Living with the knowledge that we will die in the future is thought to be a burden of the human species alone. But living with signs that life systems on the planet we inhabit may be on the brink can be overwhelming.

Yet Charles Darwin saw that species that are quick enough at picking up signals and using them to switch to a better adapted behaviour are most likely to survive changes.

The earth is changing, and on a historical scale it is changing fast. Our unease at this knowledge may be reflected in our taking refuge in a diverse range of entertainment. Much of our interaction now takes place in that hazy realm of cyberspace. For some, the physical world may even begin to take on a dreamlike quality.

How unreal it seemed as we watched an online underwater video of oil gushing into the sea at the Deepwater Horizon explosion site in the Gulf of Mexico last April.

A recent hearing found that the rig's general blow-out alarm had been manually switched off. The event has been described as an ecological holocaust on the scale of Bhopal and Chernobyl.

Being ocean-based rather than on land, the long-term effects are likely to be more widespread. The sea's entire food chain could suffer years of devastation, with almost no marine life in the region escaping its effects.

To give an idea of the size of the disaster, a clean-up force of 37,000 people was deployed, with 6,200 vessels involved in the operation using 788 kilometres of containment booms and 1.5 million gallons of chemical dispersant.

It is impossible to clean up an oil spill. Any corporate attempts to claim otherwise have been debunked by Greenpeace (sea link below). An unprecedented amount of dispersant was sprayed on Louisiana shorelines and poured into the ocean with the aim of breaking the oil into small globules.

The solvents used are produced by Nalco Holding Company, which is associated with BP and Exxon.

Corexit, one of the products used in the clean-up, is banned in the UK since it contains arsenic, cadmium, cyanide, and mercury. It is considered by the US environment protection agency (EPA) to be an acute health hazard, potentially harmful to red blood cells, kidneys and liver and may irritate eyes and skin. The more dangerous solvents can cause rupture of blood cells and internal bleeding in fish and humans.

A month into the disaster, the EPA forced BP to switch to a less toxic version of solvent. On May 20, it ordered BP to look for less toxic alternatives to Corexit, and later ordered the oil company to stop spraying dispersants. However, BP argued that Corexit was the best alternative, and continued spraying it.

A difficult choice was made by the agency when it decided to give the green light to underwater dispersants. The agency admits that dispersants are no silver bullet. Their use underwater was only chosen as "the lesser of two environmental outcomes".

A directive issued by the EPA restricted surface use to minimal amounts and only as a as a last resort. Cautioned to keep within the limits for dispersants, BP took the final word from the US coast guard.

Even more harmful than the dispersants is the highly toxic oil which takes longer to biodegrade. The underwater application of solvents was described as an important step to reduce the potential for damage from oil reaching fragile wetlands and coastal areas. EPA allowed BP to use up to 15,000 gallons of undersea dispersant daily.

Solvents spread the oil in three directions, including downward, keeping much of the spilled oil submerged. The problem is that the oil may remain suspended, forming underwater plumes instead of rising to the surface.

Underwater clouds, toxic to marine life, are being monitored by NOAA, the US federal agency for oceans and the atmosphere. If these plumes enter Gulf eddies, the loop current could carry them to Florida.

At least two submerged clouds of noxious oil and chemical dispersants have been confirmed by research vessels, and scientists are seeing signs of several more. The largest is 22 miles long by six miles wide and over 3,000 feet deep.

To add to the effect of the solvents, the weight of the crude oil and water pressure at extreme depth is keeping much of the leaked oil below the surface. If it does eventually rise to the surface, shorelines could see a second wave of destruction. It may take years before the true toll of the BP disaster is known.

Solvent breaks oil into smaller droplets which may harm fish if consumed. Predators such as tuna, which eat smaller fish with the toxin in their systems, may end up with much higher levels in their flesh.

There is concern that the quantities of solvent used in the Gulf will create unprecedented underwater damage to organisms. Keeping the oil underwater and away from the shore may help animals at the surface but it is more toxic to marine life.

Clouds of crude and chemical dispersants have formed in the Gulf of Mexico, and oceanologists fear these could have devastating effects on the food chain.

What happens next to these underwater clouds - or plumes - depends largely on the currents. If they do eventually rise to the surface, they may end up on the shoreline months or years from now, causing a second wave of destruction.

www.greenpeace.org/international/en/multimedia/videos/ScamWow

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