The Guardian has posted examples of how climate scientists have been using the peer review process to control which science gets published--and to blackball journals that don't play along:

The Guardian's investigation into the emails stolen from the University of East Anglia reveals how climate scientists acted to keep research papers they did not like out of academic journals. One UEA scientist, Dr Keith Briffa, wrote to a colleague to ask him for help rejecting a paper from a journal which he edited. "Confidentially I now need a hard, and if required, extensive case for rejecting." The request apparently broke the convention that the review process should be independent and anonymous. Briffa was not able to comment because of an ongoing independent review into the stolen emails.

In another email, sent in March 2003, the leading US climate scientist Prof Michael Mann suggested ostracising a journal for publishing a paper that attacked his work.

"I think we have to stop considering Climate Research as a legitimate peer-reviewed journal. Perhaps we should encourage our colleagues … to no longer submit to, or cite papers in, this journal." Mann denies any attempt to "stifle legitimate sceptical views".

The emails also reveal that one of the most influential data sets in climate science – the "hockey stick" graph of temperature over the past 1,000 years – was controversial not just with sceptics but among climate scientists themselves. "I know there is pressure to present a nice tidy story [in the forthcoming IPCC report], but in reality the situation is not quite so simple," wrote Briffa in September 1999.

There is more on this here:

The head of the CRU, Professor Phil Jones, as a top expert in his field, was regularly asked to review papers and he sometimes wrote critical reviews that may have had the effect of blackballing papers criticising his work.

Here is how it worked in one case.

A key component in the story of 20th-century warming is data from sparse weather stations in Siberia. This huge area appears to have seen exceptional warming of up to 2C in the past century. But in such a remote region, actual data is sparse. So how reliable is that data, and do scientists interpret it correctly?

In March 2004, Jones wrote to Professor Michael Mann, a leading climate scientist at Pennsylvania State University, saying that he had "recently rejected two papers [one for the Journal of Geophysical Research and one for Geophysical Research Letters] from people saying CRU has it wrong over Siberia. Went to town in both reviews, hopefully successfully. If either appears I will be very surprised".

Critics of Jones such as the prominent sceptical Stephen McIntyre, who runs the Climate Audit blog have long accused him of preventing critical research from having an airing. McIntyre wrote on his web site in December: "CRU's policies of obstructing critical articles in the peer-reviewed literature and withholding data from critics have unfortunately placed issues into play that might otherwise have been settled long ago." He also says obstructing publication undermine claims that all is well in scientific peer review.

Dr Myles Allen, a climate modeller at the University of Oxford and Professor Hans von Storch, a climate scientist at the Institute for Coastal Research, in Geesthacht, Germany signed a joint column in Nature when the email hacking story broke, in which they said that "no grounds have arisen to doubt the validity of the thermometer-based temperature record since it began in about 1850." But that argument is harder to make if such evidence, flawed though it might be, is actively being kept out of the journals.

in July 2004, Jones wrote an email to Mann about two papers recently published in Climate Research – the Soon and Balunias paper and another he identified as by "MM". This was almost certainly a paper from the Canadian economist Ross McKitrick and Michaels that returned to an old sceptics' theme. It claimed to find urbanisation dominating global warming trends on land. Jones called it "garbage".

More damagingly, he added in an email to Mann with the subject line "HIGHLY CONFIDENTIAL": "I can't see either of these papers being in the next IPCC report. Kevin [Trenberth] and I will keep them out somehow – even if we have to redefine what the peer review literature is!"

This has, rightly, become one of the most famous of the emails. And for once, it means what it seems to mean. Jones and Trenberth, of the National Centre for Atmospheric Research in Boulder, Colorado, had recently become joint lead authors for a key chapter in the next IPCC assessment report, called AR4.

They had considerable power over what went into those chapters, and to have ruled them out in such a manner would have been a clear abuse of the IPCC process.