YAKUTSK, Russia, Dec 5, 2018 (BSS/AFP) – The Earth’s vast tracts of
permafrost hold billions of tonnes of planet-heating greenhouse gases that
scientists warn will be released by global warming, along with diseases long
locked into the ice.
Here is some background.
– A quarter of the north –
Permafrost — soil that is frozen, although not necessarily permanently as
it name implies — is found mostly in the Northern Hemisphere, where it
covers about a quarter of exposed land and is generally thousands of years
old.
It covers a wide belt between the Arctic Circle and boreal forests,
spanning Alaska, Canada, northern Europe and Russia.
Permafrost exists to a lesser degree in the Southern Hemisphere where there
is less ground to freeze, including in the South American Andes and below
Antarctica.
It can vary in depth from a few metres to more than 100.
– Tonnes of locked-in carbon –
Locked into the permafrost is an estimated 1.7 trillion tonnes of carbon in
the form of frozen organic matter — the remains of rotted plants and long-
dead animals trapped in sediment and later covered by ice sheets.
When permafrost thaws, this matter warms up and decomposes, eventually
releasing the carbon that it holds as carbon dioxide (CO2) and methane, gases
which have a greenhouse warming effect on the planet.
Permafrost soils contain roughly twice as much carbon — mainly in the form
of methane and CO2 — as Earth’s atmosphere.
Most of the carbon stocks are thought to reside fairly close to the
surface.
– Vicious circle of warming –
The release of greenhouse gases threatens a vicious circle in the warming
of the Earth, jeopardising the objective set in the 2015 Paris Agreement to
strive to limit the rise in temperature to 1.5 degrees Celsius (2.7 degrees
Fahrenheit) above pre-industrial levels.
CO2 is the most abundant greenhouse gas blamed for global warming but
methane is 25 times more efficient at trapping heat.
Adding these into the atmosphere will spur further warming and ice melt,
which will in turn cause more thawing of the permafrost and free up more
locked-up carbon.
Even if global warming were stabilised at around 2 C, research points to a
30-percent loss of permafrost by 2100, researcher Susan Natali of the Woods
Hole Research Center told 2015 climate talks in Bonn.
This could reach up to 70 percent assuming emissions continue on their
current trajectory, her research said, warning that “emissions from
permafrost could lead to out-of-control global warming”.
– Frozen diseases? –
The thawing of the permafrost also threatens to unlock disease-causing
bacteria and viruses long trapped in the ice.
There have already been some cases of this happening. In 2016 a child died
in Russia’s far northern Siberia in an outbreak of anthrax that scientists
said seemed to have come from the corpses of infected reindeers buried 70
years before but uncovered by melting permafrost.
Released from the ice, the anthrax seems to have been passed to grazing
herds.
Scientists have also warned that other dormant pathogens entombed in frozen
soil may be roused by global warming, such as from old smallpox graves.
In 2014 scientists revived a giant but harmless virus, dubbed Pithovirus
sibericum, that had been locked in the Siberian permafrost for more than
30,000 years.
– Risks to roads, pipelines –
A permafrost thaw could be a boon for the oil and mining industries,
providing access to previously difficult-to-reach reserves.
But it also presents a serious and costly threat to infrastructure, risking
mudslides and damage to buildings, roads and oil pipelines.
A Greenpeace report published in 2009 said thawing soil in Russia’s
permafrost zones caused buildings, bridges and pipelines to deform and
collapse, costing up to 1.3 billion euros (nearly $1.5 billion) a year in
repairs in western Siberia.