Generally speaking, as the climate
warms, ice around the planet melts. But how fast it melts and
where it melts is complicated by factors like how the
climate’s changing and local weather patterns.
Here at NASA, we use satellites, airplanes and research ships to take a closer
look at the regional causes of melting and what’s driving them.
NASA’s mission Ocean Melting Greenland, or OMG for short, is
designed to figure out how much of Greenland’s ice loss is being caused
by the oceans.
Sometimes the oceans affected Greenland’s ice in surprising ways.
This year, we figured out for the first time in almost 20 years,
Greenland’s biggest glacier, Jakobshavn, stopped retreating
and got thicker. The big question: Why?
After looking at dozens of potential causes,
we figured out that Jakobshavn’s slowdown was caused by
cold water that flowed in from offshore.
Where Jakboshavn meets the ocean, it sits in water that’s almost
2,400 feet deep — that’s like eight football fields —
and this water can affect the glacier very far inland.
Water in Disko Bay, shown here, flows into the canyon,
or fjord that holds Jakobshavn, sometimes the
water is warm, speeding up the melt of the glacier, and sometimes,
it slows it down. In 2016, the water in Disko Bay
got cold, reaching temperatures that were lower than at any time
since the late 1980s.
Natural cycles cool and then warm the
far north Atlantic Ocean about once every 20 years. This cold water
from 2016 arrived just as the Atlantic was shifting to its
next cold period.
Watch as the deep water temperatures warm up slowly
through the years, until 2016, then get cold again.
These waters are brought into Disko Bay by the currents of the North Atlantic,
which flow around the southern tip of Greenland, carrying water
northward up its west coast.
The cold water in Disko Bay caused a dramatic change
in Jakobshavn, making it grow taller by 100 feet,
or 30 meters, between 2016 and 2017.
What does this mean for Greenland? It means that the oceans play a key role in
Greenland’s melt, and we have to watch the water just as closely as the ice
if we want to know what the future holds. Here at NASA,
we’re hard at work in the field, and the lab, to better understand
how the ocean affects Greenland’s melting and how that will continue
to change with the climate.
NASA