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Coastal flooding could bring $500bn of annual damages to the Asia-Pacific by the year 2100, if countries do not adapt to rising sea levels.

This is according to new research, published in the journal Scientific Reports, which assesses how coastal flooding is impacting the Asia-Pacific region – and models how the damages could worsen as sea level rises over the 21st century. 

The paper finds that coastal flooding is already driving $26.8bn of damage every year across 29 countries in Asia and the Pacific, equivalent to 0.1% of the region’s GDP.

It projects that, under current policies, annual coastal flood damages in the region could rise to $518bn by 2100 – but this could drop to $338bn if warming is capped at 1.5C.

Small island states face the greatest risks from coastal flooding and will continue to bear the brunt of the damage as the planet continues to warm, according to the research.

For example, it finds that Tuvalu will face annual coastal flood damage equivalent to 38% of its GDP by the end of the century.

Meanwhile, small island states such as Kiribati, the Maldives, Micronesia and Tuvalu will permanently lose around 10% of their total land area.

The study’s lead author says the research shows how “rising seas” create “existential” and “economic” risks for low-lying islands in the Asia-Pacific.

He tells Carbon Brief that the paper highlights a “sharp inequality”, as developing nations with little historical responsibility for sea level rise face the brunt of its impacts.

Coastal damage

More than one billion people – about 15% of the world’s population – currently live within 10km of a coast.

Asia is home to some of the largest cities in the world, many of which are located near the sea, such as Mumbai, Tokyo, and Shanghai. The continent is home to 60% of the world’s coastal population.

However, there are hazards to living near the water.

Coastal flooding is caused by a combination of gradually rising sea levels and “episodic extreme sea levels”, such as high tides and storm surges, the study explains.

To assess these two factors, the study combines components including an ocean model and tide-height data.

The authors model flooding in all coastal Pacific and Asian countries that are listed as “developing member countries” by the Asian Development Bank. These 29 countries include Bangladesh, the Philippines and Tuvalu. 

They calculate the economic damage caused by flooding, by combining their flood model with data on land use and “asset values” across the residential, commercial, industrial, infrastructure and agricultural sectors. 

The authors assume when land floods permanently, the “assets” are completely lost. For areas that only flood periodically, the authors use a model linking flood depth to a percentage of land damaged to calculate the economic consequences.

They find that coastal flooding currently drives $27bn of damage every year in the Asia-Pacific.

China and Indonesia bear the greatest damage, each losing more than $6bn every year. The study authors say this is because both countries have “extensive coastlines, large populations in flood-prone areas and critical economic infrastructure concentrated near the coast”.

However, the study finds that small islands face the greatest economic damage as a percentage of their GDP.

The percentage of its annual GDP currently lost to coastal flooding in 29 Asia-Pacific countries. Small islands are shown in red.
The percentage of its annual GDP currently lost to coastal flooding in 29 Asia-Pacific countries. Small islands are shown in red. Data: Monioudi et al, (2025). Chart by Carbon Brief.

The study shows that the five most-severely affected countries are small island states. Vanuatu tops the ranking, losing 1.5% of its GDP to flooding every year. It is followed by Papua New Guinea and Micronesia.

Dr Michalis Vousdoukas is a researcher in coastal geography at the University of the Aegean in Greece and lead author of the study.

He tells Carbon Brief that even these damage estimates are “conservative” as they do not consider indirect economic losses, such as disruption to business, the loss of critical infrastructure, such as airports, or social impacts, such as migration.

Vousdoukas tells Carbon Brief that the study “highlights a sharp inequality between responsibility and impact”, explaining that the “countries that contributed the least to global emissions, particularly atoll nations, face the highest relative damages”.

Island nations in the Asia-Pacific region made of atolls – ring-shaped coral reefs or islands – include Kiribati, the Marshall Islands and Tuvalu.

Exposure

The authors also calculate population exposure to flooding, by overlaying their flood model with world population data.

Vousdoukas explains that “a person is considered exposed if they live in an area that appears as flooded in our model”.

The paper finds that six million people across the Asia-Pacific are currently at risk of coastal flooding each year, accounting for 0.2% of the region’s total population. The paper says:

“Although this may appear to be a small percentage, it still represents millions of individuals and families whose lives and livelihoods are under constant threat.”

Ranjan Panda is the convenor of the Combat Climate Change Network in India. Panda, who was not involved in the study, tells Carbon Brief that sea level rise is already forcing “millions of people to migrate out in distressed conditions to cities and other countries”.

China and Bangladesh rank the highest, with 2.2 million and 1.5 million people, respectively, exposed to coastal flooding each year.

However, small islands have the greatest percentage of their population exposed to flooding. Vanuatu again tops the table, with 2% of its population facing coastal flooding every year, according to the study. It is followed by Micronesia and the Maldives.

Bangladesh is the highest ranking non-island country, due to its “densely populated and flood-prone delta region”, the study finds.

Rising seas

As the climate warms, coastal flooding is worsening.

Average global sea levels have risen by more than 20cm since 1900, driven mainly by the thermal expansion of the ocean and the melting of glaciers and ice sheets.

Global warming is also “supercharging” hurricanes and typhoons, causing storm surges – the temporary rise in sea level that happens during a storm – to become more intense.

The study uses projections from the IPCC’s sixth assessment report to model sea level rise over the 21st century. These include thermal expansion and meltwater from glaciers and ice sheets, but exclude “low-likelihood, high-impact” events, such as ice-sheet collapse.

The authors assess five future scenarios:

  • SSP1-1.9: A very-low emissions reductions pathway that “aligns with” the Paris Agreement’s 1.5C limit
  • SSP1-2.6: A “low” emissions pathway achieving net-zero emissions after 2050
  • SSP2-4.5: A “moderate” emissions scenario, often described as the trajectory under current climate policies. 
  • SSP3-7.0: A “high” emissions pathway
  • SSP5-8.5: A very-high emissions pathway of “high fossil fuel reliance” throughout the 21st century

They find that, even under the lowest 1.5C warming scenario, countries in the Asia-Pacific will face damages of $338bn due to coastal flooding every year by the end of the century. This accounts for 1.3% of the region’s present-day GDP. (The authors assume no adaptation measures, changes in land use or inflation over the century.)

Under the current policy scenario, annual damage from coastal flooding rises to $518bn by the end of the century.

The chart below shows coastal flood damage as a percentage of annual GDP by the end of the century under the five scenarios for each country. Each horizontal bar shows the damage for one country, with the lowest warming SSP1-1.9 scenario on the left (grey) and highest warming SSP5-8.5 scenario (black) on the right.

Coastal flood damage as a percentage of annual GDP by the year 2100 under the five emissions scenarios, for 29 countries in the Asia Pacific.
Coastal flood damage as a percentage of annual GDP by the year 2100 under the five emissions scenarios, for 29 countries in the Asia Pacific. Data: Monioudi et al, (2025). Chart by Carbon Brief.

The study finds that, by the end of the century, the Pacific island of Tuvalu will face the worst economic consequences from coastal flooding. Even under the 1.5C warming scenario, its annual economic losses due to coastal flooding will reach 38% of its GDP.

The authors also assess the amount of land that will be permanently lost to the sea.

They find that small island states – such as Kiribati, the Maldives, Micronesia and Tuvalu – will experience the highest percentage of their land permanently submerged, each losing around 10% of their total land area.

Two million people currently live in areas of the Asia-Pacific that will be permanently flooded by the end of the century under the 1.5C warming scenario, according to the research.

Finance gap

Countries can reduce the impacts of coastal flooding through adaptation. This can include building flood defenses, making infrastructure more resilient to flooding, or arranging “managed retreat” to move people away from vulnerable areas as the seas encroach.

The study authors model the cost of building defences – such as sea walls, levees, embankments and sand dunes – high enough that the economic damage from coastal flooding over the 21st century does not worsen beyond 2020 levels.

The research highlights that the cost of investing in these defences is substantially lower than the potential economic damages of sea level rise.

The authors estimate that, under a 1.5C warming scenario, building flood defenses to limit flood damage to 2020 levels would cost $9bn in total. However, building these defences would avoid $157bn in damages due to coastal flooding, they find.

Dr Rafael Almar is a researcher at the Laboratory of Space Geophysical and Oceanographic Studies in France and was not involved in the study. He says the study has “significant implications for development banks and financial institutions” as it could help them prioritise investments in “clearly identified hotspots”. 

However, he emphasises that building flood defences “is not the only solution”. For example, he argues that “relocation and renaturalisation” – the process of moving people away from the coast and allowing the area to return to its natural state – can make an area “more resilient”.

Panda also warns that physical flood defenses “could actually be triggering further local environmental crises that accelerate the losses and damages faced by people due to sea level rise and flooding impacts”.

Sea walls have been shown to damage wildlife – for example, blocking animals such as turtles from reaching parts of the beach – according to an article in Climate Home News. The piece adds that physical defenses are “inflexible” and “mainly benefit the rich and encourage risky building near the coast”.

Sourcing money for developing countries to adapt to the impacts of climate change is an ongoing talking point at international climate negotiations. 

A group of developed nations, including much of Europe, the US and Japan, is obliged under the Paris Agreement to provide international “climate finance” to developing countries. This money can be used for both mitigation – reducing emissions to limit warming – and adaptation.

In 2023, developed nations provided $26bn in international adaptation finance to developing nations, according to a recent UN report. This is roughly the amount that Asia-Pacific countries currently lose every year due to coastal flooding alone.

The post Asia-Pacific faces ‘$500bn-a-year’ hit from rising seas if current policies continue appeared first on Carbon Brief.

Asia-Pacific faces ‘$500bn-a-year’ hit from rising seas if current policies continue

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Supreme Court’s Limitation on Wetlands Protection Will Make Flooding Worse

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A new study calculates the dollar value of wetlands in reducing river flooding. But in Sackett vs. EPA, the high court rolled back protections for nature’s first line of defense.

The destruction of wetlands in the United States has increased the amount of flood insurance claims by $10 billion over the past 40 years, a phenomenon expected to worsen in tandem with climate change, according to new research.

Supreme Court’s Limitation on Wetlands Protection Will Make Flooding Worse

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Young South Africans take up sustainable agriculture for food security

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In a school in South Africa, a group of students stare at a row of small plants growing in a greenhouse. Each one is involved in the lesson, caring for the growing crops.

But this is no ordinary classroom setting. These children are learning about aquaponics, a method of growing plants and fish in a mutually beneficial water system. This ancient technique of food production is now being taught to millions of schoolchildren after being introduced by the South African government seven years ago.

Laerskool Kempton Park on the edge of Johannesburg was one of the first schools to introduce the subject with the aim of improving food security. This is a serious challenge in a country where an estimated 19.7 million people, or around 30% of the population, experience moderate levels of food insecurity, meaning that they struggle to afford enough food for a healthy, balanced diet.

Bringing the farm to school

Aquaponics is a way of supporting communities to access food in a sustainable and efficient way. The solution is simple: fish waste is turned into available nutrients by bacteria in the water. Plants absorb these nutrients and the cleaned water is returned to the fish tank.

There are multiple benefits to this approach. The system doesn’t require chemical fertilisers, soil or large tracts of land. It is also highly efficient, with recirculated water being used over and over again. This is an important feature in areas of South Africa that experience drought or unpredictable weather.

Agricultural subsidies can be repurposed for a just and sustainable rural transition

Aquaponics can offer a range of benefits depending on the local context. In South Africa, townships in major cities such as Johannesburg don’t always have the space to produce their own food, while in other places, such as the Northern Cape, extreme weather is making agriculture much harder.

Learners participating in a practical aquaponics lesson in Kempton Park. Image: INMED

Learners participating in a practical aquaponics lesson in Kempton Park. Image: INMED

Schoolchildren observing fish grown in an aquaponics system. Image: INMED

Schoolchildren observing fish grown in an aquaponics system. Image: INMED

At Laerskool Kempton Park, the students have benefited from the innovative work of INMED, a non-profit organisation that supports vulnerable children and families in the country.

INMED has trained hundreds of teachers and over 7,000 children on the benefits of aquaponics. With the help of funding from the Adaptation Fund through the UNDP-Adaptation Fund Climate Innovation Accelerator (AFCIA), the organisation was able to develop its own aquaponics system to be used in schools.

Scaling up the solution

INMED describes its prototype as a ‘plug and play’ system, designed to be modular and easy to install and manage. The system includes a 2,000-litre fish tank powered by a solar pump to circulate water. The design is simple with a view that it could be easily replicated across different school settings.

Unathi Sihlahla, director at INMED South Africa, told Climate Home News that “aquaponics speaks to a number of challenges… including limited access to nutritious food, high youth unemployment, water scarcity, and in many cases, poor or no access to arable land.”

Giving nature breathing room builds climate resilience

INMED’s prototype allows communities to work around these problems as it doesn’t need soil and uses far less water than conventional agriculture.

“We’ve seen schools that previously had no food production now able to grow vegetables consistently, while also producing fish. That food often goes straight into school meals or supports vulnerable households nearby,” Sihlahla added. The project estimates that over 5,300 kilogrammes of food have been harvested in each quarter the system has been operating.

As aquaponics is now part of the school curriculum, many educational departments across South Africa have been looking at ways to teach the subject. INMED’s innovative design could provide a handy solution. The organisation has already started to roll it out across different provinces and a new collaboration with the Eastern Cape Provincial Department of Education is in the works. INMED is also scaling the ‘plug and play’ model in Tanzania.

Plant inspection at one of INMED’s ‘plug and play’ aquaponics prototypes. Image: INMED

Plant inspection at one of INMED’s ‘plug and play’ aquaponics prototypes. Image: INMED

Giving youth a sense of pride

For educators, teaching schoolchildren new agricultural skills is not only about improving food security, but also about creating the next generation of farmers. This group will need to grow food with the increased threat of extreme weather events and having knowledge of alternative methods, such as aquaponics, could be key.

“Agriculture is not seen as something young people want to go into, but when they are exposed to something like aquaponics, it feels modern and relevant,” said Sihlahla, adding that some students have started their own projects at home or are looking to continue studying the method.

“There’s also a sense of pride. Producing food that supports your school or community changes how young people see themselves and their role.”

Engaging the next generation

The Adaptation Fund’s support for young people extends beyond South Africa. Several other related projects aim to equip youth with practical skills for climate adaptation.

In Costa Rica, a $10-million project implemented by private foundation Fundecooperación included several creative youth-focused programmes in climate-vulnerable areas. It trained young people in coral reef restoration and farming techniques, involved high school students in community water resource monitoring and management, shared knowledge on adaptation through a theatre tour in schools, and created an art mural competition using AI.

Extreme heat is rewriting food security. The best fixes are already within reach

In Lesotho, meanwhile, climate education is being integrated into the school curriculum through climate-smart agriculture materials and teacher training rolled out across primary and secondary schools. This is equipping students from an early age with practical, locally relevant knowledge to build resilience.

“Children and young people are among the most vulnerable to climate change,” said Mikko Ollikainen, head of the Adaptation Fund. “These programmes are not only training young people in adaptation but empowering them.”

Adam Wentworth is a freelance writer based in Brighton, UK.

The post Young South Africans take up sustainable agriculture for food security appeared first on Climate Home News.

Young South Africans take up sustainable agriculture for food security

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Santa Marta process can confront trade protection for fossil fuels, experts say

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Just as Colombia – a coal-producing country that has halted new exploration licenses for hydrocarbons – was set to host the first fossil fuel phase-out summit in late April, the government received notice from a foreign energy firm operating on its soil. It was being sued for millions of dollars.

One day before Colombia hosted representatives from around 60 countries for the first Global Conference on Transitioning Away from Fossil Fuels, Spain-based firm Termocandelaria Power, which operates two of the country’s diesel- and gas-fired power plants, sued the government for $198 million alleging a breach of investor protection rules under a bilateral agreement.

Termocandelaria said government measures since 2024 have prevented its Colombian subsidiaries from receiving full payment for the power they supplied to a public utility, while the Colombian government justified its actions as needed to guarantee financial solvency and deliver electricity to rural communities.

While Termocandelaria declined to comment for this article, the company said in a press release last month that investment protection treaties “are designed to provide a stable and predictable legal framework for long-term investments in strategic sectors”.

The timing shows how trade agreements that offer investors protection when government decisions are seen as causing harm to their business – a system known as investor-state dispute settlement (ISDS) – can hamper the transition away from fossil fuels even when countries are pushing for it. Governments in the Global South are particularly exposed, experts told Climate Home News.

    As part of the official academic contribution to the Santa Marta conference, researchers recommended that governments should “recognise” ISDS as a barrier to the energy transition, and called for negotiations on an international initiative to dismantle ISDS protection for fossil fuel investments, either through “a new standalone” international agreement or as part of a broader treaty.

    Mario Osorio, a research fellow at the Center for Economic and Policy Research (CEPR), said Termocandelaria’s claim against Colombia “puts in perspective how serious, concrete and real these threats are” for developing countries.

    Osorio said the second fossil fuel transition conference – to be held next year in Tuvalu – presents an opportunity for advancing ISDS reform from discussion to “something more concrete”.

    Plenary of the first conference on the Transition Away from Fossil Fuels in Santa Marta. (Photo: Ministry of Environment of Colombia)
    Plenary of the first conference on the Transition Away from Fossil Fuels in Santa Marta. (Photo: Ministry of Environment of Colombia)

    Colombia pledges to exit ISDS

    ISDS is a mechanism in international trade that allows foreign corporations – many of them linked to fossil fuel interests – to sue governments in international arbitration courts. One 2022 study estimated that possible legal claims from fossil fuel investors could reach $340 billion.

    In the lead-up to the Santa Marta conference, Colombian President Gustavo Petro pledged to exit the ISDS system by reviewing Colombia’s 129 investment protection agreements. This came after more than 200 economists sent Petro an open letter urging Colombia to abandon the ISDS system.

    Eunjung Lee, a senior policy advisor at UK-based think-tank E3G, said the Santa Marta conference had helped elevate ISDS reform as a key element of the transition away from fossil fuels, despite the issue remaining relatively little-known, even among climate negotiators.

    She added that governments tend to be cautious about discussing ISDS at climate summits, as these treaties also implicate trade and economy ministries. “If it is not your file, then you can’t really say much about it and taking action is not necessarily up to you,” she explained.

    Kyla Tienhaara, Canada Research Chair in Economy and Environment and a professor at Queen’s University who has worked on the issue for two decades, said the conference in Santa Marta marked a new approach, and that Colombia had placed ISDS “prominently in the agenda”.

    The next transition conference presents an opportunity for governments to land on something more practical, particularly under the agreed work stream on “macroeconomic dependence and financial architecture”, but it will depend on the co-chairs Tuvalu and Ireland, she said.

    Ireland was sued in May by oil company Lansdowne for failing to award a lease in the Barryroe offshore field. The claim was made under the Energy Charter Treaty (ECT), which fossil fuel companies have used to sue several governments over the consequences of enacting their climate policies.

    Following a similar move by some other European states, Ireland left the ECT in April while the Santa Marta conference was ongoing, but existing fossil fuel investments are still protected for 20 years under a “sunset clause”.

      “Disappointing” conference report

      Despite the prominence of the issue in the conference rooms, experts told Climate Home that the chairs’ takeaways report was “disappointing”, as it did not explicitly mention ISDS as a key obstacle to the energy transition.

      The Netherlands, which co-hosted the summit, may have faced conflicting interests, said Tienhaara, as it is second only to the US as a “home state” for the investors bringing the most ISDS cases, including foreign companies structuring their investments through the country.

      The Dutch government also withdrew from the ECT last year, which means it understands and has acted on the threat of investment treaties to climate action, the researcher said. “Unfortunately, they seem unwilling to extend their concern to the harm that these treaties cause in other countries, particularly in the Global South,” she added.

      Lee of E3G said Global North countries like the Netherlands tend to export capital to developing countries, which is why they seek to protect their investors’ interests and are unlikely to drive a dismantling of the ISDS system themselves.

      Developing countries like Colombia, which have been negatively affected by ISDS claims, have an incentive in “voicing their concerns” and forming a bloc around this topic. “Uniting Global South countries can make a stronger case,” Lee said.

      The post Santa Marta process can confront trade protection for fossil fuels, experts say appeared first on Climate Home News.

      Santa Marta process can confront trade protection for fossil fuels, experts say

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