Page 28 - ARUBA TODAY

A28 SCIENCE
Tuesday 18 april 2017

Canada glacier melt rerouted in rare case of ‘river piracy’

SETH BORENSTEIN dust storms with this fine
AP Science Writer dust getting into your nose
WASHINGTON (AP) — Sci- and your mouth,” Best said.
entists have witnessed the The lack of water in the
first modern case of what Slims wasn’t because of
they call “river piracy” and changes in rainfall, Shugar
they blame global warm- said. They know that be-
ing. Most of the water gush- cause it’s a river fed mostly
ing from a large glacier by glacial melt, not rain,
in northwest Canada last and the Alsek increased in
year suddenly switched amounts similar to what dis-
from one river to another. appeared from the Slims.
That changed the Slims The Kaskawulsh glacier
River from a 10-foot (3 me- covers about 9,650 square
ters) deep, raging river to miles (25,000 square kilo-
something so shallow that meters), about the size of
it barely was above a sci- Vermont. The front of the
entist’s high top sneakers glacier has retreated near-
at midstream. The melt ly 1.2 miles (1.9 kilometers)
from the Yukon’s Kas- since 1899, Shugar said.
kawulsh glacier now flows The scientists calculate
mostly into the Alsek River that there is only a 1 in 200
and ends up in the Pacific chance that the retreating
Ocean instead of the Arc- In this photo provided by Jim Best/University of Illinois, taken in 2016, a close-up view of the ice- glacier and river piracy is
tic’s Bering Sea. walled canyon at the terminus of the Kaskawulsh Glacier, with recently collapsed ice blocks. completely natural without
It seemed to all happen in Associated Press man-made global warm-
about one day — last May ing. They used weather
26 — based on river gauge the melting water, Shugar time to occur, such as be dangerous to wade and ice observations and
data, said Dan Shugar, a and his colleagues wrote in tens of thousands of years, through, Shugar said. They a computer simulation
University of Washington a study published in Mon- and had not been seen in returned last year to find that models how likely the
Tacoma professor who day’s journal Nature Geo- modern times, especially the river shallow and as still glacier retreat would be
studies how land changes. science . not this quickly, said study as a lake, while the Alsek, with current conditions
A 100-foot (30-meter) tall The term “river piracy” is co-author Jim Best of the was deeper and flowing and without heat-trapping
canyon formed at the end usually used to describe University of Illinois. It’s dif- faster. greenhouse gases.
of the glacier, rerouting events that take a long ferent from something like “We were really surprised Several outside scientists
the Mississippi River chang- when we got there and praised the study as signifi-
ing course at its delta and there was basically no wa- cant and sensible.
it involves more than one ter in the river,” Shugar said “This is an interesting study
river and occurs at the be- of the Slims. “We could and reconfirms that cli-
ginning of a waterway, not walk across it and we mate change has large,
the end. wouldn’t get our shirts wet. widespread and some-
The scientists had been to It was like a snake-shaped times surprising impacts,”
the edge of the Kaskawul- lake rather than a river.” Pennsylvania State Uni-
sh glacier in 2013. Then the What had been a river del- versity glacier expert Rich-
Slims River was “swift, cold ta at the edge of the Slims ard Alley, who wasn’t part
and deep” and flowing River had changed into of the study, said in an
fast enough that it could a place full of “afternoon email.q