It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Wednesday, November 05, 2025
New study reveals southern ocean’s winter CO₂ outgassing underestimated by 40%
A collaborative research team has discovered that the Southern Ocean releases substantially more carbon dioxide (CO2) during the dark austral winter than previously thought. Their new study reveals that this winter outgassing has been underestimated by up to 40%.
The team comprises researchers from the Second Institute of Oceanography, Ministry of Natural Resources (SIO-MNR), and the Nanjing Institute of Geography and Limnology (NIGLAS) of the Chinese Academy of Sciences. Their findings were published in Science Advances on Nov. 5.
The Southern Ocean plays a pivotal role in the global carbon cycle, absorbing a significant portion of human-caused CO2. However, it remains the "largest source of uncertainty" in global CO2 flux estimates.
This uncertainty stems from a critical data gap. Shrouded in polar darkness and battered by harsh weather, the region becomes an "observational black box." Traditional satellites, which rely on sunlight (passive sensors) to measure ocean properties, are unusable during this period, forcing scientists to depend on incomplete models.
To address this challenge, the team adopted an innovative methodology, integrating 14 years of data from satellite LIDAR (on the CALIPSO mission) with machine learning.
Unlike passive sensors, LIDAR is an active sensor that operates like radar but uses a laser, carrying its own light source. This enabled the researchers to "see" in the dark and provide the first-ever year-round, observation-based assessment of these critical winter fluxes.
The study confirmed the 40% underestimation of the winter CO2 source. "Our findings suggest that the Southern Ocean's role in the global carbon cycle is more complex and dynamic than previously known," said Prof. SHI Kun from NIGLAS.
The findings do not just revise the numbers; they reshape the fundamental understanding of how the Southern Ocean's carbon cycle functions. The team proposed a new "three-loop framework" to mechanistically explain the different processes controlling CO2 exchange at different latitudes.
In the Antarctic Loop (south of 60°S), CO2 exchange is dominated by physical processes such as sea ice dynamics and salinity. In the Polar Front Loop (45°S–60°S), a complex interplay between atmospheric CO2 and biological activity (chlorophyll) was identified. In the Subpolar Loop (north of 45°S), CO2 exchange is primarily controlled by sea surface temperature.
Correcting this gap has implications for the global carbon budget, which serves as the basis for climate models used by bodies like the Intergovernmental Panel on Climate Change (IPCC) to project future climate scenarios.
This work underscores the innovative application of active remote sensing in global climate studies.
URI climate scientist contributes to research illustrating future impacts of Antarctic ice sheet melting
Geosciences professor Ambarish Karmalkar is part of team using interactive modeling to predict impact of ice sheet meltwater discharge on climate and sea level
Melting of the Antarctic ice sheet due to global warming has long-term, irreversible societal impacts with important implications for people around the world; shown: Southern Ocean from NBP1502. (Photo / Anna Ruth Halberstadt)
Melting of the Antarctic ice sheet due to global warming has long-term, irreversible societal impacts with important implications for people around the world. Spatial patterns of sea level change from ice sheet mass loss vary in cause, and have world-wide impacts.
Despite the importance of understanding global impacts of ice sheet mass loss, imperfect understanding of ice sheet-climate interactions poses challenges for projecting the impacts it has on the world’s future climate and sea levels.
Ambarish Karmalkar, an assistant professor in the University of Rhode Island’s Department of Geosciences, has partnered with lead author Shaina Sadai and colleagues to better simulate ice sheet-climate interactions and their evolution over the next century. The team published their findings in the recent issue of Nature Communications, reporting that sea level and climate projections are significantly different from simulations that lack interactive ice sheets and realistic Antarctic meltwater discharge.
To study the effects of Antarctic ice sheet melting, the team designed an experiment depicting simultaneous interactions between the ice sheet, ocean, and atmosphere. Their results show that while cold Antarctic meltwater will slow human-induced warming, it also causes uneven sea level rise and significant climatic changes worldwide, highlighting the importance of lowering greenhouse gas emissions.
Working in collaboration with other modelers, Sadai set up and ran simulations on a supercomputer and assembled a team of sea level, ocean, and atmosphere experts, including Karmalkar, to analyze the simulation results. “We predict higher regional sea levels for low-lying islands in the Pacific due to melting in Antarctica,” says Karmalkar. “Simulating ice-sheet-climate interactions also indicates higher Northern Hemisphere temperatures and altered precipitation patterns worldwide.”
“Doing this kind of modeling work is challenging but critical to understanding the full impact of global warming on ice sheets, and how the ice sheets, in turn, affect the climate,” says Karmalkar, who is part of URI’s new specialization in water and climate science. He studies changes in atmospheric and oceanic conditions and their impact. A key focus of his research looks at climate trends, variability, and extremes in different parts of the world, with an emphasis on understanding the atmospheric and oceanic drivers of regional climate change. His career has brought him into varied terrain, from studying fire-climate-vegetation dynamics in the eastern U.S. and climate extremes in the Arctic to work on climate projects across the Americas.
Assessing climate and sea level changes
The team’s research predicts that while Antarctic meltwater will dampen temperature rise in the Southern Hemisphere, it can lead to warming in the North Atlantic and surrounding regions, including in eastern North America.
The paper also notes that insufficient global mitigation could lead to large-scale ice sheet mass loss, exposing people and ecosystems around the world to substantial sea level rise. By 2060, over one billion people could be living in low elevation coastal areas, increasing the risk of sea level rise impacts for socially and geographically vulnerable populations. Understanding interactions between ice sheets and the broader climate system are key to constrain future Antarctic ice sheet stability, global climate, and sea level. The group notes that current pledges submitted by parties to the United Nations Framework Convention on Climate Change are insufficient for meeting the Paris Agreement’s long-term temperature goal of limiting global mean surface temperature rise. Robust mitigation will be crucial for preventing Antarctic ice sheet mass loss and resulting sea level rise.
Their modeling experiment predicts a contribution to sea level rise from the East Antarctic Ice Sheet in a very high emissions scenario. This is especially noteworthy because the ice sheet in East Antarctica is enormous but is currently more stable than its counterpart in West Antarctica. The study shows that the Antarctic contribution to sea level rise by 2200 is over 3m (10 feet) in a very high emissions scenario and about 1m (3 feet) in a medium emissions scenario, underscoring the importance of reducing greenhouse gas emissions.
Consistent with prior research, the team found that regions of the world far away from Antarctica will experience higher sea level rise due to gravitational and Earth deformational effects. They predict that regional sea level rise of up to 1.5m (5 feet) will occur in the Pacific and Indian Ocean basins and Caribbean Sea. In other words, the loss of ice sheet mass will drive substantial sea level rise. Even with a slower rate of warming, any continued increase in sea level poses risks to island and coastal communities, raising wide-ranging issues of intergenerational inequity and injustice as the lead author Sadai has shown in her previous research. Last week’s destruction in the Caribbean caused by Hurricane Melissa shows how storm surge can devastate vulnerable coastal communities.
“Rising sea levels makes these impacts worse, which is why studies like this that quantify the uneven future rise in sea level are absolutely critical,” says Karmalkar.
The team’s work was supported by funding from the National Science Foundation and the National Center for Atmospheric Research.
Peppers from Spain or from Germany? When consumers assess the environmental impact of food, their decision largely depends on its origin. This is shown by a new survey by researchers at the University of Göttingen. According to the survey, domestic products in supermarkets are perceived as particularly environmentally friendly. But this impression can be misleading. The results raise questions about the design of labelling and advertising. The study has been published in the journal Food Quality and Preference.
The researchers surveyed around 1,000 people in Germany about the environmental impact of peppers, apples and beef from Germany, EU countries and non-EU countries. “The data shows a clear pattern,” explains Dorothea Meyer, lead author and PhD researcher in Marketing for Food and Agricultural Products. “Imported food – especially from non-EU countries – is perceived as significantly more damaging to the environment. However, it can be similar or in fact even more environmentally friendly than local products.” For example, Spanish peppers from unheated greenhouses often have environmental advantages over German peppers from heated facilities, which consume more energy due to less favourable conditions. “There can be many advantages to choosing regional products. However, environmental friendliness is not always one of them. It is worth taking a closer look here,” says Meyer. International trade is not necessarily harmful to the environment. In particular, the impact of transport is often overestimated.
The study concludes that information about origin should therefore be more precise and disclose the actual impact on the environment. “Information about origin alone is not enough to inform correct decision-making about sustainability,” emphasises Professor Achim Spiller from the same research group. “Instead, information is needed that makes the actual impact clearer, for example through climate or environmental labels.” This could prevent consumers from accidentally choosing foods that are more damaging to the environment.
Original publication: Dorothea Meyer, Achim Spiller, Sarah Iweala. “Perceived environmental impact of food: Upgrading of domestic products and downgrading of imported products.” Food Quality and Preferences (2025). DOI: 10.1016/j.foodqual.2025.105718
Contact:
Dorothea Meyer
University of Göttingen
Marketing for Food and Agricultural Products
Platz der Göttinger Sieben 5, 37073 Göttingen, Germany
The ITU delegation, led by Deputy Secretary-General Tomas Lamanauskas, will work with governments, private-sector leaders, and civil society to leverage digital transformation as a catalyst for climate solutions and work toward a sustainable digital sector.
Why digital technologies at COP30 matter
As global demand for technology grows, the tech sector's environmental impact cannot be ignored. The sector's energy consumption particularly is rising significantly as artificial intelligence, cloud computing, and digital systems expand. COP30 provides a crucial opportunity to address this challenge while harnessing technology's potential to drive climate solutions across sectors.
Building on the momentum from COP28 and COP29, the Green Digital Action track at COP30, convened by ITU together with a coalition of over 50 partners, will demonstrate how commitments made through the initiative are translating into practical tools, measurable data, and tangible results.
Highlights for reporters:
10 November 2025:
High-Level Roundtable – Leadership and Action Towards a Green Digital Future (Special Events Room 2 – “Madeira”, 16:30-18:00), in partnership with the COP30 Presidency.
11 November 2025:
Measuring What Matters – Balancing AI Innovation, Impact, and Sustainability (UN Climate Change Global Innovation Hub – SPE 4, 09:00-10:00).
Advancing Green Digital Action Towards a Net-Zero ICT Sector (UN Brazil Pavilion, 15:00-16:30).
12 November 2025:
Digital Pathways to a Greener Future: Empowering Climate Solutions Through Technology (Side Event Room 2, 11:30-13:00).
AI Innovation Factory (Standards Pavilion, 14:30-15:45).
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Editor’s notes:
The full list of Green Digital Action events is available here.
ITU’s COP30 media kit and latest data is available here.
Interviews with ITU representatives, including Deputy Secretary-General Tomas Lamanauskas, may be available upon request. Please contact pressinfo@itu.int.
For more information about the Green Digital Action initiative, please click here.
