So now we know.

Following release of the US government's latest estimate, the Deepwater Horizon disaster is confirmed as the biggest ever accidental release of oil into the oceans.

US Oil Spill

* Biggest ever, but how bad?
* Timeline: BP oil spill
* Controlling a robot claw
* Oil dispersant 'not more toxic'

It exceeds the 1979 Ixtoc I leak - also in the Gulf of Mexico. It's comfortably bigger than tanker releases such as the Torrey Canyon and Amoco Cadiz, and 20 times the size of the 1989 Exxon Valdez spill with which it is often compared.

Now that BP finally appears to have the flow under control, an important question - perhaps the most important of all - is being asked: it may have been the biggest, but was it the worst?

It is a simple-sounding question, but devilishly hard to answer.

What impacts are we talking about - on the coast, on the ocean surface, or the sea floor?

Which species are we including - fish, shrimp, insects, plants, birds, whales, turtles - or some combination of them all?

Are we looking long-term or short-term, local or regional - and are we to include or exclude impacts from the use of chemical dispersants and fires and the other containment measures?

One thing that is clear is that different parts of the Gulf coast have seen very different levels of impact.
Damaged grasses Grasses in the wetland regions show damage - but they may recover

Two weeks ago, the National Oceanic and Atmospheric Administration (Noaa) announced that so little oil was being seen in a zone covering more than 26,000 square miles (67,000 sq km) - a quarter of US territorial waters in the Gulf - that fishing could safely re-start.

Yet in other areas, particularly along the coast, people are struggling daily to nurse oil-soaked birds back to health.

Many commentators were saying during the early days of the episode that the ecological impacts would depend largely on the vagaries of winds and tides; and so it has proven.

Noaa has said that about three-quarters of the 4.9 million barrels leaked into the Gulf waters has already vanished from the area - through evaporation, capture, burning, or dispersion.

But that still leaves more than a million barrels at sea.

As a formerly significant US figure said in the context of a different Gulf: there are known unknowns, and unknown unknowns.
Danger zone
Continue reading the main story
“Start Quote

Once it makes to it to shore it is causing an impact on our most sensitve ecosystem that is extremely difficult to clean up”

End Quote Paul Anastas EPA

Andy Nyman, an associate professor of Wetland Wildlife Ecology at Louisiana State University in Baton Rouge, has spent years conducting laboratory and field research into the possible impacts of oil spills on the coastal wetlands that are so vital as nurseries for fish and shrimp, nesting grounds for birds and as coastal defences.

"It's going to be difficult to pick up the impacts of the oil spill and separate those from natural seasonal variability," he says.

"Impacts we'll be looking for in the short term include the loss of wetland grasses and reductions in fish and other things that live in the water.

"In the longer term we could see reduced productivity in these populations, but we may not be able to detect it because the annual variations are quite large."

He relates taking two trips along the coastal fringe in recent weeks.

In one zone, they could see virtually no impact on the grasses. In the other, a stretch of coast about 10km (six miles) long showed significant damage, with swathes of grass brown and shedding leaves.

Yet on many plants, new green stems were sprouting - just as happened on the grasses in Professor Nyman's experimental plot after he had coated them in oil to see how they would perform.

It looks like to me at least, that the US government has had a 32 billion dollar Windfall at the expense of BP. I just bet the accounting for the money is very poor as usual. Look at the Irag aid accounting..8 Billion dollars never to be seen again.