Within the ocean’s vast expanse lie immense reservoirs of carbon – surpassing those found in either the atmosphere or the land.
The ocean actively captures and incorporates carbon through various natural mechanisms, locking in a significant portion that would otherwise circulate within the Earth’s systems, thereby functioning as a continuous carbon sink.
This crucial role mitigates climate change by reducing the amount of carbon which ends up in the atmosphere. If the ocean remains as a net carbon sink, it can aid in offsetting ongoing emissions and slowing global warming.
Unfortunately, a longstanding misconception persists that the ocean has an infinite resilience to human exploitation and negligence – likely stemming from the fact that the consequences of our actions are obscured beneath the surface.
Unsustainable use of the ocean’s resources – such as through overfishing – coupled with warming and acidification progressively erode the ocean’s capacity to regulate carbon and heat and its ability to sustain essential resources and services.
Consequently, rates of carbon sequestration are weakening and the vast carbon reserves held within marine ecosystems are increasingly susceptible to release.
This guest post lays out the climate opportunities presented by “blue carbon” and the challenges these ecosystems face.
Blue carbon is a term that refers to carbon captured by the world’s ocean and coastal ecosystems that has potential to be conserved or enhanced. Blue carbon is stored in vegetated coastal and marine ecosystems such as seagrass, mangroves and salt marshes.
The opportunity of coastal ecosystems
Coastal ecosystems – particularly vegetated ones, such as mangroves, seagrasses and salt marshes – are among the most crucial marine systems for storing carbon. Like plants on land, marine vegetation absorbs CO2 through photosynthesis. Because their waterlogged soils are low in oxygen, the carbon stored there can be locked away for centuries.
Despite only occupying approximately 0.5% of the ocean, these ecosystems boast remarkable carbon sequestration capabilities, contributing more than 50% of total carbon buried in marine sediments.
However, these vital ecosystems also face relentless human-caused pressures, from runoff of nutrients and sediments to urban expansion. They are being destroyed at an alarming pace – an average of 2% loss per year for mangroves – and are among the most threatened ecosystems on the planet.
Nevertheless, amidst this threat lies an opportunity: by reversing the conditions that are causing their decline, we can restore lost ecosystems and harness their potential as carbon sequestration hotspots once more.
The chart below shows the annual carbon storage potential of coastal ecosystems around the world, with yellow and light green indicating low storage potential and darker blues indicating high storage potential. The US, Mexico, Australia, Indonesia and Mexico stand out as countries with particularly high storage potential.
Managing coastal vegetated ecosystems to enhance carbon sequestration, often referred to as “blue carbon”, represents a valuable nature-based strategy for mitigating climate change.
While the amount of carbon that is offset through these methods is estimated to be at least an order of magnitude below other mitigation approaches – such as ocean alkalinisation and direct carbon capture and storage – they have additional benefits.
These ecosystems also enhance adaptation by stabilising coastlines, safeguarding against erosion and storms, enhancing water quality and nurturing marine life – thus promoting biodiversity through the provision of shelter, food and nursery grounds.
Climate and biodiversity
Blue carbon is a prime example of how climate change and the alarming decline in global biodiversity are connected.
Initiatives focused on blue carbon restoration – such as the “Mangroves for Coastal Resilience” project in Indonesia, the largest such initiative in the world – not only enhance carbon sequestration, but also reverse habitat loss and bolster biodiversity. Safeguarding marine biodiversity can also help secure the long-term well-being and prosperity of people whose lives and livelihoods are tightly linked to the oceans.
For example, declines in marine biodiversity undermine ecosystem resilience, heightening vulnerability to environmental disturbances and impacting economies reliant on marine resources. Loss of species degrades the food webs underpinning fisheries, jeopardising food security and livelihoods.
Furthermore, biodiversity loss directly compromises human health by fostering the emergence of zoonotic diseases that pass from animals to humans, diminishing water quality and impeding the exploration of new pharmaceuticals and treatments.
Protecting communities
Coastal restoration projects are already being carried out around the world, from small, local projects to larger initiatives.
They also encompass a range of activities, from planting new mangrove trees to managing tidal flows.
There are several crucial factors that demand careful consideration before implementing such a project.
Among these is the need to prioritise the protection of intact ecosystems. By safeguarding these areas, we can prevent the loss of carbon they have already sequestered and sidestep the time lag associated with re-establishing vital ecosystem services following habitat restoration.
Additionally, it is imperative to address the underlying pressures contributing to ecosystem loss, such as sewage discharge and agricultural runoff.
Restoration efforts must also be designed to withstand potential future challenges, such as changing land-use patterns and the projected impacts of climate change. Proactive measures to safeguard and restore coastal ecosystems should account for these complex and dynamic factors to ensure their long-term success and resilience in the face of ongoing environmental changes.
Local engagement and support for blue carbon initiatives are also needed because coastal communities often directly interact with these ecosystems for livelihoods, fishing, tourism and protection from natural disasters. Engaging these communities ensures that conservation efforts are sustainable. Additionally, tapping into the knowledge and expertise of local communities about coastal ecosystems is essential for informed decision-making.
Integrating carbon sequestration goals with other conservation and management objectives, such as sustainable fisheries and coastal resilience, is possible by empowering local communities to lead blue carbon initiatives. This can help ensure social equity, address economic opportunities and reduce conflicts over resource use.
Ultimately, garnering people’s buy-in for blue carbon solutions is essential for their effectiveness, sustainability and equitable distribution of benefits.
Considering marine sediment
Blue carbon “solutions” can be regarded as any intervention which aims to enhance the ocean’s natural capacity to store and sequester carbon.
As such, one might consider the management of commercial species and natural populations to increase the biomass of, and thereby carbon contained in, marine organisms. Managing interactions with the seabed can also be an important blue carbon solution.
Recent estimates suggest marine sediments are the largest store of organic carbon on the planet. Therefore, activities which disrupt them, such as bottom trawling or deep-sea mining, may be stirring up this sediment and leading to carbon being released back to the atmosphere.
Although the full picture has yet to emerge, examining the impacts of where and how trawling is conducted allows us to make choices informed by all of the potential impacts. And before deep-sea mining activities are further scaled up, a more comprehensive understanding of their impacts is vital.
The post Guest post: The role of ‘blue carbon’ in addressing climate change appeared first on Carbon Brief.
Guest post: The role of ‘blue carbon’ in addressing climate change
Consumers remain vulnerable to price spikes despite record domestic oil and gas production. But experts doubt the crisis will boost clean energy, absent strong policy.
In President Donald Trump’s telling, the United States has fuel enough to hover above the chaos that his attack on Iran has triggered in global energy markets.
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A World War II-era policy is stopping old coal plants from closing, despite high costs and the wishes of their owners.
At one time, the U.S. electricity grid ran mostly on coal.
Italy has delayed the permanent closure of its four coal-fired power plants to 2038, after the war in the Middle East caused the cost of producing electricity from gas to spike.
The government inserted the measure into a broader bill aimed at addressing the energy crisis. Parliament approved the legislation on Wednesday after the government tied it to a confidence vote, meaning that losing the vote would see the right-wing coalition government collapse.
The decision marks a climbdown from a pledge first made under centre-left Prime Minister Paolo Gentiloni in 2017 to phase out coal by 2025 on the mainland and by 2028 on the island of Sardinia.
The Mediterranean island’s 1.5 million people remain heavily dependent on coal for electricity due to limited grid connections with the European mainland and a slow rollout of renewable energy.
Riccardo Molinari, a member of Parliament for the governing coalition Lega party, which championed the amendment, said the plants could be kept open as a “strategic reserve”, which can be turned on if needed.
“Unnecessary” decision
But analysts say the practical impact of the move is likely to be limited. Luca Bergamaschi, executive director of Italian climate think tank ECCO, described the extension as “largely symbolic”.
“Keeping them open will not materially affect electricity prices, which are driven by gas – for most hours of the day – and EU market rules,” he told Climate Home News. “The decision sends a negative signal but we don’t expect any meaningful impact on prices or emissions, which shows how unnecessary this is”.
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Coal has already been largely phased out of Italy’s power mix. Generation from coal has fallen over 90% since 2012 and accounted for less than 2% of electricity production last year, almost entirely in Sardinia.
In 2024, Italy got about half of its electricity from gas and half from clean sources like hydropower, solar and wind.
Coal plants on stand-by
Italy has four coal-fired power plants left but only two, both in Sardinia, are still producing electricity.
The other two are run by the country’s largest utility Enel, in Brindisi and Civitavecchia. They were shut down at the end of last year after they became uneconomic.
The company had planned to begin decommissioning them, but the government intervened at the last minute, requiring them to remain on standby in case of an energy crisis.
Gilberto Pichetto Fratin, Italy’s Minister of Environment and Energy Security, said at the end of March that these two power plants could be switched back on “right away, with a government decree”.
“If the price of gas exceeds 70 euros per megawatt hour, producing with coal would be convenient,” he told Italian newspaper Il Corriere della Sera.
European gas prices spiked to just below that level in mid-March as the Iran war escalated, but have since come down to around 50 euros per megawatt hour.
Coal surge in Asia
Italy’s move comes amid a broader, though limited, shift back towards coal in some parts of the world as countries respond to restricted gas supply. Germany slightly increased coal-fired generation in March and has considered reactivating idle plants as a precaution.
Outside Europe, the trend has been more pronounced. Several Asian countries heavily exposed to disruptions in Gulf gas supplies have increased coal use.
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Japan has allowed its coal power plants to operate at a higher rate to reduce the need for liquified natural gas (LNG). Bangladesh, Thailand and the Philippines have also increased electricity generation from coal since the start of the conflict in the Middle East.
But analysis from Zero Carbon Analytics suggested that producing electricity from solar is cheaper than coal in most south-east Asian countries.
“Energy security in Southeast Asia will not come from switching between fossil fuels,” Amy Kong added. “It will come from reducing dependence on them altogether.”
The post Italy pushes coal exit back after gas prices rise appeared first on Climate Home News.
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