https://www.weforum.org/agenda/2019/05/greenland-is-approaching-the-threshold-of-an-irreversible-melt-and-the-consequences-for-coastal-cities-could-be-dire-974b963f45
[images and links in online article]
We're approaching a point of no return in Greenland. Here's why
Greenland's ice sheet is melting six times faster than it was in
the 1980s — that's even faster than scientists thought.
A new study has revealed that melting Greenland ice has contributed
to more than half an inch of global sea-level rise since 1972. Half of
that increase happened in the last eight years.
If all of Greenland's ice were to melt, it would raise sea levels
23 feet, submerging some coastal cities. In the US, that would put
everything south of West Palm Beach, Florida underwater.
Greenland's ice is melting six times faster now than it was four decades
ago.
The authors of a new study published in the journal Proceedings of the
National Academy of Sciences estimate that the Greenland ice sheet is
now sloughing off an average of 286 billion tons of ice per year. In
2012, Greenland lost more than 400 billion tons of ice.
Two decades ago, the annual average was just 50 billion.
All that lost ice means Greenland's melting has contributed to more than
0.5 inches of global sea-level rise since 1972, the researchers
reported. Alarmingly, half of that increase came about in the last eight
years alone.
Another study published in January 2019 used data from satellites and a
GPS network to determine that Greenland's ice is melting faster than
scientists previously thought. That study highlighted risks of melting
in Greenland's southwestern region, which isn't typically known to be a
source of ice loss, as Quartz reported.
"This is going to cause additional sea-level rise," Michael Bevis, lead
author of the January study and a professor at Ohio State University,
told National Geographic. "We are watching the ice sheet hit a tipping
point."
This news comes in the wake of another ominous finding: Antarctica's
melting is also speeding up. In the 1980s, Antarctica lost 40 billion
tons of ice annually. In the last decade, that number jumped to an
average of 252 billion tons per year — just a hair behind Greenland's
new average.
What happens if the entire Greenland ice sheet melts?
Roughly 1.7 million square kilometers (656,000 square miles) in size,
the Greenland ice sheet covers an area almost three times that of Texas.
Together with Antarctica's ice sheet, it contains more than 99% of the
world's fresh water, according to the National Snow and Ice Data Center.
Most of that water is frozen in masses of ice and snow that can be up to
10,000 feet thick. But as human activity sends more greenhouse gases
into the atmosphere, the oceans absorb 93% of the excess heat those
gases trap. The warm air and water is leading ice sheets to melt at
unprecedented rates.
If the entire Greenland ice sheet were to melt — granted, this would
take place over centuries — it would mean a 23-foot rise in sea level,
on average. That's enough to submerge the southern tip of Florida.
If both Antarctica and Greenland's ice sheets were to melt, that would
lead sea levels to rise more than 200 feet (and Florida would disappear).
NASA has created an interactive tool that helps track sea-level rise
projections based on how much the two ice sheets are melting. One thing
the tool makes very clear: Coastal cities will be heavily impacted.
In the event of a full ice melt, according to a map from National
Geographic, cities like Amsterdam, Netherlands; Stockholm, Sweden;
Buenos Aires, Argentina; Dakar, Senegal; and Cancun, Mexico (to name
just a few) would vanish.
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