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
Climate Change
North Carolina Regulators Nix $1.2 Billion Federal Proposal to Dredge Wilmington Harbor
U.S. Army Corps of Engineers failed to explain how it would mitigate environmental harms, including PFAS contamination.
The U.S. Army Corps of Engineers can’t dredge 28 miles of the Wilmington Harbor as planned, after North Carolina environmental regulators determined the billion-dollar proposal would be inconsistent with the state’s coastal management policies.
North Carolina Regulators Nix $1.2 Billion Federal Proposal to Dredge Wilmington Harbor
Australia has some of the largest areas of high volume, consistent solar and wind energy anywhere in the world. It is a natural advantage that many countries in our region and across Europe will envy as they ramp up their efforts to reduce carbon pollution.
Australia has an amazing opportunity to utilise this abundance of reliable energy not only to transform our own energy systems but also that of our neighbours – if we get the policy settings right.
We are, in fact, already seeing the benefits of renewable energy flowing into our electricity grids. With all the inflation pressures on our bank accounts it looks like electricity pricing may be one cost that could be turning a corner – largely thanks to cheap solar and wind energy.
Renewables are Bringing Down the Cost of Producing Electricity
Here at Greenpeace, while we think there are some important questions to ask about renewable energy, it is clear that solar and wind are certainly the cheapest energy options available.
In contrast, coal, oil and gas are not only big on pollution, they are also proving costlier as they struggle to cope with the changing nature of our electricity systems. Plus, fossil fuels are much more exposed to international price fluctuations – as we all experienced when our electricity bills rapidly rose following the Russian invasion of Ukraine.
Wouldn’t it be great if we instead had energy independence, sourced from an infinite supply of clean energy?
Solar and wind (backed by batteries) can do just that and the reality is that they are already out-competing the old guard of gas and coal simply because they are quicker and cheaper to deploy. Which is good news for electricity prices!
Although whether energy retailers are passing on those savings to customers is another question. Short answer: no, they’re not – but it is a bit complex.
Why are my electricity bills still high?
There are a number of elements that make up the final amount we see on our bills. The graph below shows the breakdown of energy costs covered by our bills.
You will see roughly a third (36.2% in 2025-26) of the cost goes to maintenance and build out of the electricity grid. This includes the transmission lines needed to connect to new renewable energy sites and to connect states so they can better share their energy resources. The ‘network’ costs have been increasing but so have other components of our bill, most notably the ‘wholesale’ cost of producing electricity.
Thankfully, the cost of producing the electricity is now starting to go down (thanks to renewables and batteries), but they are coming off record highs thanks to the exorbitant cost of gas and the unreliability of coal power stations that are old and no longer fit for purpose.
During high demand times (eg, when we all get home from work on a hot day and turn on the air conditioning) spot prices can quickly jump. Add to that a couple of coal power plants breaking down (as they increasingly do), and expensive gas fired power use spikes in the system. This can quickly cancel out any of the cost savings solar power may have created during the day when prices can actually go negative.
The good news is that this is exactly the problem batteries can solve. Batteries are great at soaking up the surplus supply of solar during the middle of the day, which creates a more efficient system, and then rapidly pumping out that power during the evening peak at a cheaper rate than gas.
How much have costs come down?
According to the Australian energy regulator (AEMO), wholesale electricity prices across the east coast have dropped by 44% when comparing prices in quarter 4 of 2025 to the same period in 2024.
AEMO directly attributes the change to the significant growth in wind (up 29%), solar (up 15%), and batteries (3,796 MW of new battery capacity added). This influx of cheap renewable energy has seen a corresponding decrease in the use of polluting fossil fuels to power the grid. Coal fired power dropped by 4.6% and gas fired power fell by a staggering 27%.
The same trend can be seen in the world’s largest standalone grid in WA where renewable energy and storage supplied a record 52.4% of the grid’s energy across the final 3 months of 2025. That is an impressive result given there is no interstate connection to borrow energy from and there is no hydroelectric power in the system.
As a result, WA has seen a 13% drop in wholesale electricity prices thanks to a 5.8% reduction in coal fired power and a 16.4% reduction in gas fired power.
Australian Households Lead the Way on Solar and Batteries
Despite all the attempts to discredit clean energy by Trump and other conservative politicians, Aussie households have long known the value of renewable energy. In fact, Australia now holds the title for the highest rate of solar energy per capita in the world.
This is now being followed by the rapid takeup of household batteries with the Clean Energy Regulator being overwhelmed with interest in the Cheaper Home Batteries Program. They now expect to receive “around 175,000 valid battery applications corresponding to a total usable capacity of 3.9 GWh by the end of 2025.”’
All these extra batteries storing the surplus solar energy across our neighbourhoods during the day is not only creating drastic bill reductions for those households who are installing them, it is helping the whole grid. Which eventually will help everyone’s electricity bills.
If Australia as a whole follows the lead of suburban families by switching to cheap solar (plus wind) backed-up by batteries, it has an unparalleled opportunity to build its economy on the back of unlimited, local, clean energy harnessed from the sun and wind.
Powering our Future Economy
If there was ever something Australia has a natural advantage in, its sun and wind. But given the growing demand for electricity from data centres and the electrification of heavy industry, we are going to need more than just rooftop solar panels.
That’s where Australia has the potential, more than almost any other country, to become a renewable energy powerhouse and punch above our weight in the fight against climate change. See for example the unique opportunity to enter into the production and export of green iron.
While there is still quite a way to go before our electricity is fully sourced from solar and wind, we are well on the way. The clean energy charge is gathering pace – and our communities, oceans, wildlife and bank balances will be the better for it.
Climate Change
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New research finds that rising ocean temperatures are shrinking cool-water feeding grounds, pushing humpbacks into gear-heavy waters near shore. Scientists say ocean forecasting tool could help fisheries reduce the risk.
Each spring, humpback whales start to feed off the coast of California and Oregon on dense schools of anchovies, sardines and krill—prey sustained by cool, nutrient-rich water that seasonal winds draw up from the deep ocean.
Whale Entanglements in Fishing Gear Surge Off U.S. West Coast During Marine Heatwaves
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