Why might Trump want to buy Greenland? Take a visual tour.

President Trump has asked top aides to explore the possibility of the United States purchasing strategically located Greenland, an ice-covered island off Canada’s northeastern coast. Aides are reportedly bewildered. Greenland’s government has said the territory, which remains part of Denmark, is not for sale. And some Danes have ridiculed the proposal as a joke. Here are some basic facts about the island.

The Scale

Greenland is huge — about 850,000 square miles, to be exact. But it’s not quite as large as many Americans might think. That’s because many popular Web mapping services use the Mercator map projection. This view of the world is good for navigation and displays areas with accuracy near the equator, but it heavily distorts the size of landmasses near the poles.

When viewed with an equal-area projection, the true size of Greenland is more apparent. It’s still pretty big — Greenland would stretch from northern Mexico to southern Canada if overlaid atop the Central Plains — but not as massive as it appeared in the Mercator map.

Climate Change

Greenland is already feeling the devastating effects of climate change. Ice has covered around 77 percent of the Arctic island, according to the CIA’s World Factbook. But that ice is melting — and quickly.

Last month, Greenland saw its most extreme melt event since 2012, as a heat wave turned large swaths of Greenland’s ice sheet into billions of tons of water. Apart from raising sea levels, climate change has made hunting more difficult and floods more dangerous for the 58,000 people who live on the island.

Hunting and fishing

For Greenland’s largely indigenous population, fishing is a way of life. It makes up 90 percent of Greenland’s exports, and Greenland broke away from the European Union in 1985 largely to protect its fishing rights.

One Inuit dialect has multiple ways just to say “seal.” But climate change is threatening the livelihoods of Greenlanders. Dog-sled routes that hunters have used to pursue sea mammals such as walruses and seals are melting away, and high mercury levels in large sea animals worry villagers.

Quest for independence

Denmark colonized Greenland more than 300 years ago, and it still retains some oversight of the island. Greenland won a degree of autonomy from Denmark in 1979 and near full self-government in 2009. Copenhagen still controls Greenland’s defense and foreign affairs, though, and the island relies on subsidies from Denmark to stay afloat.

For a majority of Greenlanders who long for complete independence, Trump’s idea struck a nerve. “Greenland is not for sale,” Greenland’s government wrote in a statement. Some Danish politicians described Trump’s apparent suggestion as having colonialist overtones.

Why does the United States care about Greenland?

A major landmass that straddles the Arctic and Atlantic oceans, Greenland has long been of interest to U.S. presidential administrations eager to counter rival superpowers.

The Pentagon built an air base there in 1951 for missile defense. American engagement in the region has grown recently as Russia and China have sought to expand their Arctic footholds.