United Nations negotiators are in London this week for the International Maritime Organisation (IMO) meeting where they will discuss ways to cut back on pollution coming from the global shipping sector.

Shipping isn't going anywhere in the foreseeable future.  As much as 80 percent of the world's goods by volume are transported by ship, which produces 3 percent of the world's greenhouse gas emissions - about the same as the nation of Germany.

But a new report from campaign groups Seas at Risk and Transport & Environment says that simply slowing down the freighters would make a significant contribution to curbing greenhouse gases.  A 20 percent reduction in the average speed of all freighters would cut greenhouse gases, as well as pollutants such as black carbon and nitrogen oxides that harm human health.  

The seas would be quieter and safer as well.  Slowing down the freighters would cut underwater noise by 66 percent and reduce the chances of whale collisions by 78 percent.

"It's a massive win, win, win, win," said John Maggs from Seas at Risk.  "We've got a win from a climate point of view, we've got a win from a human health point of view, we've got a win for marine nature, we've got a potential safety gain, and up to a certain point we are saving the shipping industry money.

"It is also of course by far the simplest of the regulatory options," Maggs continued.  "Thanks to satellites and transponders on commercial vessels it really is quite easy to track their movements and the speed they are travelling."

Some shipping companies favor speed limits, because it will reduce fuel costs and can be implemented immediately - others, like the giant Maersk, oppose it.