"When you walk in, you are overcome by the smell of decay, and by awe at the sight of these staggeringly high piles of paper, " said Kate Doyle, of the National Security Archive, an American campaign group that specialises in tracing documents.

BBC: NEWS | Americas | Guatemala secret files uncovered

"Seymour's work provided evidence with which to propose and eventually launch the Cryosat mission, which is now - as his last paper describes - providing the first observations of the annual cycle of sea-ice growth and decay throughout the Arctic Ocean, " Dr Giles said.

BBC: Cryosat spots Arctic sea-ice loss in autumn