Alun Hubbard is one of the hardest of hard core glaciologist, and a friend that I’ve spent some time with in Greenland over the years. As the pictures richly illustrate here, he knows ice, up close and personal.
I’m striding along the steep bank of a raging white-water torrent, and even though the canyon is only about the width of a highway, the river’s flow is greater than that of London’s Thames. The deafening roar and rumble of the cascading water is incredible – a humbling reminder of the raw power of nature.
As I round a corner, I am awestruck at a completely surreal sight: A gaping fissure has opened in the riverbed, and it is swallowing the water in a massive whirlpool, sending up huge spumes of spray. This might sound like a computer-generated scene from a blockbuster action movie – but it’s real.
A moulin is forming right in front of me on the Greenland ice sheet. Only this really shouldn’t be happening here – current scientific understanding doesn’t accommodate this reality.
As a glaciologist, I’ve spent 35 years investigating how meltwater affects the flow and stability of glaciers and ice sheets.
This gaping hole that’s opening up at the surface is merely the beginning of the meltwater’s journey through the guts of the ice sheet. As it funnels into moulins, it bores a complex network of tunnels through the ice sheet that extend many hundreds of meters down, all the way to the ice sheet bed.
When it reaches the bed, the meltwater decants into the ice sheet’s subglacial drainage system – much like an urban stormwater network, though one that is constantly evolving and backing up. It carries the meltwater to the ice margins and ultimately ends up in the ocean, with major consequences for the thermodynamics and flow of the overlying ice sheet.
Scenes like this and new research into the ice sheet’s mechanics are challenging traditional thinking about what happens inside and under ice sheets, where observations are extremely challenging yet have stark implications. They suggest that Earth’s remaining ice sheets in Greenland and Antarctica are far more vulnerable to climate warming than models predict, and that the ice sheets may be destabilizing from inside.
I bagged a long sought after interview late last March, with Jeff Severinghaus (we have a connection I’ll explain tomorrow) of Scripps Oceanographic Institute. Big Ice guy.
Jeff has some current research that I’ll be examining in coming videos, but as I spoke to Jeff he was just returning from a stay in Antarctica, so I asked him to summarize the best assessments.
Then of course, Covid hit, and my county in Michigan got devastated by a dam failure, and a whole load of the madness that is 2020 got in the way – but I finally came back around to this. I matched Jeff’s clips with some from Richard Alley and Eric Rignot, well known to readers here. They spoke to me in New Orleans in 2017.
I had also talked to Susheel Adusumilli, also of Scripps, and I featured prominently the new work from Stef Lhermitte, of Delft University of Technology. Then I wrapped it with a summary from Twila Moon of the National Snow and Ice Data Center. My Yale Climate Connections colleague Karen Kirk also had a pass at this research as well, her @CC_Yale piece:
Climate researchers have long monitored ice sheet dynamics in the Amundsen Sea, focusing specifically on the Thwaites and Pine Island glaciers. The two sit side by side on Antarctica’s western peninsula covering an area roughly the size of nine U.S. coastal states stretching from Maine to Maryland. The two glaciers alone store ice that could account for about 4 feet (1.2 meters) of global sea level rise. Their “seaboard” location may help bring increased public attention and interest to the West Antarctic Ice Sheet, which if it melted could raise seas by a catastrophic 11 feet (3.4 meters).
An international effort led by the British Antarctic Survey recently published two papers (Hogan et al. and Jordan et al.) showing the first detailed maps of the seafloor at the edge of the Thwaites Glacier. The team mapped deep submarine channels that have been funneling warm water to this vulnerable location. High-resolution imagery pinpoints the pathways that allow warm water to undermine the ice shelf. Lead author Kelly Hogan of the British Antarctic Survey says the findings will improve estimates of sea-level rise from Thwaites Glacier. “We can go ahead and make those calculations about how much warm water can get under the ice and melt it,” Hogan said.
The other researchers, led by Stef Lhermitte, found stark visual confirmation of glacier disintegration using decades of time-lapse satellite imagery. Their work sheds light on the accelerating feedback process, wherein the rapid loss of ice is opening the door to ever-increasing melting.
