a limitation — the sheer amount of data that has to be assessed is a big task ….”

David Appell

David Appell is a science writer living in Oregon and a regular contributor to Yale Climate Connections. (E-mail: david@yaleclimatemediaforum.org, Twitter: @davidappell)
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