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Interpreting Cumulative Distribution Functions (CDFs)

CDFs show the probability level associated with climate changes either greater than or less than a specific value.

Interpreting the graph below

The CDF below shows that 90% of the projections indicate an increase in precipitation of less than 57%. Similarly, 10% of the projections indicate an increase in precipitation of less than 16%. The projected change in the middle of the range (as likely as not) is an increase of 26%.

You can use CDFs to identify the likely range of the projections. Do this by looking at the values between the 10th and 90th percentiles, as these are seen as robust. In this example, the range is projected to be between a 16% and a 57% increase in precipitation.

CDF for the 2080s, edium emissions scenario