Pacific climatologists at a four-day meeting here this week, said warming was already producing more pronounced extremes, The New Zealand Herald reported Friday.

A bigger part of annual rainfall was now falling on the four wettest days of the year, with less rain and possibly droughts for the rest of the year.

Blair Trewin, of the Australian Meterorological Office, told the third Asia-Pacific workshop on climate variability that the extremes are strongest in the tropical parts of Southeast Asia and the Pacific islands.

Average temperatures were continuing to rise in East Asia and the Pacific with the minimum night temperature generally rising faster than the maximum day temperature.

Jim Salinger from New Zealand's National Institute of Water and Atmospheric Research (Niwa) said climate change was particularly important in the Pacific, citing atolls such as Aitutaki in the Cook Islands as dependent on rain for water supplies.

"If it doesn't arrive there are all sorts of problems. If there is too much high-intensity rainfall, things get washed away."

Niwa climatologist Brett Mullan said warmer air rose more quickly than cold, allowing more moisture to build up before turning into rain.

"That process builds up and results in heavier, extreme rains over often narrower, smaller regions," he said.

"Therefore the drier areas might expand as well, so you have the apparent contradiction of more heavy rain and more drought."

Scientists believe that carbon dioxide from vehicle emissions and other industrial pollution is causing the warmer weather through the "greenhouse effect", trapping the sun's rays in the lower part of the atmosphere.

SPACE.WIRE