Last decade is the warmest on record, scientists say

The Telegraph 16 Dec 08;

The last decade has been the warmest on record because of man-made climate change, according to scientists.

Global warming has pushed the world's temperature up by more than 1.26F (0.7C), said the Met Office, as they unveiled figures that show the dramatic effect human influence has had on the Earth's climate.

They predict that this year will be the tenth warmest worldwide since records began in 1850, with a global mean temperature of 58F (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 over 0.7 degrees C warmer than if humans were not altering the climate."

The UN's Intergovernmental Panel On Climate Change have said that a global temperature increase of 1.8F (1C) may be beneficial for some regions, but warned that any more could result in extensive coral bleaching.

They suggest increasing damage if global warming warms between 1.8F (1C) and 5.4F (3C), with 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 0.36F (0.2C), compared to the average for the previous decade.

They confirm the past decade was the warmest ever recorded. In addition the ten warmest years on record have all occurred in the eleven years since 1997. The warmest, in 2005 was an average of 59F (14.8C).

This year's average global temperature of 58F (14.3C) was 0.56F (0.31C) above the 1961-90 average.

Dr Stott said: "As a result of climate change, what would once have been an exceptionally unusual year has now become quite normal. Without human influence on climate change we would be more than 50 times less likely of seeing a year as warm as 2008."

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 take into account 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, which reacts faster to conditions in the atmosphere than the sea.

In the north the mean temperature was 0.91F (0.51C) above average and in the south, it was 0.2F (0.11C) above average.

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

Professor Phil Jones at the UEA's Climate Research Unit said: "The most important component of year-to-year variability in global average temperatures is the phase and amplitude of equatorial sea surface temperatures in the Pacific that lead to La Nina and El Nino events." Ends