Associated PressAugust 16, 2019 10:43:45 AM IST
The 500-foot pulsating ice fields beneath NASA's aircraft give way to blue-green from water strewn with irregular pieces of bleached white ice, some the size of battleships, some as tall as 15-story buildings.
Like almost any other Greenland glacier, the massive Kangerlussuaq is melting. In fact, the giant Frozen Island has seen one of its biggest melt-ins to record this year. NASA scientist Josh Willis is scrutinizing the phenomenon, hoping to figure out exactly how global warming eats Greenland's ice. In particular, he wants to know whether melting is caused by more than warm air or warm seawater. The answer can be decisive for the future of Earth.
Water carries more heat for something frozen faster than air than anyone who has ever thawed a steak under the tap.
If Willis's theory that much of the damage was from water turned out to be correct, he said, "There is much greater potential for Greenland to melt faster than we had thought." This means that seas are rising faster and coastal communities are flooding. More ▼.
Greenland contains enough ice to allow sea levels to rise by 20 feet if everything melts. In just one day this month, it lost a record 13.7 billion tonnes (12.5 billion tonnes) by one estimate.
"It's a little scary," Willis said, looking down at an area filled with more water than ice. "We are definitely watching the ice sheet disappear in front of us."
Climate change is eating up the Greenland glaciers in two ways. The most obvious way is from the warm air above, which was brutal this summer, with European heat wave working in July as an ice dryer. The other way is from warm, salt water, part of it from the Gulf Stream in North America, carrying the coastal glaciers below.
When Georgia University ice scientist Tom Mott, who was not part of the project, began exploring Greenland's glaciers in the early 1990s, researchers really didn't think water was a big factor.
The Willis project – called Oceans Melting Greenland, or OMG – shows this to be the case. Now the question is how much and how fast.
What Willis measures is water 200 feet or more 660 feet below the surface that is warmer and saltier than the things that touch the air. It is this deep water that causes the greatest damage.
To measure this, NASA spent five years crossing the island in a deceptively 77-year-old DC-3 built for World War II. Willis, project manager Ian McCubin and mechanic Rich Gill, run long cylindrical probes through a special tube into the floor of the aircraft, watching the sensors parachute down and then dive into the cold water.
McCubin then waits for a tone on his computer, which tells him that the probe is underwater and measures temperature and salinity. When all five flight probes start signaling – with a sound that McCubin resembles a "fax machine or AOL modem" – he and Willis are high five.
In the meantime, pilots Andy Ferguson and Don Watrows board the plane to the blue-green spots, searching for the next destination and pointing out stunning giant icebergs and signs of glacial retreat on the radio.
As the data is transmitted back from a $ 2000 probe now deep into the water near Kangerlussuaq in eastern Greenland, initially it seems that temperature has not changed much in the last year or two, which may be good news. But this is just one data point. Every year for the past four years, NASA has been exploring all over Greenland, and overall the numbers are not so calming.
If water plays a much larger role than scientists thought, it could mean that the seas will rise faster and higher than expected. That's because 90 percent of the heat from climate change goes to the oceans, Willis said. Hot water provides a "bigger bang for the buck" than air when it comes to melting ice, Willis said.
How crucial the melting point is to seawater has been paradoxically demonstrated by the Jacobsbavn Glacier, the fast-growing glacier on the more populated West coast of Greenland. In recent years, it has suddenly started to increase slightly, probably due to water cooling as a result of temporary changes in weather and water patterns, Willis said.
In general, the oceans warm much more slowly than the air, but still stay warmer. Water weakens glaciers and causes icebergs to break. These icebergs eventually melt away, adding to the seas.
"Some of them are as big as a city," Willis said.
A 2019 study by Danish climatologist Ruth Mottram examined 28 glaciers in Greenland with long-term data. Almost all of them melt away, with only one or two being considered as stable.
"Retreating a glacier seems like a carelessness, but the 28 retreat is a sign of something that's happening," says Motram Associated Press,
A 2017 study concluded that coastal glaciers and ice caps – what Willis was studying – reached a "tipping point" for the loss of ice in 1997 and have since deteriorated rapidly. A NASA satellite found that the Greenland iceberg was losing about 255 billion metric tons annually between 2003 and 2016, with the overall loss rate worsening.
It will take centuries to melt all of Greenland's massive ice sheet, but how fast is the main question. If warm water plays a greater role than scientists suspect, by 2100 Greenland alone can cause 3 or 4 feet (more than 1 meter) sea level rise, Willis said.
Other scientists, such as Ted Scambos of the University of Colorado, say Greenland's contribution to raising sea level by 2100 is likely to be closer to 1 foot (30 centimeters).
This is a big spread.
"I'm leaning toward more, but I'm hoping for fewer," said Maryland Baltimore County glaciologist Christopher Schumann, whose family owns coastal properties.
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