The scientists I spoke with cite four basic reasons the initial eco-fears seem overblown. First, the Deepwater Horizon oil, unlike the black glop from the Valdez, is comparatively light and degradable, which is why the slick in the Gulf is dissolving surprisingly rapidly now that the gusher has been capped. Second, the Gulf of Mexico, unlike Prince William Sound, is balmy at more than 85 degrees, which also helps bacteria break down oil. Third, heavy flows of Mississippi River water helped keep the oil away from the coast, where it can do much more damage. Finally, Mother Nature can be incredibly resilient.
But taking the long view, maybe not:
When Worm and colleagues combined the satellite data, the early shipboard records, and direct measurements of chlorophyll made from the 1950s onward, they found that the recent dip in phytoplankton wasn't a passing phase. It had been happening in most parts of the ocean for more than a century. On average, the planet has lost 1% of its phytoplankton every year since 1900, the team reports in the 29 July issue of Nature.
"You compound that over a century, this becomes a huge, huge decline," says Paul Falkowski, an oceanographer at Rutgers University in New Brunswick, New Jersey, who was not part of the study. Indeed, Worm's team estimates that phytoplankton numbers have plummeted 40% since 1950.
What's more, the team found that phytoplankton numbers were more likely to dwindle in areas of the ocean that were warming, suggesting that climate change is responsible for the drop.
Actual paper here. This is one of the feedback loops that has some of us deeply worried that the cost of climate change may be far worse than we now imagine: