The analysis, published in Science in June1, analyzed NOAA’s temperature records and found that global warming has continued apace in the early twenty-first century. The study contradicts previous findings — often cited by global-warming sceptics — suggesting that warming has slowed since the 1990s.

Representative Lamar Smith, the Texas Republican who leads the House of Representatives Committee on Science, Space, and Technology, asked NOAA in July for the data used in the study and for any internal communications related to it. NOAA has provided the committee with the publicly available data and has briefed committee staff on the research, but the agency has not turned over the communications.

Although NOAA’s latest response to the committee skirted the issue, the agency suggests in a 27 October statement to Nature that it has no intention of handing over documents that reveal its internal deliberations.

“Because the confidentiality of these communications among scientists is essential to frank discourse among scientists, those documents were not provided to the Committee,” the agency said. “It is a long-standing practice in the scientific community to protect the confidentiality of deliberative scientific discussions.”

In response to queries from Nature, Smith released a statement accusing NOAA of rigging its temperature records and stonewalling the House committee.

“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 said. “The Committee intends to use all tools at its disposal to undertake its Constitutionally-mandated oversight responsibilities.”

NOAA spokeswoman Ciaran Clayton denies the accusations. She notes that the agency’s study was peer-reviewed and published in a respected scientific journal, and that the agency has provided the committee with temperature data and briefings on the research.

“We stand behind our scientists, who conduct their work in an objective manner,” Clayton says. “We have provided all of the information the Committee needs to understand this issue.”