UK Scientists Change Weather Measures, World Warms
Date: 07-Jun-07
Country: UK
Author: Sylvia Westall
The national weather forecaster compares average temperatures in Britain to the long-term average for 1971-2000, but forecasters say this benchmark is increasingly irrelevant and is being supplanted by new ways of calculating the average.
"Climate references are changing, so there is a need to revolutionise the way we do this," climate scientist Richard Graham said on the sidelines of a Met Office conference.
The last nine British summers have been hotter than the 1971-2000 average of 14.1 degrees Celsius, and forecasters expect this summer will be no exception.
For the first time, weather scientists are generating a new 30-year average, calculated using 15 years of historic data and 15 years of predicted future temperatures, Graham said.
Future temperatures are calculated using a forecasting system introduced this year and give a far more accurate picture of how individual summers compare over a long-term period.
"This new method is great for business uses; it could be of use to the public forecast as well," Graham said.
While the Met Office is likely to continue quoting the 1971-2000 benchmark in its public forecasts, Graham said the new forward-looking average is preferred by the scientists who produce the forecast because it takes into account the effects of global warming.
Forecasters also said that warmer temperatures in Britain are a good example of worldwide global warming.
"One of the reasons it is a good gauge is that we actually know what is normal here. We've got records going back to 1659, and nowhere else in the world has such a long time series," said Matt Huddleston, principal climate change consultant at the Met Office.
Since the mid 1980s the average UK surface air temperature has warmed by around one degree Celsius - roughly double the global warming trend averaged over all land areas.
The Met Office said in its summer forecast, issued last week, that the likelihood of exceptionally hot summers, experienced during the heat waves of 2003 and 2006, has increased.