Because some ships may be less carbon intensive than others, customers can influence emissions

"If the shipping industry were a country, it would be the sixth-biggest industrial carbon emitter in the world. Whereas big countries have plans for cutting emissions, shipping does not. The UN climate talks in Cancún are unlikely to change that. But customers, who indirectly pay for shipping fuel, might be better placed to put pressure on the industry.

To help them, a 'do tank' (yes, really) called the Carbon War Room has set up a website designed to rate ships as if they were refrigerators or boilers. Shippingefficiency.org uses data from IHS Fairplay, a vessel registry, to calculate how fuel-efficient each ship was at the time it was built. The energy implications are converted into letter grades, from squeaky-clean A to dirty G.

The idea is that cost-, environment- or publicity-conscious companies could choose to use only those ships with the best grades. Ports could charge more efficient ships less for their services. Island nations sensitive to climate issues could choose the least carbon dioxide-intensive shipping lines. Kevin Conrad, Papua New Guinea's special envoy on climate change, says his country may consider such a step.

The War Room says it will provide data on 60,000 vessels, giving their owners a new basis on which to compete. If the idea catches on, consumers will be able to shun ships that emit a lot and reward the ones that don't."

From The Economist: http://www.economist.com/node/17676040?story_id=17676040.

The Carbon War Room can be found at http://www.carbonwarroom.com/.

The report on shipping noted in the article can be found at http://www.carbonwarroom.com/shipping-register.