President Bush has said it.
A lot of government scientists have said it.
But until yesterday, it appeared that no news release on annual climate trends out of the National Oceanic and Atmospheric Administration under the Bush White House had said unequivocally that a buildup of greenhouse gases was helping warm the climate.
The statement came in a release that said 2006 was the warmest year for the 48 contiguous states since regular temperature records began in 1895. It surpassed the previous champion, 1998, a year heated up by a powerful episode of the periodic warming of the tropical Pacific Ocean by El Niño. Last year, another El Niño developed, but this time a long-term warming trend from human activities was said to be involved as well.
“A contributing factor to the unusually warm temperatures throughout 2006 also is the long-term warming trend, which has been linked to increases in greenhouse gases,” the release said, emphasizing that the relative contributions of El Niño and the human influence were not known.
A link between greenhouse gases and climate change was also made in a December news conference by Dirk Kempthorne, the secretary of the interior, as that agency proposed listing polar bears as threatened under the Endangered Species Act.
Still, the climate agency’s shift in language came as a surprise to several public affairs officials there. They said they had become accustomed in recent years to having any mention of a link between climate trends and human activities played down or trimmed when drafts of documents went to the Commerce Department and the White House for approval.
James L. Connaughton, chairman of the White House Council on Environmental Quality, said the release reflected longstanding views within the administration.
“It’s helpful for them to describe what is a question in many people’s minds — what is the human factor, what is the El Niño factor,” Mr. Connaughton said of the NOAA release. “From our perspective, what was in the press release was a direct reflection of what the president and folks in his administration have been saying for some time.”
Mr. Bush has made two speeches on climate. He first expressly accepted that humans were contributing to global warming in a news conference in Denmark in July 2005 on the way to an economic summit in Scotland, saying, “Listen, I recognize that the surface of the Earth is warmer and that an increase in greenhouse gases caused by humans is contributing to the problem.”
But the government’s scientific bureaucracy, where public affairs officials and scientists as recently as last year complained that findings pointing to climate dangers were being suppressed, has taken time to catch up.
“There’s been some sensitivity to the fact that some people have complained that NOAA and other parts of the government haven’t been as open as they would like them to have been on this,” said Jay Lawrimore, a climatologist at the National Climatic Data Center in Asheville, N.C., where the temperature trends are compiled. “Now NOAA is making an effort to be clearer on some of the influences.”
“Year after year as we continue to see warmer temperatures,” he said, “there are more and more converts convinced that it’s not just natural variability and not just something that’s going to return back to temperatures we saw 40 or 50 years ago — that in fact we are doing something to the climate.”