Excerpt from NRO:
One thing to remember about oil and the environment is that it does biodegrade. For a lot of bacteria, oil is just food. In this case, it was too much food. It’s kind of like eating salty potato chips — you can only eat so many salty potato chips at a time. Same thing with this
The whole purpose of dispersing the oil wasn’t to make the oil go away or hide it from the public or something like that. You disperse the oil because you make one big slab of oil that the bacteria can’t get to into billions and billions of tiny little drops of oil that the bacteria can easily get to, so you’re just increasing the surface area of the oil by creating millions of dots. And you’re breaking it up, literally, into bite-size chunks, billions and billions and billions of little bite-size chunks of oil so that then the bacteria can do their thing.
The other thing to remember is that bacterial activity doubles with every ten-degree change in temperature, so whatever level of bacterial activity you have at 50 degrees, you get twice as much at 60 degrees, and twice as much as that at 70 degrees, and twice as much as that at 80 degrees. So that’s why your refrigerator keeps your food from spoiling, keeps it down in the low 30s so it’ll last a lot longer than it will sitting in your house in the mid-70s.
The Gulf of Mexico is hot. That’s why it spurs hurricanes — the surface water temperature in the Gulf of Mexico is 80. The amount of bacterial activity you get there is enormous, so if you did what they did, which is disperse a whole lot of the oil in a warm-weather environment like that, it’s going to just magically disappear, in a short period of time, once you cut off the source.