A combination of reduced aerosol pollution and global warming have resulted in increasing levels of solar radiation across Europe, according to a new analysis.
The study by researchers at the Universities of Malaga and Murcia in Spain and data company Solargis found Europe’s solar irradiance increased by 2% each decade between 1994 and 2023.
The study also found the increase in solar radiation has not been homogeneous across the continent or throughout time.
The results show that central-western Europe experienced greater growth than other areas, especially during the last 20 years.
According to the analysis, areas including north-eastern France, the Benelux and western Germany have experienced nearly 4% increase between 1994 to 2023, even higher in the last 20 years (5%).
The study found the amount of sunlight reaching the ground is influenced by two principal factors – aerosol pollution levels and cloud cover.
The study finds that changes in cloud opacity and coverage account for around 80% of the total solar radiation increase.
While reducing aerosol pollution levels over the past 30 years have accounted for the remaining 20%.
Nonetheless, the ‘indirect’ role of aerosols in determining cloud opacity and coverage has been pivotal, elevating the importance of aerosol pollution beyond the former 20%. The reason is that aerosols have a two-fold impact on solar radiation levels.
The first impact is they absorb and scatter solar radiation directly, which is known as the aerosol direct effect.
This, in turn, affects the heating and cooling of the atmosphere, which influences cloud properties.
The second is the aerosol indirect effect, whereby clouds becoming less reflective and letting more sunlight pass through.
These, combined with temperatures rising as a result of global warming, also leads to lower cloud formation, which the study says has significantly increased the level of solar radiation reaching the ground in Europe.
Lead researcher and professor at the University of Malaga, José Antonio Ruiz-Arias, said the reduction in aerosol pollution means less cloud coverage and more sunlight coming through in the region, in an interview.
Ruiz-Arias added with less aerosol pollution, the impacts of global warming become more visible, with higher temperatures on the ground.
“Our atmosphere is becoming more transparent,” he told me. “With fewer aerosols there are fewer clouds, so the solar radiation comes straight down to the ground much more easily.”
Ruiz-Arias said increased solar radiation will effectively mean more fuel for solar PV panels in Europe, but added such increases are likely to plateau over the next 30 years.
“Changing irradiance levels impact the solar power industry greatly, with a direct influence on the long-term production, sustainability and bankability of projects,” he added.
“Beyond the energy sector, a ‘brighter’ Europe translates into more energy, rising temperatures and altered precipitation patterns.”
Ruiz-Arias said these factors will have broad impacts on societal patterns and almost all economic sectors, from farming and tourism to education.
Dr. Christopher Williams, a professor of earth system science within Clark University’s School of Geography, said in general, more sunlight leads to higher temperatures, but the strength of the relationship depends on several factors, in an email.
Dr. Williams said these factors include including how reflective the surface is, how much sunlight energy goes to evaporative cooling, and how readily surface heat is carried away by winds.
He added on the whole, aerosols cool the climate system, but it involves a complex set of direct and indirect effects that include scattering of sunlight, enhancing cloud cover, and changing cloud reflectivity.
“Humans contribute to a higher concentration of aerosols when we burn fossil fuels, and this leads to a modest and temporary masking of the global warming from greenhouse gas emissions,” said Dr. Williams.
“As we reduce air pollution and shift toward cleaner energy sources we can expect to see lower aerosol levels, and that unmasks the full warming effects of greenhouse gas concentrations, making the planet hotter.”