Last week the climate world was rocked — or at least, strongly buffeted — by the publication of memos that were allegedly from the Heartland Institute, a nonprofit research group that takes a strongly skeptical attitude toward climate science. The memos detailed budget information — including news that groups like the archconservative Koch Foundation and corporations like Microsoft had donated money to Heartland — and detailed strategies that included fighting the teaching of climate science in U.S. schools.

To advocates of climate action, the memos were proof that the Heartland Institute and its allies were playing unfair, seeking to spread doubt about climate science as a way to delay action that could harm corporate interests. A group of climate scientists — many of whom had been victimized by the Climategate e-mail hacks of 2009 and ’11 — even wrote a letter to the Heartland Institute criticizing the group.

For its part the Heartland Institute implicitly acknowledged that at least some of the memos were real — apologizing to donors who had been promised anonymity. But the group claimed that the memo detailing its supposed climate strategy was false and announced that it would prosecute the person who had obtained the documents.

The question was who. And now we know: Peter Gleick, the president of the Pacific Institute and a veteran climate and water expert.

Gleick admitted his actions in a blog post put up Monday evening on the Huffington Post:

At the beginning of 2012, I received an anonymous document in the mail describing what appeared to be details of the Heartland Institute’s climate program strategy. It contained information about their funders and the Institute’s apparent efforts to muddy public understanding about climate science and policy. I do not know the source of that original document but assumed it was sent to me because of my past exchanges with Heartland and because I was named in it. Given the potential impact however, I attempted to confirm the accuracy of the information in this document. In an effort to do so, and in a serious lapse of my own and professional judgment and ethics, I solicited and received additional materials directly from the Heartland Institute under someone else’s name. The materials the Heartland Institute sent to me confirmed many of the facts in the original document, including especially their 2012 fundraising strategy and budget. I forwarded, anonymously, the documents I had received to a set of journalists and experts working on climate issues. I can explicitly confirm, as can the Heartland Institute, that the documents they emailed to me are identical to the documents that have been made public. I made no changes or alterations of any kind to any of the Heartland Institute documents or to the original anonymous communication.

You can read the rest here. The major question now — beyond the legal ramifications for Gleick and the Heartland Institute — is whether the original document Gleick says he received, the strategy memo, is real or whether it’s a falsification as the Heartland Institute maintains. The problem for climate advocates, of course, is that suspicion will only grow that Gleick falsified the original document now that he has admitted using deception to get the additional memos. (And just so we’re clear, this is deception — no reputable investigative reporter would be permitted to do what Gleick did. It’s almost certainly a firing offense.)

The entire Heartland affair underscores just how politicized and fraught the battle over climate change has become — in case you hadn’t already noticed. As Andrew Revkin points out at Dot Earth, it also claims a water and climate expert who had done truly good work over the past two decades:

One way or the other, Gleick’s use of deception in pursuit of his cause after years of calling out climate deception has destroyed his credibility and harmed others. (Some of the released documents contain information about Heartland employees that has no bearing on the climate fight.) That is his personal tragedy and shame (and I’m sure devastating for his colleagues, friends and family).