Famous Paintings Offer Clues To Earth's Past Atmosphere

The analysis of famous paintings has helped researchers estimate the pollution levels in Earth's past atmosphere, a new study reveals.

A team of Greek and German researchers suggest that colors of sunsets painted by famous artists can offer clues to the pollution levels in Earth's past atmosphere. They mainly focused on the artwork that depicted ash and gas emitted from a volcanic eruption. Such pictures disperse different colors of sunlight, making sunsets look redder.

During the 1815, when the Tambora volcano in Indonesia erupted, painters in Europe witnessed sunsets change from bright red or orange. The volcanic ash and gas that was emitted during this event travelled round the globe as the aerosol particles scattered sunlight. As a result of this, for the next three years after the eruption, there were bright red and orange sunsets in Europe.

This colorful image of the sky was beautifully captured by J.M.W Turner, an artist who painted sunsets during that period. In the current study, researchers analyzed the art work of such painters to understand the composition of the planet's past atmosphere.

"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 a statement. "But we have found that, when colouring sunsets, it is the way their brains perceive greens and reds that contains important environmental information."

For this study, the team analyzed over hundreds of high quality digital photographs of stunning sunset painting that were created between 1500 and 2000. During this time, there were nearly 50 massive volcanic eruptions worldwide. The researchers examined whether the red and green colors near the horizon of each painting offered hints on the concentration of aerosols in the atmosphere.

"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," says Zerefos.

Skies highly polluted by volcanic ash dispersed more sunlight, making them appear redder. A similar effect is seen with manmade aerosols. Using the red to green ratio in the paintings, researchers measured the parameter aerosol optical depth.

These values were later compared with ice-core and volcanic-explosivity data.  To further validate this, the team asked a renowned painter to create the sunset before and after the passage of the Saharan dust cloud over the island of Hydra in June 2010. The artist was unaware of the dust event. The result was as expected and all the data matched perfectly.

"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 finding was documented in the journal Atmospheric Chemistry and Physics.