The maps above show temperature anomalies in five-year increments since 1880. (Click on the arrow to run the animation.) These are not absolute temperatures, but changes from the norm for each area. The data reflect how much warmer or cooler each region was compared to a base period of 1951-1980. (The global mean surface air temperature for that period was 14C (57F), with an uncertainty of several tenths of a degree.)