From 2001 to early 2009, the US was governed by an administration which frequently got involved in climate science.
When an oil company demanded that climate scientists working on the IPCC and the United States' own National Assessment be removed:
Exxon's wish was the CEQ's command. According to an internal e-mail obtained by Rolling Stone, Connaughton's first order of business - even before his nomination was made public - was to write his White House colleagues-to-be from his law firm of Sidley & Austin. He echoed Exxon's call that Bierbaum, the acting director of the Office of Science and Technology Policy, be "dealt." In the end, each of the scientists on Exxon's hit list was replaced. "It was clear there was a strong lobby and activity against me by some in the energy industry - especially ExxonMobil," says Watson.
The Bush administration then appointed industry lobbyists to head the White House's Council on Environmental Quality. They edited scientific reports being put out by scientists working in the administration to undermine their conclusions:
On the opening page of the chapter on climate impacts, Cooney inserted a litany of language in bold intended to cast doubt on the science: "the weakest links in our knowledge . . . a lack of understanding . . . uncertainties . . . considerable uncertainty . . . perhaps even greater uncertainty . . . regarded as tentative."
And after it turned out that those modifications weren't enough:
"We tried to put some qualifiers on that chapter in the report," Cooney told him. "We'd take the text from EPA, and then we'd add a sentence like, 'We don't really know if this is really happening.' So we tried to do it, but I can see now that we made a total mess of it."
After that, Cooney was then given veto power over scientists working within the administration:
From then on, Cooney wielded a heavier pen when editing official reports on global warming. Not content to obscure science with uncertainty, he began to rewrite the science itself. Draft documents made public by the House Oversight Committee reveal that Cooney now had veto power over federal scientists, including Richard Moss, coordinator of the Climate Change Science Program Office, and even James Mahoney, the assistant commerce secretary nominally in charge of America's climate science.
The Council on Environmental Quality also controlled which administration scientists would be able to speak to the media, and edited the statements they made:
Dr. Karl, it says, "was not allowed to comment in his written testimony that 'modern climate change is dominated by human influences,' that 'we are venturing into the unknown territory with changes in climate,' or that 'it is very likely (>95 percent probability) that humans are largely responsible for many of the observed changes in climate.' " Instead of saying that global warming "is playing" a role in increased hurricane intensity, his comment became "may play" a role.
However, in the midst of all this, the scientific community made statements that contradicted the White House position. For example, in 2006 the world's largest general scientific society, the American Association for the Advancement of Science, put out a statement saying:
The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society. Accumulating data from across the globe reveal a wide array of effects: rapidly melting glaciers, destabilization of major ice sheets, increases in extreme weather, rising sea level, shifts in species ranges, and more. The pace of change and the evidence of harm have increased markedly over the last five years.
In 2005 the Joint Science Academies, a group of 11 national scientific societies, including the US National Academy of Sciences, stated that:
There will always be uncertainty in understanding a system as complex as the world’s climate. However there is now strong evidence that significant global warming is occurring. The evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and from phenomena such as increases in
average global sea levels, retreating glaciers, and changes to many physical and biological systems. It is likely that most of the warming in recent decades can be attributed to human activities (IPCC 2001). This warming has already led to changes in the Earth's climate.
In 2003 the American Geophysical Union stated that:
Human activities are increasingly altering the Earth's climate. These effects add to natural influences that have been present over Earth's history. Scientific evidence strongly indicates that natural influences cannot explain the rapid increase in global near-surface temperatures observed during the second half of the 20th century.
An article in the New York Times gives many examples of several administrations attempting to prevent the Surgeon-General from issuing statements on politically sensitive topics:
Dr. Koop, said he had been discouraged by top officials in the Reagan administration from discussing the AIDS crisis. He did so anyway.
Dr. Satcher said that the Clinton administration discouraged him from issuing a report showing that needle-exchange programs were effective in reducing disease. He released the report anyway.
Former Surgeon General Richard H. Carmona told a Congressional panel Tuesday that top Bush administration officials repeatedly tried to weaken or suppress important public health reports because of political considerations. The administration, Dr. Carmona said, would not allow him to speak or issue reports about stem cells, emergency contraception, sex education, or prison, mental and global health issues. Top officials delayed for years and tried to “water down” a landmark report on secondhand smoke, he said. Released last year, the report concluded that even brief exposure to cigarette smoke could cause immediate harm.
Dr. Carmona described being invited to testify at the government’s nine-month racketeering trial of the tobacco industry that ended in 2005. He said top administration officials discouraged him from testifying while simultaneously telling the lead government lawyer in the case that he was not competent to testify. Dr. Carmona testified anyway.
Probably the most famous example of political interference in science is, of course, Lysenkoism in Soviet Russia, described in Martin Gardner's Fads and Fallacies in the Name of Science [copied by hand, blame me for any typos]:
Seldom before in the history of modern science has a crackpot achieved the eminence, adulation and power achieved by Trofim D. Lysenko, the Soviet Union's leading authority on evolution and heredity. Not only have his opinions been pronounced dogma by the Kremlin, but his Russian opponents (whose views are held everywhere but in the USSR) in recent years have been systematically eliminated from their posts. Some have died in prison camps. Some have simply vanished. A few remain at work - but it is work in other fields of biology...
A host of experiments have been designed to test Lamarckianism. All that have been verified have proved negative. On the other hand, tens of thousands of experiments - reported in journals and carefully checked and rechecked by genticists throughout the world - have established the correctness of the gene-mutation theory beyond all reasonable doubt...
Just as Lamarckianism combines easily with an idealism in which the entire creation is fulfilling God's vast plan by constant upward striving, so also does it combine easily with political doctines which emphasize the building of a better world...
"In 1933 or thereabouts," Muller wrote, "the geneticists Chetverikoff, Ferry, and Ephroimson were all, on separate occasions, banished to Sibera, and Levitsky to a labor camp in the European Arctic... in 1936, the Communist geneticist Agol was convicted of 'Menshevik idealism' in genetics... Certain it is, however, that from 1936 on Soviet geneticists of all ranks lived a life a terror. Most of them who were not imprisoned, banished, or executed were forced to enter other lines of work.
In an expression of grim humour, Tony Judt observed in "A History of Europe Since 1945":
Stalin left his nuclear physicists alone... [He] may well have been mad but he was not stupid.
Whilst the Soviet government was able to use coercive pressure on scientists within the Soviet Union, Lysenkoism never caught on outside the reach of the Soviet bloc, and eventually collapsed even within it.
These are just a few examples - clearly politicians (on both sides of politics) do frequently attempt to interfere with science - ranging from outright oppression to limiting speech or editing reports - where the scientific results went against their political positions. However, it does seem that again and again the independent, international scientific community has been robust to government interference and influence.
In the US, the Climate Action Report, was still largely seen as in support of climate science in spite of the bits where extra uncertainty was edited in for political reasons. The Surgeons-General were still able to publish health warnings even when the government were able to oppose it. And the ultimate judge will be the independent scientific community, who continued to strongly support climate science even when the government of the day was trying to edit it out.