LONDON—The British university whose stolen emails caused a global climate science controversy in 2009 says those behind the breach have apparently released a second and potentially far larger batch of old messages.

University of East Anglia spokesman Simon Dunford said that while academics didn't yet have the chance to examine all the roughly 5,000 emails apparently dumped into the public domain Tuesday, a small sample seen by the university "appears to be genuine."

The university said in a statement that the emails did not appear to be the result of a new breach. Instead, the statement said that the emails appeared to have been stolen two years ago and held back until now "to cause maximum disruption" to the imminent U.N. climate talks next week in Durban, South Africa.

If that is confirmed, the timing and nature of the leak would follow the pattern set by the so-called "Climategate" emails, which caught prominent scientists stonewalling critics and discussing ways to keep opponents' research out of peer-reviewed journals.

Those hostile to mainstream climate science claimed the exchanges proved that the threat of global warming was being hyped, and their publication helped destabilize the failed U.N. climate talks in Copenhagen, Denmark, which followed several weeks later.

Climategate also dealt a blow to the reputation of the University of East Anglia's Climatic Research Unit, which is one of the world's leading centres for the study of how world temperatures have varied over time.

Although a host of reviews have since vindicated the unit's science, some of its practices — in particular efforts to hide data from opponents — have come under strong criticism. The university says it is now much more open about what it does.

Excerpts quoted on climate skeptic websites appeared to show climate scientists talking in conspiratorial tones about ways to promote their agenda and freeze out those they disagree with. There are several mentions of "the cause" and discussions of ways to shield emails from freedom of information requests.

Penn State University professor Michael Mann — a prominent player in the earlier controversy whose name also appears in the latest leak — said on Twitter that "the cause" he was referring to was the cause of "communicating science in face of massive disinformation effort."

In an email exchange with the AP he described Tuesday's development as "a truly pathetic episode," blaming agents of the fossil fuel industry for "smear, innuendo, criminal hacking of websites, and leaking out-of-context snippets of personal emails."

He said that the real story behind the leak was "an attempt to dig out 2-year-old turkey from Thanksgiving '09. That's how desperate climate change deniers have become."

Bob Ward, with the London School of Economics' Grantham Research Institute on Climate Change, said in an email that he wasn't surprised by the leak.

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"The selective presentation of old email messages is clearly designed to mislead the public and politicians about the strength of the evidence for man-made climate change," he said. "But the fact remains that there is very strong evidence that most the indisputable warming of the Earth over the past half century is due to the burning of fossil fuels and other human activities."

The source of the latest leaked emails was unclear. The perpetrator of the original hack has yet to be unmasked, although British police have said their investigation is still active.

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