oceans
Newsletter
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Melting ice and microplastics signal deepening disruption in Antarctica’s climate system
A team of international scientists circumnavigating Antarctica has documented widespread environmental decline, including microplastics in ice and seawater, receding glaciers, and falling ocean salinity.
In short:
- Researchers found microplastics in Antarctic glacial ice and seawater, signaling how far global plastic pollution has spread.
- Glacier retreat and increasing meltwater are diluting ocean salinity, disrupting phytoplankton populations and ocean circulation.
- Atmospheric “rivers” from Amazon forest fires carry black carbon to Antarctica, accelerating ice melt by reducing the reflectivity of snow and ice.
Key quote:
“Microplastics were visible when seawater was passed through a kind of strainer; they could even be seen through the camera lens.”
— Venisse Schossler, climatologist and mission coordinator
Why this matters:
Antarctica may seem remote, but its role in regulating the planet’s climate is immediate and vital. Its ice sheets help stabilize sea levels, and its cold waters serve as a massive carbon sink, absorbing heat and CO₂ from the atmosphere. As microplastics accumulate and glaciers melt faster, the Southern Ocean’s salinity and acidity are shifting, stressing marine life and weakening its capacity to buffer climate change. Disruption to phytoplankton — the foundation of ocean food webs and a major oxygen producer — has ripple effects throughout global ecosystems. Meanwhile, soot from Amazon fires, transported by high-altitude winds, darkens Antarctic snow, speeding melt. These linked systems show how human activities in one region can destabilize life-supporting processes halfway across the planet.
Related: Plastic debris could carry invasive species to Antarctica, threatening ecosystems
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World leaders back ocean treaty and new marine reserves, but critics say action still lags
The United Nations Ocean Summit in France ended with pledges to ratify a treaty protecting international waters, but world leaders faced pushback for slow progress and weak commitments on key issues like bottom trawling and deep-sea mining.
In short:
- Sixty heads of state and 190 ministers met in Nice for the UN ocean summit, where France announced that the high seas treaty is expected to take effect by January 2026.
- Four new nations joined calls for a ban or moratorium on deep-sea mining, while 90 ministers supported a strong global plastics treaty ahead of negotiations in August.
- Critics, including Pacific island leaders and ocean advocates, said rich nations, especially France, fell short in addressing destructive fishing practices like bottom trawling.
Key quote:
“President Macron promised action on bottom trawling in marine protected areas but delivered only artificial limits and empty words.”
— Alexandra Cousteau, adviser to Oceana and granddaughter of Jacques Cousteau
Why this matters:
Oceans are central to life on Earth, producing over half the oxygen we breathe and absorbing much of the planet’s carbon dioxide. But decades of industrial overfishing, pollution, warming, and climate-driven acidification have pushed marine ecosystems toward collapse. Bottom trawling, a fishing method that scrapes the ocean floor, destroys habitats vital to biodiversity and carbon storage. Deep-sea mining threatens to scar untouched seafloors before their ecological value is even understood. While marine protected areas and international treaties offer hope, only a fraction of the ocean is currently safeguarded. Without enforceable limits and meaningful investment, rhetoric at high-level summits risks becoming a substitute for action, leaving frontline nations and future generations to bear the cost of marine decline.
Read more: Global effort to protect international waters nears milestone as more countries back UN ocean treaty
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Costa Rica pushes global ocean protections and deep sea mining moratorium
Costa Rica’s president used the United Nations Ocean Conference to call for a global pause on deep sea mining and greater international cooperation to protect marine ecosystems.
In short:
- Costa Rica, which protects 30% of its marine territory, co-hosted the U.N. Ocean Conference in Nice, urging countries to halt deep sea mining until more research is available.
- President Rodrigo Chaves Robles emphasized that safeguarding oceans benefits all nations and that harmful practices like plastic pollution and bottom trawling must be addressed collectively.
- Costa Rica is using payments for environmental services and technology like satellite tracking to curb illegal fishing and support conservation efforts, especially in vulnerable coastal communities.
Key quote:
“For decades now, we have treated the ocean as a sort of infinite pantry or food store, but also we’ve treated it as a global waste dump.”
— Rodrigo Chaves Robles, president of Costa Rica
Why this matters:
The ocean covers over 70% of the planet and absorbs around a quarter of the carbon dioxide humans emit each year, buffering us from climate catastrophe. But industrial fishing, plastic pollution, warming waters, and now deep-sea mining threaten marine biodiversity and the livelihoods of millions who depend on healthy seas. Deep sea mining in particular risks damaging fragile ecosystems that scientists barely understand, yet it’s gaining momentum due to demand for metals used in electric batteries. Costa Rica’s call for a moratorium reflects growing concern that industry is outpacing science. As some nations expand marine protections, others resist regulation, leaving the ocean vulnerable. Decisions made now could shape the fate of Earth’s largest carbon sink — and a cornerstone of global food security — for generations.
Related: Global effort to protect international waters nears milestone as more countries back UN ocean treaty
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Warming oceans could help submarines hide better from sonar detection
Submarine detection is growing more difficult as climate change alters how sound moves through warming seas, shrinking the range of sonar in key military regions.
In short:
- NATO scientists modeled how underwater sound propagation has changed due to climate warming and found it could sharply reduce sonar detection range in areas like the North Atlantic and western Pacific.
- Warmer ocean surfaces bend sound downward into cooler layers, making it harder for sonar systems to detect submarines at a distance.
- These changes may give strategic advantage to nations like Russia and China, while U.S. climate-related defense programs are being canceled under President Trump.
Key quote:
“If it becomes even more difficult to detect them, then the result is that things become harder for navies that are on the defensive.”
— Mauro Gilli, military technology researcher at the Hertie School in Berlin
Why this matters:
Sound is the main tool navies use to detect submarines, especially in the deep ocean where radar and satellites fall short. But as climate change warms surface waters, it also reshapes how sound travels, creating underwater “shadow zones” where submarines can disappear from detection. That makes it harder for military forces to track threats, raising concerns not just about conventional warfare but nuclear deterrence, since ballistic missile submarines rely on secrecy. As the climate shifts faster than military technology can adapt, both environmental and geopolitical stability are at greater risk.
Related: Scientists call on UN to adopt bold ocean policies to combat climate and biodiversity threats
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Global effort to protect international waters nears milestone as more countries back UN ocean treaty
Eighteen more nations signed onto a United Nations treaty to protect biodiversity in international waters, leaving the agreement just 11 ratifications short of taking effect.
In short:
- The High Seas Treaty, formally called the Agreement on Biodiversity Beyond National Jurisdiction, would be the first legally binding international agreement to safeguard biodiversity in areas of the ocean beyond national control.
- With 49 countries and the European Union now ratifying the treaty, only 11 more are needed to start a 120-day countdown to formal adoption, allowing for the creation of marine protected areas and enforcement mechanisms.
- The treaty’s framework includes limits on extractive activities, supports equitable science and technology sharing, and mandates multilateral decision-making through future Conferences of the Parties.
Key quote:
“Until now, it has been the wild west on the high seas. Now we have a chance to properly put protections in place.”
— Megan Randles, global political lead for oceans at Greenpeace
Why this matters:
Nearly half the planet’s surface lies in the high seas — international waters that until now have had no enforceable conservation rules. These waters hold rich ecosystems crucial to planetary health, but they face growing threats from overfishing, climate change, and industrial ambitions like deep-sea mining. Without legal guardrails, fragile marine habitats could suffer irreversible damage. The High Seas Treaty represents a long-awaited step toward global ocean governance, providing a means to designate protected zones and regulate harmful activities. Scientists and advocates stress that achieving the treaty’s goal of protecting 30% of Earth’s oceans by 2030 is essential not only to preserve marine biodiversity but also to maintain the oceans’ role in carbon storage and climate regulation. What happens on the high seas can shape the future health of the entire planet.
Recent news: World leaders to meet in France to confront ocean crisis and push for $100 billion in pledges
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Scientists revise timeline for possible collapse of key Atlantic ocean current
The Atlantic current system that helps regulate global climate may be weakening slower than some previous studies predicted, though uncertainty remains about when — or if — it could reach a tipping point.
In short:
- The Atlantic Meridional Overturning Current (AMOC), which helps distribute heat and nutrients globally, is weakening, but new studies suggest a slower pace than previously feared.
- Recent modeling finds the current could decline by 18-43% by 2100, with collapse possibly pushed beyond this century; earlier studies predicted a midcentury breakdown.
- Scientists caution that data gaps and limitations in climate models, particularly regarding Greenland meltwater, could lead to overconfidence in optimistic projections.
Key quote:
“You cannot adapt to this.”
— Peter Ditlevsen, ice and climate researcher, University of Copenhagen
Why this matters:
The AMOC is one of Earth’s most powerful drivers of climate, redistributing heat from the tropics to the poles and regulating weather patterns across continents. A collapse would redraw the world’s climate map: Some regions would freeze, others would dry out or flood. Its weakening threatens food production, biodiversity, and the stability of coastlines, especially on the U.S. East Coast. Scientists say even partial slowdown could trigger sharp sea level rise and disrupt carbon absorption by the oceans, accelerating global warming. Yet predictions remain deeply uncertain, partly because we’ve only been closely tracking this system since 2004, and many of the forces shaping it, like Greenland’s melt, are themselves evolving fast.
Learn more: Polar ice melt may collapse key ocean current by 2050, scientists warn
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Scientists call on UN to adopt bold ocean policies to combat climate and biodiversity threats
In the lead-up to the United Nations Ocean Conference that opens today in France, scientists released ten policy recommendations urging world leaders to act swiftly on climate change, overfishing, and marine pollution based on existing scientific evidence.
In short:
- An 18-member international scientific committee presented a ten-point plan to guide global ocean recovery at the One Ocean Science Congress in Nice, France.
- The recommendations call for phasing out fossil fuels, ending harmful fishing subsidies, recognizing the legal rights of marine ecosystems, and pausing deep-sea extraction activities.
- Scientists argue that ocean health has long been neglected, receiving less than 2% of research funding on average, despite its vital role in climate regulation and food security.
Key quote:
“You cannot deal with the crisis of the climate without also dealing with the crisis of the ocean and vice versa.”
— John Kerry, former U.S. secretary of state
Why this matters:
Oceans absorb more than 90% of the planet’s excess heat and about a third of carbon dioxide emissions, making them a frontline buffer against global warming. Yet marine ecosystems are nearing a tipping point. Warming seas trigger coral bleaching and disrupt fish migrations, threatening food security in coastal regions. Plastic pollution and chemical runoff suffocate marine species and enter the food chain, with unknown health impacts on humans. Overfishing, sometimes propped up by state subsidies, continues to deplete fish populations faster than they can regenerate.
Adding to the stress, nations are eyeing the deep ocean for mining and carbon sequestration, despite scant understanding of its ecology. While the UN’s “Life Below Water” goal seeks to address these issues, it remains one of the least-funded parts of the international sustainability agenda. Scientists warn that ignoring ocean science in policymaking — especially on climate and biodiversity — could lead to irreversible harm.
Related: There's a plan to turn oceans into climate sponges, but will it work?
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