Steve McIntyre wants access to more UK data. Credit: S. MCINTYRE

A leading UK climatologist is being inundated by freedom-of-information-act requests to make raw climate data publicly available, leading to a renewed row over data access.

Since 2002, Steve McIntyre, the editor of Climate Audit, a blog that investigates the statistical methods used in climate science, has repeatedly asked Phil Jones, director of the Climatic Research Unit (CRU) at the University of East Anglia, UK, for access to monthly global surface temperature data held by the institute. But in recent weeks, Jones has been swamped by a sudden surge in demands for data.

Several organizations worldwide collect and report global average temperature data for each month. Of these, a temperature data set held jointly by CRU and the UK Met Office's Hadley Centre in Exeter, known as HadCRU, extends back the farthest, beginning in 1850. Although these data are made available in a processed format that shows the global trend, access to the raw data is restricted to academics.

Between 24 July and 29 July of this year, CRU received 58 freedom-of-information-act requests from McIntyre and people affiliated with Climate Audit, requesting access to the data or information about their use. In the past month, the UK Met Office, which receives a cleaned-up version of the raw data from CRU, has received ten requests of its own.

McIntyre, based in Toronto, Ontario, is best known for questioning the validity of the statistical analyses used to reconstruct the past 1,000 years of climate, but has more recently turned his attention to criticizing the quality of global temperature records. Jones concedes that raw climate data have imperfections — such as duplication of stations — but says that such minor errors would not alter the overall global temperature trend. McIntyre insists that he is not interested in challenging the science of climate change or in nit-picking, but is simply asking that the data be made available. "The only policy I want people to change is their data-access policy," he says.

Data release needs to be done in a systematic way.

Jones says he can't fulfil the requests because of confidentiality agreements signed in the 1990s with some nations, including Spain, Germany, Bahrain and Norway, that restrict the data to academic use. In some cases, says Jones, the agreements were made verbally, and in others the written records were mislaid during a move.

He says he is now working to make the data publicly available online. As Nature went to press, Jones was expected to post a statement on the CRU website to that effect, including any existing confidentiality agreements. Jones says any such data release "needs to be done in a systematic way".

"We're trying to make them all available," says Jones. "We're consulting with all the meteorological services — about 150 members [of the World Meteorological Organization] — and will ask them if they are happy to release the data." A spokesperson for the Met Office confirmed this, saying "we are happy for CRU to take the lead on this, as they are their data".

But getting the all-clear from other nations won't be without its challenges, says Jones, who estimates that it could take several months. In addition, some nations may object if they make money by selling their wind, sunshine and precipitation data.

The dispute is likely to continue for some time. McIntyre is especially aggrieved that Peter Webster, a hurricane expert at the Georgia Institute of Technology in Atlanta, was recently provided with data that had been refused to him.

Webster says his team was given the station data for a very specific request that will result in a joint publication with Jones. "Reasonable requests should be fulfilled because making data available advances science," says Webster, "but it has to be an authentic request because otherwise you'd be swamped."

Indeed, Jones says he has become "markedly less responsive to the public over the past few years as a result of this".