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 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.
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
N.C. Gov. Josh Stein wants state lawmakers to rethink tax breaks for data centers. The industry’s opacity makes it difficult to evaluate costs and benefits.
Tax breaks for data centers in North Carolina keep as much as $57 million each year into from state and local government coffers, state figures show, an amount that could balloon to billions of dollars if all the proposed projects are built.
The Global Environment Facility (GEF), a multilateral fund that provides climate and nature finance to developing countries, has raised $3.9 billion from donor governments in its last pledging session ahead of a key fundraising deadline at the end of May.
The amount, which is meant to cover the fund’s activities for the next four years (July 2026-June 2030), falls significantly short of the previous four-year cycle for which the GEF managed to raise $5.3bn from governments. Since then, military and other political priorities have squeezed rich nations’ budgets for climate and development aid.
The facility said in a statement that it expects more pledges ahead of the final replenishment package, which is set for approval at the next GEF Council meeting from May 31 to June 3.
Claude Gascon, interim CEO of the GEF, said that “donor countries have risen to the challenge and made bold commitments towards a more positive future for the planet”. He added that the pledges send a message that “the world is not giving up on nature even in a time of competing priorities”.
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Donors under pressure
But Brian O’Donnell, director of the environmental non-profit Campaign for Nature, said the announcement shows “an alarming trend” of donor governments cutting public finance for climate and nature.
“Wealthy nations pledged to increase international nature finance, and yet we are seeing cuts and lower contributions. Investing in nature prevents extinctions and supports livelihoods, security, health, food, clean water and climate,” he said. “Failing to safeguard nature now will result in much larger costs later.”
At COP29 in Baku, developed countries pledged to mobilise $300bn a year in public climate finance by 2035, while at UN biodiversity talks they have also pledged to raise $30bn per year by 2030. Yet several wealthy governments have announced cuts to green finance to increase defense spending, among them most recently the UK.
As for the US, despite Trump’s cuts to international climate finance, Congress approved a $150 million increase in its contribution to the GEF after what was described as the organisation’s “refocus on non-climate priorities like biodiversity, plastics and ocean ecosystems, per US Treasury guidance”.
The facility will only reveal how much each country has pledged when its assembly of 186 member countries meets in early June. The last period’s largest donors were Germany ($575 million), Japan ($451 million), and the US ($425 million).
The GEF has also gone through a change in leadership halfway through its fundraising cycle. Last December, the GEF Council asked former CEO Carlos Manuel Rodriguez to step down effective immediately and appointed Gascon as interim CEO.
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New guidelines
As part of the upcoming funding cycle, the GEF has approved a set of guidelines for spending the $3.9bn raised so far, which include allocating 35% of resources for least developed countries and small island states, as well as 20% of the money going to Indigenous people and communities.
Its programs will help countries shift five key systems – nature, food, urban, energy and health – from models that drive degradation to alternatives that protect the planet and support human well-being by integrating the value of nature into production and consumption systems.
The new priorities also include a target to allocate 25% of the GEF’s budget for mobilising private funds through blended finance. This aligns with efforts by wealthy countries to increase contributions from the private sector to international climate finance.
Niels Annen, Germany’s State Secretary for Economic Cooperation and Development, said in a statement that the country’s priorities are “very well reflected” in the GEF’s new spending guidelines, including on “innovative finance for nature and people, better cooperation with the private sector, and stable resources for the most vulnerable countries”.
Aliou Mustafa, of the GEF Indigenous Peoples Advisory Group (IPAG), also welcomed the announcement, adding that “the GEF is strengthening trust and meaningful partnerships with Indigenous Peoples and local communities” by placing them at the “centre of decision-making”.
The post GEF raises $3.9bn ahead of funding deadline, $1bn below previous budget appeared first on Climate Home News.
GEF raises $3.9bn ahead of funding deadline, $1bn below previous budget
Tropical cyclones that rapidly intensify when passing over marine heatwaves can become “supercharged”, increasing the likelihood of high economic losses, a new study finds.
Such storms also have higher rates of rainfall and higher maximum windspeeds, according to the research.
The study, published in Science Advances, looks at the economic damages caused by nearly 800 tropical cyclones that occurred around the world between 1981 and 2023.
It finds that rapidly intensifying tropical cyclones that pass near abnormally warm parts of the ocean produce nearly double – 93% – the economic damages as storms that do not, even when levels of coastal development are taken into account.
One researcher, who was not involved in the study, tells Carbon Brief that the new analysis is a “step forward in understanding how we can better refine our predictions of what might happen in the future” in an increasingly warm world.
As marine heatwaves are projected to become more frequent under future climate change, the authors say that the interactions between storms and these heatwaves “should be given greater consideration in future strategies for climate adaptation and climate preparedness”.
‘Rapid intensification’
Tropical cyclones are rapidly rotating storm systems that form over warm ocean waters, characterised by low pressure at their cores and sustained winds that can reach more than 120 kilometres per hour.
The term “tropical cyclones” encompasses hurricanes, cyclones and typhoons, which are named as such depending on which ocean basin they occur in.
When they make landfall, these storms can cause major damage. They accounted for six of the top 10 disasters between 1900 and 2024 in terms of economic loss, according to the insurance company Aon’s 2025 climate catastrophe insight report.
These economic losses are largely caused by high wind speeds, large amounts of rainfall and damaging storm surges.
Storms can become particularly dangerous through a process called “rapid intensification”.
Rapid intensification is when a storm strengthens considerably in a short period of time. It is defined as an increase in sustained wind speed of at least 30 knots (around 55 kilometres per hour) in a 24-hour period.
There are several factors that can lead to rapid intensification, including warm ocean temperatures, high humidity and low vertical “wind shear” – meaning that the wind speeds higher up in the atmosphere are very similar to the wind speeds near the surface.
Rapid intensification has become more common since the 1980s and is projected to become even more frequent in the future with continued warming. (Although there is uncertainty as to how climate change will impact the frequency of tropical cyclones, the increase in strength and intensification is more clear.)
Marine heatwaves are another type of extreme event that are becoming more frequent due to recent warming. Like their atmospheric counterparts, marine heatwaves are periods of abnormally high ocean temperatures.
Previous research has shown that these marine heatwaves can contribute to a cyclone undergoing rapid intensification. This is because the warm ocean water acts as a “fuel” for a storm, says Dr Hamed Moftakhari, an associate professor of civil engineering at the University of Alabama who was one of the authors of the new study. He explains:
“The entire strength of the tropical cyclone [depends on] how hot the [ocean] surface is. Marine heatwave means we have an abundance of hot water that is like a gas [petrol] station. As you move over that, it’s going to supercharge you.”
However, the authors say, there is no global assessment of how rapid intensification and marine heatwaves interact – or how they contribute to economic damages.
Using the International Best Track Archive for Climate Stewardship (IBTrACS) – a database of tropical cyclone paths and intensities – the researchers identify 1,600 storms that made landfall during the 1981-2023 period, out of a total of 3,464 events.
Of these 1,600 storms, they were able to match 789 individual, land-falling cyclones with economic loss data from the Emergency Events Database (EM-DAT) and other official sources.
Then, using the IBTrACS storm data and ocean-temperature data from the European Centre for Medium-Range Weather Forecasts, the researchers classify each cyclone by whether or not it underwent rapid intensification and if it passed near a recent marine heatwave event before making landfall.
The researchers find that there is a “modest” rise in the number of marine heatwave-influenced tropical cyclones globally since 1981, but with significant regional variations. In particular, they say, there are “clear” upward trends in the north Atlantic Ocean, the north Indian Ocean and the northern hemisphere basin of the eastern Pacific Ocean.
‘Storm characteristics’
The researchers find substantial differences in the characteristics of tropical cyclones that experience rapid intensification and those that do not, as well as between rapidly intensifying storms that occur with marine heatwaves and those that occur without them.
For example, tropical cyclones that do not experience rapid intensification have, on average, maximum wind speeds of around 40 knots (74km/hr), whereas storms that rapidly intensify have an average maximum wind speed of nearly 80 knots (148km/hr).
Of the rapidly intensifying storms, those that are influenced by marine heatwaves maintain higher wind speeds during the days leading up to landfall.
Although the wind speeds are very similar between the two groups once the storms make landfall, the pre-landfall difference still has an impact on a storm’s destructiveness, says Dr Soheil Radfar, a hurricane-hazard modeller at Princeton University. Radfar, who is the lead author of the new study, tells Carbon Brief:
“Hurricane damage starts days before the landfall…Four or five days before a hurricane making landfall, we expect to have high wind speeds and, because of that high wind speed, we expect to have storm surges that impact coastal communities.”
They also find that rapidly intensifying storms have higher peak rainfall than non-rapidly intensifying storms, with marine heatwave-influenced, rapidly intensifying storms exhibiting the highest average rainfall at landfall.
The charts below show the mean sustained wind speed in knots (top) and the mean rainfall in millimetres per hour (bottom) for the tropical cyclones analysed in the study in the five days leading up to and two days following a storm making landfall.
The four lines show storms that: rapidly intensified with the influence of marine heatwaves (red); those that rapidly intensified without marine heatwaves (purple); those that experienced marine heatwaves, but did not rapidly intensify (orange); and those that neither rapidly intensified nor experienced a marine heatwave (blue).
Dr Daneeja Mawren, an ocean and climate consultant at the Mauritius-based Mascarene Environmental Consulting who was not involved in the study, tells Carbon Brief that the new study “helps clarify how marine heatwaves amplify storm characteristics”, such as stronger winds and heavier rainfall. She notes that this “has not been done on a global scale before”.
However, Mawren adds that other factors not considered in the analysis can “make a huge difference” in the rapid intensification of tropical cyclones, including subsurface marine heatwaves and eddies – circular, spinning ocean currents that can trap warm water.
Dr Jonathan Lin, an atmospheric scientist at Cornell University who was also not involved in the study, tells Carbon Brief that, while the intensification found by the study “makes physical sense”, it is inherently limited by the relatively small number of storms that occur. He adds:
“There’s not that many storms, to tease out the physical mechanisms and observational data. So being able to reproduce this kind of work in a physical model would be really important.”
Economic costs
Storm intensity is not the only factor that determines how destructive a given cyclone can be – the economic damages also depend strongly on the population density and the amount of infrastructure development where a storm hits. The study explains:
“A high storm surge in a sparsely populated area may cause less economic damage than a smaller surge in a densely populated, economically important region.”
To account for the differences in development, the researchers use a type of data called “built-up volume”, from the Global Human Settlement Layer. Built-up volume is a quantity derived from satellite data and other high-resolution imagery that combines measurements of building area and average building height in a given area. This can be used as a proxy for the level of development, the authors explain.
By comparing different cyclones that impacted areas with similar built-up volumes, the researchers can analyse how rapid intensification and marine heatwaves contribute to the overall economic damages of a storm.
They find that, even when controlling for levels of coastal development, storms that pass through a marine heatwave during their rapid intensification cause 93% higher economic damages than storms that do not.
They identify 71 marine heatwave-influenced storms that cause more than $1bn (inflation-adjusted across the dataset) in damages, compared to 45 storms that cause those levels of damage without the influence of marine heatwaves.
This quantification of the cyclones’ economic impact is one of the study’s most “important contributions”, says Mawren.
The authors also note that the continued development in coastal regions may increase the likelihood of tropical cyclone damages over time.
Towards forecasting
The study notes that the increased damages caused by marine heatwave-influenced tropical cyclones, along with the projected increases in marine heatwaves, means such storms “should be given greater consideration” in planning for future climate change.
For Radfar and Moftakhari, the new study emphasises the importance of understanding the interactions between extreme events, such as tropical cyclones and marine heatwaves.
Moftakhari notes that extreme events in the future are expected to become both more intense and more complex. This becomes a problem for climate resilience because “we basically design in the future based on what we’ve observed in the past”, he says. This may lead to underestimating potential hazards, he adds.
Mawren agrees, telling Carbon Brief that, in order to “fully capture the intensification potential”, future forecasts and risk assessments must account for marine heatwaves and other ocean phenomena, such as subsurface heat.
Lin adds that the actions needed to reduce storm damages “take on the order of decades to do right”. He tells Carbon Brief:
“All these [planning] decisions have to come by understanding the future uncertainty and so this research is a step forward in understanding how we can better refine our predictions of what might happen in the future.”
The post Marine heatwaves ‘nearly double’ the economic damage caused by tropical cyclones appeared first on Carbon Brief.
Marine heatwaves ‘nearly double’ the economic damage caused by tropical cyclones
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