The colors of sunsets in painted works by famous artists can be used to estimate the levels or particulate pollution in our atmosphere in centuries, past, European researchers say.

Scientists in Greece and Germany have been studying paintings by great masters to retrieve information on the composition of the atmosphere in the past.

For example, painters in Europe produced works showing a change in sky colors following the 1815 eruption of the Indonesian volcano Tambora, which belched huge volumes gas and ash, scattered sunlight in the atmosphere and producing brilliant orange and red sunsets around for world for a period of 3 years.

British artist J. M. W. Turner and many other artists painted the spectacular sunsets during that period.

"Nature speaks to the hearts and souls of great artists," study lead-author Christos Zerefos, a professor of atmospheric physics at the Academy of Athens in Greece, said. "But we have found that, when coloring sunsets, it is the way their brains perceive greens and reds that contains important environmental information."

Turner's paintings were among hundreds of sunset paintings analyzed by Zerefos and his colleagues.

The paintings spanned the years from 1,500 to 2,000, a span of centuries that saw more than 50 large volcanoes erupt in various regions of the globe.

The researchers examined the artists' use of red and green to capture sunsets on the horizon of each painting, looking for clues to the amount of aerosols in the atmosphere.

Skies polluted by volcanic ash scatter sunlight more, making sunsets show more red; similar results are seen with dust or man-made aerosols.

They calculated the red-to-green ratios in the paintings, and found they correlated well to other evidence such as ice-core data.

 "We found that red-to-green ratios measured in the sunsets of paintings by great masters correlate well with the amount of volcanic aerosols in the atmosphere, regardless of the painters and of the school of painting," Zerefos said.

Better understanding of the effect of aerosols on Earth's climate in the past can help climate scientist make better predictions of climate change trends in the future, the researchers said.

"We wanted to provide alternative ways of exploiting the environmental information in the past atmosphere in places where, and in centuries when, instrumental measurements were not available," Zerefos said.

The team's findings have been published in Atmospheric Chemistry and Physics, an open access journal of the European Geosciences Union.