Some scientists say the controversial practice of deep-sea trawling stirs up buried organic matter, some of which rises to the surface as carbon dioxide.
Environmentalists have long criticized the practice of dragging giant nets across the seabed to catch fish – a practice known as bottom trawling – as destructive to underwater ecosystems. Research shows that it is also bad for the climate.
The study, published in the journal Frontiers in Marine Science, found that bottom trawling could release up to 370 million tons of carbon dioxide into the atmosphere each year. The International Energy Agency estimates that this is equivalent to about half of the emissions produced annually by the entire international shipping industry.
This carbon comes from organic material that has been buried on the ocean floor for a long time. Without human intervention, these sediments can persist for thousands of years. However, trawling causes them to mix and release the accumulated carbon back into the water column. Some of this material returns to the seafloor and becomes compressed. However, some of them rise to the surface as carbon dioxide (a powerful greenhouse gas) and diffuse into the air.
According to research, around 55 to 60% is CO2 Through trawls it enters the water column and ultimately the atmosphere. This typically occurs within seven to nine years, meaning the effects of trawling can be felt after a short period of time.
The study’s authors say they were able to identify an often-overlooked source of emissions and suggest that regulators have the ability to quickly address the problem. When policy makersCreate a different strategy to manage where and how fishermen fishsaid the study’s lead author, Tricia Atwood, an aquatic ecologist at Utah State University.The impact of these measures on the climate would be almost immediate“.
Other opinions on emissions from trawling
However, these results may be controversial. Some scientists believe the article overestimates emissions from trawling.
“I am very skeptical of your estimatesJan Geert Hiddink, a marine researcher at Bangor University in the United Kingdom who was not involved in the new study, said in an email E&E News.
He said the paper may have overestimated the total amount of CO2 are released into the water column by trawl nets, so that the amount of CO2 released into the atmosphere would be “overestimated by many orders of magnitude“.
The debate has increased in recent years. The new paper builds on previous research published in 2021 that looked at the benefits of marine protected areas. The article was written by Enric Sala, a former academic who later founded the US Pistino Sea program National Geographic Society to protect the world’s oceans. Sala and many of the authors of the original paper, including Atwood, also conducted the new study, which was partially funded Pristine seas.
A 2021 study found that restricting fishing and other human activities could protect biodiversity, boost fisheries and protect marine carbon sinks. The 2021 document also estimates that trawling can release more than a billion tons of CO22 to the water column per year.
These are only rough estimates and do not take into account the actual amount of CO2 released into the atmosphere.
However, the article included a number of headlines comparing the climate impact of trawling to that of other carbon-intensive industries such as aviation.
While in the spotlight, he also faced criticism from Hiddink and other researchers who said his estimates were exaggerated. In 2023, Hiddink and other scientists published an article saying that a 2021 study had exaggerated the amount of CO2 released into the water by trawling.
As seafloor sediments break down, they are eaten by bacteria and other marine life and converted into CO2. But Hiddink and his colleagues say the 2021 study overestimated how much long-trapped carbon is actually converted into CO.2.
In contrast, Atwood and her co-authors argued in their response that Hiddink’s criticism was based on false assumptions about the marine sediments disturbed by trawls and the rate at which they are removed and converted into CO2.2. “Our response questioned their assumptions, which we believe are inaccurate and lack quantitative support.“said the authors in a recent statement.
Atwood said the new document goes a step further with the 2021 results. Estimate the CO content2 which enters the atmosphere in addition to the total amount from the ocean.
The study showed that this proportion does not change in relation to the total amount of CO2 in water. No matter how much CO2 Beech floats, between 55 and 60 percent always escapes into the air. That is, if future studies further reduce the absolute amount of CO2 Animals released through trawling can still rely on that ratio to be correct, Atwood said.
Atwood said this is the first study of its kind to conduct such an assessment.
“In reality, it simply serves to provide policymakers with the information they need to make good decisions.“, he claimed.
With information from:
