Quotes of the Day

Carl Safina headed down to the Gulf Coast just days after the Deepwater Horizon rig exploded on April 20, 2010. A veteran of the Exxon Valdez spill — and the head of the Blue Ocean Institute, a nonprofit that focuses on marine health — Safina wanted to see the Gulf oil spill up close, to document something he was sure would be an environmental catastrophe. Researching what would become the book A Sea in Flames — which goes on sale April 19 — Safina spent time with Gulf fishermen and ecologists, toured oiled beaches and spoke to people involved in the cleanup. As long as the oil kept spilling, just about everyone had the same opinion: the spill would be truly catastrophic for the Gulf and its coast. "We didn't know how it would stop or when it would stop," says Safina. "Gulf fishermen who'd invested their lives in the industry were convinced they'd never fish again."

Yet nearly a year after the spill began, it seems clear that the worst-case scenario never came true. It's not that the oil spill had no lasting effects — far from it — but the ecological doomsday many predicted clearly hasn't taken place. There is recovery where once there was only fear. "A lot of questions remain, but where we are now is ahead of where people thought we'd be," Safina says. "Most people expected it would be much worse."

As we approach the anniversary of the spill, Safina's judgment is becoming the accepted wisdom: it could have been worse. That isn't to minimize what did happen in the Gulf of Mexico. Roughly 4.9 million barrels of oil blew out of BP's broken well and bled into the water, with a portion of that crude making landfall along the coastline. Add in the unknown effect of 1.84 million gallons (7 million L) of chemical dispersants, much of which were applied directly to the well deep below the surface of the ocean — something that had never been done before. Even the cleanup might have had an impact on the environment, thanks to the burning of oil on the surface of the Gulf, and the tens of thousands of workers who trampled along the sensitive wetlands of Louisiana, corralling crude wherever they could. Scientists caution that a single year isn't long enough to draw any final conclusions about an environmental insult so huge.

Yet the damage does seem so far to have been less than feared. Take the oil itself: scientists with the National Oceanic and Atmospheric Administration estimated last August that much of the oil had remained in the Gulf, where it had dispersed or dissolved. Many environmentalists attacked the report for underplaying the threat of large underwater oil plumes still active in the Gulf, yet later independent scientific studies indeed found that oil had largely disappeared from the water. Turns out we can thank bacteria. Scientists from Lawrence Berkeley National Laboratory; University of California, Santa Barbara; and Texas A&M University traveled to the site of the blown well and found that microbes had digested much of the oil and methane that remained in the water. By autumn, the levels were back to normal. "It's very surprising it happened so fast," John Kessler, an oceanographer with Texas A&M, told me earlier this year. "It looks like natural systems can handle an event like this somewhat on their own."

Indeed, for all the work and the billions poured into the cleanup, nature itself — and luck — played a very big role. Fortunate ocean currents kept some of the oil from ever reaching shore, while the decision to increase the flow of the Mississippi River provided an additional pushback. As a result, while parts of the southern Louisiana coast were hit hard by the oil — and crude can still be seen in the marshes — much of the Gulf Coast was spared heavy oiling, and the spill never curled around Florida as forecasters feared in the early days. Around 8,000 birds were identified as killed by the spill, though researchers suggest that at least eight times as many likely died but were never found. Even so, that would be far less than the 250,000 birds estimated killed in the aftermath of the Valdez spill, even though that spill was far smaller. Local conditions mattered — the Valdez spill occurred in the relatively compact Prince William Sound, maximizing the impact on birds in the area, while the BP spill spread out over some 1,600 miles (2,580 km) of the Gulf Coast.

The Gulf's valuable fisheries also seem to have escaped the worst damage. John W. Tunnell Jr., the associate director of the Harte Research Institute at Texas A&M, estimated in a report that the region's shrimp fisheries would rebound to normal within two years, while blue-crab populations would be back to normal this year and commercial fish species such as red snapper and grouper largely escaped any negative impact. (Oyster beds, hit hard by the oil, might take up to a decade to recover, however.) It's possible that the lengthy moratorium on fishing in much of the Gulf during the worst days of the spill — when up to 84,000 sq. mi. (217,600 sq km) were off limits — may have even given some fish species a much needed break from exploitation, allowing them to recover in population.

Nonetheless, 1,000 sq. mi. (2,600 sq km) of water over the original Deepwater Horizon site are still off-limits, and we won't really know how quickly fishing will rebound until boats are back in the water in large numbers, reporting back to scientists. (The herring fishery in Alaska's Prince William Sound seemed fine after the Valdez spill, only to collapse three years later.) The already overfished bluefin tuna saw some of its spawning areas in the Gulf hit by the oil and dispersants, though it looks like the fish managed to weather the worst of the accident. In recent weeks marine biologists have found unusually high numbers of dead dolphins washing up on the Gulf Coast — the fate, some scientists suspect, of many of the species' young born during the spill. And Samantha Joye, a marine scientist at the University of Georgia in Athens, found evidence of dead invertebrates — starfish and even coral — on the bottom of the Gulf, along with oily, sticky bacteria. "These are keystone species to the ecosystem," Joye said at the meeting of the American Association for the Advancement of Science in February.

Indeed, that's the challenge for any scientists trying to tally up the ecological cost of the oil spill. We simply don't know enough about what has happened — and what may happen in the years and decades to come. "The Gulf spill is far from over," says Doug Inkley, senior scientist with the National Wildlife Federation. A year has passed, but we may only be at the beginning.

• Bryan Walsh
• The Gulf oil spill wasn't as bad as many environmentalists feared, but the ultimate outcome is still far from certain