Several climate-change experts are forecasting that 2007 will be the warmest year on record, with fierce weather patterns that could bring drought to Indonesia and leave California under a deluge.

Professor Phil Jones, director of the Climatic Research Unit at the University of East Anglia, said the long-term trend of global warming – blamed for bringing drought to the Horn of Africa and melting the Arctic ice shelf – is set to worsen with the arrival of El Niño, caused by above-average sea temperatures in the Pacific.

“El Niño makes the world warmer and we already have a warming trend that is increasing global temperatures by one- to two-tenths of a degree celsius per decade. Together, they should make 2007 warmer than last year and it may even make the next 12 months the warmest year on record” said Jones

The warning of the escalating impact of global warming was echoed by Jim Hansen, the American scientist who, in 1988, was one of the first to warn of climate change. In an interview with The (UK) Independent, Hansen predicted global warming would run out of control and change the planet for ever unless the rise in carbon emissions is reversed.

Hansen’s call for action is shared by Sir David King, Britain’s chief scientific adviser, who said 2006 had shown the “discussion is now over” on whether climate change is happening. Writing in today’s Independent, King says it is “essential” a global agreement on emissions is struck quickly: “Ultimately, only heads of state, working together, can provide the new level of global leadership we need to steer the world on a path towards a sustainable and prosperous future. We need to remember: action is affordable – inaction is not.”

The demands came as the UN’s World Meteorological Organization issued a warning that El Niño is already established over the tropical Pacific basin and is set to bring extreme weather from the Americas and south-east Asia to the Horn of Africa for at least the first four months of 2007.