̽��ֱ�� of Cambridge - oceans

Thriving Antarctic ecosystems found following iceberg calving

Anonymous — Tue, 25 Mar 2025 10:22:45 +0000

An international team of scientists have uncovered a thriving underwater ecosystem off the coast of Antarctica that had never before been accessible to humans.

̽��ֱ��team, including researchers from the ̽��ֱ�� of Cambridge, were working in the Bellingshausen Sea off the coast of Antarctica when a massive iceberg broke away from the George VI Ice Shelf in January of this year.

̽��ֱ��team, on board Schmidt Ocean Institute’s R/V Falkor (too), changed their plans and reached the newly exposed seafloor 12 days later, becoming the first to investigate the area.

Their expedition was the first detailed study of the geology, physical oceanography, and biology beneath such a large area once covered by a floating ice shelf. ̽��ֱ��A-84 iceberg was approximately 510 square kilometres (209 square miles) in size, and revealed an equivalent area of seafloor when it broke away from the ice shelf.

"We seized upon the moment, changed our expedition plan, and went for it so we could look at what was happening in the depths below," said expedition co-chief scientist Dr Patricia Esquete from the ̽��ֱ�� of Aveiro, Portugal. "We didn't expect to find such a beautiful, thriving ecosystem. Based on the size of the animals, the communities we observed have been there for decades, maybe even hundreds of years.”

Using Schmidt Ocean Institute’s remotely operated vehicle, ROV SuBastian, the team observed the deep seafloor for eight days and found flourishing ecosystems at depths as great as 1300 meters.

Their observations include large corals and sponges supporting an array of animal life, including icefish, giant sea spiders, and octopus. ̽��ֱ��discovery offers new insights into how ecosystems function beneath floating sections of the Antarctic ice sheet.

Little is known about what lies beneath Antarctica’s floating ice shelves. In 2021, British Antarctic Survey researchers first reported signs of bottom-dwelling life beneath the Filchner-Ronne ice shelf in the Southern Weddell Sea. ̽��ֱ��current expedition was the first to use an ROV to explore this remote environment.

̽��ֱ��team was surprised by the significant biomass and biodiversity of the ecosystems and suspect they have discovered several new species.

Deep-sea ecosystems typically rely on nutrients from the surface slowly raining down to the seafloor. For centuries, the ecosystems under the ice shelf have been covered by ice almost 150 metres thick, completely cutting them off from surface nutrients. " ̽��ֱ��fact that we found long-living species suggests that the lateral transport, which mostly consists of glacial meltwater from the ice shelf, could be the source of the nutrients to sustain the life we found," said team member Dr Laura Cimoli, from Cambridge’s Department of Applied Mathematics and Theoretical Physics.

̽��ֱ��newly exposed Antarctic seafloor also allowed the team, with scientists from Portugal, the United Kingdom, Chile, Germany, Norway, New Zealand, and the United States, to gather critical data on the past behaviour of the larger Antarctic ice sheet. ̽��ֱ��ice sheet has been shrinking and losing mass over the last few decades due to climate change.

“ ̽��ֱ��ice loss from the Antarctic Ice Sheet is a major contributor to sea level rise worldwide,” said expedition co-chief scientist Sasha Montelli of ̽��ֱ�� College London (UCL). “Our work is critical for providing longer-term context of these recent changes, improving our ability to make projections of future change — projections that can inform actionable policies. We will undoubtedly make new discoveries as we continue to analyse this data.”

“We were thrilled by the opportunity to explore the newly exposed seafloor,” said team member Dr Svetlana Radionovskaya from Cambridge’s Department of Earth Sciences. “ ̽��ֱ��research will provide key insights into ice sheet dynamics, oceanography and sub-ice shelf ecosystems. At a time when the West Antarctic Ice Sheet is melting at an alarming rate, understanding these dynamics and their impacts is crucial.”

photo1_fkt250110-20250117-gliderdeploymentzodiac-ingle-2717.jpg

̽��ֱ��oceanography team, led by Cimoli in collaboration with the ̽��ֱ�� of East Anglia and the British Antarctic Survey, used autonomous underwater vehicles to characterise the ocean circulation of the region and study the impacts of glacial meltwater on the physical and chemical seawater properties. "Antarctica and the Southern Ocean are a nexus point for ocean circulation, so changes that happen around Antarctica can affect global ocean circulation and global climate," said Cimoli.

̽��ֱ��researchers are also investigating how the iceberg calving event has contributed to mix the upper ocean, not just in the recently exposed area, but also further downstream as the iceberg floats away. As the giant iceberg drifts, it can generate turbulence that mixes water properties and could potentially mix the deep nutrient-rich water with the surface waters, fuelling biological productivity.

̽��ֱ��expedition was part of Challenger 150, a global cooperative focused on deep-sea biological research and endorsed by the Intergovernmental Oceanographic Commission of UNESCO (IOC/UNESCO) as an Ocean Decade Action.

“ ̽��ֱ��science team was originally in this remote region to study the seafloor and ecosystem at the interface between ice and sea,” said Schmidt Ocean Institute Executive Director, Dr Jyotika Virmani. “Being right there when this iceberg calved from the ice shelf presented a rare scientific opportunity. Serendipitous moments are part of the excitement of research at sea – they offer the chance to be the first to witness the untouched beauty of our world.”

Svetlana Radionovskaya is a Junior Research Fellow at Queens’ College, Cambridge. Laura Cimoli is a Research Fellow at the Institute of Computing for Climate Science, Department of Applied Mathematics and Theoretical Physics at the ̽��ֱ�� of Cambridge.

Adapted from a media release by the Schmidt Ocean Institute.

Inset image: Dr Cimoli (right) and Dr Meyer (UEA, left) prepare an underwater glider for deployment. Credit: Alex Ingle/Schmidt Ocean Institute.

Scientists explore a seafloor area newly exposed by iceberg A-84; discover vibrant communities of ancient sponges and corals.

ROV SuBastian / Schmidt Ocean Institute

Deep-sea coral at a depth of 1200 metres

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Scientists warn of ‘invisible threat’ of microplastics as global treaty nears completion

sc604 — Tue, 26 Nov 2024 10:50:47 +0000

Even if global production and pollution of new plastic is drastically reduced, scientists, writing in the journal Nature Communications, say that legacy plastics, the billions of tonnes of waste already in the environment, will continue to break down into tiny particles called microplastics for decades or centuries.

These fragments contaminate oceans, land, and the air we breathe, posing risks to marine life, food production and human health.

̽��ֱ��researchers – from the ̽��ֱ�� of Cambridge, GNS Science in New Zealand and ̽��ֱ��Ocean Cleanup in ̽��ֱ��Netherlands – say the problem lies in a gap between ambition and action, called the fragmentation gap.

At a meeting this week in Busan, South Korea, the Intergovernmental Negotiating Committee on Plastic Pollution is meeting to finalise the Global Plastics Treaty, the first legally binding treaty to tackle plastic pollution.

While the treaty’s initial discussions highlight prevention of plastic pollution, the researchers say it largely overlooks the need to remove existing waste. This omission means microplastics will continue to accumulate, even if plastic pollution slows.

“ ̽��ֱ��treaty is aiming to eliminate plastic pollution by 2040, but this goal is unlikely without stronger action,” said co-author Zhenna Azimrayat-Andrews, a PhD student at Cambridge’s Department of Earth Sciences. “Even with a sharp reduction in plastic entering the ocean, existing debris will split into smaller pieces and persist for centuries.”

These microplastics have already infiltrated marine ecosystems and are harming marine ecosystems, degrading commercial seafood quality, and disrupting critical ocean processes.

̽��ֱ��researchers argue that plastic clean-up efforts must be prioritised alongside reduction targets. Strategies to remove plastics from terrestrial and marine environments, such as those targeting pollution in beaches and rivers, could help prevent microplastics from forming. In fact, a 3% annual removal of legacy plastic, combined with aggressive reduction measures, could significantly curb future contamination, they say.

Without action to address legacy plastic, the treaty risks leaving behind a long-lasting problem for marine life and future generations. Experts are calling for clean-up efforts to become an equal pillar of the treaty, alongside prevention and recycling.

As world leaders gather to negotiate the treaty this week, the spotlight is on their ability to craft a comprehensive plan that doesn't just slow pollution but also begins to reverse the damage that has already been done.

Reference:
Karin Kvale, Zhenna Azimrayat Andrews & Matthias Egger. ‘Mind the fragmentation gap.’ Nature Communications (2024). DOI: 10.1038/s41467-024-53962-3

As the UN meets this week to finalise the Global Plastics Treaty, researchers warn that the agreement could fail to address one of the biggest threats to marine environments—microplastics.

Alistair Berg via Getty Images

Researcher holding small pieces of micro plastic pollution washed up on a beach

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‘Missing’ sea sponges discovered

sc604 — Wed, 05 Jun 2024 12:56:30 +0000

At first glance, the simple, spikey sea sponge is no creature of mystery.

No brain. No gut. No problem dating them back 700 million years. Yet convincing sponge fossils only go back about 540 million years, leaving a 160-million-year gap in the fossil record.

In a paper released in the journal Nature, an international team including researchers from the ̽��ֱ�� of Cambridge, have reported a 550-million-year-old sea sponge from the “lost years” and proposed that the earliest sea sponges had not yet developed mineral skeletons, offering new parameters to the search for the missing fossils.

̽��ֱ��mystery of the missing sea sponges centred on a paradox.

Molecular clock estimates, which involve measuring the number of genetic mutations that accumulate within the Tree of Life over time, indicate that sponges must have evolved about 700 million years ago. And yet, there had been no convincing sponge fossils found in rocks that old.

For years, this conundrum was the subject of debate among zoologists and palaeontologists.

This latest discovery fills in the evolutionary family tree of one of the earliest animals, connecting the dots all the way back to Darwin’s questions about when the first animals evolved and explaining their apparent absence in older rocks.

Shuhai Xiao from Virginia Tech, who led the research, first laid eyes on the fossil five years ago when a collaborator texted him a picture of a specimen excavated along the Yangtze River in China. “I had never seen anything like it before,” he said. “Almost immediately, I realised that it was something new.”

̽��ֱ��researchers began ruling out possibilities one by one: not a sea squirt, not a sea anemone, not a coral. They wondered, could it be an elusive ancient sea sponge?

In an earlier study published in 2019, Xiao and his team suggested that early sponges left no fossils because they had not evolved the ability to generate the hard needle-like structures, known as spicules, that characterise sea sponges today.

̽��ֱ��team traced sponge evolution through the fossil record. As they went further back in time, sponge spicules were increasingly more organic in composition, and less mineralised.

“If you extrapolate back, then perhaps the first ones were soft-bodied creatures with entirely organic skeletons and no minerals at all,” said Xiao. “If this was true, they wouldn’t survive fossilisation except under very special circumstances where rapid fossilisation outcompeted degradation.”

Later in 2019, Xiao’s group found a sponge fossil preserved in just such a circumstance: a thin bed of marine carbonate rocks known to preserve abundant soft-bodied animals, including some of the earliest mobile animals. Most often this type of fossil would be lost to the fossil record. ̽��ֱ��new finding offers a window into early animals before they developed hard parts.

̽��ֱ��surface of the new sponge fossil is studded with an intricate array of regular boxes, each divided into smaller, identical boxes.

“This specific pattern suggests our fossilised sea sponge is most closely related to a certain species of glass sponges,” said first author Dr Xiaopeng Wang, from Cambridge’s Department of Earth Sciences and the Nanjing Institute of Geology and Palaeontology.

Another unexpected aspect of the new sponge fossil is its size.

“When searching for fossils of early sponges I had expected them to be very small,” said co-author Alex Liu from Cambridge’s Department of Earth Sciences. “ ̽��ֱ��new fossil can reach over 40 centimetres long, and has a relatively complex conical body plan, challenging many of our expectations for the appearance of early sponges”.

While the fossil fills in some of the missing years, it also provides researchers with important guidance about what they should look for, which will hopefully extend understanding of early animal evolution further back in time.

“ ̽��ֱ��discovery indicates that perhaps the first sponges were spongey but not glassy,” said Xiao. “We now know that we need to broaden our view when looking for early sponges.”

Reference:
Xiaopeng Wang et al. ‘A late-Ediacaran crown-group sponge animal.’ Nature (2024). DOI: 10.1038/s41586-024-07520-y

Adapted from a Virginia Tech press release.

̽��ֱ��discovery, published in Nature, opens a new window on early animal evolution.

Xiaopeng Wang

Heliocolocellus fossil

Yes

Ancient seafloor vents spewed tiny, life-giving minerals into Earth’s early oceans

cmm201 — Fri, 02 Feb 2024 16:38:44 +0000

Their study, published in Science Advances, examined 3.5-billion-year-old rocks from western Australia in previously unseen detail and identified large quantities of a mineral called greenalite, which is thought to have played a role in early biological processes. ̽��ֱ��researchers also found that the seafloor vents would have seeded the oceans with apatite, a mineral rich in the life-essential element phosphorus.

̽��ֱ��earliest lifeforms we know of—single-celled microorganisms, or microbes—emerged around 3.7 billion years ago. Most of the rocks that contain traces of them and the environment they lived in have, however, been destroyed. Some of the only evidence we have of this pivotal time comes from an outcrop of sediments in the remote Australian outback.

̽��ֱ��so-called Dresser Formation has been studied for years but, in the new study, researchers re-examined the rocks in closer detail, using high magnification electron microscopes to reveal tiny minerals that were essentially hidden in plain sight.

̽��ֱ��greenalite particles they observed measured just a few hundred nanometres in size—so small that they would have been washed over thousands of kilometres, potentially finding their way into a range of environments where they may have kick-started otherwise unfavourable chemical reactions, such as those involved in building the first DNA and RNA molecules.

“We’ve found that hydrothermal vents supplied trillions upon trillions of tiny, highly-reactive greenalite particles, as well as large quantities of phosphorus,” said Professor Birger Rasmussen, lead author of the study from the ̽��ֱ�� of Western Australia.

Rasmussen said scientists are still unsure as to the exact role of greenalite in building primitive cells, “but this mineral was in the right place at the right time, and also had the right size and crystal structure to promote the assembly of early cells.”

̽��ֱ��rocks the researchers studied contain characteristic layers of rusty-red, iron-rich jasper which formed as mineral-laden seawater spewed from hydrothermal vents. Scientists had thought the jaspers got their distinctive red colour from particles of iron oxide which, just like rust, form when iron is exposed to oxygen.

But how did this iron oxide form when Earth’s early oceans lacked oxygen? One theory is that photosynthesising cyanobacteria in the oceans produced the oxygen, and that it wasn’t until later, around 2.4 billion years ago, that this oxygen started to skyrocket in the atmosphere.

̽��ֱ��new results change that assumption, however, “the story is completely different once you look closely enough,” said study co-author Professor Nick Tosca from Cambridge’s Department of Earth Sciences.

̽��ֱ��researchers found that tiny, drab, particles of greenalite far outnumbered the iron oxide particles which give the jaspers their colour. ̽��ֱ��iron oxide was not an original feature, discounting the theory that they were formed by the activity of cyanobacteria.

“Our findings show that iron wasn’t oxidised in the oceans; instead, it combined with silica to form tiny crystals of greenalite,” said Tosca. “That means major oxygen producers, cyanobacteria, may have evolved later, potentially coinciding with the soar in atmospheric oxygen during the Great Oxygenation Event.”

Birger said that more experiments are needed to identify how greenalite might facilitate prebiotic chemistry, “but it was present in such vast quantities that, under the right conditions its surfaces could have synthesized an enormous number of RNA-type sequences, addressing a key question in origin of life research – where did all the RNA come from?”

Reference:
Rasmussen, B, Muhling, J, Tosca, N J. 'Nanoparticulate apatite and greenalite in oldest, well-preserved hydrothermal vent precipitates.' Science Advances (2024). DOI: 10.1126/sciadv.adj4789

Researchers from the universities of Cambridge and Western Australia have uncovered the importance of hydrothermal vents, similar to underwater geysers, in supplying minerals that may have been a key ingredient in the emergence of early life.

MARUM − Zentrum für Marine Umweltwissenschaften, Universität Bremen

̽��ֱ��hydrothermal vent 'Candelabra' in the Logatchev hydrothermal field on the Mid-Atlantic Ridge at a water depth of 3300 metres.

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World’s most threatened seabirds visit remote plastic pollution hotspots

jg533 — Tue, 04 Jul 2023 15:00:00 +0000

̽��ֱ��extensive study assessed the movements of 7,137 individual birds from 77 species of petrel, a group of wide-ranging migratory seabirds including the Northern Fulmar and European Storm-petrel, and the Critically Endangered Newell’s Shearwater.

This is the first time that tracking data for so many seabird species has been combined and overlaid onto global maps of plastic distribution in the oceans.

̽��ֱ��results show that plastic pollution threatens marine life on a scale that transcends national boundaries: a quarter of all plastic exposure risk occurs in the high seas. This is largely linked to gyres - large systems of rotating ocean currents - where vast accumulations of plastics form, fed by waste entering the sea from boats, and from many different countries.

Seabirds often mistake small plastic fragments for food, or ingest plastic that has already been eaten by their prey. This can lead to injury, poisoning and starvation, and petrels are particularly vulnerable because they can’t easily regurgitate the plastic. In the breeding season they often inadvertently feed plastic to their chicks.

Plastics can also contain toxic chemicals that can be harmful to seabirds.

Petrels are an understudied but vulnerable group of marine species, which play a key role in oceanic food webs. ̽��ֱ��breadth of their distribution across the whole ocean makes them important ‘sentinel species’ when assessing the risks of plastic pollution in the marine environment.

“Ocean currents cause big swirling collections of plastic rubbish to accumulate far from land, way out of sight and beyond the jurisdiction of any one country. We found that many species of petrel spend considerable amounts of time feeding around these mid-ocean gyres, which puts them at high risk of ingesting plastic debris,” said Lizzie Pearmain, a PhD student at the ̽��ֱ�� of Cambridge’s Department of Zoology and the British Antarctic Survey, and joint corresponding author of the study.

She added: “When petrels eat plastic, it can get stuck in their stomachs and be fed to their chicks. This leaves less space for food, and can cause internal injuries or release toxins.”

Petrels and other species are already threatened with extinction due to climate change, bycatch, competition with fisheries, and invasive species such as mice and rats on their breeding colonies. ̽��ֱ��researchers say exposure to plastics may reduce the birds’ resilience to these other threats.

̽��ֱ��north-east Pacific, South Atlantic, and the south-west Indian oceans have mid-ocean gyres full of plastic waste, where many species of threatened seabird forage.

“Even species with low exposure risk have been found to eat plastic. This shows that plastic levels in the ocean are a problem for seabirds worldwide, even outside of these high exposure areas,” said Dr Bethany Clark, Seabird Science Officer at BirdLife International and joint corresponding author of the study.

She added: “Many petrel species risk exposure to plastic in the waters of several countries and the high seas during their migrations. Due to ocean currents, this plastic debris often ends up far away from its original source. This highlights the need for international cooperation to tackle plastic pollution in the world’s oceans.”

̽��ֱ��study also found that the Mediterranean Sea and the Black Sea together account for over half of petrels’ global plastic exposure risk. However, only four species of petrel forage in these enclosed, busy areas.

̽��ֱ��study was led by a partnership between the ̽��ֱ�� of Cambridge, BirdLife International and the British Antarctic Survey, in collaboration with Fauna & Flora International, the 5 Gyres Institute, and over 200 seabird researchers in 27 countries.

It was published on 4 July in the journal Nature Communications.

To get their results, the researchers overlaid global location data, taken from tracking devices attached to the birds, onto pre-existing maps of marine plastic distribution. This allowed them to identify the areas on the birds’ migration and foraging journeys where they are most likely to encounter plastics.

Species were given an ‘exposure risk score’ to indicate their risk of encountering plastic during their time at sea. A number of already threatened species scored highly, including the Critically Endangered Balearic Shearwater, which breeds in the Mediterranean, and Newell’s Shearwater, endemic to Hawaii.

Another Endangered species, the Hawaiian Petrel also scored high for plastic exposure risk, as did three species classified by the IUCN as Vulnerable: the Yelkouan Shearwater, which breeds in the Mediterranean; Cook’s Petrel, which breeds in New Zealand, and the Spectacled Petrel, which only breeds on an extinct volcano called Inaccessible Island, part of the Tristan da Cunha archipelago, a UK Overseas Territory.

“While the population-level effects of plastic exposure are not yet known for most species, many petrels and other marine species are already in a precarious situation. Continued exposure to potentially dangerous plastics adds to the pressures,” said Professor Andrea Manica at the ̽��ֱ�� of Cambridge’s Department of Zoology, a co-author of the study.

He added: “This study is a big leap forward in understanding the situation, and our results will feed into conservation work to try and address the threats to birds at sea.”

̽��ֱ��research was funded by the Cambridge Conservation Initiative’s Collaborative Fund for Conservation, sponsored by the Prince Albert II of Monaco Foundation, and the Natural Environment Research Council.

Reference

Clark, B.L. et al.: ‘Global assessment of marine plastic exposure risk for oceanic birds.’ Nature Communications, July 2023. DOI: 10.1038/s41467-023-38900-z

Analysis of global tracking data for 77 species of petrel has revealed that a quarter of all plastics potentially encountered in their search for food are in remote international waters – requiring international collaboration to address.

Ocean currents cause big swirling collections of plastic rubbish to accumulate far from land

Lizzie Pearmain

Beth Clark

Northern Fulmar bird in flight

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Giant underwater waves affect the ocean’s ability to store carbon

sc604 — Thu, 16 Mar 2023 15:00:53 +0000

An international team of researchers, led by the ̽��ֱ�� of Cambridge, the ̽��ֱ�� of Oxford, and the ̽��ֱ�� of California San Diego, quantified the effect of these waves and other forms of underwater turbulence in the Atlantic Ocean and found that their importance is not being accurately reflected in the climate models that inform government policy.

Most of the heat and carbon emitted by human activity is absorbed by the ocean, but how much it can absorb is dependent on turbulence in the ocean’s interior, as heat and carbon are either pushed deep into the ocean or pulled toward the surface.

While these underwater waves are already well-known, their importance in heat and carbon transport is not fully understood.

̽��ֱ��results, reported in the journal AGU Advances, show that turbulence in the interior of oceans is more important for the transport of carbon and heat on a global scale than had been previously imagined.

Ocean circulation carries warm waters from the tropics to the North Atlantic, where they cool, sink, and return southwards in the deep ocean, like a giant conveyer belt. ̽��ֱ��Atlantic branch of this circulation pattern, called the Atlantic Meridional Overturning Circulation (AMOC), plays a key role in regulating global heat and carbon budgets. Ocean circulation redistributes heat to the polar regions, where it melts ice, and carbon to the deep ocean, where it can be stored for thousands of years.

“If you were to take a picture of the ocean interior, you would see a lot of complex dynamics at work,” said first author Dr Laura Cimoli from Cambridge’s Department of Applied Mathematics and Theoretical Physics. “Beneath the surface of the water, there are jets, currents, and waves – in the deep ocean, these waves can be up to 500 metres high, but they break just like a wave on a beach.”

“ ̽��ֱ��Atlantic Ocean is special in how it affects the global climate,” said co-author Dr Ali Mashayek from Cambridge’s Department of Earth Sciences. “It has a strong pole-to-pole circulation from its upper reaches to the deep ocean. ̽��ֱ��water also moves faster at the surface than it does in the deep ocean.”

Over the past several decades, researchers have been investigating whether the AMOC may be a factor in why the Arctic has lost so much ice cover, while some Antarctic ice sheets are growing. One possible explanation for this phenomenon is that heat absorbed by the ocean in the North Atlantic takes several hundred years to reach the Antarctic.

Now, using a combination of remote sensing, ship-based measurements and data from autonomous floats, the Cambridge-led researchers have found that heat from the North Atlantic can reach the Antarctic much faster than previously thought. In addition, turbulence within the ocean – in particular large underwater waves – plays an important role in the climate.

Like a giant cake, the ocean is made up of different layers, with colder, denser water at the bottom, and warmer, lighter water at the top. Most heat and carbon transport within the ocean happens within a particular layer, but heat and carbon can also move between density layers, bringing deep waters back to the surface.

̽��ֱ��researchers found that the movement of heat and carbon between layers is facilitated by small-scale turbulence, a phenomenon not fully represented in climate models.

Estimates of mixing from different observational platforms showed evidence of small-scale turbulence in the upper branch of circulation, in agreement with theoretical predictions of oceanic internal waves. ̽��ֱ��different estimates showed that turbulence mostly affects the class of density layers associated with the core of the deep waters moving southward from the North Atlantic to the Southern Ocean. This means that the heat and carbon carried by these water masses have a high chance of being moved across different density levels.

“Climate models do account for turbulence, but mostly in how it affects ocean circulation,” said Cimoli. “But we’ve found that turbulence is vital in its own right, and plays a key role in how much carbon and heat gets absorbed by the ocean, and where it gets stored.”

“Many climate models have an overly simplistic representation of the role of micro-scale turbulence, but we’ve shown it’s significant and should be treated with more care,” said Mashayek. “For example, turbulence and its role in ocean circulation exerts a control over how much anthropogenic heat reaches the Antarctic Ice Sheet, and the timescale on which that happens.”

̽��ֱ��research suggests an urgent need for the instalment of turbulence sensors on global observational arrays and a more accurate representation of small-scale turbulence in climate models, to enable scientists to make more accurate projections of the future effects of climate change.

̽��ֱ��research was supported in part by the Natural Environment Research Council (NERC), part of UK Research and Innovation (UKRI).

Reference:
Laura Cimoli et al. ‘Significance of Diapycnal Mixing Within the Atlantic Meridional Overturning Circulation.’ AGU Advances (2023). DOI: 10.1029/2022AV000800

Underwater waves deep below the ocean’s surface – some as tall as 500 metres – play an important role in how the ocean stores heat and carbon, according to new research.

Turbulence plays a key role in how much carbon and heat gets absorbed by the ocean, and where it gets stored

Laura Cimoli

Laura Cimoli/GLODAP

Map of depth-integrated anthropogenic carbon

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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What did Megalodon eat? Anything it wanted — including other predators

sc604 — Thu, 23 Jun 2022 16:32:36 +0000

New research involving the ̽��ֱ�� of Cambridge shows that prehistoric megatooth sharks — the biggest sharks that ever lived — were the ultimate top predators, operating higher up the food chain than any other marine predators through history.

Arctic Ocean started getting warmer decades earlier than we thought

sc604 — Wed, 24 Nov 2021 18:56:45 +0000

̽��ֱ��Arctic Ocean has been getting warmer since the beginning of the 20th century – decades earlier than records suggest – due to warmer water flowing into the delicate polar ecosystem from the Atlantic Ocean.