The figure above depicts how much air temperatures near the Earths surface changed relative to the global mean temperature from 1951 to 1980. NASA researchers used maps of urban areas derived from city lights data to account for the heat island effect of cities.
The red and orange colors show that temperatures are warmer in most regions of the world when compared to the 1951 to 1980 normal temperatures.
Warming around the world has been widespread, but it is not present everywhere. The largest warming is in Northern Canada, Alaska and Siberia, as indicated by the deeper red colors. The lower 48 United States have become warmer recently, but only enough to make the temperatures comparable to what they were in the 1930s.
The scale on the bottom of these temperature anomaly images represent degrees in Celsius. The negative numbers represent cooling and the positive numbers depict warming.
Overall, the air temperature near the Earths surface has warmed by 1°F (0.6°C) globally, on average, over the last century.
For more information and additional images, read Satellites Shed Light on a Warmer World.
Image courtesy Goddard Institute for Space Studies (GISS).