A new study reveals how oxygen first reached Earth’s oceans
Researchers use vanadium isotopes to track the rise of oxygen in ancient seas
Woods Hole Oceanographic Institution
image:
South Africa’s exceptionally preserved ancient rocks hold key evidence for the rise ofatmospheric oxygen. Within them, researchers see the disappearance of sulfur mass-independent fractionation, evidence for a GOE.
view moreCredit: Photo by Daniel Hentz, ©Woods Hole Oceanographic Institution
Woods Hole, Mass (December 9, 2025) – For roughly two billion years of Earth’s early history, the atmosphere contained no oxygen, the essential ingredient required for complex life. Oxygen began building up during the period known as the Great Oxidation Event (GOE), but when and how it first entered the oceans has remained uncertain.
A new study published in Nature Communications shows that oxygen was absorbed from the atmosphere into the shallow oceans within just a few million years—a geological blink of an eye. Led by researchers at Woods Hole Oceanographic Institution (WHOI), the work provides new insight into one of the most important environmental shifts in Earth’s history.
“At that point in Earth’s history, nearly all life was in the oceans. For complex life to develop, organisms first had to learn not only to use oxygen, but simply to tolerate it,” said Andy Heard, lead author of the study and assistant scientist at WHOI. “Understanding when oxygen first accumulated in Earth’s atmosphere and oceans is essential to tracing the evolution of life. And because ocean oxygenation appears to have followed atmospheric oxygen surprisingly quickly, it suggests that if we detect oxygen in the atmosphere of a distant exoplanet, there’s a strong chance its oceans also contain oxygen.”
Researchers used new chemical analyses of black shales, organic-rich marine sedimentary rocks from South Africa, that formed in the ocean during the ongoing Great Oxidation Event. They found that the trace metal vanadium saw a shift in the relative abundance of its stable isotopes in shales formed before and after the stratigraphic level marking the occurrence of oxygenation in the atmosphere.
“South Africa is one of the few places on Earth with exceptionally well-preserved rock records from this pivotal time in our planet’s history. These sedimentary rocks play host to some of our strongest indicators for the rise of atmospheric oxygen,” said Chad Ostrander, one of the study’s co-authors and an isotope geochemist at the University of Utah. “These rocks have relatively tight age constraints, and within them we see the disappearance of sulfur mass-independent fractionation—the traditional ‘smoking gun’ evidence for a GOE.”
“Vanadium is especially powerful because it responds to relatively high levels of dissolved oxygen compared to other geochemical proxies used for this period of Earth’s history. That means we can detect when oxygen in the oceans first rose above roughly 10 micromoles per liter—a few percent of modern levels,” said Sune Nielsen, one of the study's co-authors and adjunct scientist at WHOI. Nielsen is also noted as one of the first scientists to use the vanadium isotope redox method to study past ocean oxygen levels. “For context, today’s oceans average about 170 micromoles of dissolved oxygen per liter. It’s not much by modern standards, but in oceans that were previously almost entirely oxygen-free, it represents a major step in Earth’s oxygenation.”
These findings show that Earth’s oceans began accumulating oxygen far earlier, and more rapidly, than previously thought, reshaping our understanding of how the planet became habitable for complex life.
“This study helps clarify one of the biggest turning points in Earth’s history,” Heard continued. “By tracing when oxygen first reached the oceans, we’re getting closer to understanding how the conditions for complex life emerged on our planet—and how they might arise elsewhere.”
This work was funded by NASA Exobiology, the WHOI postdoctoral scholar program, the Agouron Institute Fellowship in Geobiology, Discovery and Accelerator Grants from the Natural Sciences and Engineering Research Council of Canada, ACS Petroleum Fund, and the Natural Environmental Research Council.
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About Woods Hole Oceanographic Institution
Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Founded in 1930, its mission is to understand the ocean, its interactions with the Earth, and its role in a changing global environment. WHOI’s pioneering discoveries arise from a unique blend of science and engineering that has made it one of the world’s most trusted leaders in ocean research and exploration. Known for its multidisciplinary approach, advanced ship operations, and unmatched deep-sea robotics, WHOI also operates the most extensive suite of ocean data-gathering platforms worldwide. More than 800 concurrent projects—driven by top scientists, engineers, and students—push the boundaries of knowledge to inform people and policy for a healthier planet. Behind the scenes, ship captains, mates, craftsmen, marine operations, and other skilled professionals provide essential support that makes this work possible. Learn more at whoi.edu.
Caption
Researchers analyzed South African black shales and found a shift in vanadiumisotopes across the GOE interval, providing evidence for when Earth’s oceans first becameoxygen-rich.
Credit
(Photo by Daniel Hentz, ©Woods Hole Oceanographic Institution)
Journal
Nature Communications
Method of Research
Meta-analysis
Subject of Research
Not applicable
Article Title
Onset of persistent surface ocean oxygenation during the Great Oxidation Event
Article Publication Date
9-Dec-2025
Ocean current and seabed shape influence warm water circulation under ice shelves
image:
Autonomous underwater vehicle Boaty McBoatface was used to gather data from underneath the Dotson Ice Shelf.
view moreCredit: Hannah Wyles
New research reveals how the speed of ocean currents and the shape of the seabed influence the amount of heat flowing underneath Antarctic ice shelves, contributing to melting.
Scientists at the University of East Anglia (UEA) used an autonomous underwater vehicle to survey beneath the Dotson Ice Shelf in the Amundsen Sea, an area of rapid glacial ice loss largely due to increasing ocean heat around and below ice shelves.
The circulation of warm water and the heat transport within ice shelf cavities - significant areas beneath ice shelves - remains mostly unknown. To address this the team collected data from over 100 kilometres of dive tracks the underwater robot made along the seabed in the Dotson cavity.
The findings are published today in the journal Ocean Sciences.
Lead author Dr Maren Richter, from UEA’s Centre for Ocean and Atmospheric Sciences, said: “Upward transport of deep warm water to the shallower ice-ocean boundary in ice shelf cavities is what drives melting at the underside of the ice shelf. This melting makes the ice shelf thinner, and therefore less strong.
“We found that while there is mixing of warm water with other, cooler, water, under the Dotson Ice Shelf most of the warm water is not mixed upward. Instead, it flows horizontally to the grounding line, the point where the glacier loses contact with the seabed and starts to float.
“This means that the water stays warm all the way to the grounding line, where it can melt the glacier directly. This can cause the glacier to retreat, speed up and lose more ice into the ocean. Together, the retreat, increased speed, and increased melt contribute to sea level rise globally.”
During the mission, the first of its kind under the Dotson Ice Shelf, the researchers found warm, salty water below colder, fresher water. It is already known that warm water is transported upward by mixing, however this study shows that the mixing and upward transport of warm water are strongest in the inflow areas to the east of the ice shelf, where the currents are faster and the seabed is steep, with the gradient of the bedrock being particularly significant.
Current speeds recorded in this area by the Autosub Long Range (ALR) autonomous underwater vehicle - named Boaty McBoatface and operated by the National Oceanography Centre - were around five centimetres per second up to 10 centimetres per second. The gradient was about 45 degrees in the steepest areas.
Dr Richter added: “We were expecting the influence of current speed on the mixing to be much higher than what we found. Instead, the shape of the seabed seems to be really important.
“We also found water in the deepest part of the cavity that was surprisingly warm, and we are now working to explain how and when it got there.”
The data was collected over four missions in 2022 when Boaty, equipped with sensors to measure properties of the water including temperature, current, turbulence (mixing) and oxygen, travelled along the bottom of the ice shelf cavity, staying about 100 metres above the seabed. Boaty was in the cavity for approximately 74 hours.
Missions to send a robot into an ice shelf cavity and then get it back at the end are very difficult, and ones with an instrument that can measure mixing are especially rare.
“This mission was the first of its kind under the Dotson Ice Shelf,” said Dr Richter. “We gained very valuable baseline measurements which can now be compared to assumptions about mixing in regional and global models of ice shelf-ocean interactions, and to measurements under other ice shelf cavities, helping us understand how these cavities are similar or different from each other.”
Warm deep water that is mixed upward not only increases the temperature in the upper ocean, it can also transport nutrients and trace-metals upward, which is very important for local algae blooms and the creatures that depend on them for food.
While this study did not measure nutrient transports through mixing, the data can be used by other researchers who want to calculate the effects of mixing in the cavity.
The work was carried out as part of a project for the International Thwaites Glacier Collaboration, a major five-year research programme aiming to understand what is causing ice loss and better predict how this could contribute to sea level rise. It was funded by the UK’s Natural Environment Research Council and the US National Science Foundation.
‘Observations of turbulent mixing in the Dotson Ice Shelf cavity’, Maren Richter, Karen Heywood, Rob Hall and Peter Davis, is published in Ocean Sciences on December 10.
The Dotson Ice Shelf, Antarctica
Credit
Anna Wåhlin, University of Gothenburg
Autonomous underwater vehicle Boaty McBoatface was used to gather data from underneath the Dotoson Ice Shelf in Antarctica.
Credit
Hannah Wyles
Method of Research
Data/statistical analysis
Subject of Research
Not applicable
Article Title
‘Observations of turbulent mixing in the Dotson Ice Shelf cavity
Article Publication Date
10-Dec-2025
Tsinghua University Press launches ocean journal to promote global marine research collaboration
Tsinghua University Press
Tsinghua University Press is pleased to announce the official launch of Ocean (www.sciopen.com/journal/3008-1203), an international, peer-reviewed open-access journal dedicated to advancing research in ocean science, technology, and engineering. Ocean serves as a multidisciplinary platform for the latest research and innovations in these fields, with a focus on sustainable global development.
The journal will publish original research articles, reviews, and perspectives, showcasing the most recent advancements in theoretical, experimental, and numerical research within the marine domain.
“Ocean brings together cutting-edge research from marine biogeochemistry to ocean engineering, addressing critical global issues,” said Professor Jian-Min Zhang, Editor-in-Chief of Ocean. “We believe this journal will set a new benchmark in global marine research, fostering interdisciplinary collaboration and solving pressing challenges in ocean science and technology.”
Ocean aims to provide a high-level platform for academic exchange, promoting collaboration among marine experts and researchers worldwide. The journal’s editorial board includes renowned scholars from across the globe, ensuring the highest standards of academic quality and peer review.
“We are excited to offer Ocean as an open-access platform that ensures the broad dissemination of research globally,” said Professor Zhang. “The journal will cover various topics, from ocean science and engineering to emerging technologies, providing scientific and technological support for the sustainable development of ocean resources.”
The journal will implement a rigorous peer-review process to maintain high academic standards. Submissions are now open, and the first articles will be published soon on the journal’s website.
In addition to scientific advancements, Ocean will explore new technologies in the marine industry, such as ocean robotics and digital twins, providing innovative solutions for ocean resource management and environmental protection.
“With the support of the global academic community and industry, Ocean is set to become a key platform for advancing ocean research and technology,” Professor Zhang said. “We look forward to Ocean becoming an academic flagship in the global marine field, driving significant breakthroughs in marine science and engineering.”
Tsinghua University Press is pleased to announce the official launch of Ocean (www.sciopen.com/journal/3008-1203), an international, peer-reviewed open-access journal dedicated to advancing research in ocean science, technology, and engineering. Ocean serves as a multidisciplinary platform for the latest research and innovations in these fields, with a focus on sustainable global development.
The journal will publish original research articles, reviews, and perspectives, showcasing the most recent advancements in theoretical, experimental, and numerical research within the marine domain.
“Ocean brings together cutting-edge research from marine biogeochemistry to ocean engineering, addressing critical global issues,” said Professor Jian-Min Zhang, Editor-in-Chief of Ocean. “We believe this journal will set a new benchmark in global marine research, fostering interdisciplinary collaboration and solving pressing challenges in ocean science and technology.”
Ocean aims to provide a high-level platform for academic exchange, promoting collaboration among marine experts and researchers worldwide. The journal’s editorial board includes renowned scholars from across the globe, ensuring the highest standards of academic quality and peer review.
“We are excited to offer Ocean as an open-access platform that ensures the broad dissemination of research globally,” said Professor Zhang. “The journal will cover various topics, from ocean science and engineering to emerging technologies, providing scientific and technological support for the sustainable development of ocean resources.”
The journal will implement a rigorous peer-review process to maintain high academic standards. Submissions are now open, and the first articles will be published soon on the journal’s website.
In addition to scientific advancements, Ocean will explore new technologies in the marine industry, such as ocean robotics and digital twins, providing innovative solutions for ocean resource management and environmental protection.
“With the support of the global academic community and industry, Ocean is set to become a key platform for advancing ocean research and technology,” Professor Zhang said. “We look forward to Ocean becoming an academic flagship in the global marine field, driving significant breakthroughs in marine science and engineering.”
About the Journal
Ocean (ISSN: 3008-1203) is an international, peer-reviewed, open-access journal hosted by Tsinghua University. The journal is dedicated to publishing cutting-edge research in ocean science, technology, and engineering. It focuses on interdisciplinary studies and promotes innovation across the marine sciences, including oceanography, marine ecology, ocean engineering, and more.
Ocean (ISSN: 3008-1203) is an international, peer-reviewed, open-access journal hosted by Tsinghua University. The journal is dedicated to publishing cutting-edge research in ocean science, technology, and engineering. It focuses on interdisciplinary studies and promotes innovation across the marine sciences, including oceanography, marine ecology, ocean engineering, and more.
About Tsinghua University
Tsinghua University, founded in 1911, is a world-class top-tier institution in China. Renowned for its strengths in science, engineering, humanities, and social sciences, it embraces a multidisciplinary approach. Committed to innovation and global collaboration, Tsinghua nurtures outstanding talents and drives cutting-edge research, striving to address global challenges and contribute to human progress.
Tsinghua University, founded in 1911, is a world-class top-tier institution in China. Renowned for its strengths in science, engineering, humanities, and social sciences, it embraces a multidisciplinary approach. Committed to innovation and global collaboration, Tsinghua nurtures outstanding talents and drives cutting-edge research, striving to address global challenges and contribute to human progress.
About Tsinghua University Press
As an integral part of China's most prestigious university, Tsinghua University Press (TUP) was established in 1980 and has since evolved into a leading comprehensive publisher in China. TUP publishes 64 academic journals, 44 of which are in English, with 24 indexed in the Web of Science Core Collection. Additionally, TUP has developed SciOpen, an innovative digital publishing platform offering end-to-end services for the production, publication, and dissemination of STM journals.
As an integral part of China's most prestigious university, Tsinghua University Press (TUP) was established in 1980 and has since evolved into a leading comprehensive publisher in China. TUP publishes 64 academic journals, 44 of which are in English, with 24 indexed in the Web of Science Core Collection. Additionally, TUP has developed SciOpen, an innovative digital publishing platform offering end-to-end services for the production, publication, and dissemination of STM journals.
Journal
Ocean
Ocean
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