- Black carbon emissions (colloquially known as soot) produced by marine shipping contribute to Earth’s warming climate and also reduce ice and snow cover. In the Arctic, those emissions are hastening regional heating and sea ice loss.
- In the 21st century, climate change has so diminished Arctic sea ice thickness and extent that transpolar crossings in summer by large numbers of commercial vessels has not only become possible but also increasingly frequent, resulting in a marked increase in black carbon emissions from dirty fossil fuels.
- In February, members of the International Maritime Organization (IMO) voted on a proposal by several nations to require use of cleaner polar fuels, which emit lower amounts of black carbon. But the effort was blocked and delayed by large petrostates, including the U.S., Russia and Saudi Arabia.
- Implementation of the measure is expected to be delayed by at least two years. With Arctic sea voyages forecast to soar from thousands of trips annually to tens of thousands by 2050, NGOs are calling for greater support for clean polar fuels as a quick and effective way of reducing warming pressure on the Arctic region.
International shipping is on the rise in the Arctic region now that climate change regularly opens up transpolar sea routes in summer. That surge in traffic is leading to higher emissions of black carbon — colloquially known as soot, considered a “super pollutant.” Those emissions are escalating climate change and quickening sea ice and snow loss across the Arctic, which is already Earth’s most rapidly warming region.
At a recent meeting of the International Maritime Organization (IMO), member states (led by Denmark, and including France, Germany and the Solomon Islands), proposed new regulations to require ships sailing in the Arctic to use fuels that emit low amounts of black carbon.
But in February, global petrostates, including Russia, Saudi Arabia and the United States, opposed this effort, meant to slow Arctic warming. This delay follows a 2025 postponement of an IMO plan that had been widely expected to succeed, which would have accelerated the decarbonization of global shipping. That plan was blocked by the U.S. along with other oil-producing nations.
The just-nixed Arctic proposal would have required ships sailing in the Far North to stop burning residual fuels — responsible for high black carbon emissions — and instead move to less polluting fuels.
NGOs criticized the lack of IMO progress, noting that the black carbon issue has been on the organization’s agenda for nearly 15 years. “We’re calling for shipping in the Arctic to move away from fuels that are so dirty that even diesel is a better alternative,” says Sian Prior, lead adviser with the Clean Arctic Alliance. “This regulation would move away from those dirtier fuels and require that only cleaner fuels, largely distillate fuels, are used.”
Others see the stalled initiative more optimistically: That IMO member nations would put an Arctic ban on polluting fuels to a vote represents limited progress and is a “big breakthrough” in efforts to slash polar emissions, says Elena Tracy, senior sustainable development adviser at WWF Arctic.
“Previously it was mostly environmental organizations that were there in the IMO supporting this [regulation],” she notes. “But this time, we actually see larger support of member states.”
Black carbon’s Arctic ‘double whammy’
Black carbon is a short-lived particulate pollutant, formed by the incomplete combustion of fossil fuels. Even though it only lasts in the atmosphere for days or weeks, it can travel far and wide on winds. And in the Arctic, it can have a disproportionate impact on warming, Prior says.
“The problem with black carbon is that, not only is it a climate heater, it actually has a double whammy effect when it settles out onto snow and ice,” she explains. That’s because polar ice and snow — which in the past reflected large amounts of solar energy back into space — is now darkened by the black carbon, so it absorbs more sunlight, accelerating melting.
This increased melting also reduces Earth’s albedo effect over time, as the widening loss of sea ice and snow exposes larger areas of darker-colored land and water, which absorb even more heat, reducing the reflective capacity of the polar ice cap, which in turn results in more melting.
“You end up with this never-ending cycle of warming,” Prior explains.
Accelerating loss of Arctic sea ice is a major concern, scientists say, with some estimates forecasting ice-free Arctic summers as early as the 2050s. Stating a common refrain uttered by climate scientists for decades, researcher Anna Poltronieri at UiT The Arctic University of Norway notes that what happens in the Arctic doesn’t stay in the Arctic.
Transforming the Arctic Ocean in summer from icy reflective white ice to heat-absorbing blue water will almost certainly bring huge repercussions, impacting worldwide weather patterns (possibly increasing the frequency of strong destructive El Niños), helping push global ecosystems past tipping points and potentially altering ocean circulation.
“Black carbon is unlikely to trigger Arctic tipping points on its own, but it can affect how soon they are reached,” Poltronieri tells Mongabay in an email. “The Arctic is already changing rapidly, and additional warming from black carbon deposition can push processes in this region closer to critical thresholds earlier than anticipated.”
Low-hanging fruit
Shipping is not the main source of black carbon in the Arctic, with industry and record numbers of gigantic wildfires among other important sources. But as more ships spend longer times crossing the region, they are depositing more soot in close proximity to increasingly fragile sea ice. That can intensify melting and other impacts.
A 2025 report by the Clean Arctic Alliance estimates that between 2019 and 2024, black carbon emissions from shipping increased substantially. Over that period, soot emissions rose from 259 metric tons to 759 metric tons in the IMO-designated Polar Code region. Emissions increased from 1,704 metric tons to 2,487 metric tons in northern waters designated under the Arctic Monitoring and Assessment Programme, and from 2,696 metric tons to 3,310 metric tons above the 60° north latitudinal band.
Currently, dense seasonal sea ice allows only about 2,000 voyages annually along Arctic Sea Routes (ASRs). But by 2050, ASR voyages are projected to top 12,218-23,205 journeys (under both “pessimistic” and “optimistic” scenarios), according to a 2025 study. “By 2100, the Arctic is expected to support year-round navigation for all major vessel types, allowing the ASR to handle 2.25% of global traffic,” totaling 180,608-569,214 voyages.
A murky regulatory future
With the latest IMO decision, it will be up to a year before further shipping decarbonization proposals are reconsidered, delaying the implementation of cleaner fuels for at least two years. “That’s assuming everyone comes together behind it and is supportive of it,” Prior says.
Environmental NGOs are also calling for an expansion of the northern polar area subject to a potential ruling. Currently, the Polar Code region used by the IMO excludes some of the busiest shipping lanes, Tracy says. Her organization is proposing that the regulations cover the widest definition of Arctic waters: “Essentially all waters north of 60° latitude.”
Adopting cleaner polar fuels is really “low-hanging fruit” for tackling this issue, she adds. “We actually have the fuels that meet the definition of low content of black carbon,” she says. “So, it’s kind of a simple solution.”
Implementing Far North shipping measures won’t solve humanity’s global climate problem, Prior says, but fuel regulation there is an essential step to lessen warming pressure on the Arctic. “It will reduce the local impact in the Arctic, and it will contribute to the slowing down of climate warming,” she says.
“Black carbon has a relatively short lifetime in the atmosphere, and cutting these emissions can produce rapid climate benefits,” Poltronieri emphasizes. “Failing to do so means losing one of the few levers that can slow Arctic change on short timescales.”
Banner image: Aerial view as a container ship sails through Arctic sea ice. Image by wifesun via Adobe Stock.
Citations:
Zhao, P., Li, Y., Zhang, C., Kang, T., He, Z., Huang, G., … Kong, W. (2025). Arctic Sea route access reshapes global shipping carbon emissions. Nature Communications, 16(1). doi:10.1038/s41467-025-64437-4
Cho, Y., Kim, H., Park, R. J., & Kim, S. (2025). Unprecedented East Siberian wildfires intensify Arctic snow darkening through enhanced poleward transport of black carbon. Science of The Total Environment, 961, 178423. doi:10.1016/j.scitotenv.2025.178423
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