(CNN) -- The blowout is stopped. The oil disaster that began with an explosion 100 days ago has not ended by any means. But we seem to be seeing a murky ending to the beginning of the crisis. We have an enormous amount of floating oil, and Gulf waters polluted by oil and dispersant. Most estimates range from 2 million to 4 million barrels (84 million to 168 million gallons). The higher end would make it the largest unintended release of oil ever. (In 1991, Saddam Hussein's army intentionally released about 400 to 500 million gallons into the Persian Gulf to slow American troops.) Added to the Gulf of Mexico's troubles: about 2 million gallons of dispersant, a major intentional pollution event in itself.
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Carl Safina says precise size of oil disaster and impact on wildlife is not known
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He says impact on people is clearer -- since many lost their livelihood
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Safina says accident was avoidable if proper safeguards had been in place
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Decades of government deregulation helped lead to disaster, he says
Migrants include millions of shorebirds, ducks and geese; herons and egrets; gannets, loons, terns, skimmers and other seabirds; peregrine falcons, ospreys and @placeholder-crossing songbirds that often land exhausted on beaches and marshes.