While extreme events per se are not abrupt climate changes as defined in this report, changes in extreme events could lead to abrupt changes in two ways: (1) an abrupt change in a weather or climate extremes regime, for example a sudden
shift to persistent drought
conditions; or (2) a gradual trend in the frequency or severity of extremes that causes abrupt impacts when societal or
ecological thresholds are crossed, as illustrated in Figure 2.10.