
11The Fifth Revolution
the average of these predictions. Again, the black line represents the observed
surface temperature. Note that these values are not the actual temperatures
but the departure from the average temperature over the period 1910 to 1950.
Perhaps the most difcult thing for climate models to predict is precipi-
tation. Figure 1.4 shows global precipitation distribution as observed and
(a)
60
30
–30
–60
–120 –60 0
060 120 180
–120 –60 0
0
060 120 180 240 300
30 90 150 210 270 330
(cm)
60 120 180
60
30
–30
–60
EQ
FIGURE 1.4
Annual averaged precipitation in centimeters per year, observed (a) and model predicted
(b), based on a multi-model mea