Meanwhile a new study warns extreme weather is likely to become more common because of human-generated greenhouse gas emissions. Researchers at Purdue University say the United States will see harsher instances of heat waves, floods and drought over the next one hundred years. The study projects temperatures of up to 18 degrees warmer on the coldest days of the year, and says warmest temperatures currently experienced in just over a half a month today will eventually endure for up to two months.