Scientists at the University of East Anglia have admitted throwing away much of the raw temperature data on which their predictions of global warming are based.
It means that other academics are not able to check basic calculations said to show a long-term rise in temperature over the past 150 years.
The UEA’s Climatic Research Unit CRU was forced to reveal the loss following requests for the data under Freedom of Information legislation.
The data were gathered from weather stations around the world and then adjusted to take account of variables in the way they were collected. The revised figures were kept, but the originals — stored on paper and magnetic tape — were dumped to save space when the CRU moved to a new building.
The admission follows the leaking of a thousand private emails sent and received by Professor Phil Jones, the CRU’s director. In them he discusses thwarting climate sceptics seeking access to such data.
In a statement on its website, the CRU said: "We do not hold the original raw data but only the value-added (quality controlled and homogenized) data."
The CRU is the world’s leading center for reconstructing past climate and temperatures. Climate change sceptics have long been keen to examine exactly how its data were compiled. That is now impossible.