Climate science after ‘climate-gate’

It can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries.

The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years. This conclusion has subsequently been supported by an array of evidence ...

Mann was again caught up in the so-called “climate-gate affair”, following the release of emails hacked from the Climate Research Unit (CRU) at the University of East Anglia (UEA). Again the deniers of climate change claim these emails show that climate scientists have been colluding to cook their data to support the theory of global warming. But this is not what the four enquiries into the matter have concluded.

The UEA, in consultation with the Royal Society, asked an international panel of seven distinguished scientists, chaired by Lord Oxburgh, to consider whether, in the CRU’s publications, “climatic data had been dishonestly selected, manipulated and/or presented to arrive at pre-determined conclusions that were not compatible with a fair interpretation of the original data”.

The panel reported that:

We saw no evidence of any deliberate scientific malpractice in any of the work of the Climatic Research Unit and had it been there we believe that it is likely that we would have detected it.

A second review, chaired by Sir Muir Russell, looked at the behaviour of the scientists rather than the soundness of their research, examining “the honesty, rigour and openness” with which the CRU scientists acted.

This review did find that:

… there has been a consistent pattern of failing to display the proper degree of openness, both on the part of the CRU scientists and on the part of the UEA, who failed to recognise not only the significance of statutory requirements but also the risk to the reputation of the University and, indeed, to the credibility of UK climate science.

But the review reached this conclusion only after stating (PDF 1.39MB) that:

On the specific allegations made against the behaviour of CRU scientists, we find that their rigour and honesty as scientists are not in doubt.

In addition, we do not find that their behaviour has prejudiced the balance of advice given to policy makers. In particular, we did not find any evidence of behaviour that might undermine the conclusions of the IPCC assessments.

The House of Commons Science and Technology Committee also enquired into the matter. Its report is critical of the CRU and the university, but does not find fault with the science itself. The review states (PDF 312KB):

Consideration of the complaints and accusations made against CRU has led us to three broad conclusions.

Conclusion 1: The focus on Professor Jones and CRU has been largely misplaced. On the accusations relating to Professor Jones’s refusal to share raw data and computer codes, we consider that his actions were in line with common practice in the climate science community. We have suggested that the community consider becoming more transparent by publishing raw data and detailed methodologies. On accusations relating to Freedom of Information, we consider that much of the responsibility should lie with UEA, not CRU.

Conclusion 2: In addition, insofar as we have been able to consider accusations of dishonesty - for example, Professor Jones’s alleged attempt to “hide the decline” -  we consider that there is no case to answer. Within our limited inquiry and the evidence we took, the scientific reputation of Professor Jones and CRU remains intact. We have found no reason in this unfortunate episode to challenge the scientific consensus as expressed by Professor Beddington [UK Government Chief Scientific Advisor - MR], that “global warming is happening [and] that it is induced by human activity”.

Conclusion 3: A great responsibility rests on the shoulders of climate science: to provide the planet’s decision makers with the knowledge they need to secure our future. The challenge that this poses is extensive and some of these decisions risk our standard of living. When the prices to pay are so large, the knowledge on which these kinds of decisions are taken had better be right. The science must be irreproachable.