The new e-mails appeared remarkably similar to the ones released two years ago just ahead of a similar conference in Copenhagen. They involved the same scientists and many of the same issues, and some of them carried a similar tone: catty remarks by the scientists, often about papers written by others in the field.
Climate scientists said the release was likely intended to torpedo any potential progress in the Durban negotiations, though not much progress had been expected anyway given that countries have been reluctant to commit to binding emissions limits.
The University of East Anglia, the British institution at the middle of the previous hacking episode, confirmed that at least some of the newly released e-mails were authentic. The cache released in 2009 appeared to have come from a file someone obtained by hacking into the university’s computers, a crime for which no charges have been filed or suspects named. The new batch of more than 5,000 e-mails is evidently a fresh selection from the same set of records.
A string of investigations following the 2009 release all came to the conclusion that scientists had not manipulated data to support their findings, though some of the reports did criticize them on minor points, such as failing to share their data or to respond properly to freedom of information requests.
Myron Ebell, a climate-change skeptic who works for the Competitive Enterprise Institute, a free-market think tank based in Washington, called the new e-mails “strong evidence that a small group of scientists centered around East Anglia were engaged in a conspiracy to provide a scientifically misleading assessment of the case for catastrophic global warming.” Senator James M. Inhofe, the Oklahoma Republican who is the most prominent climate-change contrarian in Congress, cited the e-mails in a statement attacking the Obama administration’s attempts to limit greenhouse gases.
But Michael E. Mann, a Pennsylvania State University scientist who wrote or received some of the e-mails, said they showed the opposite of any conspiracy, demonstrating instead that climate science is a vigorous enterprise where scientists were free to argue over conclusions. “Scientists rely on the ability to have frank, sometimes even contentious discussions with each other,” Dr. Mann said in an interview Tuesday. “Science requires that.”
In one of the e-mails, Raymond S. Bradley, director of the Climate System Research Center at the University of Massachusetts, Amherst, criticized a paper that Dr. Mann wrote with the climate scientist Phil Jones, which used tree rings and similar markers to find that today’s climatic warming had no precedent in recent natural history. Dr. Bradley, who has often collaborated with Dr. Mann, wrote that the 2003 paper “was truly pathetic and should never have been published.”
Dr. Bradley confirmed in an interview that the e-mail was his, but said his comment had no bearing on whether global warming was really happening. “I did not like that paper at all, and I stand by that, and I am sure that I told Mike that” at the time, he said. But he added that a disagreement over a single paper had little to do with the overall validity of climate science. “There is no doubt we have a big problem with human-induced warming,” Dr. Bradley said. “Mike’s paper has no bearing on the fundamental physics of the problem that we are facing.”
Some of the other e-mails involved comments about problems with the computer programs used to forecast future climate, known as climate models. For instance, a cryptic e-mail apparently sent by Dr. Jones, a researcher at East Anglia, said, “Basic problem is that all models are wrong — not got enough middle and low level clouds.”
Gavin A. Schmidt, a climate modeler at NASA, said he found such exchanges unremarkable. He noted that difficulties in modeling were widely acknowledged and disclosed in the literature. Indeed, such problems are often discussed at scientific meetings in front of hundreds of people.
Of the new release of e-mails, Dr. Schmidt said, “It smacks of desperation.”
Dr. Mann said he hoped the fresh release, apparently first posted to a computer server in Russia, would provide new clues for the British police as they seek to catch the hacker or hackers.
“Who are the criminals?” he asked. “Who is funding this effort, not just to steal these materials but to promote them?”