Shell’s oil spill in the North Sea this week is the worst in a decade, but compensation for any environmental damage could be in short supply says Susie Wilks from ClientEarth

What is the difference between a sea bird dying because its feathers are coated in crude oil, and a sea bird starving to death because its food source has been destroyed by chemical dispersants used to break up an oil slick? To the bird, not a lot. To a conservation organisation or local authority trying to recover the costs of restoring ecosystems and animal populations, the difference could be everything.

The WeatherBird II is not a pretty ship. A boxy, businesslike, 194-ton vessel, it prowls the waters off St Petersburg, Fla. where it competes for attention with the cruise ships and sport yachts and other glamour boats. But the WeatherBird II was the buzz of the Gulf on Friday, after its alarming findings about the extent of the BP oil spill that's spreading invisibly below the surface.