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.