The potential for disaster in oil spills lies in the volatility of petroleum. Crude oil is an ever-varying stew of hydrocarbon bonds that release huge amounts of energy when they’re broken. Some of these hydrocarbons are very light, like methane gas—just a single carbon molecule attached to three hydrogen molecules. Isooctane, an additive in gasoline, has eight carbon atoms surrounded by 18 of hydrogen in a formation that looks a bit like the original starship Enterprise. It’s very flammable and so light that it evaporates quickly when spilled. Benzenes, formed of complex rings of carbon and hydrogen, are heavier and frequently toxic. Other compounds are heavier still—waxes, for example, and asphaltenes.

Asphaltenes are partially to blame for the damage that an oil tanker called Prestige caused to hundreds of miles of coastline in northwestern Spain last November and the thousands of birds it killed. The tanker’s fuel oil was whipped into an emulsion by strong waves, much as mayonnaise is whipped by an electric mixer. “Asphaltenes like to have their legs in water and their bum in oil,” Buist says. “They line up at the oil-water interface and create a barrier that prevents the water droplets from banging together, coalescing, and settling out of the oil.”

Depending on the asphaltene content of the oil, the emulsion can be very stable—some have hung out on laboratory shelves for nine years, unchanged. The oil on the Prestige was a particularly heavy fuel oil, with an asphaltene content of 6.8 percent. As it emulsified, it quickly spread over 1,000 square miles of sea, floating to shore in sticky patties the size of sofa cushions. Worse, it multiplied in volume. When water mixes with oil, the amount of the goo can double or triple. In addition, the viscosity of the oil changes when it emulsifies. In the early days of the Prestige spill, the oil was as viscous as molasses, but later it was more like chewing gum. Shore cleanup crews had to resort to using buckets and shovels because the goop clogged the pipes and hoses that are normally used to vacuum up a spill.

For the people who clean up oil spills, the lessons are clear: The sooner you clean it up, the better. "There's a narrow window of opportunity," says John Parson, a supervisor on the North Slope Spill Response Team. Parson oversees a fleet of 92 boats, 211 skimmers, eight helitorches (flamethrowers mounted on helicopters), a gaggle of snowmobiles and airboats, and a bank of mobile command centers kept heated and ready. There are about 1,000 spills across the North Slope every year, ranging in size from a few buckets up to 250,000 gallons. Vacuums, skimmers, and absorbents can clean up only 10 to 20 percent of a large spill, so Parson has to resort to alternatives. In other areas, for instance, chemical dispersants are used to quickly break up an oil slick on water. Sprayed from planes or boats, dispersants reduce the surface tension at the oil-water interface, allowing waves to break the slick into tiny droplets. Dispersants can keep a spill from harming coastlines or wildlife, and they speed up biodegradation. Nevertheless, the oil stays in the water. Dagmar Schmidt Etkin, an analyst with Environmental Research Consulting in Cortlandt Manor, New York, compares the use of dispersants to chemotherapy. "People wish the cancer had never happened, and the chemo causes new problems. But you have to look at the net benefit."

Critics of burning say the technique just moves pollution from the water to the air. But the smoke is not much different from that of a wood-burning stove—a mixture of carbon dioxide and water, with about 10 percent particulate matter. Depending on the type of oil and the wind conditions, burns must be conducted up to six miles from populated areas; within an hour, the particles disperse. A 1999 spill off the coast of Oregon all but disappeared when the governor gave orders to burn it. An oil slick, by contrast, can take months or even years to be removed from a shoreline.

Containing the oil from the Prestige required a different sort of technology. A tiny three-person French submarine named Nautile descended more than 12,000 feet to the wreck, where it used robotic arms to close valves and seal cracks with steel plates and steel bells, which were then ballasted with sandbags. After 40 dives, the amount of oil escaping the ship fell from 125 tons to less than two tons a day. The spill has been reduced to a thin sheen above the wreck.

Back in Alaska, long after it gets dark and the temperature drops below zero, Buist continues to make spills and set them on fire, looking for patterns among the oils and the ice. The oil, which has weathered for two weeks, burns sluggishly among the ice chunks, its flames drowning in the waves. It dies out, then flares up wildly. Buist shakes his head. Then he heads off to weigh the oil left in the water, a measure of the burn's efficiency. "We're trying to peek into the situation and get an idea of what might happen," he says. "When we're done, we hope to establish some rules of thumb."