The ocean plays a vital role in regulating the climate, storing roughly 50 times more carbon dioxide (CO2) than the atmosphere.
Marine life plays a significant part in this process, as organisms transfer carbon from the ocean surface to the deep sea upon death or as they migrate.
Our new research, published in Nature Communications, suggests the contribution of ocean biology to climate regulation is more complex than previously thought.
To explore how ocean biology shapes the past, present and future climate, we explore an extreme scenario where all marine life has been wiped out.
We find that – in a pre-industrial climate – CO2 levels would rise by 50% without marine life, leading to 1.6C of global warming.
In a separate study in Nature Climate Change, we estimate that ocean biology sequesters the equivalent of 10bn tonnes of CO2 each year.
This is more than one quarter of annual fossil-fuel emissions from human activity.
We also calculate that the contribution of marine life to carbon storage is worth hundreds of billions of dollars each year.
Biological carbon pump
The ocean takes up and stores vast amounts of CO2 every year through two mechanisms known as “carbon pumps”.
The first is the “solubility pump”. This is the process by which dissolved CO2 in seawater is transported from the ocean’s surface to its depth through the sinking and upwelling of water mass.
The second is the “biological carbon pump”. This is the process where carbon is converted into organic materials by plankton and other marine organisms at the ocean’s surface and then transported to the deep sea when they die or migrate.
Scientists have long known that the biological carbon pump played an essential role in maintaining low atmospheric CO2 levels before the industrial revolution.
However, the conventional view is that the solubility pump has been responsible for the ocean’s steady absorption of rising CO2 emissions caused by human activity.
Our findings challenge this view, by showing the biological carbon pump plays a crucial role in the modern ocean’s sequestration of atmospheric CO2.
We find that, without marine life, the ocean’s capacity to capture CO2 emissions would be significantly diminished.
Two scenarios
To get an estimate of the contribution of the marine carbon pump in a stable pre-industrial climate, we simulate the planet’s climate as it was before the industrial era using a complex Earth system model.
(This is the second generation of the Norwegian Earth system model, which contributed to the sixth Coupled Model Intercomparison Project.)
We then explore what would happen to the Earth’s climate system under two scenarios:
- A reference, “healthy ocean” scenario where ocean biology conditions were as realistic as possible.
- An “abiotic” scenario where all marine life is removed.
In a pre-industrial scenario with no marine life, we find that atmospheric CO2 levels would rise to 445 parts per million (ppm). This is an increase of more than 50% on the “healthy ocean” scenario, where CO2 levels are 282ppm.
(This suggests that the influence of marine life on global CO2 levels is greater than the sum of all human activity, which has – so far – raised atmospheric CO2 concentrations to around 425ppm).
The rise in CO2 levels caused by the absence of marine life would result in about 1.64C of global warming at the surface and a 1.15C increase in global sea surface temperature.
This warming would have considerable impacts on the wider world, including declines in sea ice area at the Arctic and Antarctic of close to 25% and an Atlantic Meridional Overturning Circulation that was around 9% weaker.
The value of exploring such an extreme scenario is to investigate the role biological processes in the ocean play in carbon storage, as well as the implications of damage to marine life.
The role of terrestrial ecosystems
Our estimation that pre-industrial atmospheric CO2 would rise by 163ppm without ocean biology is on the lower end of the 150-240ppm range approximated by some previous studies.
However, previous estimates of the contribution of the biological carbon pump in a pre-industrial climate neglect the interactions between oceanic and terrestrial biospheres.
Our research reveals that terrestrial ecosystems – such as tropical forests and grasslands – play a crucial role in compensating for the increase in CO2 concentrations when ocean life declines. (This is due to the CO2 fertilisation effect, when higher CO2 concentrations speed up photosynthesis).
We find that in the extreme pre-industrial scenario, approximately half the carbon lost from the ocean is absorbed by the land.
The figure below illustrates the Earth’s carbon reservoirs in a pre-industrial climate with (left) and without (right) marine life. It shows how, if marine life is wiped out, carbon content decreases in the ocean and marine sediment, whereas more carbon accumulates in the atmosphere and on land.
Ramifications for the future
Today, the ocean captures approximately 25% of human-caused CO2 emissions – which allows it to play a crucial role in slowing global warming.
In order to estimate the overall importance of marine life to carbon sequestration in the ocean, we also conduct experiments for various future emission pathways – both with, and without, marine life.
In all cases, we find that more CO2 emitted by human activities remains in the atmosphere when there is no marine life.
One might think that the ocean’s lower concentrations of carbon in the pre-industrial climate, relative to the atmosphere, might mean it would be able to absorb more additional carbon.
However, we find the absence of marine life fundamentally alters the vertical distribution of carbon in the ocean. Although the total amount of carbon stored is lower, there is more carbon at the surface due to an absence of organisms. This, in turn, hinders additional CO2 from entering the ocean.
Another surprising finding of the simulations was that the terrestrial biosphere’s capacity to absorb excess CO2 by increasing its vegetation mass diminishes over time, potentially due to limited nutrients.
The figure below shows the distribution of human-caused CO2 in the Earth’s carbon reservoirs under two 2100 scenarios. The chart on the left shows a scenario with ocean life, and the chart on the right shows one without ocean biology.
It illustrates how, without marine life, more CO2 stays in the atmosphere and less goes into the land and the ocean.
The study shows that in the absence of marine life, future warming would occur faster and more intensely.
This acceleration in warming would potentially trigger other processes that could further amplify warming, such as greater ocean stratification, longer sea-ice free Arctic summers and greater loss of permafrost.
Economic benefits
Damaging marine life is economically costly given the many and various benefits – or “ecosystem services” – provided by carbon sequestration.
We estimate that the sinking of organic matter sequesters approximately 2.8bn tonnes of carbon annually, locking it away from the atmosphere for at least 50 years.
This carbon sequestration capacity is equivalent to 10bn tonnes of atmospheric CO2 – or roughly 27% of emissions generated by fossil fuels in 2024.
We estimate – based on a carbon price of $90 per tonne of CO2 – that the carbon storage provided by the marine carbon pump is worth $545bn per year in international waters and $383bn per year within national waters. Its total value is projected to exceed $2.2tn by 2030.
Carbon storage is valuable because it helps avoid climate impacts.
This economic value is important for developing countries, particularly small island developing states whose national waters are collectively responsible for 11% of biological carbon pump sequestration activity, in terms of carbon stored.
The top eight countries where the biological carbon pump value is highest in proportion to gross domestic product (GDP) are small island states. These are the Cook Islands, Kiribati, the Marshall Islands, Micronesia, Nauru, Niue, Palau and Tuvalu. Of these nations, just one – the Cook Islands – is classified by the World Bank as high income.
These climate-impacted nations’ key role in preserving ocean health should be considered in discussions of international climate finance.
The figure below shows the economic value of carbon sequestration of the biological carbon pump for each of these eight small island states, calculated on the basis of a carbon price of $90 per tonne of CO2.
For example, it illustrates how Micronesia and Kiribati have an estimated biological carbon pump value of $4,620m and $8,525m each year, respectively.
A healthy ocean buys the world time in the battle against global warming, but the window to protect it is closing rapidly.
Marine ecosystems remain vulnerable to a raft of human activities, including industrial fishing, pollution, shipping and deep-sea mining. Stronger conservation policies, enhanced financial incentives for lower income countries and increased international cooperation are essential to protect the services provided by ecosystems.
These are important steps towards not only protecting 30% of the global ocean as agreed under the new Global Biodiversity Framework – but it will help to reach the Paris Agreement’s climate target.
There are a number of tools at governments disposal to protect the valuable services provided by marine ecosystems. This includes promoting sustainable fishing and ecotourism, establishing marine protected areas and undertaking robust environmental impact assessments.
Nations can also support protection of the biological heat pump within international waters by ratifying the High Seas Treaty, which recognises the importance of protecting biogeochemical cycles.
The post Guest post: How marine life provides climate benefits worth billions of dollars appeared first on Carbon Brief.
Guest post: How marine life provides climate benefits worth billions of dollars
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Climate Change
DeBriefed 19 June 2026: Bonn talks end in ‘gridlock’ | Energy’s ‘new era’ | Oceans in climate negotiations
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Bonn talks close
‘SIDE-STEPPING AND STALLING’: UN climate talks in Bonn have ended in “gridlock”, according to Climate Home News. The outlet reported on the failure to balance developing countries’ need for climate-adaptation finance with “richer nations’ desire to move forward” on emissions cuts. It added that both topics were subject to “rule 16”, meaning no agreement could be reached and work will be pushed to the COP31 summit in Turkey. Inside Climate News quoted UN climate executive secretary Simon Stiell, who said the talks had seen “side-stepping and stalling”.
JUST TRANSITION: One “glimmer of hope” came from negotiations on achieving a “just transition”, reported Euronews. The news outlet said negotiators “made headway on operationalising the Belém-Antalya mechanism”, intended to support people in the shift to a low-carbon economy. However, Politico concluded that much of the focus in Bonn had “shift[ed] to efforts outside diplomatic talks – raising questions about the future of global climate negotiations”.
‘ATTACKING SCIENCE’: Agence France-Presse reported on the EU, Switzerland and “dozens of developing nations” warning of “attacks on science” by a “small group of fossil-fuels interests” in Bonn. Table Briefings explained that “the 1.5C target is increasingly being challenged” and the role of the UN climate-science panel – the Intergovernmental Panel on Climate Change (IPCC) – in an upcoming assessment of global climate progress “remains controversial”. See Carbon Brief’s full write-up of the talks for more detail.
US-Iran deal
PRICE DROP: The US and Iran announced that they have reached an interim agreement to halt the war and reopen the strait of Hormuz, reported Bloomberg. Oil prices have fallen, as the “long-awaited deal” began the process of “eas[ing]” the global energy crisis triggered by the conflict, according to the New York Times. The Associated Press noted that high fuel prices will “likely outlast the Iran war”.
‘OIL GLUT’: The Financial Times reported that the International Energy Agency (IEA) has forecast a “glut of oil” emerging next year, if the peace deal holds. The IEA said this would allow countries to build new strategic reserves, as they “review their energy strategies and policies in response to the crisis”, according to Reuters.
‘NEW ERA’: Agence France-Presse reported that oil and gas companies have “few illusions about a return to normal for the Gulf energy industry after more than three months of blockage”. One analyst told the newswire that the war “showed the oil and gas industry that Hormuz risk is no longer just a geopolitical headline”.
Around the world
- OCEAN MONITOR: The Trump administration is “abandoning its plan” to dismantle a $368m ocean monitoring system key for tracking climate change after a “bipartisan backlash on Capitol Hill”, reported the New York Times.
- CORAL HAVEN: The New York Times covered preliminary research, presented at the Our Ocean Conference in Kenya, suggesting there could be three times as many “coral refugia” – where corals are relatively safe from climate change – than previously thought.
- BAD CREDIT: Down to Earth reported that the first carbon credits issued under the Paris Agreement’s new Article 6.4 mechanism are “facing scrutiny over alleged links to institutions controlled by Myanmar’s military junta”.
- OIL BACKTRACK: Reuters reported that oil-and-gas company Equinor has dropped a renewable-energy target and scaled back clean investments, while another Reuters story noted that Shell is selling off its offshore wind assets.
1.1 billion
The number of children facing “at least three overlapping climate hazards”, according to a new Unicef report covered by Agence France-Presse.
Latest climate research
- Including the “permafrost carbon-climate feedback” in climate models increases the chance of exceeding “tipping elements” – such as the Greenland ice sheets, Atlantic Meridional Overturning Circulation or Amazon rainforest – by up to 50% | Environmental Research Letters
- The intensity of influenza outbreaks could decline in temperate regions, but increase in tropical areas over the next century, as the climate warms | PNAS Nexus
- European snow cover has declined by 20% for December and January since the start of the industrial era, revealing an “unprecedented ongoing shrinkage of European winters” | Communications Earth & Environment
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured
The more than 2m battery electric vehicles (BEVs), 1m “plug-in” hybrids (PHEVs) and 100,000 electric vans on UK roads are already saving drivers a total of around £3bn a year, according to new Carbon Brief analysis. This amounts to savings of more than £1,100 a year in fuel costs for each BEV driver in the UK. The analysis comes amid reports in UK media this week that the government is considering “watering down” its EV sales targets.
Spotlight
Oceans rising at UN climate talks
The state of the world’s oceans is inextricably linked to the changing climate – and many delegates at UN climate talks want to see more focus on this issue, reports Carbon Brief.
Oceans are often described as the world’s “greatest ally” against climate change – absorbing 30% of carbon dioxide (CO2) emissions and most of the heat generated by those emissions.
They are also the site of important climate solutions, such as huge offshore windfarms and the shipping industry’s transition to cleaner fuels.
At the same time, the oceans themselves present a growing danger to coastal communities and sea life due to sea level rise, marine heatwaves and ocean acidification.
These diverse issues have led to growing calls within the UN climate process for more focus on oceans. During climate negotiations this week in Bonn – known as SB64 – nations and civil society had a chance to air these views during an “ocean and climate change dialogue”.
‘Elevate action’
Oceans first entered UN climate outcomes in 2019, when the final COP25 negotiated text requested a new “dialogue” on “the ocean and climate change to consider how to strengthen mitigation and adaptation action”.
The following years saw this dialogue established as an annual event. However, the political weight of these discussions has been limited.
COP31 is being co-led by Turkey and Australia, but with Pacific islands playing a supporting role. These small islands sometimes self-identify as “large ocean states”, stressing the ocean’s centrality in their societies.
In Bonn, figures from across the presidency threw their weight behind this issue. Chris Bowen, an Australian minister and incoming COP31 “president of negotiations”, told attendees:
“Australia, Turkey and the Pacific see an important opportunity to elevate ocean-based climate action.”
Strategies and finance
The two-day dialogue in Bonn involved a series of panels, statements and breakout groups.
One of the main topics was how oceans are integrated into national climate plans under the Paris Agreement, known as “nationally determined contributions” (NDCs).
Three-quarters of the latest round of NDCs mention oceans, with conservation of “blue carbon” ecosystems the most frequently described action. (Landscapes such as mangroves can both absorb CO2 and protect coastal areas.)
Delegates also discussed alignment with the UN biodiversity process, as well as ocean finance, which currently makes up less than 1% of all climate finance.
(As discussions were taking place in Bonn, country officials also gathered in Mombasa, Kenya for the 11th Our Ocean Conference. Carbon Brief’s associate editor Giuliana Viglione attended the conference and will publish a full summary shortly.)
Developing countries were clear that many of the ocean-related actions in their NDCs would depend on receiving more financial support.
‘Political momentum’
With the backing of the COP31 presidency, delegates were hopeful about where this year’s dialogue could lead.
Charles Hamilton, an advisor for the Bahamas who spoke for the Alliance of Small Island States (AOSIS) in the dialogue, told Carbon Brief that island representatives “are not traveling thousands of miles to just talk and pat ourselves on the back”. He added:
“A dialogue that just remains a dialogue is just more talk – no action.”
Given that, he said “discussions in the dialogue must move into COP decisions and the decisions must be actioned”, noting the importance of finance.
Marina Corrêa, oceans lead at WWF-Brazil, pointed to an upcoming UN climate change Standing Committee on Finance forum as a space to ramp up pressure on ocean finance.
More broadly, she wanted to see the presidencies translate their support into a “leader-level ocean initiative” that could “mainstream” oceans across negotiations.
“We have a really interesting opportunity, in terms of political momentum,” Corrêa told Carbon Brief.
Watch, read, listen
‘HOTTER THAN HELL’: An episode of the BBC’s Rare Earth podcast titled “hotter than hell” considered the issue of extreme heat, with input from experts and “people facing up to the hottest temperatures on the planet”.
NOT BROKEN?: John Drake, a professor of ecology at the University of Georgia, wrote an essay for Aeon – also re-published as a Guardian “long read” – questioning the framing of ecosystems and climate systems “breaking down”.
ON COURSE: On his Volts podcast, US climate journalist David Roberts interviewed UK climate minister Katie White, quizzing her about whether the UK will “stay the course with its climate plans”.
Coming up
- 20-28 June: London climate action week
- 21 June: Colombia presidential runoff
- 24 June: UK Climate Change Committee progress in reducing emissions 2026 report to parliament
Pick of the jobs
- Mongabay, managing editor – Africa | Salary: Unknown. Location: Global
- Contexte, environment reporter – Brussels | Salary: €45,000-€60,000. Location: Brussels
- Climate 200, communications director | Salary: Unknown. Location: Australia
- Energy Tracker Asia, energy transition correspondent | Salary: $3,000-$4,000 per month. Location: South-east Asia (remote)
DeBriefed is edited by Daisy Dunne. Please send any tips or feedback to debriefed@carbonbrief.org.
This is an online version of Carbon Brief’s weekly DeBriefed email newsletter. Subscribe for free here.
The post DeBriefed 19 June 2026: Bonn talks end in ‘gridlock’ | Energy’s ‘new era’ | Oceans in climate negotiations appeared first on Carbon Brief.
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