New Study: Greenhouse Gas Emissions are Rising as Vessel Traffic Grows

Commercial fishing is an energy-intensive business, and not just for the fishers hauling in the catch. Fishing vessels burn a lot of fuel. In fact, according to Naya Olmer, Marine Program Associate at the International Council on Clean Transportation, industrial-sized commercial fishing vessels are responsible for more than 4 percent of the greenhouse gas emissions released from all commercial vessels involved in transporting goods on the ocean.

Olmer is the lead author of a new study released today week that presents a global inventory of greenhouse gas emissions from the shipping trade. She and her team used data from Global Fishing Watch, IHS, and AIS satellite data to look at emissions from vessels that operate around the world—from tankers, bulk carriers and general cargo ships to tugboats, ferries and fishing vessels—from 2013 and 2015. They found that, despite improvements in operational fuel efficiency, increases in fuel consumption are outpacing the gains, and CO2 emissions from the shipping sector increased from 910 to 932 million tonnes between 2013 and 2015.

“These findings are important, because they suggest that improvements in operational efficiency alone are not enough to reduce net greenhouse gas emissions from ships,” Olmer said. “We found that ships are traveling farther and making more voyages in 2015 than they did in 2013, and if the global economy continues to grow, the demand for shipping will likely increase with it.” The authors of the study hope their work will contribute to the International Maritime Organization (IMO) discussions as they consider how to reduce emissions from the shipping sector next week at the second Greenhouse Gas Intercessional in London.

Another key finding of the study is that in addition to increasing ship traffic, emissions are rising as a result of vessel behavior. “Since the economic crash in 2008, there has been an artificial suppression of fuel consumption, because many ships were economizing on fuel by slowing their voyages.” Olmer says. “Now, as the economy is picking up, we are seeing that the biggest ships – the tankers and large container ships – are starting to speed up again.” And of course, that burns more fuel.

Although Olmer and her colleagues were not focused specifically on commercial fishing, it appears to follow the same general trend. During the course of the study, as overall emissions rose, the percentage represented by fishing remained relatively consistent, moving from 4.2 percent in 2013 to 4.5 percent in 2015. (The slight rise may reflect a greater increase in fishing activity compared to other vessels or it may reflect a bump in AIS use by fishing vessels. That would be a question for another study.)

What is known is that fishing vessels are traveling farther and staying at sea longer than in the past. According to the New York Times, the Chinese distant water fishing fleet alone added 400 vessels between 2014 and 2016.

Given the pace of growth in both the fishing industry and the transport of goods around the globe, the answer to reducing total greenhouse gas and carbon emissions seems to be to step up the push for improved energy efficiency and to get serious about alternative fuels-and perhaps even alternative propulsion concepts such as wind and steam turbine systems. There is reason to believe it can be done, because there’s plenty of room for growth. According to Olmer, the shipping industry lags behind most other modes of transportation in developing low-carbon and zero carbon technologies.

To conduct the study, the authors used the Global Fishing Watch Neural Network to classify 399,553 ships by vessel type and activity, then combined that with data from 107,944 vessels identified from IHS vessel registries. They then calculated the fuel consumption of all the vessels based on their voyages to determine emissions.

The vessels Global Fishing Watch added to the study were responsible for 16 percent of CO2 emissions from non-fishing domestic ships such as tugs, ferries, local transport, 15 percent of emissions from the fishing fleet, meaning any fishing-activity related ship operations, and 4 percent of emissions from large international transport vessels such as general cargo and bulk carrier vessels.

“With the help of Global Fishing Watch, we were able to classify and estimate the emissions of many ships in our data set that would otherwise be excluded from our estimates,” Olmer said.