1. Predictions about climate change are based on computer model projections.

Table 4.1 shows data for the percentage difference in warming rates between model projections and observed values between 1975 and 2013.

Table 4.1

Key
+ model overestimated warming rate
– model underestimated warming rate

(i) Plot these data as a bar chart on the grid.

[3]

(ii) Calculate the range for these data.

range = ................................................ [1]

(iii) Comment on the reliability of these computer model projections in predicting the rate of warming between 1975 and 2013.

[2]

(iv) Outline the difficulties in using climate change models.

[4]