I don't know, because they have an agenda maybe? Perhaps money? Incentive to keep one's job? All three? There are many reasons why. It's been well discussed that peer review isn't really all that. Fraud happens and I'm willing to bet it happens more than you or I believe it does.Wow, this is totally new information to me. Why haven't the climate scientists studied the history of the climate? Seems like if they knew about these cycles, they could give us all much better recommendations.
"Peer review isn't good at catching outright fraud - the reviewers aren't charged with actually repeating the experiments described, and deliberate manipulation of data and tables can slip by even the most careful of reviewers. When fraud is discovered, articles are typically retracted."
But peer review isn't perfect
Millions for Mann
Michael Mann Received Stimulus Money
The Wall Street Journal writes that $2.4 million of stimulus money went to climate scientist Michael Mann who helped rig the climate change consensus.