One scenario, called “Blueprints,” painted a moderately hopeful vision of green energy and concerted action within the constraints of technological change, of a swiftly rising price on carbon emissions as the world comes together to remake its energy systems. In this vision of the future, there is active carbon trading. There is a strong global climate treaty. There is still far more warming than society can easily bear — approaching 7 degrees Fahrenheit — but the world still averts the very worst of climate change.

The second scenario, called “Scramble,” envisioned a future in which countries fail to do much of anything to reduce emissions, and instead race to secure oil and coal deposits. Only when climatic chaos breaks out does society take it seriously, and by then great damage has already been done. Drilling in the Arctic, thought to hold up to a quarter of the world’s untapped oil and gas, has a role in both scenarios — but under “Scramble,” it is irresistible.

In 2008, Shell surprised observers by announcing that it had a preferred scenario. The company would prepare for both outcomes, but for the good of the world and the good of Shell itself, it hoped for the carbon-constrained future of “Blueprints.” The oil giant awaited government action: a market signal in the form of a carbon price. But when I interviewed him four years later, Bentham admitted to me that the future, so far, was looking a lot more like the chaos of “Scramble.” We had no working international climate agreement and no real price on carbon. Instead, we had a global race for gas, coal and the last drops of conventional oil.

When I talked to Bentham, it was early December 2012. Three weeks later, on New Year’s Eve, Shell’s Arctic drill rig, the Kulluk, crashed into an island off the Alaskan coastline in a violent winter storm — a disaster I wrote about in this magazine. After the accident, political and economic circumstances seemed to turn decisively against Shell’s Arctic aspirations. The Obama administration began talking tough: “Shell screwed up,” said Ken Salazar, the interior secretary at the time. ConocoPhillips and Statoil, Shell’s rivals in the Alaskan Arctic, delayed their own offshore-drilling plans. Global oil prices soon dropped precipitously, making expensive plays in the high north even riskier.

Yet the drilling plan that the Obama administration approved on May 11 is not much different from the one that ran aground along with the Kulluk two and a half years ago. One of company’s drill ships will be the same as before: the Noble Discoverer, a 49-year-old converted log carrier that was previously at the center of eight felony pollution charges. Last month, the vessel failed another Coast Guard inspection in Hawaii. In place of the Kulluk, Shell will use a squarish, 319-foot-tall behemoth called the Polar Pioneer. This replacement rig flies the same Marshall Islands flag of convenience as the Kulluk and will be towed along the same general route to and from the Chukchi Sea from Seattle — a 2,000-mile voyage by tugboat. The Discoverer and the Pioneer will cross the same churning waters in the Gulf of Alaska. They’ll begin drilling in the same assuredly oil-rich patch of seabed in the Chukchi, some 70 miles from shore and a thousand miles from the nearest permanent Coast Guard base from which help could be dispatched if something goes wrong.