American Physical Society Reviews Its Position On Climate Change

  • Date: 20/02/14
  • Judith Curry, Climate Etc

The American Physical Society (APS) is in the process of reviewing its 2007 Climate Change Statement.  The process itself is remarkable, and I’ve been privileged to participate in the process.


The APS has a public website for the Climate Statement Review [link].  From the main text:

The American Physical Society formally reviews its statements every five years. In accordance with that process, the APS Panel on Public Affairs (POPA) formed a Subcommittee to review its Climate Change Statement. The members of the Subcommittee are: Steven Koonin (chair), Phillip Coyle, Scott Kemp, Tim Meyer, Robert Rosner and Susan Seestrom. The Charge to the Subcommittee was approved by POPA and the APS Executive Board and is included in the Supporting Documents links.

As part of the POPA-approved process, on January 8, 2014 the Subcommittee convened a workshop with six climate experts. The Subcommittee used that meeting to delve more deeply into aspects of the IPCC consensus view of the physical basis of climate science. In doing so, it hoped to illuminate for itself, for the APS membership, and for the broader public both the certainties and boundaries of current climate science understanding. The framing document, expert bios, and the complete transcript for the workshop are included in the Supporting Documents links.

The workshop was the first step in a deliberative process. As a membership organization of over 50,000 physicists, APS adheres to rigorous scientific standards in developing all its statements. If the Subcommittee recommends updating the existing APS Climate Change Statement, then, consistent with APS by-laws, all APS members will be given an opportunity to review the statement and provide input during a comment period.


The text of the 2007 APS Climate Change statement is found [here].

This statement resulted in the public resignations from the APS of several high profile physicists (this was followed closely at WUWT).  These resignations prompted additional commentary to be appended to the statement, with some clarifications and mentions of uncertainty.

The charge to the POPA Subcommittee considering the statement can be found [here].


I was one of the experts invited to attend the January 8 Workshop.  The other invitees were  Bill Collins, Ben Santer, Isaac Held, Richard Lindzen, and John Christy.  [link] for biosketches.

Several weeks before the Workshop, we received a framing document that posed a series of questions that had arisen from their reading of the IPCC AR5 WG1 Report.  Not only did they carefully read the AR5 Report (they picked up some things that I hadn’t spotted), but their analysis and questions reflected a good skeptical perspective.  None of the Subcommittee Members have any apparent expertise in climate science; rather they viewed the AR5 report through the eyes of physicists.

Each Workshop participant was invited to select questions to respond to in a 30 minute presentation.  The Workshop format allowed for extensive questioning and discussion.   My presentation can be found here [JC APS].

The APS produced a complete transcript of the workshop [link], with ppt slides embedded within.  This is a remarkable document — more than anything else that I’ve seen, it provides in my opinion what is the most accurate portrayal of  the scientific debates surrounding climate change.  There was some fascinating (and new to me) science that was presented. In a future post i will discuss the scientific presentations. But one general reaction is that while the 6 of us agreed on the primary scientific evidence (apart from some tiffs between Santer and Christy on the satellite-derived tropospheric temperature trends), we each had a unique perspective on how to reason about the evidence.

For now, lets focus on the closing discussion, starting on page 467.  The Chair tried to nail down what we could all agree on versus what we disagree on.  This didn’t get very far – anything meaningful ended up being the subject of debate and disagreement and labeled as ‘uncertain’.  Much discussion on the ‘more than half’ attribution issue, also the role of expert judgment.  And finally we discussed what we thought the scope of the APS statement be (starting on p 516), and how APS could make a contribution; all 6 agreed it should be on the science and not advocate for policies.  In fact, Subcommittee members  had all read my blog post on (Ir)responsible advocacy.

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