US: Much of the world is facing into more deadly heatwaves, intense rainstorms and prolonged dry spells before the end of the century, according to a new climate change study.
Focusing not on averages, but on extremes, the research, published on Thursday, draws on nine climate models to predict what will happen if worldwide greenhouse gases keep increasing.
Longer periods of high heat and heavy rainfall are predicted for nearly all areas by 2080 to 2099.
In addition, dry periods will last longer in southern Europe, the southwestern United States and several other areas, the scientists reported.
"It's the extremes, not the averages that cause the most damage to society and to many ecosystems," said Claudia Tebaldi, lead author of the report by the National Centre for Atmospheric Research in Boulder, Colorado, Texas Tech University, and Australia's Bureau of Meteorology Research Centre.
"In the future, rising frequency, intensity and duration of temperature extremes . . . are likely to have adverse effects on human mortality and morbidity," according to the scientists' report, Going to Extremes, which will be published in the December issue of the journal Climatic Change.
"Changes in precipitation-related extremes such as heavy rainfall and associated flooding also have the potential to incur significant economic losses and fatalities."
The analysis is among the first to use advanced, super-computer simulations developed in the US, Japan, France and Russia for an international committee of scientists - the Intergovernmental Panel on Climate Change.
The climate scenarios are based on three projections in volumes of greenhouse gas emissions, which come largely from the burning of gasoline, coal and other fossil fuels.
Even under the lowest emissions scenario, more extreme events are predicted, although the trend is significantly weaker.
This means that if greenhouse gases are reduced, it will lower the risk of severe heat waves and heavy storms.
Wetter climate is one of the most significant and consistent patterns which showed up in the modeling, the study shows. Extra precipitation is tied to global warming because warm oceans evaporate more and warm air holds more moisture.
The higher latitudes, above 40 degrees north are expected to feel the most severe effects of extreme precipitation.Other changes that were called pronounced in the models include a longer growing season and fewer frost days in northwestern US and eastern Europe, and more heat waves in northern Australia.
Although scientists say that global temperatures already have increased, the report says the rate will be magnified.