Eight key scientific bodies warn Republican congressman Lamar Smith that his committee’s investigation into Noaa could have a ‘chilling effect’ on science

Leading scientists have accused a Republican-led committee of subjecting climate researchers to politically motivated “harassment” amid an increasingly fractious investigation into the activity of the National Oceanic and Atmospheric Administration (Noaa).

Eight key scientific bodies have written to Republican congressman Lamar Smith, chairman of the House committee on science, to warn that the committee’s inquiry into Noaa could have a “chilling effect on the willingness of government scientists to conduct research that intersects with policy-relevant scientific questions”.

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The letter added: “Scientists should not be subjected to fraud investigations or harassment simply for providing scientific results that some may see as politically controversial.

“Science cannot thrive when policymakers – regardless of party affiliation – use policy disagreements as a pretext to attack scientific conclusions without public evidence.”

Concern has mounted among scientists as Smith has pursued Noaa over what he has called “prematurely rushed” climate data that he claims has been used to suit the policy agenda of President Barack Obama.

Smith’s ire has focused upon research led by Thomas Karl and colleagues at Noaa, published in the journal Science in June. The research found there has been no “pause” in global warming over the past 15 years, despite previous claims that there has been a slowdown or flatlining in rising global temperatures.

This finding has been backed by several other climate papers this year that dispute the idea of a warming hiatus. On Wednesday, the World Meteorological Organisation announced that 2011 to 2015 had been the warmest five-year period on record, with this year set to be the hottest year ever registered. This warmth had been driven by climate change, caused by the release of greenhouse gases from human activity.

But Smith has used new subpoena powers to threaten the leadership of Noaa, demanding that the federal climate and weather agency hand over all internal correspondence between scientists to find out if there has been a grand conspiracy to alter or misrepresent the data.

“It was inconvenient for this administration that climate data has clearly showed no warming for the past two decades,” Smith said last month.

“The American people have every right to be suspicious when Noaa alters data to get the politically correct results they want and then refuses to reveal how those decisions were made. Noaa needs to come clean about why they altered the data to get the results they needed to advance this administration’s extreme climate change agenda.”

Smith has written twice to Penny Pritzker, the commerce secretary, in recent weeks, to express his “disappointment” at Noaa’s “efforts to obstruct the committee’s work”, prompting a subpoena compelling the release of the internal information.

A letter from Smith to Pritzker, whose department has oversight of Noaa, on 18 November stated that “because the Karl study was apparently prematurely rushed to publication, the timing of its release raises concerns that it was expedited to fit the administration’s aggressive climate agenda.

“Allegations regarding the rush to publish the Karl study raise serious concerns about the study’s scientific integrity.”

The American Association for the Advancement of Science, which publishes Science, said the Karl paper went through two peer review processes and was not rushed to publication.

“There’s no way this was hurried and this wasn’t something that researchers had control over in terms of the publication timing,” said Rush Holt, chief executive of the AAAS and one of the signatories to the letter to Smith.

“This is political tampering with the scientific process. Subpoenas or threats of subpoenas and demands for internal communications clearly go beyond raising questions about the research. It has a chilling effect because researchers can’t focus on the science or critique each other. If you meddle with science politically, you can really cause damage to public welfare.

“Politicians may not like the outcome, it may not fit with their political picture but to tamper with the process politically only serves to weaken the ability of scientific work. Climate science has become politicised which is unfortunate because this subject, more than any other, needs good scientific investigation.”