This month started with big news from oil company BP, which said it found an oil field deep below the Gulf of Mexico that may hold three billion barrels of oil. That’s a lot of oil–pull all of it out of the ground and it meets nearly three years of global oil needs. Realistically, though, much less than that is likely recoverable, perhaps as little as 10% or as much as 50%. We won’t know until BP tries. The find is significant given the fact that for many years the Gulf was considered barren of truly large oil fields,...