UPDATED: The World’s Worst Oil Spills

I've been thinking a lot lately about oil spills. At the beginning of the month, a Chinese freighter ran aground on the Great Barrier Reef off the coast of Australia, grinding a couple miles coral into dust and leaking oil along the way. A couple of weeks ago came news of a new study showing that oil left behind by the Exxon Valdez disaster 17 years ago can still be found buried in the silt and sand of the intertidal zone, prime feeding territory for a host of wildlife, including sea otters and ducks. Then, last week, an explosion destroyed an oil rig in the Gulf of Mexico and killed 11 workers. The oil pouring from the drill hole—42,000 210,000 gallons per day—has created a slick half the size of Indiana and endangers coastlines from Florida to Louisiana.

The oil company BP has sent robots to plug up the hole—it's too deep to send divers—but it could be months before the leak stops. At its current rate, the hole would have to spew oil for about 292 58 days to surpass the Exxon Valdez disaster as the largest oil spill in U.S. history. But the Exxon Valdez spill wasn't all that big in historical terms; it's only 34th or 35th on the list of the worst spills of all time globally. The current Gulf spill would have to flow for 2,143 429 days to make the top three:

3) July 19, 1979: Two oil tankers, the Atlantic Empress and the Aegean Captain, collided off the coast of Trinidad and Tobago in the Caribbean. The Aegean Captain managed to contain the damage and was towed to port, though it spilled a small amount of oil along the way. The Atlantic Empress, however, was towed out to sea in flames, spilling its oil until it sank on August 3. An estimated 90 million gallons of oil were released into the ocean as a result of the collision.

2) June 3, 1979: The Ixtoc I exploratory oil well off the coast of Mexico in the Gulf blew out and began to leak. When the oil ignited, the platform above collapsed. Attempts to seal the well were unsuccessful until March 23, 1980. A total of 140 million gallons of oil—at a rate of 42,000 to 126,000 gallons per day—was dispersed into the Gulf of Mexico.

1) January 19, 1991: As Iraqi troops left Kuwait, they opened the taps on an offshore oil terminal and several oil tankers, spilling some 380 to 520 million gallons of oil into the Persian Gulf. They created an oil slick 4,000 square miles in size and 4 inches thick. Despite the slick's record size, a UNESCO report found little lasting environmental damage.

Note: This post was updated on Thursday, April 29 following news that the oil leak was five times worse than originally thought.

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Sarah Zielinski is an award-winning science writer and editor. She is a contributing writer in science for Smithsonian.com and blogs at Wild Things, which appears on Science News.