By Stephanie Nebehay GENEVA, Dec 14 (Reuters) - 2006 is set to be the world's sixth-warmest year since records began 150 years ago, the World Meteorological Organisation said on Thursday, offering more evidence of a trend most scientists blame on greenhouse gases. The ten warmest years have all occurred in the last 12 years, according to the United Nations weather agency. It said 2006 had been marked by extreme drought and heavy flooding in the greater Horn of Africa, record wildfires in the United States, torrential rainfall in the Philippines, shrinking sea ice in the Arctic and the warmest autumn in Europe. An average temperature of 0.42 degrees Celsius above the annual average from 1961-90 put 2006 on track to be the "sixth warmest year on record", the WMO said in a preliminary report based on data through November. 1998 was the warmest year. "There are many parts of the world where temperature records were broken," WMO secretary-general Michel Jarraud told a news briefing. "With respect to temperatures, there were quite a few very, very strong anomalies. It was the warmest autumn in many European countries," he added. Global warming is a contentious issue, but most scientists now agree that world average temperatures may rise by between two and six degrees Celsius this century due to emissions of so-called greenhouse gases like carbon dioxide, released by burning fossil fuels for power and transport. The U.N.'s Intergovernmental Panel on Climate Change (IPCC) in 2001 cited evidence that most of the warming observed over the last 50 years was "attributable to human activities". Jarraud said that the next report of an IPCC working group, due on Feb. 2, was expected to shed further light. Temperatures were more than 3 degrees Celsius warmer than normal in large parts of Europe this autumn, the WMO said. "It was the warmest (autumn) in the U.K. since records began, so we can very safely say it was the warmest since the 17th century," Jarraud said. It was also the warmest autumn in the Netherlands since 1706 and since 1768 in Denmark. Australia had its second hottest day ever on Jan. 1 and its warmest spring on record, while Brazil also had heat waves. Canada experienced its mildest winter and spring on record and the United States had its warmest January-September ever. SEA ICE Jarraud also said that 2006 had "the second smallest recorded extent of sea ice over the Arctic -- just after 2005". The area is declining at a rate of nearly 8.6 percent per decade, or more than 60,000 sq kilometres (23,000 sq miles) per year -- larger than the size of Switzerland, he said. "It is quite a fast and significant decrease," he added. Severe drought affected more than 10 million people in the Greater Horn of Africa, but the region also suffered some of the worst floods in 50 years, the Geneva-based organisation said. Drought also took 11 percent of the soybean crop in Brazil and damaged millions of hectares of crops in China, it said. There were a normal number of hurricanes in the Caribbean and fewer than average typhoons in south-east Asia, but in China it was the worst year in a decade for tropical cyclones, which caused more than 1,000 fatalities, the WMO said. The current moderate El Nino, a phenomenon in the tropical Pacific blamed for disrupting weather patterns, was to continue to at least into the first quarter of 2007, WMO said. This would cause more rainfall than usual in some areas and less in others. Next year might eclipse 1998 as the warmest year on record because of the El Nino, said Phil Jones, head of the Climatic Research Unit at Britain's University of East Anglia. "Next year we expect the year to be even warmer because of the El Nino event in the Pacific. Next year might be the warmest year -- we've been waiting for a major El Nino event to break the record from 1998," he said.
