https://www.theguardian.com/environment/shortcuts/2019/feb/25/what-russias-green-snow-reveals-about-the-rise-of-pollution
[links and images in online article]
What Russia's green snow reveals about the rise of pollution
Incidents of snow turning green and black are causing increasing alarm.
So just how worried should we be about the world’s increasingly
colourful snow?
Fiona Harvey
Mon 25 Feb 2019 16.26 GMT Last modified on Mon 25 Feb 2019 17.40 GMT
Don’t eat yellow snow has always been good advice. To that we can now
add warnings against green, pink, orange and black snow, as new evidence
of our trashing of the planet is now being etched out on the most
pristine of environments – our dwindling snow caps.
A spate of incidents in Russia has grabbed internet attention. Residents
of Siberian towns watched with dismay as the snow around them turned
green and black, with toxic emissions forcing some to wear masks. These
seem to be connected to local factories, with a chrome plant in
particular behind the green snow, and, as protests gather pace, the
Putin government has come under pressure.
Snow pollution is not new. Campaigners have been warning for years of
the dangers of dark snow, – black, brown and grey streaks across the ice
that can be clearly seen from the air above Arctic regions – because of
its effects on climate change. Dark snow is stained by black carbon, AKA
soot – unburnt particles released by the combustion of fossil fuels in
coal-fired power plants, factories and other sources, and carried to the
ice caps on the wind. When soot falls on white snow, it is not only an
aesthetic disaster: reflective snow and ice enhance the earth’s albedo
((the ability of a surface to reflect sunlight), bouncing light and heat
back into space, but dark snow absorbs heat instead, accelerating global
warming. Eliminating soot could slow climate change, helping to reduce
temperatures by up to 0.5C.
Snow is sometimes stained by natural phenomena. Chlamydomonas nivalis
algae can make it appear pink or red, an effect documented by scientists
since the 19th century. Orange snow spreading across eastern Europe last
year may have been from particles of dust and sand from the Sahara,
though pollution was a more likely cause of orange snowfalls in Siberia
a decade earlier.
As far as eating snow goes, don’t try the white stuff. Researchers in
Canada found in 2017 that melting urban snow releases a cocktail of
toxic chemicals, largely from car exhausts, trapped in the snow from
polluted air. Snow in its beauty has always exercised a hold over our
imaginations, symbolising purity and transcendence, harking back to a
mythical state of innocence. As the snow around us stains black, grey,
brown, green and the rest, there could hardly be a more potent emblem of
our runaway global problem with pollution.
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