Climate change causes hottest decade ever

THE 10 warmest years on record have all been since 1997 because of man-made climate change, scientists revealed today.

Global warming has pushed the world's temperature up by more than 0.7C, said the Met Office, as it unveiled figures that show the dramatic effect of human influence on the Earth's climate. In a new report, it says this year will be the tenth warmest worldwide since records began in 1850, with a global mean temperature of 14.3C.

This would have been "exceptionally unusual" just a few years ago, but is now "quite normal," say climate scientists. Dr Peter Stott from the Met Office said: "Human influence, particularly emission of greenhouse gases, has greatly increased the chance of having such warm years.

"Comparing observations with the expected response to man-made and natural drivers of climate change it is shown that global temperature is now more than 0.7 degrees centigrade warmer than if humans were not altering the climate."

The UN's Intergovernmental Panel On Climate Change has said a global temperature increase of 1C may be beneficial for some regions, but warned that any greater increases could result in extensive coral bleaching.

It suggests there will be increasing damage with warming of between 1C and 3C, leading to rising sea levels and risks of large scale irreversible system disruption.

Today's figures show that in the last eight years alone, the global temperature has risen by 0.2C, compared with the average for the previous decade.

The research confirms the past decade was the warmest ever recorded. In addition the ten warmest years on record have all occurred since 1997.

The warmest, in 2005, was an average of 14.76C. This year's average global temperature of 14.3C was 0.31C above the 1961-90 average.

Dr Myles Allen from the Climate Dynamics group at Oxford University added: "Globally this year would have been considered warm, even as recently as the 1970s or 1980s, but a scorcher for our Victorian ancestors."

The figures are calculated for the World Meteorological Organization by the Met Office and the University of East Anglia. They use data from more than 3,000 land-based weather stations across the world. They also measure sea surface temperatures from merchant and naval ships.

This year's warming was more pronounced in the northern hemisphere, which scientists believe is warming faster than the south because a greater proportion of it is land rather than sea, with landmasses reacting faster to conditions in the atmosphere.

In the north, the mean temperature was 0.51C above average and in the south, it was 0.11C above average.

Even though 2008 was hot by comparison with previous decades, climate scientists say these temperatures were lower than would be expected because of La Nina, a weather phenomenon that typically coincides with cooler global temperatures.