"How to Think About Oil Spills"

Stephen Hayward gathers relevant facts:

Over the last 50 years, offshore drilling spills, including the Deepwater Horizon, have unleashed a little more than 1 million tons of oil; tanker accidents have spilled 4 million. For every offshore drilling spill, there have been seven tanker spills, many much larger than the Exxon Valdez, only the 40th largest tanker spill on record.

He writes without hysteria and points to relevant studies

The ecological effects of the Ixtoc 1 disaster should be borne in mind when we hear claims that the Deepwater spill will inflict large and long-lasting effects. According to a 1981 study by the Royal Swedish Academy of Sciences, about half of the Ixtoc 1 oil evaporated, and another 25 percent sank to the bottom of the ocean, much of it broken up by wave action and chemical dispersants.

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A recent study of seven basic ecosystem types, and their most typical perturbations, found that of ecosystems that make a recovery from various catastrophic events (and, it must be noted, not all do), ocean ecosystems disrupted by oil spills were the fastest to recover, often within a span of one to four years.

He speculates reasonably:

While we still don’t know the precise cause of the failure of the blowout preventer on the Deepwater Horizon (a technology that has successfully prevented spills in more than 150 offshore drilling accidents over the last 40 years), early accounts suggest that the same factors that cause most airplane crashes came into play: complacency and sloppy maintenance.

And he comes to sensible conclusions:

As some environmentalists have come to regret, the limitation of nuclear power after 1979 resulted in the expansion of coal-fired electricity instead, but coal is now environmental enemy number one because of its high greenhouse gas emissions. A halt to offshore drilling now would be equally ill-advised.
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In short, there is considerable risk that overreaction to the BP/Deepwater spill will have second-order environmental impacts that could be cumulatively worse than the spill itself, both for the Gulf and for other environmental arenas.