<table><table><tr><td><b>Presenter:</b></td><td> Martin Wild</td></tr><tr><td><b>Affiliation:</b></td><td> ETH Zurich, Institute for Atmospheric and Climate Science</td></tr><tr><td><b>Title:</b></td><td> Decadal changes in solar radiation reaching the Earth’s surface</td></tr><tr><td><b>Authors:</b></td><td> Martin Wild</td></tr><tr VALIGN=top><td><b>Abstract:</b></td><td> Solar radiation incident at the Earth surface plays a key role in a wide range of physical and ecological processes and is the primary energy source for life on our planet. Variations in this quantity therefore profoundly affect the human and terretrial environments and are a major driver of climate change. Long-term observational records show that solar radiation reaching the Earth’s surface is not stable over time, but undergoes significant decadal variations. These include a decrease ("solar dimming") from the 1950s to the 1980s as well as a more recent partial recovery as measured at widespread surface observation sites ("brightening"). Variations in the output of the Sun seem to be too small to explain these variations, and are furthermore not correlated. Therefore, the changes have to be caused by processes altering the transparency of the atmosphere. Increasing air pollution and associated increase in aerosol concentration in the atmosphere  are considered as a major determinant of the surface solar dimming up to the 1980s, while the implementation of air pollution regulations from the 1980s onward may have favoured the more recent recovery. A growing body of literature demonstrates that the decadal variations in surface solar radiation have a considerable impact on various aspects of global change, through their ability to modulate the global warming rates, the intensity of the global water cycle, the growth of the biosphere and associated carbon cycle as well as snow cover and glacier retreat. On a more applied level, these decadal variations also affect solar power production and need to be taken into account in the planning of solar energy infrastructures and solar resource assessments.

Selected References:

Wild, M. et al. 2005: From dimming to brightening: Decadal changes in solar radiation at the Earth’s surface. Science, 308, 847-850.

Wild, M., 2009: Global dimming and brightening: A review. J. Geophys. Res. 114, D00D16, doi:10.1029/2008JD011470.

Wild, M. 2012: Enlightening Global Dimming and Brightening. Bull. Amer. Meteor. Soc., 93, 27–37, doi:10.1175/BAMS-D-11-00074.1

Wild, M., 2016: Decadal changes in radiative fluxes at land and ocean surfaces and their relevance for global warming, WIRES Clim Change, 7, 91–107, doi: 10.1002/wcc.372.

Schwarz, M., Folini, D., Yang, S., Allan, R.P., and Wild, M., 2020: Changes in atmospheric shortwave absorption as important driver of dimming and brightening, Nature Geoscience, 13, 110–115,  doi: 10.1038/s41561-019-0528-y

Wild, M., et al. 2025:  A perspective on global dimming and brightening worldwide and in China. Adv. Atmos. Sci., Doi:10.1007/s00376-025-4534-2.

</td></tr><tr><td><b>Last update:</b></td><td> 06-10-2025</td></tr></table>
Presenter:	Martin Wild
Affiliation:	ETH Zurich, Institute for Atmospheric and Climate Science
Title:	Decadal changes in solar radiation reaching the Earth’s surface
Authors:	Martin Wild
Abstract:	Solar radiation incident at the Earth surface plays a key role in a wide range of physical and ecological processes and is the primary energy source for life on our planet. Variations in this quantity therefore profoundly affect the human and terretrial environments and are a major driver of climate change. Long-term observational records show that solar radiation reaching the Earth’s surface is not stable over time, but undergoes significant decadal variations. These include a decrease ("solar dimming") from the 1950s to the 1980s as well as a more recent partial recovery as measured at widespread surface observation sites ("brightening"). Variations in the output of the Sun seem to be too small to explain these variations, and are furthermore not correlated. Therefore, the changes have to be caused by processes altering the transparency of the atmosphere. Increasing air pollution and associated increase in aerosol concentration in the atmosphere are considered as a major determinant of the surface solar dimming up to the 1980s, while the implementation of air pollution regulations from the 1980s onward may have favoured the more recent recovery. A growing body of literature demonstrates that the decadal variations in surface solar radiation have a considerable impact on various aspects of global change, through their ability to modulate the global warming rates, the intensity of the global water cycle, the growth of the biosphere and associated carbon cycle as well as snow cover and glacier retreat. On a more applied level, these decadal variations also affect solar power production and need to be taken into account in the planning of solar energy infrastructures and solar resource assessments. Selected References: Wild, M. et al. 2005: From dimming to brightening: Decadal changes in solar radiation at the Earth’s surface. Science, 308, 847-850. Wild, M., 2009: Global dimming and brightening: A review. J. Geophys. Res. 114, D00D16, doi:10.1029/2008JD011470. Wild, M. 2012: Enlightening Global Dimming and Brightening. Bull. Amer. Meteor. Soc., 93, 27–37, doi:10.1175/BAMS-D-11-00074.1 Wild, M., 2016: Decadal changes in radiative fluxes at land and ocean surfaces and their relevance for global warming, WIRES Clim Change, 7, 91–107, doi: 10.1002/wcc.372. Schwarz, M., Folini, D., Yang, S., Allan, R.P., and Wild, M., 2020: Changes in atmospheric shortwave absorption as important driver of dimming and brightening, Nature Geoscience, 13, 110–115, doi: 10.1038/s41561-019-0528-y Wild, M., et al. 2025: A perspective on global dimming and brightening worldwide and in China. Adv. Atmos. Sci., Doi:10.1007/s00376-025-4534-2.
Last update:	06-10-2025