Thursday, December 7, 2023

Greenland’s melting glaciers spew a complicated treasure: sand


Sand is building up on Greenland's coast, carried by water from the melting ice sheet.
It's an exceedingly valuable resource.
Photograph: Nicolaj Krog Larsen

From Wired by Matt Simon
 
Greenland’s Melting Glaciers Spew a Complicated Treasure: Sand
Meltwater from the island’s ice sheet is loaded with the right kind of sand for concrete production—which further warms the planet.

Sand is both abundant and rare.
Earth has vast deserts of the stuff, of course, but not the kind that’s in such high demand that sand mafias are killing for it.
That special variety is a critical component of the concrete used in buildings and infrastructure, the production of which has skyrocketed exponentially over the last few decades.
That has come at a significant climate cost: The industry now accounts for 8 percent of global carbon emissions.

Sand is also at the center of a strange climate story.
Climate change is destroying Greenland’s ice sheet, producing an extraordinary amount of meltwater.
(Even if we somehow totally stopped emissions today, Greenland’s melting could still contribute nearly a foot of sea-level rise.) And in a twist of fate, that meltwater is loaded with the right kind of sand for concrete production, which causes more warming and more melting.
Great plumes of glacial sediment are swirling along the coast, actually adding land along the edges of the island.
Even though Greenland is only three times the size of Texas, its ice sheet is the source of 8 percent of suspended river sediments flowing into the oceans.

The country now has to figure out whether exploiting that valuable, abundant resource on a wider scale would be environmentally, socially, and economically tenable.
“It is quite controversial—we're saying Greenland can benefit from climate change,” says Mette Bendixen, a geographer at McGill University in Canada, who’s studying the idea.
“Contrary to most of the other parts of the Arctic coast, Greenland is not eroding.
It's in fact growing bigger, because the ice sheet is melting.
So you can think of the ice sheet as a tap that pours out not only water, but also all the sediment.”


Greenland is actually growing as an island, thanks to all that sediment.
Photograph: Nicolaj Krog Larsen

That sediment is special, indeed.
Desert sand from, say, the Sahara is no good for making concrete because it’s too rounded and uniform.
Over millennia, winds push those grains around, polishing them.
If you make concrete out of such sand, “it's almost like building with marbles,” says Bendixen.
“You want particles that are more angular in shape, not rounded.
And that type of material is exactly what you get from rivers, for example, or material that has been deposited by glaciers.”

As Greenland’s ice sheet—which covers 700,000 square miles and is up to 10,000 feet thick—rubs against the land, it grinds up sediment, including sand, fine silt, and larger chunks of gravel.
And as the ice melts, torrents of water carry all that debris to the sea, while the pounding of the rivers themselves further erodes the landscape.
Compared to the thousands of years that sand spends rolling around the Sahara and becoming rounded, the particles coming off Greenland are fresher.
They’re more angular and more diversely shaped.
Instead of acting like marbles, they fit together like pieces of a jigsaw puzzle, which is good for concrete.

 
 
Photograph: Nicolaj Krog Larsen

Greenland already harvests its sand for local, small-scale concrete production, since importing sand would be prohibitively expensive.
This is limited to domestic companies, who have to win non-exclusive permits after passing environmental review by the government’s scientific advisers.
They can also apply to export the sand, but that requires additional licensing.
“We are basically also open for sand extraction aiming at export, but then it will be treated like any other mining activity,” says Kim Zinck-Jørgensen, of the Greenland government’s Mineral Licence and Safety Authority.
“And for that you'll have a much greater setup with regulations and also environmental impact assessments, social impact assessments.”

Currently, dredging boats suck up sediment along the coast and filter out the sand, which is then brought back onshore.
But if Greenland decides to scale up sand extraction for export, that would mean big ships would have to haul the stuff away to international ports.
“It's important to stress that if you extract whatever natural resource, there will be environmental consequences,” says Bendixen.
“But really, here the environmental consequences can be super broad.”

For one, those big ships will also be bringing in ballast, or the water they’ve collected from elsewhere and stored in their hulls for balance.
If that ballast is released off the coast of Greenland, it may introduce invasive species.
And, of course, dredging coastal sediments would further endanger underwater native creatures—and on land, increased mining operations might scare away the game that Inuit hunters rely on.
(Greenland’s population is about 90 percent indigenous Inuit.
The Greenland branch of the Inuit Circumpolar Council, an NGO representing Inuit peoples, declined to comment for this story.)

Interestingly, though, last month Bendixen and her colleagues published a survey of Greenlanders about their opinions on sand extraction.
They found that 84 percent of adult residents are in favor of it, and three-quarters want it to be a national project.
“It turns out that the vast majority of Greenlanders think that it should be primarily a Greenlandic enterprise,” says Rasmus Leander Nielsen, a political scientist at the University of Greenland, who did the survey with Bendixen.
“Maybe you could have some smaller-scale, Greenlandic-led companies that could start off.
And then eventually, when the business case is more favorable, then we could go into a larger export.”

About that business case: While the global demand for sand has gone wild, the economics of exported Greenland sand aren’t yet clear.
A company would have to pay to run the local operations and foot the shipping costs to get the resource off the island.
Those will be considerable, since sand is heavy and takes up a lot of room in a ship.

The Greenland government recently worked with a consultancy that did an assessment, finding that exporting the sand to Europe isn’t economically feasible at the moment.
“Whether it's feasible to export it further on to the Middle East, I don't know,” says Thomas Lauridsen, chief adviser to Greenland’s Ministry of Mineral Resources and Justice.
“But we will then be in competition with European companies that will dredge sand in Europe or closer to the customer.”

Lauridsen adds that it’s up to the private sector to determine whether selling Greenland’s sand is cost-effective or not.
And that export cost calculus may change in the future.
“By 2100, the demand for sand is going to rise 300 percent, and the price 400 percent,” says Bendixen.
“So we don't have to look that much farther into the future to start seeing a different calculation here in terms of whether it's worthwhile.”

Yes, a world with more sand harvesting for making more concrete would also mean more carbon emissions, more warming, and more melting of Greenland’s ice sheet.
But, Bendixen says, all that glacial sand need not go exclusively toward concrete.
Coastal communities are increasingly clamoring for sand to hold back rising seas, a fortification known as beach nourishment.
“Just think of the irony in using the sand for beach nourishment to mitigate sea-level rise,” says Bendixen, “which is caused by—to a large extent—the melting of the Greenland ice sheet!” 

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