Heat waves like those that have hit Paris and Chicago in recent years are likely to get worse, roasting more and more cities with ever-higher temperatures, climate researchers predicted on Thursday. While some may like it hot, the forecast means misery for many, and hotter weather can affect crops, drive up fuel prices and can kill the old and weak. The heat wave that hit France a year ago killed an estimated 15,000 people. A similar heat wave that hit the U.S. Midwest last year damaged the corn and soy crops, and 739 people died in a head wave that broiled Chicago in 1995. Using a new computer model that takes into account increasing levels of greenhouse gases such as carbon dioxide, Gerald Meehl and Claudia Tebaldi of the National Center for Atmospheric Research in Boulder, Colorado, found heat waves might become more common as global warming heats the Earth. Writing in the journal Science, they said they tried to see if other pollutants such as sulfur dioxide might reflect sunlight away from the planet and perhaps offset some of the heat-trapping properties of carbon dioxide. But their model shows no such effects. Regions already prone to heat waves, such as the U.S. Midwest and Southeast and Europe's Mediterranean areas, will suffer even more, and longer, the model predicts. --MORE 2214 Local Time 1914 GMT