Any deal reached at the Copenhagen Climate Change summit is almost certain not to achieve the emissions reductions that scientists have predicted are necessary.

This is the view of former prime minister Tony Blair, who told delegates at the conference on Sunday (December 13th 2009) that many nations have a basic plan for decreasing greenhouse gas output, as well as a more ambitious one.

Countries will be prepared to commit to a greater cut in emissions if they feel that other states are prepared to match their ambitions, he said - but he warned that even these programmes could fall short of what science requires.

However, Mr Blair noted that while this may be the case, an agreement to slash emissions by as much as possible is still crucial, saying: "The accumulated impact implies a radical change in economic production and growth."

It will also have a "highly incentivising effect on the future development of technology and the propensity of business to invest in clean energy and use it", he added.

Mr Blair's remarks come after the Met Office warned that if greenhouse gas output is not cut significantly by 2020 then it will prove almost impossible to prevent global temperatures rising by 2 C.