Shipping emissions in ports are substantial, accounting for 18 million tonnes of CO2 emissions, 0.4 million tonnes of NOx, 0.2 million of SOx and 0.03 million tonnes of PM10 in 2011, according to an International Transport Forum's report. Around 85 percent of emissions come from containerships and tankers. Containerships have short port stays, but high emissions during these stays.

New York-based Natural Resources Defense Council has released a report on air pollution in China citing shipping as a major contributor and recommending the introduction of emission control areas.

As Ebola persists in West Africa, shipping lines and traders are tweaking their contracts to protect themselves if the disease puts crews at risk of infection or prevents vessels calling at affected ports.

Despite high hopes for Arctic business from mining to shipping as the ice melts rapidly and temperatures rise twice as fast as the global average, few firms say the sums still make sense.