What are the environmental consequences of the Deepwater Horizon oil spill?

On April 20, 2010, a mixture of mud, seawater, and gas from methane hydrates erupted from the oil well of the Deepwater Horizon rig. The rig was a semisubmersible platform designed to search for oil deposits. After discovering oil, the workers on the rig sealed the newly-drilled well in preparation to move forward in the search for more oil.

The oil rig was located over 5,000 feet (1,524 meters) beneath the surface of the Gulf of Mexico, with the well itself extending even deeper — over 13,000 feet (3,962 meters). The workers on the rig and the involved companies — BP, Transocean, and Halliburton — indicated disagreements regarding the capping process. Typically, at least two cement plugs would be placed and hardened within the piping before removing the drilling mud from the wellbore. The mud serves to prevent sudden surges of gas and oil.

In the end, engineers opted to remove the mud before applying a second cement plug. A surge of gas shot up the pipe, resulting in a catastrophic explosion that claimed the lives of 11 workers. Oil began spilling from the well in vast amounts — estimates suggest that between 12,000 and 60,000 barrels of oil leaked into the Gulf of Mexico daily. One barrel of oil equals 42 gallons (159 liters).

A BP report disclosed that in the worst case, the oil well could release up to 100,000 barrels of oil into the ocean every day. Two months after the initial explosion, oil continues to spill into the Gulf of Mexico. While oil recovery efforts have managed to reduce the flow, they have not stopped the oil from reaching the environment.

What is the environmental effect? It's hard to say. Since the oil spill occurred in deep waters far from shore, the impact differs from the Exxon Valdez disaster that occurred years ago. Some of the oil congeals into tar balls, which can wash up on beaches and harm local wildlife. Meanwhile, plumes of oil are drifting thousands of feet below the ocean's surface, and the full extent of the damage to deep-sea ecosystems remains unclear. Complex ecosystems could be wiped out by the influx of oil.

State and federal governments are investing millions of dollars in an attempt to control the oil spill while engineers search for a solution to stop it. BP abandoned an effort to seal the oil well with mud — a procedure called top kill — after engineers became concerned about the well bore's integrity. If the well bore has any leaks, oil could continue to spill even if the top is sealed.

Engineers predict that a permanent solution may not be in place until August, four months after the initial explosion. With no final fix in sight, the focus has shifted to capturing as much oil as possible before it spreads further. According to Admiral Thad W. Allen of the U.S. Coast Guard, the objective is to set up systems that can siphon off 60,000 to 80,000 barrels of oil daily.

It could take years or even decades to fully assess the environmental damage caused by the Deepwater Horizon disaster. While efforts are underway to minimize the effects, it's evident that accurately predicting the long-term harm to the environment remains impossible at this stage.