PRETORIA, 14 November 2011 (IRIN) - Soaring temperatures and erratic rains brought on by a changing climate may radically alter water flows in the world’s major river basins, including the Limpopo in southern Africa, forcing people to give up farming in some areas, says a new study.

Droughts and rising sea levels could reverse efforts to improve living conditions of world's poorest people, report warns

Unchecked environmental destruction will halt – or even reverse – the huge improvements seen in the living conditions of the world's poorest people in recent decades, a major new UN report warned on Wednesday.

It's the hard-working demographers of the U.N. who have counted the global population and have selected Oct. 31 as the date of the 7 billionth person. That makes sense because population is a major part of international development — and that's the business of the U.N. Bryan Walsh of TIME spoke with U.N. Secretary-General Ban Ki-moon in his office in New York City about global population, the challenges of development and the lingering threat of climate change.

* World's fastest growing populations increasingly at risk

* Africa and Asia most vulnerable to more extreme weather

* Survey can help city planners, investors adapt to wilder weather

SINGAPORE, Oct 26 (Reuters) - Rapidly growing megacities in Africa and Asia face the highest risks from rising sea levels, floods and other climate change impacts, says a global survey aimed at guiding city planners and investors.

The world is becoming a hungrier place - consuming more food, fuel and material resources - as its population bulges. But the increase in consumption is not even and not driven by the same factors. China and India are consuming more because their populations have vastly increased in the past 40 years. The United States, Japan and many countries in Europe are having much less population growth, but the people are using more resources. Meanwhile, many in South American and African countries have had relatively small population growth and much less increase in consumption.