Half the world's population could face a shortage of clean water by 2080 because of climate change, experts warned Tuesday.

Wong Poh Poh, a professor at the National University of Singapore, told a regional conference that global warming was disrupting water flow patterns and increasing the severity of floods, droughts and storms — all of which reduce the availability of drinking water.

Wong said the U.N. Intergovernmental Panel on Climate Change found that as many as 2 billion people won't have sufficient access to clean water by 2050. That figure is expected to rise to 3.2 billion by 2080 — nearly tripling the number who now do without it.

Reduced access to clean water — which refers to water that can be used for drinking, bathing or cooking — forces many villagers in poor countries to walk miles to reach supplies. Others, including those living in urban shanties, suffer from diseases caused by drinking from unclean sources.

At the beginning of the decade, the World Health Organization estimated that 1.1 billion people did not have sufficient access to clean water.

Asia, home to more than 4 billion people, is the most vulnerable region, especially India and China, where booming populations have placed tremendous stress on water sources, said Wong, a member of the U.N. panel.

"In Asia, water distribution is uneven and large areas are under water stress. Climate change is going to exacerbate this scarcity," he told the two-day Asia Pacific Regional Water Conference attended by policy makers, government officials, academics, businessmen and consumer group representatives.

Scientists have said global climate change takes many forms, causing droughts in some areas while increasing flooding and the severity of cyclones in others. Droughts reduce water supply, and floods destroy the quality of water. Rising sea levels, for instance, increase the salt content at the mouths of many rivers, from which many Asians draw their drinking water.

"As human civilization develops, the environment is increasingly affected in negative ways. Floods, drought, changing rainfall patterns and rising temperatures are signs of our misdeeds to nature," said Rozali Ismail, head of a state water association in Malaysia.

Wong and others at the conference called on governments to embrace the Kyoto Protocol climate treaty to fight global warming and protect water resources, as a short-term solution.

But eventually governments must build infrastructure to protect coastal areas, improve management of water basins and adopt new technologies to enhance availability and reliability of water resources, Wong said.

The United Nations is currently campaigning to replace the 1997 Kyoto Protocol — which regulates the emissions of 37 industrial countries — with another accord at a meeting in Copenhagen in December 2009.

The Kyoto Protocol was signed by 183 nations in 1997. But the United States — long the world's biggest emitter, though it is now rivaled by China rejected the plan over concerns it would harm the American economy.

Developing countries such as China and India also refused to accept a binding arrangement that they said would limit their development.