Climate change in Kentucky encompasses the effects of climate change, attributed to man-made increases in atmospheric carbon dioxide, in the U.S. state of Kentucky. The United States Environmental Protection Agency reports: "Kentucky's climate is changing. Although the average temperature did not change much during the 20th century, most of the commonwealth has warmed in the last 20 years. Average annual rainfall is increasing, and a rising percentage of that rain is falling on the four wettest days of the year. In the coming decades, the changing climate is likely to reduce crop yields and threaten some aquatic ecosystems. Floods may be more frequent, and droughts may be longer, which would increase the difficulty of meeting the competing demands for water in the Ohio, Tennessee, and Cumb