This year’s climate COP is taking place in Belém, at the heart of the Amazon rainforest – one of the planet’s green lungs and a long-standing symbol of the climate fight. But the world needs to look beyond the forest, to the part of the planet that’s blue.
The destruction of the rainforest happens in plain sight. But bottom trawling – a practice in which heavy fishing nets are dragged across the ocean floor, dredging up carbon that’s long been stored in the seabed – is a kind of deforestation beneath the waves. Bottom trawling is invisible to us on land, but it has devastating effects on the climate and ecosystems. COP30 in Belém is the moment to finally take a stand against the practice.
Over the last two years, science has revealed the scale of the problem. Recent research found that between 55% and 60% of all trawling-induced carbon dioxide makes it into the atmosphere over seven to nine years. That means that, every year, bottom trawling releases 370 million metric tons of carbon dioxide into the atmosphere. That’s about as much as the entire United Kingdom emits annually, and double the annual emissions from fuel combustion of the entire global fishing fleet of about 4 million vessels.
And the damage isn’t just to the atmosphere. Between 40% and 45% of the carbon dioxide that bottom trawling dislodges from the seabed remains in the ocean, where it turns the water more acidic – harming marine plants and animals where the bottom trawling took place.
Economically, the picture is no better. Bottom trawling largely survives on public money. Despite the minimal returns, governments across Europe subsidise bottom trawling to the tune of €1.3 billion every year, a figure that is nearly equivalent to the value of the jobs the industry creates.
But bottom trawling is still a regular fishing practice – even in areas that are meant to be protected. A recent investigation by the conservation group Oceana found that, in 2024, more than 100 bottom trawling vessels spent some 17,000 hours fishing in six French “marine nature parks.” That’s equivalent to one vessel trawling nonstop, night and day, for nearly two years straight. Across Europe, more than 11% of marine areas are designated for protection, but only 2% actually have management plans in place. The rest remains vulnerable to trawling.
Public awareness about bottom trawling is finally catching up, galvanised by new research, reports, and powerful imagery. Earlier this year, a David Attenborough documentary, Ocean, revealed the horrors of bottom trawling on screen for the first time.
The footage is shocking, but despite the science and reporting, countries still don’t account for bottom trawling’s significant carbon emissions in their climate action plans. And that’s where we need to see change at COP30.
We’ve had promises and declarations. Now we need to follow through. Tackling the carbon emissions of bottom trawling is a fast and effective way to forestall climate change while protecting our precious marine ecosystems. If we act now, the benefits will be immediate. If we delay, the carbon emissions of today’s bottom trawling will continue to leak into the atmosphere for another decade at least.
Ahead of COP30, the world is already celebrating new and recent steps to protect more of our ocean, having recently ratified the High Seas Treaty that will allow for the establishment of marine reserves beyond national borders from early 2026. However, these celebrations must not be premature: Nations will still need to prioritise protection within their own waters and ensure that harmful activities like bottom trawling are banned. This will ensure that all of our marine protected areas are actual sanctuaries for marine life – not unregulated “paper parks.”
COP30 is our chance to make that commitment. The ocean has long been our climate’s quiet ally. It’s time we stood up for it in return.
Enric Sala is the founder of National Geographic Pristine Seas, which has helped establish 31 marine protected areas worldwide, covering more than 6.9 million square kilometres of ocean.