Scientists Use Artistic Sunsets as Time Capsules of Climate Change

J. M. W. Turner, “Mount Vesuvius in Eruption” (1817), watercolor on paper (via WikiPaintings)

The summer of 1816 was a brutal one. Cold temperatures wrecked crops and caused widespread famine. What’s now known as the “Year Without a Summer” is widely blamed on the Mount Tambora volcanic explosion, but without scientific measurements from the period, it’s hard to say exactly what happened. Luckily for scientists, some of the greatest artists in history were out there painting the strangely vivid sunsets following the natural disaster.

In a study published today in Atmospheric Chemistry and Physics, an open-access journal from the European Geosciences Union, Greek and German researchers have compiled the results of looking at sunsets in 310 works from the Tate and National Gallery in London. The art dates from 1500 to 2000 and covers some 50 volcanic explosions and the stunning skies in their aftermath. The focus is on sunsets because, as atmospheric refractions beaming light through the Earth’s atmosphere in a way we usually can’t see, they can potentially show what the climate was like in the past and help improve climate change models for the future.

Called “Further evidence of important environmental information content in red-to-green ratios as depicted in paintings by great masters,” the study follows and confirms findings from the team’s 2007 exploration of paintings by such artists as Rembrandt, Hogarth, and Rubens. The current study is heavy on J. M. W. Turner, who was drawn to the sunsets just after the Tambora eruption.

The red/green ratios in Caspar David Friedrich’s “Woman in front of the Setting Sun” (1818) (via Atmospheric Chemistry and Physics)

As Christo Zerefos, lead researcher and Academy of Athens professor of atmospheric physics, told LiveScience: “Regardless of the school and style, all painters provided quite accurate aerosol information when red/green ratios were examined.” This mix of red and green on the horizons is an indication of what levels of polluting particles were in the atmosphere at the time. Known as “aerosols,” the particle material issued by volcanoes gives the sunset its rich red hue, with less green, as the particles change what visible light is seen from the ground. The colors respond to the levels of pollution and the wavelengths of light that are able to get through. Manmade aerosols have become a greater concern with increasing pollution, and so, according to LiveScience, “By looking at how volcanoes cooled the Earth in the past, scientists may gain a more thorough understanding of the effects of modern aerosol pollution.”

Of course, painters aren’t looking at sunsets for the same reasons as scientists. As the researchers acknowledge, “a detailed study on all possible sources of uncertainties involved (such as the impact of clouds on R / G ratios) still needs to be studied.” However, they write:

Because of the large number of paintings studied, we tentatively propose the conclusion that regardless of the school, red-to-green ratios from great masters can provide independent proxy AODs [aerosol optical depths] that correlate with widely accepted proxies and with independent measurements.

Other researchers have used relics and art of the past as a window into climate change, from ancient remains of meals to the ruins of a ghost town that was suddenly abandoned. In addition to Turner, the present study focuses on work by John Crome, James Ward, Henry Anderton, Thomas Hope McLachlan, Sir Joshua Reynolds, and Thomas Gainsborough — all artists with a realist’s eye drawn to the awe of nature. Little could they know that their paintings of brilliant evening hours would be time capsules for assisting in the study of the atmosphere.

One of the paintings used in the study: J. M. W. Turner, “Chichester Canal” (1828), oil on canvas (Tate Britain, via Wikimedia)