Recent trends in solar exergy and net radiation at global scale

The availability during the last decades of remotely sensed images and global climatic data allow us to analyse the “Earth system” as a whole in order to develop concepts for global environmental management. This system can be considered a complex, dissipative, dynamic entity, far from thermodynamic equilibrium (Schellnhuber, 1999). Energy balance has been considered for many decades to understand the functioning of ecosystems, the biosphere or the Earth planet as a whole, but it is also possible to study our planet from a thermodynamic point of view. In this letter we analyse recent trends in solar exergy and net radiation at global scale during the period 1980–2010, distinguishing between land and ocean and between different land cover classes. Variations on the solar constant were also analysed. Results show a significant global decrease in solar exergy, in accordance also with a decrease in the solar constant. Net radiation also shows a global decrease during the study period, although in this case the results were not statistically significant.

► Trends in solar exergy and net radiation have been analysed at global scale during the period 1980–2010.
► A global decrease in solar exergy and net radiation has been observed.
► The trend of the solar constant during the study period also shows a decrease.