"Whether it is second or third depends on how Siberia reacts between now and the end of the year," said Wayne Elliott, Met Office spokesman.

"1998 was the warmest ever, 2005 is looking at being second. It will be another very warm year generally, which is in line with global climate change research."

The Met Office bases its measurements on both land and sea temperatures.

After 1998, the four hottest years globally were the last four years, according to Met Office data going back to 1861. The second hottest year was 2002, followed by 2003, 2004 and 2001.

The trend adds weight to concern among many scientists that the world is hotting up and that human activity including burning of fossil fuels and generation of "greenhouse gases" by industry is playing a major part.

Two recent hurricanes have left the United States with tight fuel supplies, energy companies say.

Meanwhile, in Europe Portugal and Spain have experienced their worst droughts ever recorded, and further east, floods and torrential rain drenched Switzerland, Germany, Austria and EU membership-candidates Bulgaria and Romania.

"The vast majority of scientists would now say that there is a significant, substantial human effect on the environment," Craig Hutton, project manager at the GeoData Institute, University of Southampton, said on Friday.

"I think that's good enough to get on and start to plan in reality for the effects of climate change."

Southampton University is working with IBM to research a early warning system for UK flood responses, to anticipate storm and tidal surges.