Greenland's ice is melting
Today’s melt across the Greenland ice sheet is unparalleled for centuries, if not millennia.
Melt started increasing at the dawn of the industrial revolution, but is now increasing faster than ever.
What happens next? That's up to us.
Here's the science that led us to these conclusions...
Why is Greenland so important?
Chances are, you or someone you know lives near the ocean.
After all, nearly 40-50% of the US and global populations do, including 6 of the world's 10 largest cities.
Sea level rise
The Greenland ice sheet is over a mile thick in places and contains enough ice to raise global sea level by 7 meters (23 feet).
Answering how much -- and how fast -- this ice will melt is imperative to planning for the future.
To be able to answer these questions, we must assess how the ice sheet is responding to climate change.
How does Greenland add to sea level?
More than half of the Greenland ice sheet's sea level contributions come from melting snow and ice running off the ice sheet.
Some runoff is normal, but...
Runoff is increasing
And as a result, the Greenland ice sheet is now the leading source of new water added to the ocean every year.
This videois of the Watson River in southwest Greenland in 2012, draining water from the ice sheet after nearly its entire surface melted -- for the first time ever observed.
surface melt increases since the 1960s
Using a sophisticated, observationally-forced regional climate model called RACMO2.3p2, we can assess change in melting since 1958. This method shows that melting is both intensifying and encompassing a much larger area of the ice sheet.
What is normal?
Satellite measurements and models show that Greenland ice sheet melt and runoff are increasing.
But these methods only reliably cover the last few decades.
Drilling back in time
A longer-term context is needed to tell us whether the modern observations are unusual, and how quickly the ice is responding to climate change.
We went to Greenland on a mission to answer these fundamental questions.
A mission to extract records of Greenland ice sheet melt history.
In the cold spring of 2015, we mounted a scientific expedition to three remote field sites in Greenland.
To get to each site, we flew via Air Greenland Twin Otter (a reliable, ski-equipped aircraft) or AS350 helicopters.
There, we established temporary science camps, with the large orange and white drilling tent the center of action.
Using IDDO's Eclipse Drillwe extracted ice cores by day and slept in mountain tents at night.
Cores were recovered in 1 meter sections at a time until we reached 100 to 140 meters below the ice surface.
Science operations took up to a week at each site, after which we broke down camp and carefully packed the ice cores for cold shipment back to laboratories in the US.
We strategically targeted Greenland’s melt “Goldilocks Zone” -- where surface melting occurs enough to leave a well-persevered signal in the ice, but not enough to fully melt away the snowpack for any given year.
As a result, our ice cores accurately record not only how much melting was happening (and refreezing) at the high elevation ice core sites, but also how much water was running off Greenland’s lower-elevation margins and contributing to rising sea levels.
A new record is uncovered
Our ice cores effectively extend the satellite record 10-fold, allowing us to carefully and accurately reconstruct the ice sheet's response to climate warming.
Unprecedented rise in runoff
Recent Greenland-wide runoff is exceptional over at least the last 350 years, far surpassing the range of natural variability.
Runoff has accelerated. It now occurs at a volume 50% larger than during the pre-industrial era (the 1700s) and 33% greater than the 20th century alone.
These increases began shortly after the onset of industrial-era warming in the Arctic.
The more Greenland air temperatures rise, the faster the ice sheet melts.
Today, increases in temperature can produce twice as much melt, or more, as the same amount of warming in the mid-20th century.
Greenland's melt matters
Greenland has warmed faster than the rest of the globe.
Self-reinforcing feedbacks amplify the response of the Greenland ice sheet to warming, making its melting speed up and more likely to run off into the ocean.
This runoff raises global sea level and is altering important ocean currents, making the Greenland ice sheet's impacts globally-relevant.
What happens now?
The best way to limit the impacts of the Greenland ice sheet on our coastlines and climate is to limit additional global warming by reducing greenhouse gas emissions.
Because Greenland's ice is much more sensitive to warming today than in the past, what we do now matters more than ever.
This research was funded by the US National Science Foundation, institutional support from Rowan University and Woods Hole Oceanographic Institution, the US Department of Defense, the Netherlands Organization for Scientific Research, the Netherlands Earth System Science Center, and the Belgian National Fund for Scientific Research.
Source information for content used on this website
Page 1 image: Sarah Das
Page 2 image: Flickr user anpalacios
Page 3 image: NASA Goddard Space Flight Center
Page 4 video: NASA Goddard Space Flight Center
Page 5 video: YouTube user 76siobhan
Page 6 images: Luke Trusel, RACMO2.3p2 model
Page 7 video: Luke Trusel, Google Earth
Page 8 images: Luke Trusel, Sarah Das
Page 9 image: Sarah Das
Page 10 image: Luke Trusel
Page 11 image: Sarah Das
Page 12 image: Matt Osman
Page 13 image: Luke Trusel
Page 14-15 image: Luke Trusel
Page 16 image: Sarah Das