A new study to assess the
contribution that Asia's high mountain glaciers make to relieving water stress
in the region is published this week (29 May 2019) in the journal Nature.
The study has important economic and social implications for a region that is
vulnerable to drought. Climate change is causing most of the region's glaciers
to shrink.
British Antarctic Survey (BAS)
glaciologist Dr. Hamish Pritchard found that during droughts, glaciers become
the largest supplier of water to some of Asia's major river basins. This
melt-water is important for the people living downstream when the rains fail
and water shortages are
at their worst.
Each summer, glaciers release
36 cubic kilometres of water—equivalent to 14 million Olympic swimming pools—to
these rivers. This is enough water to fulfil the basic needs of 221 million
people, or most of the annual municipal and industrial needs of Pakistan,
Afghanistan, Tajikistan, Turkmenistan, Uzbekistan and Kyrgyzstan.
This supply is unsustainable,
though, because climate
change is causing the region's glaciers to lose 1.6 times more water
than they gain each year from new snowfall.
The high-mountain region of
Asia, known as the Third Pole, encompasses the Himalayas, Karakoram, Pamir,
Hindu Kush, Tien Shan, Kunlun Shan and Alai mountains and has 95,000 glaciers
in total. About 800 million people are partly dependent on their meltwater.
Dr. Pritchard analysed
estimates of the glacier contribution with the amount of precipitation in
average years and in drought years. He used climate datasets and hydrological
modelling to calculate the volume of glacier water entering and leaving the
region's major river basins.
Dr. Pritchard says:
""This study is
about answering the question—why do glaciers matter? Even in high-mountain
Asia, they are remote and cover quite a small part of the region. It turns out
that they are particularly valuable to society as a natural store of water that
keeps the rivers flowing through summer, even through long droughts.
"Against a background of
increasing drought-related water and food shortages and
malnutrition, which have been predicted with high confidence for the coming
decades, Asia's glaciers will play an increasingly important part in protecting
downstream populations from drought-induced spikes in water stress—spikes that,
without mitigating changes in the way water is stored and used, are the
potential trigger for a sudden jump in the price of water that could be profoundly
destabilising for this region."
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