Researchers found that by looking at sunsets depicted in old paintings they could determine the quality of past climates. The method could help researchers determine how much pollution was in the atmosphere centuries ago.
When the Tambora volcano in Indonesia erupted in 1815 painters witnessed the sunsets change to a bright red or orange. This phenomenon was caused by aerosol particles in the air scattering sunlight and lasted for about three years, a European Geosciences Union news release reported.
"Nature speaks to the hearts and souls of great artists," lead-author Christos Zerefos, a professor of atmospheric physics at the Academy of Athens in Greece, said in the 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."
The researchers analyzed hundreds of digital photos of sunset paintings created between the years of 1500 and 2000; some were painted in the wake of volcanic eruptions. The researchers hoped to discover if the presence of aerosols affected the sky's color.
"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.
This meant that skies polluted with volcanic ash appeared redder; this can also occur in cases of man-made pollutants and desert dust.
The team looked at the "aerosol optical depth" (concentration of aerosols) by analyzing the red-green ration in the paintings; they then compared these values with those of "ice-core and volcanic-explosivity data," the news release reported. The team also asked a famous painter to create the sunset before and after the passage of the "Saharan dust cloud over the island of Hydra." The artist was not told the purpose of the experiment. The team found all of their data matched up.
"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 findings were published in "Atmospheric Chemistry and Physics."
