From the archive, originally posted by: [ spectre ]

http://www.guardian.co.uk/environment/2007/oct/01/climatechange.scienceofclimatechange

How old masters are helping study of global warming

Paintings of striking sunsets show effect of huge volcanic eruptions
on climate
by David Adam  /  Monday October 1 2007

The English landscape painter JMW Turner said his work was not to be
understood but “to show what such a scene was like”. Now global
warming experts are taking advantage of his prosaic nature to improve
their predictions of the consequences of climate change.

The scientists are analysing the striking sunsets painted by Turner
and dozens of other artists to work out the cooling effects of huge
volcanic eruptions. By working out how the climate varied naturally in
the past they hope to improve the computer models used to simulate
global warming.

The team, at the National Observatory of Athens, is using the works of
old masters to work out the amount of natural pollution spewed into
the skies by eruptions such as Mount Krakatoa in 1883. Reports from
the time describe stunning sunsets for several years afterwards, as
the retreating light was scattered by reflective particles thrown high
into the atmosphere. By studying the colour of sunsets painted before
and after such eruptions, the researchers say they can calculate the
amount of material in the sky at the time.

Christos Zerefos, who led the research, said: “We’re taking advantage
of the attitudes of famous painters to portray real scenes they were
looking at. This is the first attempt to analyse this old art in a
scientific way, and tells the story of how our climate has varied
naturally in the past.”

The results will feed into the scientific study of a phenomenon called
global dimming, which is caused by air pollution blocking sunlight.
Some experts believe this has acted as a brake on global warming, and
that climate change could accelerate as air pollution from industry is
reduced.

Professor Zerefos and his team looked at natural global dimming caused
by volcanoes, the results of which can be severe. The eruption of
Mount Tambora in Indonesia in 1815 threw out so much material that it
triggered the notorious “year without a summer”, which caused
widespread failure of harvests across Europe, resulting in famine and
economic collapse.

The team found 181 artists who had painted sunsets between 1500 and
1900. The 554 pictures included works by Rubens, Rembrandt,
Gainsborough and Hogarth. They used a computer to work out the
relative amounts of red and green in each picture, along the horizon.
Sunlight scattered by airborne particles appears more red than green,
so the reddest sunsets indicate the dirtiest skies. The researchers
found most pictures with the highest red/green ratios were painted in
the three years following a documented eruption. There were 54 of
these “volcanic sunset” pictures.

Prof Zerefos said five artists had lived at the right time to paint
sunsets before, during and after eruptions. Turner witnessed the
effects of three: Tambora in 1815; Babuyan, Philippines in 1831, and
Cosiguina, Nicaragua, in 1835. In each case the scientists found a
sharp change in the red/green ratio of the sunsets he painted up to
three years afterwards.

Writing in the journal Atmospheric Chemistry and Physics, the
scientists say the redder sunsets seen in paintings “can be
tentatively attributed to the volcanic events, and not to
abnormalities in the colour degradation due to age, or other random
factors affecting each painter’s colour perception”.

The scientists used the red/green ratios to estimate the amount of
airborne dust produced by each volcano. The results, they say, are
remarkably similar to estimates prepared from historical observations,
early measurements and material found in ice cores.

Prof Zerefos’s team is now talking to the Tate in London about
repeating the study with 40 paintings from the 20th century, to see
whether artists have captured the effects of pollution on sunsets
since the industrial revolution.

Big bangs

1783 Laki, Iceland Volcanic eruption spread sulphurous haze across
western Europe, killing thousands.

1816 Tambora, Indonesia Eruption killed 10,000 people directly and
66,000 due to starvation and disease during “year without a summer”
that followed, when temperatures plunged and harvests failed.

1883 Krakatoa, Indonesia Loudest recorded bang in history. At least
36,417 people died. Average global temperatures dropped by 1.2C.

1991 Pinatubo, Philippines Killed 300 people. About 17m tonnes of
sulphur dioxide went into atmosphere, reducing sunlight by 5% and
global temperatures by 0.4C.

http://www.zerefos.gr/Zerefos-Gerogiannis.pdf
http://www.zerefos.gr/

CHRISTOS ZEREFOS
Professor, National and Kapodistrian University of Athens
President, National Observatory, Athens, Greece
email: zerefos [at] geol [dot] uoa [dot] gr
mobile: +306944570099

Christos S. Zerefos graduated in Physics from the University of Athens
and obtained MSc in Meteorology and Ph.D. in Physics-Meteorology from
the same University. He worked as a post Doctoral researcher at the
National Center for Atmospheric Research (NCAR) and at the Data
Studies Division, NOAA in Boulder CO, USA, as well as at the National
Hellenic Research Foundation, Greece and the Academy of Athens
(1973-1979). In 1979 he was elected Professor in the Chair of
Atmospheric Physics at the Aristotle University of Thessaloniki, a
position held until 2002 when he has been unanimously elected
Professor of Atmospheric Physics at the honorary invitation of the
National and Kapodistrian University of Athens. In 2005 he was elected
President of the National Observatory, Athens, Greece, which is the
oldest Research Institute of that country, established in 1842.

He has served as Member of various Expert Committees in WMO, DG
Environment and other international Organizations. He is also Member
of highly esteemed scientific societies, among which the Institute of
Physics and the American Geophysical Union (Life Member).

His total published work comprises about 500 research papers in peer
reviewed scientific journals and peer reviewed international
scientific proceedings. The majority of his publications have been
published in the Journal of Geophysical Research, Geophysical Research
Letters, Atmospheric Environment, Nature, Science and Atmospheric
Chemistry and Physics and others. His work has been acknowledged from
the scientific community with more than 3400 citations.

http://www.atmos-chem-phys.net/7/4027/2007/acp-7-4027-2007.html

Atmospheric effects of volcanic eruptions as seen by famous artists
and depicted in their paintings

C. S. Zerefos1,2, V. T. Gerogiannis3, D. Balis4, S. C. Zerefos5, and
A. Kazantzidis4
1National Observatory of Athens, Athen, Greece
2Academy of Athens, Athen, Greece
3National Meteorological Service, Athen, Greece
4Laboratory of Atmospheric Physics, Aristotle University of
Thessaloniki, Thessaloniki, Greece
5School of Architecture, National Technical University of Athens,
Athen, Greece

Abstract. Paintings created by famous artists, representing sunsets
throughout the period 1500-1900, provide proxy information on the
aerosol optical depth following major volcanic eruptions. This is
supported by a statistically significant correlation coefficient (0.8)
between the measured red-to-green ratios of a few hundred paintings
and the dust veil index. A radiative transfer model was used to
compile an independent time series of aerosol optical depth at 550 nm
corresponding to Northern Hemisphere middle latitudes during the
period 1500-1900. The estimated aerosol optical depths range from 0.05
for background aerosol conditions, to about 0.6 following the Tambora
and Krakatau eruptions and cover a period practically outside of the
instrumentation era.

Final Revised Paper (PDF, 846 KB)   Discussion Paper (ACPD)
http://www.atmos-chem-phys.net/7/4027/2007/acp-7-4027-2007.pdf
http://www.atmos-chem-phys-discuss.net/7/5145/2007/acpd-7-5145-2007.html

Citation: Zerefos, C. S., Gerogiannis, V. T., Balis, D., Zerefos, S.
C., and Kazantzidis, A.: Atmospheric effects of volcanic eruptions as
seen by famous artists and depicted in their paintings, Atmos. Chem.
Phys., 7, 4027-4042, 2007.