Shipping's total greenhouse gas emissions rose about 10 percent between 2012 and 2018. This according to the IMO's fourth report on greenhouse gases, which was released earlier this month. Most striking were the increases in climate super pollutants, including a 150% increase in methane emissions

Methane is considered a "climate super pollutant" and traps 86 times more heat in the atmosphere than carbon dioxide over a 20-year period. The 150% growth in methane emissions from 2012 to 2018 was largely due to a surge in the number of ships fueled by liquefied natural gas (LNG), many of which have engines that allow unburned methane to escape into the atmosphere.
The researchers at ICCT (International Council on Clean Transportation) who led the work on the study highlight the need to include methane in future phases of the IMO’s Energy Efficiency Design Index (EEDI) regulations. Currently, only CO2 emissions are limited under the EEDI.

“We urge IMO to include all greenhouse gases, including methane, in the next phase of the EEDI to limit emissions from new LNG-fueled ships,” Bryan Comer, senior researcher at ICCT says in a press release.

Methane emissions may be a problem, but even worse is the report's forecast, which indicates that shipping, despite efficiency gains, will increase its emissions by another 50 percent by 2050 . The study highlights that much work lies ahead if the sector is to meet IMO’s goal of cutting GHG emissions from international shipping by at least 50% from 2008 levels by 2050.

“It’s notable that improvements in fuel efficiency have slowed since 2015, with annual improvements of only 1% to 2%,” says Dr. Dan Rutherford, ICCT’s marine program director. “Policies are needed to accelerate innovative fuel-efficiency technologies like wind-assist and hull air lubrication, along with new, low-emission and zero-emission fuels.”

The study is also the first in which the IMO measured emissions of black carbon, another "super pollutant" and type of soot that has a strong negative impact on the Arctic environment in particular and, by extension, the climate. Emissions of black carbon increased by 12 percent from 2012 to 2018.