The hacker or whistle-blower who leaked a tranche of emails several years ago has struck again, releasing 5,500 emails and an encrypted set of 22,000 emails into the Internet. The emails are worth studying in full, because they raise very serious questions about the credibility of the IPCC, the journals publishing papers on climatology, the government scientific bodies commissioning research into climate and the news organizations covering them. Moreover, the emails call into disrepute the assertion, frequently made, that the warming of the climate over the past century is known to be “unprecedented”. While it is possible that it is unprecedented, we do not know this for certain, since the proofs advanced are provably flawed.