Sunset Colors In Famous Paintings Used To Estimate Past Pollution Levels
March 26, 2014

Paintings Could Shed New Light On Historical Atmospheric Pollution Levels

redOrbit Staff & Wire Reports - Your Universe Online

The colors used by legendary artists of the past to depict a sunset could be used to estimate pollution levels in the atmosphere during bygone days, according to research published Tuesday in the open-access journal Atmospheric Chemistry and Physics.

Lead author Christos Zerefos, a professor of atmospheric physics at the Academy of Athens in Greece, and his colleagues showed that paintings of famous artists reveal the ash and gas released as part of major volcanic eruptions scatter the various colors of sunlight and make sunsets look more red, the European Geosciences Union (EGU) said in a statement.

The EGU, which publishes Atmospheric Chemistry and Physics, noted that the Tamora volcanic eruption that occurred in Indonesia in 1815 spewed aerosol particles into the atmosphere, scattering sunlight and producing bright orange and red sunsets. That phenomenon lasted for up to three years, and was observed by European artists such as British Romantic landscape painter J. M. W. Turner, one of the artists to paint sunsets during that time.

“The degree of red in the skies depicted in historic paintings offers a proxy for pollution levels in the Earth's past atmosphere,” explained Scientific American author Lindsey Konkel and The Daily Climate. “What's more, artists' sunsets have gradually gotten redder over the past 150 years, likely reflecting increased manmade pollution.”

A high-quality digital photograph of Turner’s ‘The Lake, Petworth: Sunset, Fighting Bucks (c. 1829)’ was among the more than 500 sunset paintings created between 1500 and 1900 that were analyzed. Paintings from Rubens, Rembrandt, Gainsborough and Hogarth were also among the 181 artists painting sunsets during that time span.

According to Keith Perry of The Telegraph, there were 50 large volcanic eruptions that occurred worldwide during that time, and the investigators were checking to see if the relative amounts of red and green hues found along each painting’s horizons revealed any information about the atmospheric aerosol content.

“Nature speaks to the hearts and souls of great artists. But we have found that, when coloring sunsets, it is the way their brains perceive greens and reds that contains important environmental information,” Zerefos said in a statement. “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.”

Atmosphere with a higher aerosol level also had a higher ‘aerosol optical depth,’ which Sarah Griffiths of the Daily Mail explained is a measurement calculated by the team using the ratio of red to green in each of the paintings. They then compared those figures with volcanic explosiveness and ice core data to discover a potential correlation.

To further support their work, the study authors commissioned an artist to create sunsets both during and following the passage of a Saharan dust cloud over the island of Hydra in June 2010, Griffiths said. They then compared aerosol optical depth measurements made with modern-day instruments with estimates from the red-to-green ratios of the paintings and of digital photographs. They found that there was a good match with all of them.

“Aerosol optical depth can be directly used in climate models, so having estimates for this parameter helps researchers understand how aerosols have affected the Earth's climate in the past. The information can also help improve predictions of future climate change,” Griffiths 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 added. Researchers from the Navarino Environmental Observatory, the University of Patras, the National Observatory of Athens, the Hellenic Open University, Justus Liebig University of Giessen and the University of Athens were also involved in the study.