Sceptics jumped on the report. A British scientist e-mailed the report to 2,000 colleagues before spotting it was a spoof. Another from the US called it a "blockbuster".

Blogger sceptic Neil Craig wrote: "This could not be more damaging to manmade global warming theory ... I somehow doubt if this is going to be on the BBC news."

It was not clear who was behind the report, which said bacteria in the Atlantic and Pacific oceans emitted at least 300 times more carbon dioxide than industrial activity -- a finding that, if true, would overturn the widely held view of scientists that burning fossil fuels are the main cause of warming.

But scientists knocked the report down.

"The whole story is a hoax," Deliang Chen, professor of Meteorology at Gothenburg University in Sweden, told Reuters. He said two "authors" listed as from his University were unknown.