London  - A predicted rapid rise in global population to 8 billion by 2030 is set to unleash a "perfect storm" of food shortages, scarce water and energy crises that would fuel mass migration, conflict and unrest, British scientists have warned.

"There are dramatic problems out there, particularly with water and food but energy also, and they are all intimately connected," said Professor John Beddington, the British government's chief scientist.

"You can't think about dealing with one without considering the others," he said. "We must deal with all of these together. We head into a perfect storm by 2030 because all of these things are operating on the same timeframe.

If the problems are not addressed, major destabilization, an increase in rioting and potentially significant problems with international migration would be the result, Beddington predicted.

He said he believes that a major technological push is needed to develop renewable energy sources, boost crop yields and improve the use of existing water supplies.

The world needs to produce 50 per cent more food by 2030 while needing 50 per cent more energy and 30 per cent more fresh water - against a background of a current 50-year-low in food reserves, he said.

With the risk of climate change expected to have a drastic effect on food production, food shortages leading to growing urbanization, and prosperity changing diets, time is running out to come up with solutions, he warned.

A report published this year by the Global Humanitarian Forum showed that climate change already claims an estimated 300,000 lives a year around the world - a figure expected to reach 500,000 annually by 2030.

By that year, the number of people seriously affected, for example, by the loss of their homes caused by natural disasters such as flooding - or in the longer term by water scarcity, hunger or disease - could rise to 660 million, the forum said.

Professor Jules Pretty of Essex University said he believes that Beddington's general premise of a number of critical problems coming together is correct but said setting 2030 for the date "is rhetorical."

"We don't know whether things will become critical in 2027 or 2047 - no one has any idea - but within the next generation, these things are going to come to pass unless we start doing things differently," Pretty said.

"When governments talk about reducing emissions by X per cent by 2050, I despair," he said. "We need to do it by next week. Humankind has not faced this set of combined challenges before."

Professor David Pink of Warwick University said he believes Beddington is painting the "worst possible scenario" to induce governments to act now.

"It is going to become a problem feeding the world," Pink said. "The question is how big a problem."

Jonathon Porritt, Britain's leading ecologist and a former government adviser on sustainable development, said there is no room for complacency. He said he believes that the "perfect storm" could hit much closer to 2020 than 2030.

"On the analysis front, people seem blind to the fact that the causes of the economic collapse are exactly the same as those behind today's ecological crisis," he wrote.

The same self-abuses of debt-driven "casino capitalism" that caused the global economy to collapse lay behind the "impending collapse of the life-support systems on which we all ultimately depend, he argued.

According to Porritt, politicians are wrong to disconnect their policies for economic recovery from measures needed to "avoid the horrors of accelerating climate change."

"The perfect storm is inevitable," Porritt said, "unless we fundamentally change the rules of the growth game. (dpa)