From Red and Black.com: UGA geography head observes Greenland's ice sheet, finds 97 percent of ice sheet experienced melt
Greenland, despite what the name might
suggest, is topped by an ice sheet that covers 90 percent of its surface
area. At its thickest, this ice is two miles deep and at its highest is
over two miles above sea level.
During July, 97 percent of this ice sheet experienced melt — meaning
that 97 percent of the surface area had experienced some form of snow or
ice melt, not that 97 percent of the total had melted.
“There’s enough ice in Greenland to raise global sea level by 7
meters. If we had 97 percent of the ice sheet melt away, there’d be a
lot of coastal areas that’d be underwater right now,” said Tom Mote,
professor and department head of geography at the University.
On a typical summer day, around 25 percent of the ice sheet sees
melt. Temperatures this summer led to some remarkable conditions, Mote
said. Scientists recorded that 40 percent of the sheet’s surface was
getting melt when a ridge of warm air stagnated over Greenland — the
catalyst for the big melt.
Mote became aware of the melt when a Rutgers University colleague
called from the coast of Greenland. She was working near Kangerlussuaq,
towards the southwestern tip of the island, when a 60-year-old bridge
over the Watson River washed out because of floods caused by the massive
Mote, who normally waits to review the melt data until the end of the
season, contacted associates at NASA. Mary Albert, a professor at
Dartmouth, joined the conversation by satellite conference from the
summit of the ice sheet. She reported visual confirmation that there was
melt even at the highest elevation.
“We haven’t seen any other summer that’s produced as much melt
through the end of September as we’ve already seen in early August,"
Mote said. "Granted, we don’t see much in September anyway, so if you’re
going to break it, you’re probably going to break it in August. The
entire summer has been really remarkable."
Mote has produced a visual representation of the ice melt this year
from January through July (image to the left). The colors with hatch
marks represent melt: note the flair on July 11 and 12, the peak of the
melt for this season so far.
Scientists estimate that the last time a melt occurred on this scale was in 1889, based on ice samples.
“You can drill into the ice, and you can look at it just like looking
at tree rings and count back in time. We think the last time this
occurred was 1889, and prior to that we think the last time this
occurred was 680 years before,” Mote said.
While scientists have seen more melts at higher temperatures during
the past few decades, Mote emphasized that this melt was just one event.
“And that’s the way I would describe it: a very unusual weather event
that caused really extensive melt embedded within this changing climate
over Greenland that has led to more frequent and intense melting along
the edge of the ice sheet,” he said
More frequent and intense melting has led to other changes besides coastal floods like the one seen on the Watson River.
Moulins are glacial lakes. As ice melts, these lakes can fill and
empty in the course of hours. Marco Tedesco of the City University of
New York is another colleague of Mote’s. He made a video documenting one
of these moulins. As temperatures warm, the formation of these lakes
becomes more frequent.
Mote has been studying the ice sheet since the 1990s. His attention
in that area waned when there seemed to be no general interest and there
were few comparable data sources. With the introduction of new
satellite technology and global interest in climate change, Mote has
picked up the research again over the last five to 10 years.
“We’ve had some really remarkable things going on over the ice sheet
that have attracted a lot of interest in this again,” Mote said.