Oil Spill Not That Bad

New Scientist: Gulf leak: biggest spill may not be biggest disaster.

THE Deepwater Horizon blowout is the largest oil spill in US history, but its ecological impact need not be the worst. It all hinges on the amount and composition of the oil that reaches the Gulf of Mexico's most sensitive habitat: its coastal marshes. If they can be protected, the region could bounce back in just a few years.

As New Scientist went to press, estimates of the volume of crude so far ejected into the waters of the Gulf ranged from 90 to 195 million litres - dwarfing the Exxon Valdez's 40-million-litre spill in 1989. But the aftermath of previous spills shows that it is not the volume that matters most.

"Very large spills have had minimal impact and small spills have had a devastating impact," says Judy McDowell of the Woods Hole Oceanographic Institution on Cape Cod, Massachusetts, one of the authors of a 2003 National Research Council report that reviewed lessons from previous incidents. ...

In 1979, the Ixtoc I well off Mexico's Gulf coast spewed 530 million litres of oil into shallow waters - three times the worst current estimates for Deepwater Horizon. Five years later, "we had to look hard to see any lasting effects", says Arne Jarnelöv of the Institute for Futures Studies in Stockholm, Sweden, who led a UN team sent to monitor the area.