- from Extreme Weather
Earth is warming up. The average global temperature in 2014 was the warmest since people started keeping track of temperatures, way back in 1880. In fact, 14 of the 15 hottest years have occurred in this century.
Why does that matter? It means Earth’s climate is changing. In the past, it warmed and cooled very slowly. That happened due to natural causes, like changes in Earth’s orbit. But scientists say that human activity is now changing the climate quickly. One result? Weather is becoming more extreme. Weather is called extreme when it is dangerous or not normal. Droughts, hurricanes, tornadoes, and other fierce storms are types of extreme weather.