What does this mean?

The map and bar graph show how the number of days in each year the soil surface is unfrozen compares to the average for the period 1981 to 2012. On the map, areas where soil surfaces are unfrozen for more days than average are shown by reds (positive anomalies). Areas where soil surfaces are unfrozen for fewer days than average are shown by blues (negative anomalies). The map of anomalies helps to show where changes the number of days with unfrozen soil are the strongest.

The bar graph shows the anomaly in the average number of non-frozen days for the region north of 50° N. The graph helps to illustrate Arctic-wide changes in the non-frozen period. Continue reading...