An August 6 study in the Proceedings of the National Academy of Sciences concluded that climate change is causing a significant increase in the number of hot summers. According to the study, Perception of Climate Change, while 0.2 percent of the Earth’s surface experienced extremely hot summers between 1951 and 1980, about 10 percent has experienced them in the last few years. The likelihood of unusually hot summers and accompanying extreme drought conditions in the absence of global warming is very small, and the report found that rising temperatures are causing unusually heavy rain and floods, extreme drought, and changes in the geographical and seasonal range of animals, birds, and insects. The report cautioned that reducing CO2 emissions to a degree that would limit global temperature is possible, but would require a high price on emissions to transition to cleaner energy.