The review, led by researchers from Aarhus University and conducted under the Horizon Europe project POMP — Polar Ocean Mitigation Potential — brings together what is currently known about carbon captured, stored or transported by marine ecosystems in polar regions. The authors assess which habitats may contribute to long-term carbon storage, why these systems have been largely absent from existing climate and conservation instruments, and what evidence gaps must be closed before they can be meaningfully integrated into climate strategies. Their conclusion is deliberately two-sided: the potential is real, but so are the uncertainties, and neither should be used as an excuse for inaction.

Blue carbon, as a concept, has so far been defined almost entirely by the tropics and temperate zones. Mangrove forests, salt marshes and seagrass meadows dominate the policy conversation because their carbon dynamics are comparatively well quantified, their extent is mappable from satellites, and their sediments accumulate organic matter at rates that can be measured with established methods. These ecosystems have earned places in national greenhouse gas inventories and in voluntary carbon market methodologies. Polar systems, by contrast, are almost entirely absent from such frameworks — a striking omission given that the Arctic and Antarctic together account for roughly one fifth of the global ocean and rank among the regions most rapidly transformed by climate change.

The review identifies a broad portfolio of polar habitats and pathways with plausible relevance to carbon storage. In the Arctic, salt marshes and seagrass meadows exist at the margins of a warming coastline, while kelp forests line rocky substrates in cold, nutrient-rich waters. In open water, phytoplankton drive the biological carbon pump, fixing carbon dioxide at the surface and exporting a fraction of it toward the deep ocean. Ice-associated algae, which grow within and beneath sea ice, add another, poorly quantified pathway. Fjords, continental shelves and deep-sea sediments act as receiving basins where organic carbon can accumulate and, under the right conditions, remain buried for long periods. Each of these systems operates differently, and each carries a different degree of confidence in its estimated contribution.

That confidence, the authors stress, is currently the weakest link. For many polar habitats, scientists lack robust estimates of even the most basic parameters: how much area the habitat covers, how much carbon it holds in living biomass and sediments, and how much of that carbon is genuinely sequestered over climatically relevant timescales rather than recycled back into the water column. The polar environment complicates measurement in ways that temperate blue carbon science rarely encounters. Sea ice limits access and remote sensing. Seasonal darkness compresses the growing season into a few intense months. Glacial runoff, sediment plumes and permafrost thaw introduce additional carbon sources whose origins and fates are difficult to disentangle. Warming, ice loss, coastal erosion and expanding human activity are simultaneously reshaping the very systems researchers are trying to quantify, meaning that a carbon stock measured today may not behave like the same stock a decade from now.

These dynamics cut in both directions, and the review is explicit about that asymmetry. Some habitats may grow in importance as carbon stores as conditions change — expanding seagrass meadows along newly ice-free coastlines, for example, or shifting plankton communities altering export efficiency. Others may be weakened or lost as warming, ice retreat, erosion and industrial pressure erode the conditions that allowed them to accumulate carbon in the first place. Thawing permafrost coasts can release stored carbon even as new vegetated habitats establish nearby. The net trajectory for any given region is therefore an open scientific question, not a foregone conclusion, and it is precisely this uncertainty that has kept polar systems outside formal policy recognition.

The authors are equally clear about what the current state of knowledge does not justify. Treating polar blue carbon as a conventional carbon-offset solution, they argue, would be premature and potentially dangerous. Carbon markets and offset schemes rest on assumptions that cannot yet be verified in polar marine systems: that emissions reductions are additional to what would have happened anyway, that stored carbon will remain locked away permanently, that measurements are accurate and comparable across sites, and that governance structures exist to enforce protection over the long term. In polar oceans, all four assumptions are currently shaky. Measurement standards are undeveloped, permanence is threatened by rapid environmental change, and much of the relevant ocean lies in areas with contested or fragmented jurisdiction.

“Polar blue carbon is not a shortcut around reducing CO2 emissions,” says Mikael Sejr, POMP coordinator at the Department of Ecoscience at Aarhus University. “The first priority must still be to phase out fossil fuels. But protecting carbon-rich marine ecosystems can be an important part of a broader climate and biodiversity strategy.” The distinction matters. Blue carbon protection, in this framing, is a complement to decarbonization rather than a substitute for it — a way of safeguarding natural carbon infrastructure that would otherwise be degraded, while the harder work of cutting emissions proceeds.

Lead author Nadescha Zwerschke of the Department of Biology at Aarhus University frames the urgency in similar terms. “Polar marine ecosystems are changing rapidly,” she notes. “Some habitats may become more important as carbon stores, while others may be weakened by warming, ice loss, erosion and increasing human pressure. We need to understand these systems much better — but we should not wait until all uncertainties are resolved before protecting the most vulnerable and carbon-rich habitats.” The argument echoes a familiar principle in environmental governance: precautionary protection does not require perfect knowledge, only a reasonable expectation that irreversible losses are possible and that waiting carries its own costs.

Toward that end, the review lays out four coordinated actions. First, sustained investment in polar blue-carbon research, targeting the fundamental gaps in extent mapping, carbon stock assessment and sequestration rates. Second, precautionary protection of habitats already known to be carbon-rich and vulnerable, so that existing stores are not destroyed while the science catches up. Third, management approaches that treat carbon storage and biodiversity as linked objectives rather than competing ones — a natural pairing, since many of the same ecosystems that sequester carbon also support the productivity and diversity that polar food webs depend on. Fourth, clearer policy pathways through which substantial natural carbon stores in polar marine ecosystems can eventually be recognized in national and international frameworks. The near-term priority, the authors conclude, is not to create new offset markets but to protect what exists and to build the scientific foundation on which future policy decisions can rest. As polar oceans warm faster than almost anywhere else on Earth, the window for doing both is narrowing.

Subject of Research: The status of polar blue carbon and its integration into marine climate and conservation policy

Article Title: Polar oceans store carbon — but policy is not yet ready to count it

Article References: Polar oceans store carbon — but policy is not yet ready to count it. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: polar blue carbon, Arctic, Antarctic, carbon sequestration, climate policy, marine ecosystems, biodiversity, kelp forests, seagrass, ocean warming, POMP project, Global Change Biology

The research was led by Guilherme Costa Alvarenga of the Wildlife Conservation Research Unit at the University of Oxford and the Mamirauá Institute for Sustainable Development in Tefé, Brazil, with senior authorship shared by Żaneta Kaszta and Samuel Cushman of the Department of Biology at the University of Southern Denmark. What sets the work apart from earlier continental mapping exercises is its empirical foundation. Previous range-wide connectivity models for jaguars leaned heavily on expert opinion, essentially asking specialists where they believed animals could move. The new analysis instead builds its picture from the actual recorded movements of jaguars tracked across much of the species’ range, allowing the researchers to construct a model grounded in how the cats really behave on the landscape rather than how humans assume they do.

From the GPS trajectories, the team identified 307 core living areas that support high levels of predicted jaguar movement, along with 176 corridors that link those cores together. In connectivity science, core areas function as the population strongholds where animals live, breed and concentrate their activity, while corridors are the landscape threads that allow dispersing individuals, and with them their genes, to flow between those strongholds. Together, these mapped elements provide the first empirically grounded, range-wide portrait of how jaguar populations across Mexico, Central America and South America may remain connected in the face of accelerating habitat loss and fragmentation, two of the most serious threats facing wide-ranging carnivores everywhere.

The single most striking finding is the overwhelming importance of one vast South American stronghold. A connected landscape spanning parts of the Amazon, the Llanos, the Pantanal and the Chaco covers approximately 6.5 million square kilometres across 11 countries and ranked as the most important core habitat for jaguar connectivity in the entire analysis. This single region accounted for the vast majority of predicted movement density in the model, meaning that the bulk of the species’ potential for gene flow and dispersal is concentrated in this enormous swath of northern and central South America. For conservation planners, the message is clear: the fate of most of the world’s jaguars is tied to the fate of this interconnected Amazonian and surrounding lowland complex.

Outside that central stronghold, however, the picture grows considerably darker. The analysis identified major connectivity gaps in parts of Mexico, Central America, Colombia and the Atlantic Forest, the coastal rainforest belt of eastern South America that has already been reduced to a small fraction of its original extent. In these regions, many jaguar populations appear increasingly isolated, cut off from one another by agricultural land, pastures, roads and expanding human settlement. Isolation carries real biological consequences: without the movement of individuals between populations, gene flow slows, inbreeding risk rises, and local extinctions become harder to reverse because recolonisation from neighbouring areas is no longer possible.

Samuel Cushman framed the species’ situation as one of remarkable strength shadowed by real fragility. Jaguars, he noted, are in a stronger position than many other large carnivores precisely because they still retain an extensive connected stronghold in South America, a luxury that lions, tigers and wolves in much of their respective ranges no longer enjoy. At the same time, the study’s results show that connectivity is far from secure across the species’ entire range. Several populations outside the Amazon now depend on relatively narrow connections, thin ribbons of traversable habitat that could be severed if habitat conversion continues at its current pace. The loss of even a single critical link in such a chain could isolate an entire regional population.

The team did not stop at modelling connectivity between existing jaguar strongholds. In a second, complementary analysis, they examined connectivity among 905 protected areas and Indigenous lands across the jaguar’s range, identifying 507 potential corridors and highlighting specific locations where conservation action could strengthen future movement. This dual approach proved to be one of the study’s methodological strengths. Connectivity modelling based on current jaguar populations offers the most realistic representation of present-day conditions, showing where animals are actually moving today. The protected-area analysis, by contrast, reveals potential opportunities, places where restoring or maintaining habitat links between conserved lands could rebuild connectivity even where jaguar movement has already been disrupted.

The findings arrive at a moment when connectivity has moved to the centre of international biodiversity strategy. Conservation organisations and governments increasingly recognise that protecting isolated patches of habitat is not enough; the spaces between them matter just as much. Maintaining connections between populations helps sustain gene flow, facilitates the natural dispersal of young animals seeking new territories, and reduces the risk of local extinctions by allowing recolonisation after local losses. For a species like the jaguar, which requires enormous territories and ranges across dozens of national borders, connectivity conservation is inherently a transboundary enterprise, demanding cooperation among the 11 or more countries that share the species’ fate.

The authors are careful to note an important caveat: the corridors identified in the study represent modelled pathways rather than confirmed movement routes, and field validation remains necessary before they can be treated as ground truth. Models built from GPS data are powerful, but they are still inferences about where movement is likely, not camera-trap records of animals crossing specific valleys. Nevertheless, the researchers believe the maps offer a practical framework for prioritising conservation action across the jaguar’s range. As Kaszta explained, the results identify where connectivity appears strongest, where it is most vulnerable, and where future conservation efforts could have the greatest impact, giving governments and NGOs a shared, evidence-based blueprint.

The researchers hope the findings will guide habitat protection, restoration programmes and transboundary conservation initiatives designed to keep jaguar populations connected under mounting pressure from land-use change. In practical terms, that could mean safeguarding narrow corridor pinch-points before they are converted to farmland, restoring forest links in the Atlantic Forest and Central America, and ensuring that Indigenous lands, which the analysis showed to be integral to the connectivity network, remain protected. For a species that once ranged across the entire Americas and now survives in a fragmented fraction of that domain, the new maps represent both a warning and an opportunity: the science now shows precisely where the threads of jaguar connectivity run, and which of those threads are closest to snapping.

Subject of Research: Range-wide connectivity and movement corridors of jaguar populations across the Americas

Article Title: Largest-ever jaguar analysis identifies how jaguar populations are connected across the Americas

Article References: Largest-ever jaguar analysis identifies how jaguar populations are connected across the Americas. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: jaguar, connectivity, corridors, GPS tracking, habitat fragmentation, Amazon, Pantanal, Atlantic Forest, conservation, protected areas, gene flow, Global Change Biology

The study, led by Anna Gudrun Thorhallsdottir, a professor at the University of Iceland at Holar, draws on real-world data from long-term grazing cessation experiments in Iceland. By examining grasslands where grazing was abandoned for extended periods, the researchers were able to isolate the specific effects of livestock presence on soil chemistry and vegetation dynamics. The findings reveal that grazing abandonment resulted in lower soil carbon levels, while continued grazing consistently led to higher soil carbon concentrations. This counterintuitive result suggests that the interaction between herbivores and grassland plants is more complex than simple biomass removal, involving intricate feedback loops that influence root exudation, nutrient cycling, and microbial activity in the soil.

Grassland plants transfer large amounts of carbon to the soil through their root systems, and the majority of this carbon is stored below ground. In the absence of grazing, grasslands often undergo ecological shifts that can reduce their capacity to sequester carbon. The study found that long-time grazing abandonment promoted the dominance of vegetation types that are less efficient at storing soil carbon. These shifts often involve the encroachment of shrubs or the dominance of plant species that allocate less carbon to deep root systems compared to the grasses that thrive under grazing pressure. Grazing, by keeping vegetation short and stimulating new growth, may encourage plants to invest more in root production and exudation, thereby increasing the input of labile carbon into the soil.

The mechanism by which grazing enhances soil carbon storage is not fully understood, but several hypotheses are supported by the data. One possibility is that grazing stimulates plant regrowth, leading to increased root turnover and the release of root exudates that feed soil microorganisms. These microorganisms, in turn, produce stable soil organic matter that persists in the soil for longer periods. Another factor is the distribution of manure and urine, which adds nitrogen and other nutrients to the soil, promoting plant growth and microbial activity. Additionally, the physical disturbance caused by grazing animals can mix the soil, enhancing aeration and the incorporation of organic matter into deeper soil layers. These combined effects can create a positive feedback loop that supports higher soil carbon stocks over time.

The implications of these findings extend beyond local grassland management to global climate policy. As the world seeks nature-based solutions to combat climate change, understanding the role of grazing in carbon sequestration is crucial. The study highlights the potential importance of grazing to sustain grasslands and enhance soil carbon storage, suggesting that blanket exclusion of livestock may not always be the best approach. Instead, a nuanced understanding of local ecological conditions is necessary to determine whether grazing or non-grazing management is more effective for carbon sequestration. This has significant implications for land-use planning, conservation efforts, and the development of carbon credit markets that rely on accurate estimates of soil carbon changes.

Thorhallsdottir emphasizes that the findings have important implications for climate policy, nature-based solutions, and sustainable grassland management worldwide. She notes that the results highlight the potential importance of grazing to sustain grasslands and enhance soil carbon storage. This perspective challenges the prevailing narrative that grazing is inherently detrimental to soil health and carbon sequestration. Instead, it suggests that grazing can be a tool for managing grasslands in a way that supports both biodiversity and climate goals. The study underscores the need for more research to understand the specific conditions under which grazing enhances or hinders soil carbon storage, as well as the long-term stability of these carbon stocks.

The research was conducted in sub-arctic grasslands in Iceland, a region that is particularly sensitive to climate change and land-use alterations. Sub-arctic grasslands are characterized by low temperatures, short growing seasons, and permafrost, which can influence soil carbon dynamics. The study’s findings are therefore specific to this environment, but they raise important questions about the applicability of these results to other grassland types. Further research is needed to determine whether the positive effects of grazing on soil carbon storage are consistent across different climatic and ecological contexts. This will require long-term experiments and monitoring programs that can capture the slow processes of soil carbon accumulation and decomposition.

The publication of this study in Global Change Biology Communications, a peer-reviewed, open-access journal, ensures that the findings are accessible to a wide audience, including scientists, policymakers, and practitioners. The journal is a companion to Global Change Biology and publishes high-impact research on how living systems respond to global changes. By making the study openly available, the authors hope to facilitate the translation of these findings into practical management recommendations. The study also contributes to the broader scientific discourse on the role of land management in climate change mitigation, highlighting the importance of integrating ecological knowledge into policy decisions.

In conclusion, the study provides a compelling case for reconsidering the role of livestock grazing in soil carbon storage. By demonstrating that grazing can enhance carbon sequestration in sub-arctic grasslands, the research challenges conventional wisdom and offers new insights into the complex interactions between plants, animals, and soil. As the world grapples with the urgent need to mitigate climate change, understanding these interactions is essential for developing effective nature-based solutions. The findings suggest that sustainable grassland management must take into account the potential benefits of grazing, and that a one-size-fits-all approach to land management is unlikely to be successful. Future research should focus on identifying the key factors that determine the impact of grazing on soil carbon storage, and on developing management strategies that can be applied in different ecological contexts.

This research marks a significant step forward in our understanding of grassland ecosystems and their role in the global carbon cycle. It highlights the importance of long-term ecological studies in uncovering the complex dynamics that govern soil carbon storage. By providing evidence that grazing can be beneficial for soil carbon, the study opens up new possibilities for using grasslands as a tool for climate change mitigation. As we continue to seek ways to combat climate change, it is clear that we need to rethink our assumptions about land management and embrace a more nuanced understanding of the ecological processes that shape our planet. The findings of this study serve as a reminder that nature is complex, and that solutions to global challenges often require a deep understanding of the systems we seek to protect.

Subject of Research: Impact of livestock grazing on soil carbon storage in sub-arctic grasslands

Article Title: Does livestock grazing enhance or hinder soil carbon storage?

Article References: Does livestock grazing enhance or hinder soil carbon storage?. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: soil carbon, livestock grazing, grassland ecology, climate change, carbon sequestration, sub-arctic ecosystems, land management, nature-based solutions, Global Change Biology, Iceland, ecological shifts, root exudation