Updated

Average global temperatures in 2008 are forecast to be lower than in previous years, thanks to the cooling effect of the ocean current in the Pacific, U.N. meteorologists say.

The World Meteorological Organisation's secretary-general, Michel Jarraud, said it was likely that La Nina, an abnormal cooling of sea surface temperatures in the Pacific Ocean, would continue into the summer.

However, La Nina is not likely to persist for a period greater than two or more years.

Although it is reportedly the strongest event we've had this year, scientists are saying that when looking at climate change, it is important to look at trends in temperature over a period of time as opposed to changes in temperature during a particular year.

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A small number of scientists doubt whether this means global warming has peaked and the Earth has proved more resilient to greenhouse gases than predicted, but Jarraud insists this is not the case and notes that 1998 temperatures would still be well above average for the century.

"When you look at climate change you should not look at any particular year," he told the BBC. "You should look at trends over a pretty long period and the trend of temperature globally is still very much indicative of warming."

"La Nina is part of what we call 'variability'. There has always been and there will always be cooler and warmer years, but what is important for climate change is that the trend is up."

Experts at the U.K. Met Office's Hadley Centre for forecasting in Exeter said the world could expect another record temperature within five years or less, the BBC reports, probably associated with an episode of El Nino.

• Click here for the full report by the BBC.