'Humans cause global warming'

Madrid: Some of the world's leading meteorologists said on Wednesday they had no doubt that humans were responsible for global warming.

Rising temperatures, caused by a build up of carbon dioxide in the earth's atmosphere, are widely expected to bring worsening floods, droughts and hurricanes.

Melting ice caps could inundate densely populated parts of the planet if warming continues unchecked.

Most scientists agree emissions from coal, oil and gas are causing climate change, while a few argue there is no link.

Asked if natural warming cycles, as the earth has seen in the past, could be behind climate change, the director general of the Spanish National Meteorological Institute was adamant they were not.

"No, because the time scale is different. This phenomenon is happening much more quickly," Francisco Cadarso told Reuters on the sidelines of an international meteorological conference in Madrid.

He also dismissed as over simple other theories some scientists say undermine the idea humans are to blame, such as changes in solar activity, or the theory that carbon dioxide increases are lagging behind temperature rises.

"This is too complex a phenomenon to use one single scientific argument to knock it down," he said.

Other experts at the meeting of the World Meteorological Organisation (WMO), a United Nations agency, also said they were sure humans were causing climate change.

"Scientifically it is clear," the head of Brazil's Meteorological Service Antonio Divino Mouro, who is also a WMO board member, told a news conference.

"We've been measuring carbon dioxide (CO2) concentrations for many years and it's proven that these levels are rising and the explanation is that fossil fuels are getting into the atmosphere."

CO2 is not transparent to infrared light, but absorbs it and causes global warming, he said.

"There is no doubt man has done this," said Paulo Manso, head of Costa Rica's meteorological services and also a WMO executive board member.

"We are talking about nine scientists against every one," he said referring to last month's United Nations climate panel report, which concluded it is 90 per cent certain that human activity is behind global warming.