Approximately 190 miles off the coast of Newfoundland in what locals call “Iceberg Alley” sits the Hibernia oil platform, the world’s largest offshore drilling facility. Built at a cost of some $5 billion, Hibernia consists of a 37,000-ton “topsides” facility mounted on a 600,000-ton steel-and-concrete gravity base structure (GBS) resting on the ocean floor, some 260 feet below the surface. This mammoth facility, normally manned by 185 crew members, produces about 135,000 barrels of oil per day. Four companies (ExxonMobil, Chevron, Murphy Oil and Statoil) plus the government of Canada participate in the joint venture established to operate the platform.

The Hibernia platform is reinforced to withstand a direct impact by one of the icebergs that regularly sail through this stretch of water, located just a few hundred miles from where the Titanic infamously hit an iceberg and sank in 1912. Sixteen giant steel ribs protrude from the GBS, positioned in such a way as to absorb the blow of an iceberg and distribute it over the entire structure. However, the GBS itself is hollow, and contains a storage container for 1.3 million barrels of crude oil—about five times the amount released in the 1989 Exxon Valdez spill.

The owners of the Hibernia platform insist that the design will withstand a blow from even the largest iceberg. As global warming advances and the Greenland glaciers melt, however, massive chunks of ice will be sent floating into the North Atlantic on a path past Hibernia. Add increased storm activity (another effect of global warming) to an increase in iceberg frequency and you have a formula for overwhelming the Hibernia’s defenses.

Here’s the scenario: It’s the stormy winter of 2018, not an uncommon situation in the North Atlantic at that time of year. Winds exceed 80 miles per hour, visibility is zilch, and iceberg-spotter planes are grounded. Towering waves rise to heights of 50 feet or more, leaving harbor-bound the giant tugs the Hibernia’s owners use to nudge icebergs from the platform’s path. Evacuation of the crew by ship or helicopter is impossible.

Without warning, a gigantic, storm-propelled iceberg strikes the Hibernia, rupturing the GBS and spilling more than one million barrels of oil into rough waters. The topside facility is severed from the base structure and plunges into the ocean, killing all 185 crew members. Every connection to the undersea wells is ruptured, and 135,000 barrels of oil start flowing into the Atlantic every day (approximately twice the amount now coming from the BP leak in the Gulf of Mexico). The area is impossible to reach by plane or ship in the constant bad weather, meaning emergency repairs can’t be undertaken for weeks—not until at least five million additional barrels of oil have poured into the ocean. As a result, one of the world’s most prolific fishing grounds—the Grand Banks off Nova Scotia, New Brunswick and Cape Cod—is thoroughly poisoned.

Does this sound extreme? Think again. On Feb. 15, 1982, a giant drillship, the Ocean Ranger (the “Ocean Danger” to its habitués), was operating in the very spot Hibernia now occupies when it was struck by 50-foot waves in a storm and sank, taking the lives of 84 crew members. Because no drilling was under way at the time, there were no environmental consequences, but the loss of the Ocean Ranger—a vessel very much like the Deepwater Horizon— should be a reminder of just how vulnerable otherwise strong structures can be to the North Atlantic’s winter fury.