Colorful red sunsets may make for an
attractive scene but are usually a result of particulates scattering the
setting sun's rays. The deeper the red in the painting, the more
pollution in the sky at the time, researchers say. Paintings done after
volcanic eruptions, for example, have much redder skies.
"Nature speaks to the hearts and souls of
the artists," wrote the researchers. And art can help science:
"Paintings may provide reliable estimates on aerosols in the atmosphere
at times before instrumental measurements," Christos Zerefos, lead study
author and professor of atmospheric physics at the Academy of Athens in
Greece, said in an email.
Small particles, called aerosols,
suspended in the atmosphere scatter sunlight so that sunsets appear more
reddish. Aerosols can come from natural sources such as volcanic
eruptions, forest fires or dust storms, or from manmade sources such as
soot from car and truck engines.
German artist Caspar David Friedrich's
1818 painting "Woman in Front of the Setting Sun" places the silhouette
of a woman with outstretched hands under a deep ochre sky – a likely
scene, the researchers say, given the 1815 eruption of Indonesia's
Tambora volcano. That eruption scattered particles high into the
atmosphere that produced bright red and orange sunsets throughout Europe
for three years.
The effects of aerosols on Earth's climate
are complicated. They can have a major impact on climate when they
scatter light, cooling the planet in the case of the eruption of Mount
Pinatubo in the Philippines in 1991.
Or they can absorb heat and, particularly
with soot from diesel and coal smoke, hasten snow- and ice-melt.
In the study, published in the journal
Atmospheric Chemistry and Physics,
researchers from Greece and Germany analyzed 124 sunsets painted by
European artists between 1500 and 2000. During that period, more than 50
large volcanic eruptions occurred across the globe. Zerefos and
colleagues found that reddish hues in sunsets spiked during periods of
They also found that depictions of sunsets
have gotten redder from the Industrial Revolution onwards, even during
periods of no volcanic activity. Artists, they suggest, are
inadvertently capturing increases in pollution during the past 150
"Aerosols have influenced Earth's
temperature records. By correlating colors in paintings with aerosol
optical depth, this study helps to validate historical temperature
reconstructions," said A.R. Ravishankara, professor of chemistry and
atmospheric science at Colorado State University who was not involved in
To corroborate their findings, the
researchers commissioned an artist to paint a series of sunsets from the
Greek island of Hydra during and after a 2010 storm in Africa's Sahara
Desert whipped up dust particles into the atmosphere and carried them
over the Mediterranean. More pollution in the atmosphere correlated with
more warm colours in the artist's paintings, they found.
"Early artists created an inadvertent
record of climate change. That began to change around the mid-20th
century when artists deliberately started picturing the explosion of the
human footprint," said William L. Fox, director of the Centre for Art +
Environment at the Nevada Museum of Art.
While brilliant sunsets may be one
potential "upside" to smog, the harms clearly outweigh the benefits,
added Ravishankara. "Do you want vibrant colors or better quality of air
The Daily Climate
[Lindsey Konkel is a
staff writer for The Daily Climate and its sister publication,
Environmental Health News.]