NASA's Aqua satellite captured this image of the Gulf of Mexico on April 25, 2010 using its Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. With the Mississippi Delta on the left, the silvery swirling oil slick from the April 20 explosion and subsequent sinking of the Deepwater Horizon drilling platform is highly visible. The rig was located roughly 50 miles southeast of the coast of Louisiana.
The oil leak triggered by a deadly rig blast off the coast of Louisiana has the potential to cause more environmental damage than the 1989 Exxon Valdez spill, one of the largest ecological disasters ever recorded, some observers say.
"It’s quite possible this will end up being worse than the Valdez in terms of environmental impact since it seems like BP will be unable to cap the spill for months. In terms of total quantity of oil released, it seems this will probably fall short of Exxon Valdez. But because of the habitat, the environmental impact will be worse."
"Probably the only thing comparable to this is the Kuwait fires [following the Gulf War in 1991]," Mike Miller, head of Canadian oil well fire-fighting company Safety Boss, told the BBC World Service.
"The Exxon Valdez is going to pale in comparison to this as it goes on."
The spill was triggered by an explosion last week off the Louisiana coast that sank an oil rig operated by BP. Eleven workers are missing and presumed dead.
So far the leak from a blown-out well 5,000 feet under the sea is not nearly as big as the Exxon Valdez disaster, which spilled about 11 million gallons of oil into Alaska's Prince William Sound 21 years ago. BP's well is spewing about 210,000 gallons of oil a day into the ocean, the Coast Guard estimates.
But if the leak is not capped, millions of gallons of oil could spill into the Gulf of Mexico. The environmental impact could be disastrous if the oil reaches the ecologically fragile U.S. coastline.
Potential for catastrophe
Adm. Thad Allen, commandant of the Coast Guard, which is directing efforts to contain the spreading spill, told The Miami Herald's editorial board Wednesday that if the well can't be capped quickly, the accident could potentially surpass the Exxon Valdez as the largest discharge in North American history.
"If we lose the integrity of that wellhead, it could be a catastrophic spill,'' Allen said.
Greenpeace's Hocevar said he's particularly concerned about the impact to critically endangered bluefin tuna. "It's their spawning season and bluefin larvae in this part of their life-cycle would be near the surface of water," Hocevar said.
The oil could also harm sea turtles, which are approaching nesting season; fin whales; menhaden, a fish species harvested mostly for fish meal and fish oil; bottom-feeding oysters; and numerous species of birds, Hocevar said.
Experts said the spill could also destroy the livelihood of commercial fishermen and shrimp catchers and impact recreational fishermen. According to the Louisiana Department of Wildlife and Fisheries, the state’s fishing industry is worth $265 billion at dockside and has a total economic impact of $2.3 trillion.
Tourism also could take a blow if beaches are fouled.
Already, a federal class-action lawsuit has been filed on behalf of two commercial shrimpers from Louisiana seeking at least $5 million in compensatory damages plus an unspecified amount of punitive damages against Transocean, BP and other companies linked to the rig blast.
Louisiana opened a special shrimp season along parts of the coast to allow shrimpers to harvest the profitable white shrimp before the spill reaches the area.
Which way the wind blows
Alaska's Exxon Valdez spill contaminated more than 1,200 miles of shoreline and killed hundreds of thousands of seabirds and marine animals. More than $2 billion has been spent on cleanup and recovery, and Exxon has paid at least $1 billion in damages.
Jeffrey Short, science director for the Oceana conservation group based in Juneau, Alaska, and a former chemist and environmental expert for the National Oceanic and Atmospheric Administration, told USA Today the latest spill is "basically déjà vu all over again."
"The time scale for the Exxon Valdez, having lived through it, it took days and weeks to unfold and for us to really realize the nature of it. We're still in early days here. So far the trajectory of events has been pretty foreseeable."
James Opaluch, a professor of natural-resource economics at the University of Rhode Island, has studied more than a dozen oil spills, including those of the Exxon Valdez. He said the severity of the environmental consequences of the gulf spill depends largely on how much oil reaches shore.
At this point, Opaluch told msnbc.com by e-mail, the most comparable spill is the Ixtoc I oil spill in 1979, caused by a blowout and subsequent fire from a drilling rig in Mexican waters of the Gulf of Mexico. By the time the well was brought under control in March 1980, an estimated 140 million galons of oil had spilled — more than 10 times larger than Exxon Valdez. Most of the oil stayed offshore for a long time, and at least some oil ventually come onshore on Texas beaches. "Damages from Ixtoc were relatively modest, certainly much less than Exxon Valdez as far as we can tell," Opaluch said.
"I think the most important issues for the present spill are, one, how long the spill continues for, therefore how much is spilled; two, whether the spill comes ashore, and three, if it does come ashore, where it comes ashore," he said.
"The best-case scenario is for all of the oil to go into the deep waters in the gulf. The worst-case scenario is for much of the oil to come ashore in wetlands. An intermediate case is if the oil comes ashore primarily on rocky shorelines or sandy beaches."
Hocevar said he's still hopeful officials will find a way to plug the well leak, but he said a lot of environmental damage has already been done.
"This is the real cost of oil," Hocevar said. "The gulf may be the one place where we are best prepared to deal with an oil spill. This is a stark reminder of what little you can do once a spill happens."