The Significance of One Degree

In any one place, the temperature can change by many degrees from day to day, or even hour to hour. A one degree change in the average global temperature, however, is huge. As NASA's Earth Observatory explains: A one-degree global change is significant because it takes a vast amount of heat to warm all the oceans, atmosphere, and land by that much. In the past, a one- to two-degree drop was all it took to plunge the Earth into the Little Ice Age. A five-degree drop was enough to bury a large part of North America under a towering mass of ice 20,000 years ago. As the same article points out, "the average global temperature on Earth has increased by about 0.8°Celsius (1.4°Fahrenheit) since 1880. Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15-0.20°C per decade." As the ClimateInteractive Scoreboard shows, with a business as usual approach to climate change, the average global temperature is expected to rise almost 5° Celsius, approximately the same magnitude of change as between now and the last Ice Age.