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Glacial Outburst Flood — Human Hothouse Displaces Hundreds in Tajikistan
30
July, 2015
If
you lived during the 1880s, when the globe was one degree Celsius
cooler than it is now, you’d see far less in the way of heatwaves.
But an immense vomiting of greenhouse gasses into our atmosphere and
oceans by fossil fuel industry since that time has greatly multiplied
these periods of extreme temperatures. So much so that you
are now four times more likely to experience a heatwave anywhere on
the globe at any given time than you were 135 years ago.
Heatwaves,
depending on their intensity, can have serious consequences. The most
direct impact is due to the excess heat itself. In the more extreme
instances, heatwaves during recent years have featured an ominous
capacity to hospitalize tens of thousands. These heat stroke victims,
in the worst cases, perish. Such was the case
for India and Pakistan this
year where hundreds tragically lost their lives due to the impact of
increased heat alone.
But
if heatwaves occur in regions where glaciers still exist, the impact
can be even more profound.
Glacier
Outburst Flood In Tajikistan
(“The
lake disappeared and turned to salt…” Melting of glaciers in
Tajikistan is having a far-reaching impact. This UN-based program
describes how the lives of Tajikistan’s people are being threatened
by water loss due to glacier decline. But the impacts of glacier
outburst floods can be more directly destructive.)
In
Tajikistan, the heat is bringing with it a great decline in high
elevation glaciers. Some have already disappeared. It’s a loss
resulting in severe impacts to both energy and water security for the
country. But perhaps even more disturbing is what happens when water
is suddenly released from the dwindling glaciers.
Such
was the case with Tajikistan this month. Beginning on July 16, an
oppressive heatwave settled over this Central Asian nation.
Temperatures rocketed to record levels. Baking its broad mountains —
valleys, slopes and glaciers alike.
Crammed
between Afghanistan, Pakistan, China, Kyrgyzstan and Uzbekistan,
Tajikistan squats along the northwest boundary of the Tibetan
Plateau. The upthrust of great glacier-capped peaks tower over this
country. Peaks whose heads are loaded with a great volume of ice that
is now being forced to rapidly melt.
This
month’s record heatwave dealt a terrible blow to that ice. The
glaciers, of which Tajikistan boasts 8,492, were already greatly
weakened by a 3 degree Celsius temperature increase over the past
five years. All it took was the shove of the most recent temperature
surge to push some of these to the breaking point. By Tuesday, a
great outburst flood had ripped through the mountain valleys of the
Central Asia country. The outburst flood waters roared out,
overtopping rivers — washing away more than 50 homes, cutting off
major roadways, and driving 620 persons into government disaster
shelters.
Unfortunately,
this most recent climate change mass casualty event may be just one
of many. In Tajikistan, a mud dam has developed along the path of
major glacial melt. Water pressure is building behind the dam. Should
it release, more
than 30,000 people will be in the path of the outburst food.
Risk
of Outburst Flooding Near Large Glaciers is a Global Hazard
All
throughout the Tibetan Plateau region glacial outburst floods related
to human-caused warming are on the rise (see the
glacial megaflood). As
much as 70 percent of the ice within the great Himalayan glaciers
could melt out by 2100 under business as usual fossil fuel burning.
The result would be a crescendo of glacial outburst floods followed
by a period of drastically increased aridity for the lands around
Tibet.
Alaska.
Prince William Sound, waterfall flows from under Blackstone Glacier.
(The
high elevation of glaciers combined with the vastness of their
captured water and the often steep grades upon which they perch can
generate violent flooding in the event of rapid melt. In many
instances, silt from glacial outflows can develop a dam downstream of
the glacial flood. Such dams are often unstable and can be subject to
catastrophic collapse. In the worst cases, ice dams can form in the
interior sections of very large ice sheets — such as those seen in
Greenland and Antarctica. Glacial outburst floods due to such melt
and ice dam formation in the major ice sheets are catastrophic events
of geological scale and impact. Image source: ADT.)
Glacial
outburst floods are sudden, powerful, violent, and difficult to
predict. They are limited only by the amount of water the glaciers
themselves release — ice masses that hold volumes of water often
measured in cubic kilometers. The
drastic impacts and terrible violence due to this kind of flooding
was also recently witnessed during 2013 in Kedarnath, India.
And what we see in Tajikistan and India during recent years is,
sadly, just a taste of what’s to come in a fossil fuel emissions
warmed world.
Finally,
in this narrative, we cannot ignore potential glacial outburst flood
impacts from melting over the Greenland Ice Sheet and Antarctica. And
unlike Tibetan glacial melt, potential outburst flood events issuing
from Greenland or Antarctica are a hazard of global scope. Such
events would likely be driven by extended periods of rainfall over
the ice during summer heating events. An
ominous melt-driving phenomena that science is just now starting to
track.
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