Shipping is key to the smooth running of the global economy. With about 50,000 merchant ships trading across the seas, the shipping industry is responsible "for the carriage of around 90 percent of world trade," according to the International Chamber of Shipping.
However, the industry's environmental impact is not insignificant. In 2012, international shipping was responsible for 796 million tonnes of CO2 emissions – around 2.2 percent of global emissions – according to the International Maritime Organization.
"Shipping impacts the world in many positive ways by enabling trade around the world," Mads Stensen, global sustainability manager at Maersk, told CNBC's Sustainable Energy.
"But despite… all the positive impacts, you also have negative impacts, especially environmental impacts," he added.