by Gavin Schmidt and Stefan Rahmstorf
Many readers will be aware that three scientists (two of which are contributors to this site, Michael Mann and Ray Bradley) have received letters from Representative Joe Barton (Texas), Chairman of the House Energy and Commerce Committee specifically requesting information about their work on the ‘hockey stick’ papers (Mann et al (1998) and Mann et al (1999)) as well as an enormous amount of irrelevant material not connected to these studies.
Many in the scientific community would welcome any genuine interest in climate change from the committee, but the tone and content of these letters have alarmed many scientists and their professional organisations. In the words of Alan Leshner, CEO of the American Association for the Advancement of Science, the Barton letters “give the impression of a search for some basis on which to discredit these particular scientists and findings, rather than a search for understanding.” Other organisations and individual scientists have also expressed strong concerns:
- A statement from the EGU
- The American Association for the Advancement of Science (AAAS)
- A Nature editorial
- A letter from US scientists (including leading members of the NAS, a Nobel Prize winner and two of us (ES, GS))
- A letter from the head of the National Academy of Sciences, and
- A commentary from Tom Crowley in EOS
- Other politicians, the House Committee on Science and Henry Waxman.
The individual responses have now been delivered (and you can read them here):
These responses emphasise two main points that we have explained in great detail in earlier postings on this site:
- There is no case for casting doubt on the scientific value and integrity of the studies by Mann et al. – they have been replicated by other scientists, the data and the computer code are available in the public domain (including the actual fortran program used to implement the MBH98 procedure), and many other studies with different data and methods have confirmed the prime conclusion: that it is likely that the late 20th Century is the warmest period of at least the past one thousand years.
- The above studies are just one small piece of evidence in a very solid scientific case that humans are now altering the climate – and with or without this piece of evidence, this case is firm (see our post “What if the Hockey Stick were wrong?” or the commentary on Prometheus).
The real question we are faced with is not whether humans are changing climate. The science on this is clear, and decades of research have culminated in a scientific consensus on this point. The real question now is what we need to do about it. A Congressional committee concerned with energy could be – and indeed should be – a key player in exploring policy options to deal with the global warming threat. We hope that after studying the responses by the scientists, they will make a start.