Even the most potentially disturbing suggestion, which involves fertilising the oceans with iron in order to promote the growth of planktonic algae (in the hope that they would sink to the seabed, taking their carbon with them), can be covered by the London Convention on marine pollution, which regulates dumping at sea, and has already addressed itself to research in the area.

ECONOMIST: Geoengineering

The charities have urged members of the public to sign petitions by Avaaz and 38 Degrees to support their call for a ban of dumping chemicals at sea.

BBC: PIB chemical pollution kills more birds than MSC Napoli

It follows EU legislation to protect the marine environment which bans the dumping of waste at sea.

BBC: Dundrennan weapon test legality questioned

The colonel alleged to have organised the dumping of refugees at sea is also accused of overseeing an atrocity against Muslims in Thailand's strife-torn southern provinces in 2004.

ECONOMIST: Thailand