Scientists discovered something alarming seeping out from beneath the ocean around Antarctica
By Claire Thomson
News article: https://www.cnn.com/2025/10/10/climate/methane-seeps-antarctica
Journal article: https://doi.org/10.1038/s41467-025-63404-3
Background
Seafloor seeps, also called cold or marine seeps, are fissures in the seafloor that release gases and fluids rich in hydrocarbons. These seeps tend to form along areas of tectonic activity or continental margins, and are generally considered fairly stable. The methane and other chemicals released at these sites is mainly created by chemosynthetic microbes like methanogens [1]. This methane is often sequestered as methane hydrate, a solid form of methane that is stable only under sufficiently high pressures and low temperatures. When the hydrate dissociates, methane (and other gases or fluids) can be released into the ocean. Because the stability of methane hydrates is connected to temperature and to pressure (which depends on factors like ice sheet weight), climate change may affect the occurrence of methane hydrates [2].
Methane is a potent greenhouse gas, 28 times more effective than carbon dioxide but with a much shorter lifetime. According to the EPA, methane accounts for 11% of global greenhouse gas emissions, second only to carbon dioxide. Anthropogenic emissions of methane, which is the main component of natural gas and is released from landfills, fossil fuel production, and a variety of other sources, have caused the atmospheric concentration of methane to double over the last two centuries [3]. However, there are also natural sources of methane, including microbial activity. Methane hydrates are a natural source of methane to the ocean and the atmosphere when seafloor seeps form, raising concerns that these seeps could create a positive feedback loop that will cause rapid climate change [2]. A 2016 review by Ruppel and Kessler did not find evidence that methane from methane hydrates was impacting the atmosphere, as many factors influence whether the seafloor methane emissions traverse the water column and escape the water surface, but this may become a concern if seep activity increases substantially.
Peer-reviewed Article
In the article "Antarctic seep emergency and discovery in the shallow coastal environment" published in Nature Communications at the start of this month, Sarah Seabrook and co-authors describe the discovery of several seafloor methane seeps off the coast of Antarctica (see Figure 1). Seabrook et al. were motivated to search for methane seeps around Antarctica because methane emissions and subsurface fluid reservoirs in the region have been understudied, with more focus going to the Arctic. Additionally, the authors cite modeling studies that have predicted the presence of climate-reactive gases and fluids below the Antarctic ice. The researchers describe the locations of the discovered features, measure methane fluxes at some sites, and discuss how the presence of new seafloor seeps may affect the surrounding ecosystems, both locally and on a larger scale. The authors also posit a mechanism behind the increase in seep activity, proposing that the growing number of seeps is related to climate change and decreasing sea ice in the polar regions.
Figure 1. Figures 3b and 3d from Seabrook et al. 2025, images of two of the discovered methane seeps and associated ecosystems.
The researchers located the new seafloor seeps using a variety of exploratory methods during what they refer to as "primarily opportunistic surveys" in the Ross Sea. There were two main study regions: off the coast of Northern Victoria Land and McMurdo Sound. In the Victoria Land region, water column acoustic surveys were used to identify the seeps. This technique uses echosounders to "image" the water column and identify important features based on changes in the returned acoustic data (see Figure 2 below).
Figure 2. Figure 4c in Seabrook et al. 2025, an annotated acoustic echogram for a transect near a glacier ice tongue.
In McMurdo Sound, the seeps were identified by SCUBA divers or Remotely Operated Vehicles. At these sites, the researchers also took periodic samples from flux chambers deployed on the seafloor to measure methane emissions from the sediment at these sites, helping them constrain the amount of methane these seafloor seeps might contribute to the ocean or the atmosphere. McMurdo Sound was a particularly interesting region because the sites had been surveyed before, and this was the first study that found evidence for seeps, indicating recent formation.
With the discovery of increasing seep activity, the authors discuss possible reasons for this Antarctic phenomenon and explain some of the potential risks to the climate and local ecosystems. They suggest that melting ice sheets may lead to reduced pressure on methane hydrates below the ice, and argue that rising ocean temperatures may also contribute to the release of methane (and other fluids and gases) from the seafloor. There is a possibility that these seeps will lead to the emission of methane to the atmosphere, which could contribute to climate change. Furthermore, the authors report that the seeps alter the seafloor ecosystems, affecting the availability of key elements like oxygen and iron and changing which species can live at the site.
Laura Paddison's article "Scientists discovered something alarming seeping out from beneath the ocean around Antarctica", written for CNN, summarizes the findings of Seabrook et al. Paddison opens the article with a discussion of the existence of subsurface methane reservoirs and the current gaps in the scientific understanding, as well as methane's importance as a very effective greenhouse gas. The article then describes how the researchers identified upwards of 40 seeps, most of which were only recently formed. Quotes from study authors are used to explain the possibility of positive feedback loops that will affect the climate, with most of the article focusing on climate impacts and less on the impacts on local marine ecosystems. One quote from Seabrook explains how climate change and methane emissions in the Arctic are known to be connected, providing support for the argument that the same will occur in Antarctica. Paddison also mentions that the researchers are planning an expedition in the near future to gather more information.
Evaluation
The two main shortcomings of Paddison's article, in my opinion, were a lack of outside sources and an overuse of dramatic language. Paddison does interview Sarah Seabrook and Andrew Thurber, both co-authors on the study, which provides insight into the importance of the study beyond what is in the scientific article and helps clarify some of the study's points. However, it is relatively common for popular media articles to speak with scientists who were not involved in the research, in order to obtain a more objective opinion on the work and its impact. Additionally, the CNN article has a tendency to sensationalize the topic, as evidenced by the headline that using the words "something alarming". The article also describes methane as a "super-polluting gas", and uses quotes from Dr. Thurber that describe the seeps as "like a dangerous animal". Although Seabrook et al. do present real concerns and methane does have serious potential consequences as a greenhouse gas, the CNN article imparts a sense of anxiety to the reader, when in reality there is a lot left to learn about the Antarctic seeps, including the extent to which these emissions impact the atmosphere. That said, the research article itself uses language in the abstract like "striking" and "concerning", so it is understandable that Paddison would take this approach. Aside from these shortcomings, the news article does well at encapsulating the peer-reviewed article from beginning to end, and explains the importance of methane seeps in language that is accessible to the non-scientific community. Paddison faithfully reports the findings of the study, summarizing the author's motivation, results, and discussion of causes and impacts. The inclusion of pictures from the study is also very cool and helps make the science more accessible to the public. Overall, I would give this article an 8/10, because it summarizes the research article accurately and made the content understandable to a general audience, but also lacked clear outside sources and used language that was somewhat dramatic.
Sources
What is the difference between cold seeps and hydrothermal vents?; National Oceanic and Atmospheric Administration. https://oceanexplorer.noaa.gov/ocean-fact/seeps-vents/ (accessed 2025-10-26)
Ruppel, C. D. and Kessler, J. D. The interaction of climate change and methane hydrates. Reviews of Geophysics 2016, 55(1), 126-168. https://doi.org/10.1002/2016RG0005
Importance of Methane; U.S. Environmental Protection Agency. https://www.epa.gov/gmi/importance-methane (accessed 2025-10-26)
Claire, thank you for choosing this very interesting article and for your thorough analysis! It was both informative and fascinating. I had not heard about seafloor seeps before this, so it was great to learn about them. I really liked the videos shared in the article - they made it very clear how the researchers conducted some of their measurements.
ReplyDeleteIt was mentioned that there is a negative correlation between microbial mats and seafloor seepage - microbial mats decrease as seepage increases. I wonder if the chemosynthetic microbes might migrate to deeper parts of the ocean, where it is colder and more pressure, if climate change alters the shallow coastal regions and the ecosystems they are adapted to.
Additionally, I have a few questions:
1. Is it possible for dissociated methane gas to dissolve in the water and then be consumed by microbes in the water column, so that it does not reach the surface and get released into the atmosphere?
2. For the Northern Victoria Land, how do the researchers know that the acoustic signals they observed represent methane seeps and not other types of seafloor features or water column anomalies? For the McMurdo Sound, I know they used flux chambers which gives them good results of what is being released.
3. If these methane seeps become a significant problem in the near future, is it possible to harvest methane hydrates before they dissociate, or would attempting to do so cause even greater harm to the environment?
Thank you!
Hi Frozan, thanks for your questions! Here are my answers to the best of my understanding:
Delete1. Yes! Consumption by microbes is a substantial sink for methane released from the seafloor, although it seems like there's still ongoing research into the magnitude of this sink. In the water column, aerobic microbial oxidation uses up dissolved methane, and even before that methane is anaerobically oxidized while still in the seafloor sediments. This is one reason Ruppel and Kessler (2016) argue that methane hydrate emissions won't necessarily have a huge impact on the atmosphere.
2. That's a really good question – I don't completely understand the acoustic data, but I think it's a combination of previous studies, the material properties of the seeps, and associated indicators of methane emissions. Seabrook et al. write that "fluid plumes were identified as 'hazy' signal connected to the seafloor" and that specific frequencies were best for identifying the fluid and bubble plumes, so I think the reflectivity measurement and the spatial pattern of the signal allow for some differentiation between different water column anomalies.
3. The idea of harvesting the hydrates to preempt dissociation is really interesting, and something that I think is a possibility because I've come across at least one recent journal article that talked about exploiting marine methane hydrates as an energy source. That said, I also do think there would be many risks associated with recovering the hydrates, such as locally destabilizing the seabed or disrupting biogeochemical cycles in the region (although increasing methane emissions may already be doing that).
Your comment about the shift in the habitat of the chemosynthetic microbes is something I had not considered. I believe the microbial mats are actually positively correlated with the seafloor seeps, as the mats are (to my knowledge) made of methane-eating microbes. Regardless, it would be interesting to learn how those microbial communities are affected by the changes in seep activity and if they are moving to new locations due to other climate-driven changes.
Thank you so much Claire for taking the time to respond to my questions!
DeleteHi Claire, this is a really interesting topic and you wrote a great analysis! I agree with your rating of the article and I especially appreciate how the news article used content from the authors of the peer reviewed article. I do also agree with your point about sensationalizing language, specifically around methane. There is a lot of misinformation about greenhouse gases, and emphasizing which are the most potent and what their sources are is incredibly important for education of the general public. I'm curious about the role of seeps in global methane emissions. You mentioned that seeps are not currently a significant contributor of atmospheric methane that causes warming, but that this could change is seeps increase dramatically. Do you know what the threshold is for when seeps will become a significant contributor? How will scientists know when that threshold has been reached and are there methods of limiting the amount of methane released from seeps (aside from limiting emissions that trigger more seeps to be present)?
ReplyDeleteHi Eliza, thanks for your comments! I was trying to find a definitive answer on if/when methane seeps would become a serious problem for global warming, but as far as I can tell there's still not a consensus. The possibility of a rapid feedback between methane and global warming was popularized by the 'clathrate gun' hypothesis in the early 2000s, which linked past warming events to rapid dissociation of methane hydrates, also known as clathrates. Recently, however, it seems like the scientific literature has mostly taken the view that methane seeps are unlikely to trigger a catastrophic feedback loop on a timescale relevant to humans (as opposed to over the course of millenia). That said, Seabrook et al. use the possibility of methane emissions to the atmosphere as motivation for their study, and they do cite some more recent work showing that methane can be released to the atmosphere from these shallower seafloor seeps in other regions, so I don't think the matter is quite settled. In terms of methods to limit the amount of methane released from seeps, I haven't come across anything besides some talk of extracting methane from gas hydrates, but that is mostly for energy purposes and not to prevent methane emissions.
DeleteHi Claire, I really enjoyed your analysis. I agree that news articles sometimes have a habit of over-exaggeration. To what I understand, the article seemed to lean more theoretical and contemplating. A study that is underway and makes a lot of sense but without confirmed statistical evidence to back any extreme environmental impact as of today. I definitely think it is worth following to see if these floor seeps increase dramatically and if the gases coming out of it do indeed lead to a positive feedback loop; although looking back, maybe it's best we never find out. At least until we find more ways to be able to get a handle on the effects of the increasing concentration of greenhouse gases. I know you mentioned they said this positive feedback loop will leap to rapid climate change; was there any information exploring how to prevent that?
ReplyDeleteThanks for your comments Elizabeth! I agree that increasing the methane seep activity and seeing if atmospheric emissions are affected is an experiment I would rather avoid. Luckily this is already an area of fairly active research, and the authors of this study are conducting further investigations in Antarctica so I'm curious to see what publications they come out with in the future. I haven't come across anything about preventing the feedback loop between seafloor seep emissions and global warming, but I honestly think that it's not considered the most important concern right now because there are doubts about the true possibility and strength of this feedback loop. Recovering or harvesting these methane hydrates from the seafloor is one possibility, but I've seen that discussed mostly in the context of energy production and it would likely bring a whole host of other issues.
DeleteHi Claire, what a fascinating topic you chose! I've never heard of cold seeps before today. I agree with your analysis that the news article was quite sensational, although I was surprised to hear that the research paper used some more sensationalized language as well, as scientific writers tend to try to be more objective with their word choice. I appreciate that you described how the melting sea ice or increasing temperatures may lead to increased cold seeps. I am curious as to why two different analytical techniques were used to assess the location and severity of these cold seeps in each region. I wonder if it may impact the confidence in the data?
ReplyDeleteHi Elena! I also found it interesting that the researchers used different methods between the two locations, and I think you raise a legitimate concern about the validity of comparing findings between the two study sites. The number and location of seafloor seeps might be slightly more uncertain in the Northern Victoria Land region because I don't think these seeps were all directly observed, but the authors did use supporting data like water column properties and camera surveys which increase confidence in their identification of the seeps. It would be useful to have methane flux measurements from both regions, though, to see if there are spatial differences. The authors say that the surveys were "primarily opportunistic" and that they discovered the new seeps at McMurdo Sound during routine surveys, so I suspect the differing methodology is just due to what was available to them in each region.
DeleteThanks so much for sharing this article. I was excited to read an article about the Southern Hemisphere, as it is an understudied region. I read both articles prior to reading your analysis, and initially, I thought the new article did an excellent job summarizing and building upon the findings in the journal article. My perspective shifted slightly after reading your analysis, as I agree with your critique of the author's overexaggeration of the fact that methane is being released from these seeps. The journal article voiced lots of uncertainty and a need for future studies, which I think is valid since the Southern Ocean is incredibly understudied. Despite this drawback, I think there are more positives than negatives about the news article. There was a great hook at the beginning to capture the reader's interest in the topic. The science was explained simply and effectively, and I appreciated how the authors were quoted and the paper was linked.
ReplyDeleteHi Caroline, thanks for your comments! I agree that the news article did a great job summarizing the research study and that it was overall a good explanation of the science for a general audience. As much as I rather dislike that the CNN article focused primarily on climate impacts instead of impacts to the benthic ecosystem which are better understood, you make a good point that the possible climate impacts are what capture readers' attention. Also to the CNN author's credit, they don't make any claims beyond what the scientists themselves suggested. And because, like you mentioned, the study authors argue for future investigation, it's completely understandable to me that they would focus on the possible bigger impact climate issues rather than changes to the seafloor wildlife, which may seem less important to a general audience and are more certain.
DeleteHi Claire, great analysis! This topic was so interesting to read about. I liked the addition of videos of the methane seeps in the CNN article but I agree that much of the word-choice over dramatizes the peer-reviewed article.
ReplyDeleteI found it very interesting that the seeps were so new. What are some of the findings from the paper about the impacts of the methane seeps on the surrounding ecosystems?
The videos in the CNN article showed the methane seeps at a shallower depth than I had visualized. What depth were these methane seeps found at? And at what depths would the risk of methane entering the atmosphere be more of an issue?
Hi Ava, thanks for your questions! Seabrook et al. describe fluid seep ecosystems which are distinct from those surrounding the seeps, with the plumes themselves having limited fauna within them and around their edges. Some of the main concerns the article discusses in regard to the benthic ecosystems at these seeps are oxygen depletion, ocean acidification (because methane oxidation produces CO2), and the release of dissolved iron. Each of these factors could affect nutrient cycling and primary productivity locally or possibly on larger scales. To address your second question, the methane seeps were identified from depths of 5 to 240 meters, although the researchers did sample deeper locations. I believe that shallower seeps are more of a concern when it comes to atmospheric emissions, because there is less time in the water column for the methane to be eaten by microbes or to diffuse into the water.
Delete