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She said scientists should downplay their catastrophic predictions, which she said are premature, and instead shore up and defend their research. She said scientists and institutions that have been pushing for policy changes “need to push the disconnect button for now,” because it will be difficult to take action until public confidence in the science is restored.

“Hinging all of these policies on global climate change with its substantial element of uncertainty is unnecessary and is bad politics, not to mention having created a toxic environment for climate research,” she said.

Ms. Curry also said that more engagement between scientists and the public would help - something that the NAS researchers also proposed.

Paul G. Falkowski, a professor at Rutgers University who started the effort, said in the e-mails that he is seeking a $1,000 donation from as many as 50 scientists to pay for an ad to run in the New York Times. He said in one e-mail that commitments were already arriving.

The e-mail discussion began late last week and continued into this week.

Mr. Falkowski didn’t respond to an e-mail seeking comment, and an effort to reach Mr. Ehrlich was unsuccessful.

But one of those scientists forwarded The Times’ request to the National Academy of Sciences, whose e-mail system the scientists used as their forum to plan their effort.

An NAS spokesman sought to make clear that the organization itself is not involved in the effort.

“These scientists are elected members of the National Academy of Sciences, but the discussants themselves realized their efforts would require private support since the National Academy of Sciences never considered placing such an ad or creating a nonprofit group concerning these issues,” said William Kearney, chief spokesman for NAS.

The e-mails emerged months after another set of e-mails from a leading British climate research group seemed to show scientists shading data to try to bolster their claims, and are likely to feed the impression among skeptics that researchers are pursuing political goals as much as they are disseminating science.

George Woodwell, founder of the Woods Hole Research Center, said in one e-mail that researchers have been ceding too much ground. He blasted Pennsylvania State University for pursuing an academic investigation against professor Michael E. Mann, who wrote many of the e-mails leaked from the British climate research facility.

An initial investigation cleared Mr. Mann of falsifying data but referred one charge, that he “deviated from accepted practices within the academic community,” to a committee for a more complete review.

In his e-mail, Mr. Woodwell acknowledged that he is advocating taking “an outlandishly aggressively partisan approach” but said scientists have had their “classical reasonableness” turned against them.

“We are dealing with an opposition that is not going to yield to facts or appeals from people who hold themselves in high regard and think their assertions and data are obvious truths,” he wrote.