Numerous sources assert Ixtoc I was the largest accidental oil spill in history, totalling 3 million barrels of oil, spilled at the rate of 10-30k per day before it was fully capped. The Gulf Oil spill is close to a repeat of how that disaster came about: a subsea blowout followed by a difficult to contain gusher.
Until May 20, BP and NOAA were asserting that the spill was 5000 barrels/day and that getting accurate estimates of the spill rate was impossible. Now, the response effort by capturing 5000 barrels/day through their siphon "fix" while oil continues to surge out of the broken riser, has proven that initial estimate to be farcically low. BP and NOAA are no longer standing behind that number and are being extremely cagey about what a more realistic number might be.
Outside experts, using video feeds and other estimation mechanisms have deduced that the spill rate is more likely 95,000 barrels/day. Oil spilling at that rate since the initial explosion, 31 days ago, would make the BP Gulf Oil spill the largest accidental spill in history…effective tomorrow.
While it would be very helpful to have direct and scientific measurements of the spill rate (and I find it implausible in the extreme that BP and NOAA are right that flow estimates are impossible), the 95,000 barrel/day estimate is the most credible estimate out there. Certainly more credible than anything NOAA and BP have claimed in the past, particularly now that their long-held and defended estimate has been proven wrong by events.
Effective tomorrow, BP’s Gulf oil spill will be the world’s largest accidental spill.