Weather extremes to become more regular

Record extremes in weather and climate will become increasingly common as temperatures rise because of climate change, the United Nations weather agency said today.

“New record extreme events occur every year somewhere in the globe, but in recent years the number of such extremes has been increasing,” the World Meteorological Organisation said.

The agency is based in Switzerland, which has just registered the hottest June since measurements were first taken 250 years ago, with temperatures 6C (10.8F) above average.

In neighbouring France, maximum temperatures in June were more than 40C (104F).

WMO said there were 562 tornados in the United States in May, an increase of 163 on the previous record. The south-eastern part of the country was exceedingly wet and cold, with some regions receiving 13.65 inches more rain than usual in the three months from March.

At least 1,400 people died in India from hot weather that peaked at 49C (120F), while in Sri Lanka heavy rainfalls from Tropical Cyclone 01B resulted in flooding and landslides that killed at least 300 people.

WMO said all these extreme events were taken into account by the UN Intergovernmental Panel on Climate Change, which has found that average global temperatures rose by 0.6C (1.8F) over the course of the 20th Century and the increase is accelerating.

“While the trend toward warmer globally averaged surface temperatures has been uneven over the course of the last century, the trend for the period since 1976 is roughly three times that for the past 100 years as a whole,” WMO said.

“Global average land and sea surface temperatures in May 2003 were the second highest since records began in 1880.”

The agency said it does not yet know the extent of involvement of El Nino and other major short-term climate changes on extreme weather events but is continuing to carry out research.

El Nino is characterised by rising sea temperatures and changes in the jet stream, leading to increased rain on the Pacific Coast of Latin America and lower rainfall than usual in areas like Indonesia and northern Australia. The phenomenon can affect weather around the globe.