THE FULL impact of global warming has been curbed by the emissions from ship's smokestacks, according to researchers in Pennsylvania. Sulphur from burning marine fuel has been seeding clouds over the open ocean, which then reflect sunlight back into space rather than allowing it to heat the planet.
Oceanographers have recently spotted linear clouds on satellite pictures marking out the tracks of ships across the oceans. The clouds are made of water vapour like aircraft vapour trails, but they are much lower in the atmosphere and last for days instead of hours. Marine fuel is rich in sulphur and produces sulphur dioxide and sulphate particles when it burns. Cloud droplets condense around these particles.
"Everybody assumed this was not an important process," says Spyros Pandis of Carnegie Mellon University in Pittsburgh. Previous models of climate change incorporated the sulphur from burning marine fuel, but assumed that it was released at ...
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