Because warming causes more water to evaporate, climate change can alter rainfall patterns, making wet places wetter and dry places drier. This means that climate change can contribute to both increased precipitation and increased drought. Globally, there has been a rise in extreme weather events such as heat waves, drought, and heavy rainfall.
Drought Has Been More Frequent Globally
Globally, the areas affected by drought have more than doubled since the 1970s. This sequence shows the effects of a 2012 drought on the Cheyenne Bottoms Wildlife Wetlands area in central Kansas.
Heat Waves Have Been More Frequent
Heat waves often contribute to poor air quality and pose the greatest threat to vulnerable populations such as the elderly and children. A 2003 heat wave in France was associated with 14,800 excess deaths.
Graph derived from EM-DAT, The International Disaster Database, Centre for Research on the Epidemiology of Disasters (CRED; http://www.emdat.be/), Université Catholique de Louvain, Brussels, Belgium, v12.07.
Heavy Precipitation Events Have Become More Frequent
Precipitation has increased globally, as has the proportion of precipitation falling in the form of heavy rain events. This graph shows the increase in heavy rainfall events in the United States during the 20th century.
Graph provided by Dr. Kenneth Kunkel at the Cooperative Institute for Climate and Satellites (CICS-NC), North Carolina State University and NOAA's National Climatic Data Center, Asheville, NC. Source
This graph shows projected changes in light, moderate, and heavy precipitation in North America for the 21st century. Light precipitation is projected to decrease, while heavy precipitation is projected to increase, continuing observed trends.
From U.S. Global Change Research Program. Global Climate Change Impacts in the United States: 2009 Report. Source