Putting the spill in proportion

I couldn't help wincing when Tony Hayward, the beleaguered BP boss, attempted to put the current Gulf leakage into proportion. Not because he was wrong (he wasn't) but because he has handed the green lobby a sizeable stick to beat him with.
"The Gulf of Mexico is a very big ocean" he said. "The volume of oil and dispersant we are putting into it is tiny in relation to the total water volume."
If anything, he was understating. Few of us realise that natural oil spills - from undersea vents - put more petroleum into the oceans than any human activity. The biggest human disaster in recent years was the Exxon Valdez spill off Alaska, which tipped 10.8 million gallons of oil into Prince William Sound. Sounds frightful; but natural seeps in the Gulf of Mexico dump twice that amount into the sea every year, and seabed sediments off California indicate that natural submarine leakage has produced the equivalent of eight 'Exxon Valdez' spills. The diagram below - from the US National Research Council-shows the actual sources of oceanic petroleum by metric tonnes.