Book excerpt: It so happens that ever since childhood I have been in love with ocean currents, in love with those rivers hidden in the water.' As a child in Brehat, an island off the coast of Brittany, Erik Orsenna was told to give thanks for the Gulf Stream, the Atlantic Ocean current that brings warmth to the waters of Europe and gives us our relatively benign climate. It is his passion and concern for the Gulf Stream that is the motivation behind this book, in which he asks 'Wat is the Gulf Stream?', 'Where does it begin and end?', and 'Will global warming stop its flow?'