Researchers from Greece and Germany have found a way to determine the amount of pollution in the earth's atmosphere at a given time, based on the colors painted by artists during those specific periods.

In a study published in Atmospheric Chemistry and Physics, an open access journal of the European Geosciences Union, the scientists suggest old paintings reveal ash and gas released during major volcanic eruptions in the past scattered sunlight, making sunsets appear redder, as seen in period artwork.

For instance, when the Tambora volcano in Indonesia erupted in 1815, painters in Europe saw the colors of the sky changing. The ash and gas from the volcano spewed into the atmosphere and traveled over the planet.

As aerosol particles produced by Tambora scattered sunlight, they produced bright red and orange sunsets in Europe that lasted up to three years after the eruption.

Along with the work of other artists during that same time, the paintings of J. M. W. Turner, which included depictions of stunning, deep sunsets, are being used to examine the composition of the past atmosphere.

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

Zerefos and his colleagues analyzed hundreds of high-quality digital images of sunset paintings created between 1500 and 2000, a period that saw over 50 large volcanic eruptions around the planet.

The scientists were looking to see if the relative amounts of red and green along the horizon of each painting could uncover any added data on the amount of aerosols in the atmosphere.

Aerosol optical depth can be directly used to develop climate models, so having even estimated particulate levels helps researchers understand how aerosols have affected the Earth's climate in the past.

That, in turn, can improve the accuracy of climate change predictions.

In fact, said Zerefos, "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."

Just as skies more polluted with volcanic ash appear redder, air with higher amounts of aerosols has a higher so-called aerosol optical depth, a type of measurement the team calculated by using the red-to-green ratios in the paintings.

They then compared the painting data to the volcanic histories known about those periods -- and found them in good agreement.

The new data corroborates the study team's previous findings, which were published in Atmospheric Chemistry and Physics, back in 2007.

The Tambora eruption, the largest in recorded history, killed an estimated 10,000 people directly and over 60,000 more due to the starvation and disease during the resulting volcanic fallout.