Never before had anyone tried to carry out a chemistry experiment 3,600 metres under the sea. Scientists from the Monterey Bay Aquarium Research Institute in California sent their robotic submarine Ventana down to the depths of the Pacific Ocean. It gently dropped an open four litre glass beaker on the seafloor and dropped in liquid carbon dioxide until the flask was half full. The aim was to see whether it might be feasible to dump manmade CO2 - the greenhouse gas, chiefly responsible for global warming- at the bottom of the oceans.