Bottom trawling generates a similar amount of carbon emissions as the global aviation industry, driven predominantly by activity in Chinese national waters, according to a paper published in the journal Nature.
The global aviation industry produces about 2 percent of all human-induced carbon emissions.
According to The Financial Times, the researchers found bottom trawling is responsible for between 0.6 and 1.5 gigatons of carbon emissions a year, compared with the aviation industry’s emissions of close to 1 gigaton.
The majority of this pollution occurs in less than 4 percent of the ocean, in the sovereign fishing waters of coastal nations known as Exclusive Economic Zones (EEZs), said the paper.
Trawling by boats in Chinese waters generates by far the greatest volume of emissions, or about 770 million metric tons of CO2, followed by trawlers in the economic zones of Russia, then Italy.
Trawling in UK waters caused the next most pollution, the researchers said, emitting roughly 370 million metric tons of carbon a year.
“The ocean floor is the world’s largest carbon storehouse,” said Trisha Atwood of Utah State University, a co-author of the paper.
“If we’re to succeed in stopping global warming, we must leave the carbon-rich seabed undisturbed.”
Oceans play a critical role in absorbing heat and CO2.
The study said governments could achieve the triple benefits of carbon savings, increased marine biodiversity and greater fishing yields by protecting larger areas of the ocean.
Using satellite data based on fishing activity between 2016 and 2019, the researchers said roughly 1.3 percent of the ocean was trawled each year, releasing up to 1.5 gigatons of CO2, a finding they said was “a preliminary best estimate."
Since most trawling occurs within the economic zones, governments could halt the practice, said Enric Sala, lead author of the report.
“We need to make sure that the trawling effort vanishes,” he said.
The study was funded by the National Geographic Society and the Leonardo DiCaprio Foundation.