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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.

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Despite African walkout, fractious land COP ends without drought deal

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The African continent’s hopes for a legally binding agreement to combat drought have been dashed again, as UN land restoration talks in Mongolia passed the issue onto the next set of talks in Egypt in two years’ time.

For over a decade, Africa has pushed for a UN protocol on drought risk management that would acknowledge drought as an issue requiring a regional and global – not just a national – response, potentially paving the way for more finance to help ensure water is available when drought hits.

A formal protocol would enable countries to transition from reacting to drought once it hits to “a proactive enabling mechanism to address drought and its effects such as migration”, said a Tunisian negotiator on behalf of the African Group of countries last week. Once land is regularly too dry and infertile to grow crops or graze animals, people often leave to seek a living elsewhere.

But this effort to adopt a protocol, led by Africa, has been resisted at successive land restoration COPs under the UN Convention to Combat Desertification (UNCCD), mainly by developed countries, which argue that a legally weaker alternative – a framework – would be faster and cheaper to set up.

A traditional Mongolian Ger tent at COP17 (Photo: Anastasia Rodopolou/IISD ENB)

Governments at the previous COP in Saudi Arabia in 2024 failed to reach agreement despite talks running past midnight, while this year’s saw African officials coordinate a walkout from negotiating rooms on Wednesday morning, according to two sources at the talks.

Drought deal delayed until 2028

The IISD’s Earth Negotiations Bulletin, a non-governmental organisation which unlike the media is allowed to watch and report on closed-door talks, said a call to suspend negotiations on Wednesday showed negotiations had reached “boiling point” and “made some jaws drop”.

Negotiations resumed after a lunchtime meeting with the Mongolian COP presidency although governments were only eventually able to agree that they could not find consensus in Ulaanbaatar and should resume talks on an instrument to deal with drought in 2028.

Christine Colvin, WWF’s head of freshwater policy, told Climate Home News that, with droughts hitting from Honduras to the English region of Hampshire, something concrete – whether a protocol or a framework – is needed urgently “rather than the can being kicked down the road for another two years as will now happen with the protocol procrastination”.

Negotiators talk at COP17 (Photo: Anastasia Rodopolou/IISD ENB)

But, in a closing press conference on Friday, the Mongolian minister presiding over talks celebrated that governments had reached consensus on several “contentious” issues and that agenda items blocked at this year’s COP17 would be put on the agenda for COP18 in Egypt.

US blocks agenda items

Other agenda items that divided countries were on measuring land degradation’s effects on women, enhancing the involvement of civil society and women in land COPs, and the UNCCD working more closely and effectively with the UN’s climate and nature conventions.

On the COP’s opening day two weeks ago, the US representative said the Trump government objects to these agenda items “on their premise and no amount of negotiation will allow us to join consensus on these items. As such we request that they be struck from the agenda at which time we will then be able to approve it, saving us valuable negotiating time.”

A US State Department spokesperson later told Climate Home News that the US wants the UN “to get back to basics by refocusing on its core mandate, eliminating overlap, and reducing competition for scarce resources”.

The spokesperson added, “that means prioritising the concrete work member states created [the UN] to do – rather than diverting limited time, attention, and resources toward social and political agendas, including gender-related initiatives.”

A protester calls for Indigenous Peoples, local communities, women and youth to be on the agenda of COP17 (Photo: Anastasia Rodopoulou/IISD ENB)

On COP’s first day, the European Union and Brazil pushed back against the blocking of these agenda items, with a Brazilian negotiator saying his country attaches “great importance” to them. But the Mongolian presidency directed governments to adopt the rest of the agenda without the controversial items, which were discussed privately with countries throughout the two weeks.

An EU statement, read out later by Irish minister Timmy Dooley, accused “some parties” (meaning national governments) of having adopted a “less constructive approach” and preventing “discussions on important matters from even commencing”.

The agenda items the US refused to engage with were never discussed and were only placed onto the agenda for the next COP on the last day. Those talks will take place in Egypt in two years’ time, with Donald Trump due then to be in his last year as US president.

No restoration without women

The blocking of the gender agenda item has stymied attempts, agreed on by governments at the last COP, to develop gender-specific indicators for the UNCCD’s next overall framework and to facilitate more women delegates at COPs. Women made up only about a quarter of delegates to COP15 in 2022, UNCCD analysis with the latest data shows

Criticising the move to keep gender off the agenda, the EU said in a statement that it welcomes “the attention being given at COP17 to women pastoralists and herders, recognising their contribution to sustainable land management and resilient rural livelihoods”.

The head of the UNCCD, former Egyptian environment minister Yasmine Fouad, said on Friday that “regardless that the agenda item was blocked”, she was proud that she and COP17 President Batmunkh Battsetseg had led the COP as women and attended the gender caucus (a meeting of groups supporting women at the talks).

Yasmine Fouad and Batmunkh Battsetseg talk at the COP17 closing press conference (Photo: Kiara Worth/UNCCD)

“Without the women,” she told the closing press conference on Friday, “we will not be able to restore land, restore hope, restore life or restore even our children and grandchildren. And we will keep on pushing that agenda.”

The civil society agenda item aimed to allow NGOs to attend land COP negotiations, as they do at climate COPs, and included terms of reference for an Indigenous Peoples Caucus.

A representative of Indigenous Peoples told the COP’s closing plenary meeting that the group had “deep disappointment that the agenda of this COP has removed the dedicated space for indigenous peoples”. “We cannot restore the land while removing the voices of those who care for it,” she said.

On Tuesday, the UNCCD’s deputy head Andrea Meza was asked about Indigenous Peoples’ participation. She said that the blocking of “one agenda item” is “generating uncertainty in the progress” towards creating caucuses for Indigenous Peoples and for Local Communities within the talks.

Because of the “complex geopolitical situation” making it hard to obtain consensus, coalitions of the willing have become more important, she added.

Mining out, money in

Outside the formal negotiations, the summit was marked by a focus on the strongly Mongolian issues of the role played by pastoralists and rangelands like grasslands, as well as mining, in both degrading and restoring land.

Part of the conference was sponsored by Australian mining company Rio Tinto and its local partner Oyu Tolgoi. Their presence was protested by campaigners wearing T-shirts calling on the companies to “stop wasting drinking water” and to “get out of Mongolia”.

A campaigner protests at COP17 on Thursday (Photo by IISD/ENB | Anastasia Rodopoulou)

The UNCDD and others praised the success of the summit in raising more finance for land restoration. The COP saw institutions like the Asian Development Bank and Global Environment Facility pledge money to combat land degradation, with the UNCCD estimating that $645 million of new commitments were made.

An estimated $355 billion a year is needed through 2030 to meet global land restoration commitments, compared with around $77 billion currently invested. Private finance accounts for only around 6% of global investment, according to the UNCCD.

UNCCD chief scientist Baron Orr told a press conference that many of the announcements were public-private partnerships that use government money to “even the playing field” for companies that want to protect land, in a bid to ensure they are not disadvantaged compared with those that do not.

Such partnerships are a “huge opportunity”, he said, especially as “we’re not in a moment of public finance – public finance is tight in every country.”

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Pacific islands seek backing for new regional fund ahead of COP31

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Burdened by rising fuel import costs and an “ocean crisis” of record-breaking heat, Pacific island nations are seeking to build support for a new regional fund ahead of COP31, intended to channel investment into renewable energy, community resilience and ocean protection, experts said.

Leaders from the 18-member Pacific Islands Forum (PIF), including Australia and New Zealand, are expected to issue a call for global pledges to the Pacific Resilience Facility (PRF) at a high-level meeting this coming week in Palau, seeking to build a new model for financing climate action.

The new regional fund was formally launched in May this year and is meant to “serve communities at a community level”, swiftly channelling investments for their projects on the ground, according to Fiji’s assistant minister for foreign affairs, Lenora Qereqeretabua.

“We are expecting pledges for the PRF, and these funds will go to communities that apply,” she told journalists at an online briefing. “We have organised it in such a way that it makes our application processes much, much easier than applying for global funding.”

Qereqeretabua added that she expects that PRF funds will be “utilised by communities to protect themselves from climate change and the effects of climate change.”

The Pacific Islands Forum meeting is expected to shape the region’s priorities ahead of this year’s pre-COP, hosted by Fiji and Tuvalu, and COP31, which will be co-led by Australia and Türkiye.

At COP31, a dedicated session on the climate finance needs of small island states will seek to drive pledges into the PRF. The fund has so far received about $172 million in capital – with about $67 million coming from Australia – and aims to close the year with $500 million.

    Ocean heat and fossil fuel shocks

    Leaders from the Pacific will meet in Palau from Sunday amid an “ocean crisis” of record-breaking ocean heat caused by this year’s “super El Niño”, according to Kevin Chand, Pacific ocean policy director at National Geographic’s Pristine Seas conservation project.

    Leaders at the PIF are expected to put forward commitments towards new marine protected areas, which will be key for shielding ecosystems from future climate extremes, Chand said. The forum is expected to issue a statement on the need for ocean action at COP31, and announce commitments towards reaching the global goal of protecting 30% of the planet’s land and sea ecosystems by 2030.

    Rising ocean heat could lead to food insecurity and lost government earnings in the region, as key fish stocks like tuna start migrating away from their coastline in search of colder waters, said Coral Pasisi, director of climate change and sustainability at the Pacific Community (SPC).

    Climate shocks are deepening existing economic pressures, as Pacific nations have spent up to a quarter of their GDP on fossil fuel imports due to the war in Iran, according to a recent report by the University of New South Wales (UNSW) in Australia.

    Wesley Morgan, one of the study’s authors, told journalists that partner nations “ought to be putting their money where their mouth is”, and should support the energy transition in the Pacific by covering the upfront costs of switching from polluting diesel to solar power, batteries and electricity grid upgrades.

    China keeps Indonesia’s battery dream afloat but future less certain

    Given the increase in climate-related shocks and sea-level rise, the PIF should also mention the need to phase out fossil fuel extraction and consumption, said Sindra Sharma, international policy lead at the Pacific Islands Climate Action Network (PICAN).

    Last year’s COP30 failed to deliver a global roadmap on transitioning away from fossil fuels, which led to a group of countries – including several Pacific island nations – pursuing their own fossil fuel phase-out summit in Santa Marta, Colombia. Next year’s conference will be hosted by Tuvalu and co-chaired by Ireland, which should also receive backing from the PIF, Sharma said.

    Both the chairs of the Santa Marta coalition and the Australian COP31 co-presidency have vowed to continue a push for this topic to be discussed at COP31.

    A drought response brigade in Tuvalu in 2020
    A drought response brigade in Tuvalu in 2020. (Photo: Pacific Community)

    New fund to test allies

    As local communities in the Pacific struggle to access global climate funds, the PRF’s planned model for quick, direct disbursements has “very solid and good” intentions, Sharma said, but it will need political and financial backing from donor countries.

    “The proof is going to be when the fund actually starts operating and delivering to communities,” she added. “If there is too much bureaucracy in being able to access the funds, for example. These things will have to be scrutinised.”

    The facility aims to deliver funds in two categories: one for climate adaptation and “disaster resilience”, and another for social and community resilience that includes areas like community capacity-building, education, data analytics and financial management, among others. It will launch its first call for proposals at the PIF.

    Morgan added that Australia will need to “leverage global interests” so that funding is directed to the Pacific Resilience Facility “or else the Pacific won’t be able to trust Australia as a partner”. The country ratified the PRF treaty in May, triggering its entry into force.

    “The perception [of Australia] in the region is genuinely divided, and it’s worth being honest about it,” Sharma said, adding that the pre-COP31 in Fiji, which is usually limited to a technical space for negotiations, will determine how meaningful Australia’s advocacy for the Pacific can be.

    This time, Pacific nations want to use the pre-COP in early October as an opportunity to demonstrate the challenges their largely low-lying islands face and to advocate for their political priorities, including a renewed global effort to limit global warming to 1.5C by cutting emissions faster and deeper. World leaders are due to visit Tuvalu to experience the frontline of rising sea levels, although Australia and Fiji have yet to confirm who will attend.

    “In Bonn, Australia was largely missing on the negotiated outcomes that we so urgently need to see. It’s not enough to get Pacific priorities on the agenda. Agenda placement is not delivery,” Sharma added.

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    Climate Change

    Climate change exposes 580 million children to 20 extra ‘heat-stress days’ every year

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    More than 40% of children under the age of 10 globally are already experiencing at least 20 additional “heat-stress days” due to climate change.

    This is according to a new attribution study, published in Science Advances, which combines climate models with demographic data to assess the age groups and regions that are exposed to the most hot, humid days.

    The study finds that children up to the age of nine already face more additional heat-stress days globally as a result of climate change than any other age group.

    It adds that south Asia and west Africa are recording the greatest childhood exposure to dangerous levels of humid heat – largely because these regions have a rapidly growing population with the highest proportion of young children.

    As the climate warms, children will continue to be more exposed to heat stress than any other age group, the paper warns.

    The lead author of the study tells Carbon Brief that the findings should inform discussions about climate justice, noting that children in developing countries “have contributed the least to historical greenhouse gas emissions”.

    Humid heat

    High temperatures can be deadly. For example, the heatwaves that swept across Europe in the summer of 2026 have been linked to tens of thousands of “excess deaths”.

    A prominent 2021 study found that children born in the 21st century will be exposed to more extreme weather events in their lifetimes than their parents and grandparents.

    Four years later, a study conducted by scientists from the same team found that more than half of children born in 2020 – around 62 million people – will experience “unprecedented lifetime exposure” to heatwaves, even if warming is limited to 1.5C.

    Now, the latest research from the same team finds that children already face greater exposure to dangerous levels of humid heat than adults as a result of human-caused climate change.

    Extreme heat is particularly dangerous when combined with high humidity. In hot weather, the human body produces sweat to cool itself down. However, as humidity increases, sweating becomes less effective.

    The study uses wet-bulb globe temperature – a measure of temperature that takes humidity and wind into account – to calculate heat stress. It defines a “heat-stress day” as any day with a wet-bulb globe temperature above 28C, as this is considered the threshold for “moderate heat stress”

    The authors then use climate models to simulate global temperature patterns in the present-day climate. (The authors use the climate of 2023, in which human activity has caused 1.3C of warming, to represent the “present-day”.)

    They then count the number of heat-stress days that each country records on average, per year. The authors then repeat this exercise, simulating a pre-industrial climate without human-caused warming.

    By comparing the number of heat-stress days in the present-day climate with the number in a pre-industrial climate, the authors can determine how many extra heat-stress days were driven by climate change. They refer to these as “extra” or “attributable” heat-stress days.

    The authors find that “low-latitude” countries, located in the tropics, record the most extra heat-stress days.

    For example, the paper finds that people living in Côte d’Ivoire currently face 112 heat-stress days every year. It adds that around half of these are due to human-caused climate change.

    In contrast, Germany sees only 0.1 heat-stress days per year in today’s climate on average, which is largely attributable to human-caused climate change.

    Rosa Pietroiusti, a PhD student at Vrije Universiteit Brussel and lead author on the study, explains why this number may seem lower than expected.

    She tells Carbon Brief that the paper “really focuses on humid heat, at levels that are relatively rarely felt in Europe”. She adds:

    “Our data also doesn’t capture the urban heat island effect, due to the resolution of the data we use, which also would lead to underestimations of heat stress locally, and lead to a mismatch with what people are experiencing at local scales, particularly in cities.”

    Inequality

    Extreme heat affects some people more severely than others. Children, people over 65 and those with pre-existing medical conditions or certain disabilities are among the most vulnerable. This is because their bodies are less able to regulate their temperature.

    The authors use gridded demographic data to determine the age structure of each country. From this, they calculate how many people from each age cohort are exposed to extra heat days as a result of climate change.

    The research finds that globally, 583 million children under the age of 10 already live through at least 20 attributable heat days every year. This accounts for 44% of all children in this age bracket.

    In comparison, 190 million people aged 60-69 face at least 20 attributable heat days per year, accounting for 30% of this age cohort.

    The authors find that children face the greatest exposure to humid heat for two main reasons.

    First, there are more young people alive today than older people, with 1.3 billion children aged under 10 in the world, compared to 0.6 billion people aged 60-69.

    Second, they find that countries in Africa and Asia typically have rapidly growing populations with more young children. In contrast, many countries in the northern hemisphere – which are typically cooler – have older populations.

    The map below shows how many extra stress heat days each country currently faces as a result of human-caused climate change. Darker reds indicate a higher number of attributable heat days. The blue circles show the percentage of the population under the age of 10, with larger circles indicating a higher percentage.

    Map of the world showing the number of extra heat days faced by the global population at present-day warming levels as a result of human-caused climate change. Source: Pietroiusti et al (2026).
    The number of extra heat days faced by the global population at present-day warming levels as a result of human-caused climate change. Source: Pietroiusti et al (2026).

    Warming world

    The authors also repeat their analysis for a 1.5C and 2C warmer world. They use population estimates from the SSP2 scenario, which projects that the world’s population will peak at more than nine billion in the second half of the 21st century, with most growth occurring in low-latitude regions – especially in sub-Saharan Africa.

    The research finds that, in today’s climate, 11% of all under 10s currently experience 100 or more extra heat-stress days per year due to climate change. In worlds warmed by 1.5C and 2C, the percentage rises to 13% and 23%, respectively.

    In contrast, only 6% of all people aged 60-69 currently face 100 or more extra heat-stress days each year due to climate change. This number rises to 9% and 17% for 1.5C and 2C worlds, respectively.

    These results are shown in the plot below. The three rows represent the climates of 2023 (top), a 1.5C world (middle) and a 2C world (bottom). The columns show different age cohorts, from the oldest on the left to the youngest on the right.

    Each circle contains 100 coloured dots, with each dot representing 1% of the age cohort.

    The colour of the dot represents exposure to annual heat-stress day, with darker dots indicating more heat-stress days. Grey dots mean that people experience fewer than one extra heat-stress day per year due to human-caused climate change, while black dots mean more than 150 extra heat-stress days due to climate change.

    The figure shows that higher warming levels expose more people to heat stress and that younger cohorts tend to be worst affected.

    For example, the top-right circle represents heat stress for under 10s in the present-day climate. Three of these dots are coloured black, indicating that 3% faced at least 150 attributable heat-stress days in 2023.

    Attributable days of heat stress for different age cohorts (columns), at different warming levels (rows). Each circle contains 100 coloured dots, with each dot representing 1% of the age cohort. Darker dots indicate more heat-stress days. Source: Pietroiusti et al (2026).
    Attributable days of heat stress for different age cohorts (columns), at different warming levels (rows). Each circle contains 100 coloured dots, with each dot representing 1% of the age cohort. Darker dots indicate more heat-stress days. Source: Pietroiusti et al (2026).

    Pietroiusti tells Carbon Brief the study uses wet-bulb temperature because it is a “well-established heat stress metric”. However, she notes that it was not “explicitly defined to focus on children”. She continues:

    “A really important step forward in the research community would be to link up climate science and health science experts to do research on what metrics are really most representative of, for example, health impacts and educational impacts that children will be suffering.”

    Vulnerability

    Dr Qinqin Kong, a postdoctoral researcher at the departments of medicine and health policy at Stanford University, who was not involved in the study, praises its “robust” methodology.

    He tells Carbon Brief that the research provides “a timely quantitative evidence for discussions of climate justice, children’s rights and intergenerational equity”.

    However, Kong suggests that the paper “may overstate the contrast between children and the elderly and underestimate the relative burden of older adults”.

    He says:

    “The elderly may also be more vulnerable due to their social circumstances. Children often benefit from parental supervision and caregiving, whereas many older adults live alone, have limited mobility and face barriers to accessing cooling or emergency assistance during heat events.”

    Kong also notes that “people and societies in the mid-latitudes [for example, across much of Europe and North America] are less adapted to heat”, which may make them vulnerable to its impacts.

    For example, he says that Europe “shows substantially stronger relative risk of heat mortality likely due to less heat-acclimatised populations, lower air conditioning prevalence and urban designs that don’t favour heat dissipation”.

    Similarly, Dr Daniel Vecellio – a researcher at the University of Nebraska, who was not involved in the study – tells Carbon Brief that children are an “understudied cohort”.

    However, he says there is “reason for hope” because “children are typically pretty good behavioural adapters to extreme heat” and because people who are “chronically exposed to extreme heat” will “have a better chance at better acclimatisation”.

    Pietroiusti tells Carbon Brief that global reporting on heatwaves is often skewed towards wealthier nations.

    For example, she notes that large-scale databases of disasters, such as EM-DAT, often underrepresent heatwaves in Africa, due in part to a lack of news coverage and formal reporting. She adds:

    “Studies like this, which start from the climate data, can start to fill some of these gaps.”

    She adds that the paper should inform discussions about climate justice, noting that children in developing countries, who are most severely affected by the increase in heat-stress days, “have contributed the least to historical greenhouse gas emissions”.

    Pietroiusti, R. et al. (2026) Age-specific exposure to human-induced increases in humid heat, Science Advances, doi:10.1126/sciadv.aeb3232

    The post Climate change exposes 580 million children to 20 extra ‘heat-stress days’ every year appeared first on Carbon Brief.

    Climate change exposes 580 million children to 20 extra ‘heat-stress days’ every year

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