Extreme weather prompts global climate alert

Posted: 3 July 2003

A warning about the growing impact of extreme weather events around the world has been sounded by the World Meteorological Organisation. In an unusually outspoken report, the Geneva-based UN organisation says that as the global temperatures continue to rise, due to climate change, the number and intensity of extreme events might increase.

In June 2003, record high temperatures were recorded across southern France, with maximum temperatures exceeding 40°C in parts of southwest France. This resulted in June average temperatures of 5 to 7°C above the long-term average. In Switzerland, the month of June was the hottest in 250 years or more. In Geneva, since 29 May, maximum daytime temperatures did not drop below 25°C, making June the hottest June on record for the city.

In the United States, there were 562 tornados during May, which resulted in 41 deaths. This established a record for the number of tornados in any month. The previous monthly record was 399 tornados in June 1992. In the eastern and southeastern part of the US, wet and cold conditions prevailed for well over a month.

In India, this year's pre-monsoon heat wave brought peak temperatures of between 45°C and 49°C, between 2 and 5 degrees above the weekly norm. At least 1,400 people died in India due to the hot weather. In Sri Lanka, heavy rainfalls from Tropical Cyclone 01B caused flooding and landslides, and killed at least 300 people. The infrastructure and economy of southwestern Sri Lanka was heavily damaged. A reduction of 20-30 per cent in the output of low-grown tea is expected in the next three months.

New record

These record extreme events all go into calculating the monthly and annual average temperatures, which have been gradually increasing over the past 100 years. New record extreme events occur every year somewhere in the globe, but says the WMO, the number of such extremes have been increasing. According to recent climate change assessments by the Intergovernmental Panel on Climate Change (IPCC), the global average surface temperature has gone up by around 0.6°C - about 0.15°C larger than previously estimated.

New analysis shows that the increase in the Northern Hemisphere's temperature in the 20th century was probably the largest in any century during the past 1000 years. It is also likely that the 1990s were the warmest decade and 1998 the warmest year in that region. Globally, the trend towards warmer surface temperatures since 1976 is roughly three times that for the past 100 years as a whole.

Global average land and sea surface temperatures in May 2003 were the second highest since records began in 1880. On land, May was the warmest month ever recorded.