It's going to take a really long time before the worst of this oil disaster passes - and we don't even know yet what this year's hurricane season will do:

Twenty-three years earlier, in 1979, an oil well named Ixtoc I had a blowout in 150 feet of water in the southern Gulf of Mexico. The Mexican national oil company Pemex tried to kill the well with drilling mud, and then with steel and lead balls dropped into the wellbore. It tried to contain the oil with a cap nicknamed The Sombrero. Finally, after 290 days, a relief well plugged the hole with cement and the spill came to an end -- but only after polluting the gulf with 138 million gallons of crude.

That remains the worst accidental oil spill in history -- but the Deepwater Horizon blowout off the Louisiana coast is rapidly gaining on it.

The spill has now been partially contained with the cap that BP engineers lowered onto the mile-deep geyser Thursday night. That means roughly a quarter to half of the flow is being piped to a surface ship, the national incident commander, Coast Guard Adm. Thad Allen, said Saturday. BP hopes to improve the rate captured in coming days. If official government estimates are correct, 23 million to 47 million gallons of oil have spewed so far.

Ecosystems can survive and eventually recover from very large oil spills, even ones that are Ixtoc-sized. In most spills, the volatile compounds evaporate. The sun breaks down others. Some compounds are dissolved in water. Microbes consume the simpler, "straight chain" hydrocarbons -- and the warmer it is, the more they eat. The gulf spill has climate in its favor. Scientists agree: Horrible as the spill may be, it's not going to turn the Gulf of Mexico into another Dead Sea.

But neither is this ecological crisis going to be over anytime soon. The spill will have ripple effects far into the future, scientists warn.

"This spill will be lasting for years if not decades," said Doug Inkley, senior scientist at the National Wildlife Federation.