A few miles up the Sermilik Fjord in southwestern Greenland, the water has abruptly turned milky, a sign that it is loaded with suspended silt, sand and other sediment.

It is this material — carried here in a constant plume of meltwater from the Sermeq glacier at the head of the fjord — that Mette Bendixen, a Danish scientist at the University of Colorado, has come to see. As their research boat moves farther into the murky water, she and several colleagues climb into a rubber dinghy to take samples.

Dr. Bendixen, a geomorphologist, is here to investigate an idea, one that she initially ran by colleagues to make sure it wasn’t crazy: Could this island, population 57,000, become a provider of sand to billions of people?

Sand for eroded beaches, potentially from the Rockaways to the Riviera. Sand to be used as bedding for pipes, cables and other underground infrastructure. Mostly, though, sand for concrete, to build the houses, highways and harbors of a growing world.

The world makes a lot of concrete, more than 10 billion tons a year, and is poised to make much more for a population that is forecast to grow by more than 25 percent by 2050. That makes sand, which is about 40 percent of concrete by weight, one of the most-used commodities in the world, and one that is becoming harder to come by in some regions.

But because of the erosive power of ice, there is a lot of sand in Greenland. And with climate change accelerating the melting of Greenland’s mile-thick ice sheet — a recent study found that melting has increased sixfold since the 1980s — there is going to be a lot more.

“It’s not rocket science,” Dr. Bendixen said. “One part of the world has something that other parts of the world are lacking.”

Dr. Bendixen is planning a two-year study to answer basic questions about the idea, including its feasibility and the environmental effects of extracting and exporting large amounts of the material. The government of Greenland, a self-ruled territory of Denmark, is studying it as well.

It would be up to entrepreneurs, possibly with assistance from the government, to make the idea a reality. Given the potential cost of shipping sand around the world, its feasibility would depend on the price of sand rising.

Currently almost all sand is mined within 50 miles of where it is used, said Jason C. Willett, a minerals commodity specialist with the United States Geological Survey. “Once you move it any distance it then costs too much,” he said.

The idea also raises questions that go beyond science — about Greenland’s economic future, about its potential independence from Denmark, and even about the appropriateness of capitalizing on climate change.

The need to diversify the economy is a big issue in Greenland, where fishing accounts for about 90 percent of exports and Denmark provides nearly half of the government’s budget through a block grant. A large sand-exporting industry could help reduce this subsidy, which would be critical to Greenland eventually becoming independent.

“The diversification discussion is very important,” said Birger Poppel, a political science professor at the University of Greenland. “This could fit into that discussion.”

Kuupik V. Kleist, Greenland’s premier from 2009 to 2013, said that exploitation of mineral resources, including sand, were the obvious targets for greater economic growth.

“But in order to replace half of the government budget you would need a lot of profit from any new activity which might arise,” he said. “How many projects it takes and how big, I’m not sure.”

All told, Greenland’s ice sheet delivers about 900 million tons of sediment to the waters surrounding the island each year, or about 10 percent of all the sediment delivered to oceans worldwide. The glacier at Sermilik Fjord, about 50 miles south of the capital, Nuuk, delivers about a quarter of Greenland’s total. That explains the vast delta of sand visible from the air as well as from a research boat as the tide begins to go out.

The delta, with muddy rivulets crisscrossing it, stretches to the glacier more than five miles away.

Dr. Bendixen has made some hypothetical calculations. If just 15 percent of the sediment pouring into this fjord every year could be extracted, that amount of sand — 33 million tons — is twice the annual demand of San Diego County in California, one of the most populous in the United States.

Sermilik Fjord is only one of a number of places in Greenland with large amounts of sand. And the sand will keep coming as the world keeps warming and the ice sheet keeps melting. “It’s like a tap pouring not only water, but sediment,” she said.

It was Dr. Bendixen’s work on the effects of climate change on Greenland that sparked the idea. She had come across a trove of aerial photos of the island, taken by the American military during World War II. Comparing them with more recent satellite images, it was obvious that deltas like the one in Sermilik Fjord were growing as the planet warmed and more meltwater came out of the ice sheet.

Dr. Bendixen noted that Greenlanders’ contribution to global warming was very slight — their emissions are a tiny fraction of the global total. “They have a long list of negative consequences they have to deal with,” she said, including rising sea levels and thawing permafrost. “If one of the consequences is actually positive, who are we to say that they cannot benefit from it?”

Worldwide, the demand for sand and gravel is relentless and increasing. Mining, usually from open pits or by dredging, is unregulated in many areas and often illegal. In India, for example, sand “mafias” have developed, with gangs stealing sand from a river bend or a beach overnight.

A United Nations report this year noted that extraction of sand around the world is exceeding the rates by which it is replenished. Sand removal along rivers and coastal regions often leads to greater erosion and harm to ecosystems, the report said.

In addition to better regulations, the report called for reducing the demand for sand and gravel through improved designs that cut the amount of concrete in buildings and infrastructure. (Lighter designs would also help address a climate change problem: Manufacturing of cement, the reactive ingredient in concrete, is responsible for about 5 percent of global emissions of carbon dioxide.)

Concerns about the supply of sand seem far off in Nuuk, population 17,500, where it’s possible to walk from one end of the city to another in less than an hour and where the Greenland government works out of an office building above a shopping mall.

But even Nuuk has its sights on expansion. There are plans to build thousands of homes and apartments to accommodate a population that is forecast to reach 30,000 by 2030. More immediately, work crews will soon begin lengthening the airport’s sole runway to handle jets, which would help Greenland’s nascent tourism industry.

Nicolai Mogensen, who runs Nuuk’s only concrete plant, is ready. This year he stockpiled extra sand, anticipating the start of the runway project. He currently has about 15,000 cubic yards, a small gray mountain next to the plant. It comes from a nearby fjord, sucked from the bottom by a dredge.

Mr. Mogensen, who has run concrete plants in Norway, Poland, Germany and Denmark, said he thought Dr. Bendixen’s idea was a good one. “All these countries are running out of sand,” he said.

Mike Hoegh, who owns a marine salvage business, extracts sand for use in Nuuk and other communities along the coast with his 150-foot dredging ship, the Masik Sioraq. On a recent afternoon, the ship was in a small fjord less than an hour’s sail from the capital.

What Dr. Bendixen and others envision would be on a much larger scale, extracting sand from fjords like Sermilik and loading large bulk carriers for shipment elsewhere. Ports and loading facilities would have to be built.

Dr. Bendixen said there could be environmental effects, which she and her colleagues will investigate as part of their study. With all the meltwater and sediment entering it, Sermilik Fjord’s ecosystem has always been disturbed, she said. “But we’d need to assess the impacts in the vicinity of Sermilik that a dredging industry would cause.”

Kaare Winther Hansen, the World Wildlife Fund’s representative in Greenland, said the fjords themselves were not that environmentally sensitive. “To my knowledge the biggest impact would be the shipping, and a risk of accidents with those ships.”

For his dredging business, Mr. Hoegh chooses areas where he knows the sand is good and there is little of the silt that was prevalent in the middle of the Sermilik Fjord. Nature tends to self-sort sediment: As a stream of meltwater enters the fjord and slows down, the largest and heaviest material — gravel — drops out first, followed by sand and finally silt. So one of the challenges of making large-scale sand extraction work would be to figure out a way to get to the sand and avoid the fine silt, which would not be useful for concrete.

On this, their first foray in pursuit of sand samples to analyze, Dr. Bendixen and her colleagues encountered some difficulties. Even after motoring the dinghy farther into the murky water, all they were able to sample was silt.

At one point Dr. Bendixen stepped out of the dinghy to tug it along. There was so much silt in the water, she said, it was like pulling the boat through paint. She hopes to use a helicopter for future fieldwork.

Dr. Bendixen said the goal of her studies is to give Greenlanders a thorough analysis of the prospects for developing a sand industry. But that’s where her involvement would end.