According to the paper,
"observed surface solar radiation, as well as land and sea surface temperature spatio-temporal variations over the Euro-Mediterranean region are only reproduced when simulations include the realistic aerosol variations" which the authors state are "however hardly reproduced by global and regional climate models""Global brightening" is a well-known global phenomenon which may partially be due to clean air laws reducing sulfate and black carbon aerosols, as well as natural changes in cloud cover. "Global brightening" and "global dimming" show high correlation with global temperatures, yet as this paper notes are "hardly reproduced" by climate models. Another of many highly important variables including ocean oscillations, solar amplification mechanisms, convection, clouds, etc., etc. which climate models do not adequately simulate.
Note: Sulfur dioxide is an actual air pollutant, unlike harmless, essential, & beneficial carbon dioxide, despite the widespread scaremongering propaganda labelling CO2 as "carbon pollution"
Contribution of anthropogenic sulfate aerosols to the changing Euro-Mediterranean climate since 1980
Pierre Nabat et al
Since the 1980s anthropogenic aerosols have been considerably reduced in Europe and the Mediterranean area. This decrease is often considered as the likely cause of the brightening effect observed over the same period. This phenomenon is however hardly reproduced by global and regional climate models. Here we use an original approach based on reanalysis-driven coupled regional climate system modelling, to show that aerosol changes explain 81 ± 16 per cent of the brightening and 23 ± 5 per cent of the surface warming simulated for the period 1980–2012 over Europe. The direct aerosol effect is found to dominate in the magnitude of the simulated brightening. The comparison between regional simulations and homogenized ground-based observations reveals that observed surface solar radiation, as well as land and sea surface temperature spatio-temporal variations over the Euro-Mediterranean region are only reproduced when simulations include the realistic aerosol variations.