Climate Depot:

UN scientists turn on each other: UN Scientist Declares Climategate colleagues Mann, Jones and Rahmstorf ’should be barred from the IPCC process’ — They are ‘not credible any more’
A UN scientist is declaring that his three fellow UN climate panel colleagues “should be barred from the IPCC process.” In a November 26, 2009 message on his website, UN IPCC contributing author Dr. Eduardo Zorita writes: “CRU files: Why I think that Michael Mann, Phil Jones and Stefan Rahmstorf should be barred from the IPCC process.”
Zorita writes: “Short answer: Because the scientific assessments in which they may take part are not credible anymore.”
Zorita indicates that he is aware that he is putting his career in jeopardy by going after the upper echelon of UN IPCC scientists. “By writing these lines I will just probably achieve that a few of my future studies will, again, not see the light of publication,” Zorita candidly admits, a reference to the ClimateGate emails discussing how to suppress data and scientific studies that do not agree with the UN IPCC views.
Zorita was a UN IPCC Contributing Author of the Fourth Assessment Report in 2007. Since 2003, Zorita has headed the Department of Paleoclimate and has been a senior scientist at the Institute for Coastal Research of the GKSS Research Centre in Germany. Zorita has published more than 70 peer-reviewed scientific studies.
Zorita’s stunning candor continued, noting that scientists who disagreed with the UN IPCC climate view were “bullied and subtly blackmailed.”

Another theory, however, is that you turn on the discredited scientists so that you can then, after a brief hiatus, continue making the same bogus claims.