• global dimming/brightening;
  • IPCC-AR4 climate models;
  • DTR

[1] Observations indicate that greenhouse induced twentieth-century warming has been strongly modulated by variations in surface solar radiation. Between the 1950s and 1980s, declining surface solar radiation (“global dimming”) likely caused a dampening of global warming, whereas increasing surface solar radiation (“brightening”) may have contributed to the rapid warming in the last 2 decades, and possibly also in the first half of the twentieth century. This is also reflected in the decadal evolution of diurnal temperature range, which is highly correlated with surface solar radiation, and which shows a distinct transition from a strong decrease between the 1950s and 1980s, toward a leveling off thereafter. The present study investigates to what extent these effects are simulated in the latest generation of global climate models used in the fourth Intergovernmental Panel on Climate Change (IPCC) assessment report (AR4) (phase 3 of the Coupled Model Intercomparison Project (CMIP3) models). While these models reproduce the overall twentieth century warming over global land surfaces well, they underestimate the decadal variations in the warming and particularly also in diurnal temperature range, indicative of a lack of decadal variations in surface solar radiation in the models.