WASHINGTON — International climate scientists and disaster experts meeting in Africa had a message today for the world’s political leaders: Get ready for more dangerous and “unprecedented extreme weather” caused by global warming.

Making preparations, they say, will save lives and money.

These experts fear that without preparedness, crazy weather extremes may overwhelm some locations, making some places unlivable.

The Nobel Prize-winning Intergovernmental Panel on Climate Change issued a new special report on global warming and extreme weather after meeting in Kampala, Uganda. This is the first time the group of scientists has focused on the dangers of extreme weather events such as heat waves, floods, droughts and storms. Those are more dangerous than gradual increases in the world’s average temperature.

The report said “a changing climate leads to changes in the frequency, intensity, spatial extent, duration, and timing of extreme weather and climate events, and can result in unprecedented extreme weather and climate events.” And it said that some — but not all — of these extreme events are caused by the increase of man-made greenhouse gases in the atmosphere.

“We face many challenges in the future,” another study lead author, Chris Field of Stanford University, said in a news conference. Those include floods, drought, storms and heat waves. Field said scientists aren’t quite sure which will be the biggest threat to the world because disasters are weather extremes interacting with economics and where people live. Society’s vulnerability to natural disasters, aside from climate, has also increased, he said.

Field told The Associated Press in an interview that “it’s clear that losses from disasters are increasing. And in terms of deaths, “more than 95 percent of fatalities from the 1970s to the present have been in developing countries,” he said.

Losses are already high, running at as much as $200 billion a year, said Michael Oppenheimer of Princeton University, a study author.

Science now attribute the increase in many of these types of extreme weather events to global warming with increased confidence, said study author Thomas Stocker at the University of Bern.

The report said it is “virtually certain” that heat waves are getting worse, longer and hotter, while cold spells are easing.

What that means is the nasty heat wave that used to happen once every 20 years by mid-century will be once every five years and by the end of the century will be an every other year scorcher, Field and Stocker said.

The report said there is at least a two-in-three chance that heavy downpours will increase, both in the tropics and northern regions, and from tropical cyclones.

The 29-page summary of the full special report — which will be completed in the coming months — says that extremes in some unnamed regions at some point in the future can get so bad that they may need to be abandoned.