nder the Radar is a weekly special series bringing you compelling, under–the–radar stories from around the world, one region at a time. This week in the Hinterlands, multiple recent studies warn against relying on the ocean as a carbon sink. Other noteworthy under–the–radar stories from the region include major telecom operators’ push to use the X–band, a new study’s findings that coral reefs might be more resilient than previously believed, and the first potential detection of lightning on Mars.
New findings revealed during the COP30 summit reinforce a growing concern among experts: ocean–based carbon removal remains too uncertain to scale safely. As the ocean’s natural ability to store carbon appears to be weakening amid the climate crisis, scientists are warning that using the ocean as a carbon sink without first investing in ocean protections and improved monitoring of carbon storage could be dangerous.
A September 2025 study saw an increase in carbon dioxide outgassing in the ocean as the surface temperatures of the oceans rose drastically in 2023. With the increased temperatures, the ocean absorbed about 10% less carbon than anticipated. An October 2025 study tied the decrease in absorption to the overall “declining greenness” of the ocean. The two–decade study found that each year, the ocean lost around 0.35 micrograms per cubic meter of “greenness,” due to a decline in phytoplankton, which are integral to the ocean’s carbon absorption.
Other recent studies are finding unintended consequences of proposed ocean–based carbon removal methods. A June 2025 study found that three proposed strategies (ocean fertilization, macroalgae farming, and artificial upwelling) consume oxygen at a rate four to ten times greater than the natural deoxygenation of the ocean driven by the climate crisis. The study did find that geochemical approaches appeared to have less negative impacts on the ocean. However, an October 2025 study found that the continued warming of the ocean could reduce the deep sea’s ability to store carbon for long periods.
The lack of global environmental regulation is another risk in pursuing ocean–based carbon removal strategies. A July 2025 paper suggests that climate action should be seen as “planetary security,” as beginning to implement proposed strategies without developing stronger regulations could not only cause unintended environmental harm but, especially concerning ocean–based action, also increase geopolitical tensions and exploitation.
A different report released during the COP30 summit remains optimistic about ocean–based climate solutions. Beyond using the ocean as a carbon sink, the report suggests that funding climate solutions, such as phasing out offshore oil and gas production and decarbonizing shipping and supply chains, could have a substantial impact on reducing carbon emissions. Still, the report emphasizes the need for countries to increase funding to countries outside of the G20 to ensure success.
Here are some other under–the–radar stories from the Hinterlands:
- Major telecom operators are pushing regulators to allow them to use the X–band, which is currently reserved for Earth observation satellites that monitor natural disasters, the climate crisis, and even troop movements.
- A recent study suggests that some coral reefs may be able to survive at higher temperatures than previously believed, offering some hope that coral reefs may be able to recover their corals as they adapt to slightly warmer temperatures.
- A rover detected lightning on Mars.
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The risks of turning the ocean into a carbon sink
Photo by Heidi Bruce on Unsplash
December 12, 2025
Diplomatic Courier’s Stephanie Gull brings you weekly under–the–radar stories from around the world. This week in the Hinterlands: multiple recent studies reveal why plans to use the ocean as a carbon sink won’t work, and would have unintended consequences.
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nder the Radar is a weekly special series bringing you compelling, under–the–radar stories from around the world, one region at a time. This week in the Hinterlands, multiple recent studies warn against relying on the ocean as a carbon sink. Other noteworthy under–the–radar stories from the region include major telecom operators’ push to use the X–band, a new study’s findings that coral reefs might be more resilient than previously believed, and the first potential detection of lightning on Mars.
New findings revealed during the COP30 summit reinforce a growing concern among experts: ocean–based carbon removal remains too uncertain to scale safely. As the ocean’s natural ability to store carbon appears to be weakening amid the climate crisis, scientists are warning that using the ocean as a carbon sink without first investing in ocean protections and improved monitoring of carbon storage could be dangerous.
A September 2025 study saw an increase in carbon dioxide outgassing in the ocean as the surface temperatures of the oceans rose drastically in 2023. With the increased temperatures, the ocean absorbed about 10% less carbon than anticipated. An October 2025 study tied the decrease in absorption to the overall “declining greenness” of the ocean. The two–decade study found that each year, the ocean lost around 0.35 micrograms per cubic meter of “greenness,” due to a decline in phytoplankton, which are integral to the ocean’s carbon absorption.
Other recent studies are finding unintended consequences of proposed ocean–based carbon removal methods. A June 2025 study found that three proposed strategies (ocean fertilization, macroalgae farming, and artificial upwelling) consume oxygen at a rate four to ten times greater than the natural deoxygenation of the ocean driven by the climate crisis. The study did find that geochemical approaches appeared to have less negative impacts on the ocean. However, an October 2025 study found that the continued warming of the ocean could reduce the deep sea’s ability to store carbon for long periods.
The lack of global environmental regulation is another risk in pursuing ocean–based carbon removal strategies. A July 2025 paper suggests that climate action should be seen as “planetary security,” as beginning to implement proposed strategies without developing stronger regulations could not only cause unintended environmental harm but, especially concerning ocean–based action, also increase geopolitical tensions and exploitation.
A different report released during the COP30 summit remains optimistic about ocean–based climate solutions. Beyond using the ocean as a carbon sink, the report suggests that funding climate solutions, such as phasing out offshore oil and gas production and decarbonizing shipping and supply chains, could have a substantial impact on reducing carbon emissions. Still, the report emphasizes the need for countries to increase funding to countries outside of the G20 to ensure success.
Here are some other under–the–radar stories from the Hinterlands:
- Major telecom operators are pushing regulators to allow them to use the X–band, which is currently reserved for Earth observation satellites that monitor natural disasters, the climate crisis, and even troop movements.
- A recent study suggests that some coral reefs may be able to survive at higher temperatures than previously believed, offering some hope that coral reefs may be able to recover their corals as they adapt to slightly warmer temperatures.
- A rover detected lightning on Mars.
