to be reasonably similar, because they arise from the same emissions scenario, although some
differences may occur due to the different regional climate-change patterns. However, the impact
of aerosols is also seen in the SST and SIC changes, because these will have responded to changes
in regional aerosol radiative forcing in the original CMIP5 simulations. Therefore, these SST and
SIC patterns will carry the ‘memory’ of aerosol changes in the original CMIP5 projections.
One example of an impact of changing aerosol radiative forcing could be the precipitation
changes in northern South America including Amazonia. All ensemble members show a general
drying in this region, as seen in RX5day and mean run-off results. The reduction in Rx5day is
particularly notable, because the general expectation would be for an increase in heavy rainfall
events in a warmer climate, as is seen in most other regions in these projections. This reduced
rainfall in the Amazon region may be associated with the reducing net negative aerosol radiative
forcing in the North Atlantic [40]. CO2 physiological forcing may also play a role here [41,42].