BUDAPEST, Hungary: Scientists warned Thursday that climate change in coming decades will cause more floods in the Northern Hemisphere and droughts in the south and in arid areas, which may lead to a global food crisis.

Areas that will suffer water shortages include the Mediterranean Sea basin, the western U.S., parts of southern Africa and northeastern Brazil.

Intergovernmental Panel on Climate Change chairman Rajendra Pachauri said at the end of a meeting in Budapest that the rising frequency and intensity of floods and droughts could lead to a food crisis.

"This is a serious concern," Pachauri said. "We may see a decline in agriculture production, but as could be expected with higher incomes and population growth, we could get an increase in demand for food."

An IPCC report presented at the meeting said the decline of water quantity and quality would have a negative impact on health and result in more areas affected by water stress - the shortage of water for drinking and agriculture.

Some 250 million Africans could be afflicted by water stress by 2020, unless action is taken to mitigate climate change, experts said.

While the proportion of heavy rainfalls will very likely increase, so will the areas simultaneously affected by extreme droughts.

The report also referred to the problem of glaciers and mountain snow melting around the world.

U.N. climate chief Yvo de Boer told reporters that Himalayan glaciers which "provide tens of millions of people in India and China with drinking water" are "potentially disappearing".

Comment: How, exactly, does a glacier "potentially disappear"?

One of the co-authors of the IPCC report said water issues would be one of the main problems of climate change.

"Everybody pretty much agrees that water is central to the way climate change is going to affect ecosystems and every human being," said Kathleen Miller, a scientist at the National Center for Atmospheric Research in Boulder, Colorado. "It's one of the key things that we depend on."

Miller mentioned the mega-deltas of rivers in Asia, such as the Mekong, as one of the areas where floods were an increasing concern.

"Those places will be much more vulnerable in the future," Miller said.

In the U.S., "physically the changes will be pretty intense," Miller said. "There's a high likelihood of the west getting drier."

Comment: If this is an example of an "intense change" to Ms. Miller, then we recommend she read Laura Knight-Jadczyk's recent series of articles on comets - just to put things into a broader perspective.

The IPCC, which shared the 2007 Nobel Peace Prize with former U.S. Vice President Al Gore, plans to complete its next climate assessment report, the fifth since 1990, by 2014.

AP science writer Seth Borenstein contributed to this report from Washington D.C.