When a US government scientist named Joel Clement spoke at a United Nations conference in June, his subject was one that has become a lightning rod in a politically polarised nation.

Mr Clement read from a report that he had authored during the Barack Obama administration that chronicled coastal erosion in the Arctic so severe that entire villages in Alaska had already chosen to pack up and relocate.

The threat that Mr Clement described was not theoretical. It has resulted from the melting of permafrost, which has affected schools and homes built over it and also led to a loss of wildlife habitat, all of which have forced the northernmost Americans to become what he called refugees in their own country.

Within days of his address, Mr Clement was reassigned by Donald Trump¡¯s administration from his high-profile job as director of the Interior Department¡¯s Office of Policy Analysis to a position as an accountant in a branch of the agency that processes royalties paid by logging and fossil fuel companies for leasing public land.

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The intent of the shift, made by officials of an administration that has downplayed the effect of climate change, was to compel him to quit, Mr Clement said. Instead, he spoke out publicly, writing in an op-ed published by that the administration has chosen ¡°silence over science¡±.

It¡¯s one of several ways in which US scientists are beginning to push back hard against policy decisions in the Trump administration that appear to ignore science.

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¡°More and more scientists are saying, ¡®I just can¡¯t sit back and hide in my lab and hope it will all pass,¡¯¡± said Andrew Rosenberg, director of the Union of Concerned Scientists¡¯ Center for Science and Democracy.

The centre has begun a project to help government scientists safeguard research subjected to political interference. Called the Science Protection Program, the initiative encourages scientists to report any interference and to send their research through encrypted channels to be preserved. It also offers free and confidential legal advice.

That effort, which Dr Rosenberg described as technically politically agnostic, is among a growing number of responses to a Republican administration that has discounted not only climate science but also empirical conclusions about such things as the danger of pesticides.

¡°There¡¯s an attitude inside the [government] agencies of, ¡®If we want to know something from you scientists, we¡¯ll ask you,¡¯¡± Dr Rosenberg said. ¡°The law says you can¡¯t do that. The law says you¡¯ll use the best available science, not that you¡¯ll find a convenient collection of notions, facts and political positions.¡±

Yet so far, in several agencies whose newly appointed leaders align with Mr Trump, that is exactly what has happened.

References to climate change have been stripped from government websites, cuts have been proposed in funding for climate research, and a federal advisory panel on climate change has been dissolved.

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Mr Clement¡¯s boss, Ryan Zinke, the secretary of the interior, said during his confirmation hearing that the extent to which climate change was caused by humans remained an open question, as did what might be done to address that. His department has asked the National Academies of Science to stop a study of the health effects of a coal-mining technique that the senior Democrat on the House Natural Resources Committee said has been shown to cause lung cancer, heart disease and other medical problems.

Scott Pruitt, the head of the Environmental Protection Agency,?has halted a proposal to ban a pesticide called chlorpyrifos, which agency scientists say affects the brains of children and farmworkers.

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¡°The culture and climate in federal agencies is really dismissing science and scientists,¡± Dr Rosenberg said. ¡°People are self-censoring in even using the term ¡®climate change¡¯ because they know that¡¯s unacceptable and that someone [who uses it] might be targeted and fired.¡±

Other scientific organisations that historically have been apolitical are also stepping into the breach. ¡°Now is not the time to silence science,¡± the American Public Health Association pronounced. The American Geophysical Union is part of a coalition working to keep data findable, accessible, interoperable and reusable, or FAIR. It is an ¡°integral responsibility of scientists, data stewards and sponsoring institutions to ensure the preservation of those data¡±, said Chris McEntee, executive director of the association, which also has a legal education programme for scientists.

The Natural Resources Defense Council is suing over the chlorpyrifos decision. And the Center for Science and Democracy has begun raising money for a Scientists Protection Fund to defend scientists who choose the risky course of speaking out.

¡°There are some people who might say scientists should hold themselves apart as if we¡¯re all monks and nuns. I think we¡¯re beyond that,¡± Dr Rosenberg said.

He also acknowledged the frustrating, forehead-slapping nature of this work.

¡°I have a big bruise on my forehead from doing that every day,¡± Dr Rosenberg said. ¡°It¡¯s remarkable to me that we even have to have these conversations. Never in my wildest imagination did I think I¡¯d have to make the case that we should base decisions on what we actually know.¡±

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