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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).

Average maximum sustained wind speed (top) and rate of rainfall (bottom) for tropical cyclones in the period leading up to and following landfall. Storms are categorised as: rapidly intensifying with marine heatwaves (red); rapidly intensifying without marine heatwaves (purple); not rapidly intensifying with marine heatwaves (orange); and not rapidly intensifying, without marine heatwaves (blue). Source: Radfar et al. (2026)
Average maximum sustained wind speed (top) and rate of rainfall (bottom) for tropical cyclones in the period leading up to and following landfall. Storms are categorised as: rapidly intensifying with marine heatwaves (red); rapidly intensifying without marine heatwaves (purple); not rapidly intensifying with marine heatwaves (orange); and not rapidly intensifying, without marine heatwaves (blue). Source: Radfar et al. (2026)

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.”

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Marine heatwaves ‘nearly double’ the economic damage caused by tropical cyclones

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Energy transition policymaking must evolve to fit an age of rupture

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Andreas Sieber is head of political strategy at 350.0g. Cat Abreu is director of the International Climate Politics Hub.

From the US abduction of Venezuela’s president at the start of this year to the Iran war which rumbles on, disruption is the new normal for global geopolitics, more often than not linked to conflict over supplies of oil and gas. 

Events so far in 2026 – driven largely by the desire of the Trump administration to grab control of fossil fuels around the world – show that the climate community’s approach to energy diplomacy will have to evolve if we are to operate effectively and push for climate action in such a volatile landscape.

Today’s climate and energy governance must be able to cope with trade wars, genocide, fascism, spiralling inequality and challenges to multilateralism. The increasingly dominant paradigms of economic competitiveness, energy security and green industrialisation can help drive the transition but they also challenge our collective mission to deliver an equitable green shift.

US-China rivalry dominates

Longer-term geopolitical trends that are seeing power move from West to East and North to South have fuelled a US–China “superpower rivalry”, which is pulling the global economy apart and reining in trade.

A key question will be how the fracture “lines” are drawn: by the US and China, or also by other countries or blocs? Many governments will try to remain “in the middle” between the two giants to capture economic gains from both sides. Yet despite the language of “strategic autonomy”, Washington and Beijing may be in a position to force choices via market access, export controls and sanctions.

    At first glance, this may not seem particularly relevant for climate and energy politics. But Huawei’s exclusion from 5G operations across the political West and India following the so-called Clean Network Campaign by the US government serves as a warning of what could happen to climate green tech.

    And the recent debate to cut out Chinese inverters from European markets follows the same pattern – US security forces perceive a risk and start encouraging their allies to drop Chinese technology.

    The new drivers: competition and security

    Despite this fracturing geopolitical and economic context, energy transition is still happening. To ensure it is effective and equitable, we need to understand what is driving it and how to adapt climate politics so that it better responds to these drivers.

    Put simply, China is supplying the world with low-cost renewables (roughly 60% of critical wind and 80% of solar components), batteries, EVs and other key elements. Other countries now also want their piece of the green tech pie and are forming industrial policies to get it.

    It is this new competitiveness-driven logic that will shape the quest for decarbonisation, which has shifted from cooperating around the cost of tackling climate change to rivalry for the benefits of climate action.

    Over 90% of new renewables projects are now cheaper than fossil alternatives. Gas-fired power is 3–4 times more expensive than solar and wind. In 2015, most decarbonisation policies were “traditional” emissions-cutting strategies like carbon pricing or net zero dates, whereas green industrial policies now underpin the majority.

    Iran war could boost fossil fuel phase-out push, says Colombian minister

    Meanwhile, security has become a central driver of energy politics. We are living through the second major fossil fuel crisis in just four years. Elevated oil and gas prices will impose up to $1 trillion in additional costs on the global economy by the end of the year if disruption continues in the Strait of Hormuz. Fossil fuel supply chains have exposed countries to conflict, coercion and brutal price shocks.

    Fossil fuel volatility destabilises whole economies – higher fuel costs drive up food prices, increase political instability, and push millions into poverty and hunger. This incentivises governments to shield themselves from global shocks, especially in countries that are net fossil fuel importers and home to roughly three-quarters of the world’s population. 

    Yet security fears can cut both ways. The same instability that makes fossil fuel dependence untenable is also sharpening concern over China’s dominance of critical clean technologies and supply chains.

    Equity, cooperation and the opportunity for change

    Developing countries benefit from the rapid uptake of renewables enabled by low-cost Chinese technologies. But significant fiscal space and public investment is needed for the electricity grids and infrastructure required to fully unleash the energy transition, as well as for green industrialisation to diversify revenue streams.

    Despite this, industrial-scale domestic production and ownership often remain out of reach for too many countries that lack the fiscal space to allow green supply chains to flourish and compete with their traditional industrial base. But more just and diversified green tech supply chains could be achieved with concomitant support.

    Can giant batteries unlock Africa’s green industrial future?

    For the first time in decades, the international order is being substantially reshaped. If within this context, decarbonisation is increasingly driven by green industrial policy, energy security and competitiveness, the climate policy community must better anticipate where these debates are moving. We must speak the same language, and enter the forums where decisions are made, including security, trade and bilateral or trilateral spaces.

    We should build on an enlightened self interest recognising that cooperation remains essential and beneficial. This includes using the UN climate process differently: less as an ever-expanding negotiation machine, and more as a space for norm-setting, political alignment and deal-making. In an age of fragmentation, effective cooperation must not only be framed as necessary but thought of as a strategically compelling source of resilience and shared advantage.

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    Extreme heat costing India’s poorest workers 2% of GDP, survey finds

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    Low-income Indian workers, many of them migrants from rural areas hit by climate change, are paying for worsening extreme heat through lost working days and health complications, with the cost equivalent to 2% of national GDP per year, new research shows.

    The International Institute of Environment and Development (IIED), a London-based think-tank, worked with local organisations to survey around 540 households of informal workers in three Indian cities: Ajmer, Delhi and Agra. Most had migrated from rural areas to find work in industries such as construction, brick-making, garment manufacturing and food packaging.

    The survey found them struggling through long working days with little access to shade, cooling, rest or water, as well as few toilets for women. And even when they go home, many live in makeshift shelters or airless cramped rooms with barely a single fan, bringing almost no respite.

    Outdoor workers are losing about 24 days of work a year due to heat, costing them nearly a tenth of their annual earnings, while indoor workers sacrifice roughly 15 days. On top of losing income, they are also bearing the cost of health problems like heat exhaustion, psychological stress and kidney damage brought on by repeated dehydration.

    If the survey’s findings are extrapolated to a national level, the IIED researchers estimate that the decline in productivity and effects of kidney disease combined add up to lost wages of $78 billion each year.

      Vishram Meena, 45, from Alwar in Rajasthan, has worked on construction sites in Ajmer for more than a decade, toiling for 10 to 12 hours a day carrying materials and mixing cement in the full sun.

      In May 2024, on one of the hottest days, he collapsed after feeling dizzy and suffering a nosebleed. His wife and colleagues managed to get him to hospital where he was diagnosed with heat stroke. He has since returned to the same building work because the family needs the money.

      “I went back because what else could I do? We are not machines. We are human beings. The heat is killing us slowly,” he was quoted as saying in a report on the survey’s findings.

      “Victorian-era” conditions

      Ritu Bharadwaj, IIED’s director of climate resilience, finance and loss and damage, described some of the stories from workers about their experiences of extreme heat as “genuinely horrifying”.

      Kusum, a tailor at a garment manufacturing and export unit in Kapashera, Delhi, recounted how the machines for ironing finished garments are in the same tiny room where workers are making the clothes, with steam and hot air building up through her shift.

      Fans are too far apart to move the air and nothing has changed in over a decade, she said, adding that “in summer, the unit feels like a furnace”.

      “These are Victorian-era working conditions and they’re completely unacceptable in the 21st century,” said Bharadwaj. She called for stepped-up social protection from the government to pay people for days they are unable work due to heat, as well as micro-insurance schemes with payouts triggered by temperature measurements.   

      This money would help families buy food and pay medical bills when their income dips if they fall ill or cannot work their usual hours due to soaring temperatures.

      Climate change-driven heatwaves hit Delhi’s Red Fort market traders

      The aim of the IIED study, Bharadwaj added, is to get policy-makers’ attention by showing the scale of damage extreme heat is doing to India’s GDP in an economy whose growth relies on service-led industries. “If the workers within them start falling sick, you know it’s the economic growth which is going to get impacted,” she told a webinar to present the research.

      “Whether [policymakers] care about the workers or not, at least they would care about the GDP, and therefore then invest in their care,” she explained.

      Labour code leaves out heat

      However, Bharadwaj noted that a 2026 reform to India’s labour law bringing a range of regulations together in one code does not include heat-related protections for workers and only applies to businesses above a certain size. She urged the government to introduce a temperature threshold above which all workers would be able to stop their activities.

      IIED and its partners have also carried out a similar study in Bangladesh which will be published later this month, showing that extreme heat is costing its workforce the equivalent of nearly 1.4% of GDP.

      Shakirul Islam, chairperson of the Ovibashi Karmi Unnayan Program (OKUP) in Bangladesh, said the government had introduced stricter safety policies for garment-making companies after the Rana Plaza complex collapsed in 2013. But, he said, these rules are rarely followed by manufacturers, especially at the level of smaller subcontractors.

      The workers’ welfare centres that do exist are open mainly during work hours so they are difficult to visit. Some companies also make saline water available for heat stress, which is no good for those with high blood pressure, he noted.

      For Indian women workers, a just transition means surviving climate impacts with dignity

      Archana Shukla Mukherjee, CEO of India’s Change Alliance, which also partnered with IIED on the survey, said it was time to hold both the government and businesses accountable for finding solutions to the intensifying problem of extreme heat’s effects on workers.

      She said that employee state insurance schemes should identify heat stroke as an occupational disease while companies along the whole supply chain should start putting in place heat protection measures, including for informal workers and migrants.

      If the tools and mechanisms available to help workers do not reach the most vulnerable and marginalised people, “then I think we are not doing something right,” she said.

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      Top maritime court rejects bid to halt UN deep-sea mining inquiry

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      A United Nations investigation into deep-sea mining firms will continue after the world’s top maritime court rejected their bid to suspend the inquiry triggered by a US-backed push to extract critical minerals from the ocean floor.

      In two orders issued on Saturday, the International Tribunal for the Law of the Sea (ITLOS) declined to halt an inquiry launched by the International Seabed Authority (ISA) into whether permit holders, including Tonga Offshore Mining Ltd (TOML) and Nauru Ocean Resources Inc (NORI), have breached their obligations under UN exploration contracts.

      The two companies are subsidiaries of Canadian firm The Metals Company (TMC), which earlier this year sought permits from the United States to commercially mine the deep seabed in an area already covered by its UN exploration licences, bypassing the ISA’s regulatory process.

      The inquiry was opened after TMC’s move raised questions over whether its subsidiaries had complied with their contractual obligations to the ISA, which regulates mining in international waters under the UN Convention on the Law of the Sea. TOML and NORI sued the ISA last June for allegedly targeting them “in breach of due process” and without “good faith”.

        While allowing the inquiry to proceed, the court ordered the ISA to ensure the companies receive due process. Judges said the regulator must explain the factual and legal basis of its inquiry, clarify the procedures being followed and provide TOML and NORI with a meaningful opportunity to respond.

        The companies seeks to mine an area called the Clarion-Clipperton Zone, which holds vast reserves of critical minerals like nickel, manganese and rare earths but is also home to a little-studied deep ocean ecosystem with thousands of unnamed species.

        In response to the court’s ruling, the ISA welcomed the decision, saying the inquiry “remains in effect” and would continue “with due regard to all applicable legal requirements”.

        Last week, during an annual meeting of its member governments, ISA secretary-general Leticia Carvalho said the resources in the ocean floor are “the common heritage of humankind” and upheld the agency’s role as “more important than ever”.

        TMC also welcomed the court decision in a statement and claimed that judges ruled to “protect the rights of TMC subsidiaries”.

        “Contractors like NORI and TOML, who have together spent hundreds of millions of dollars on the promise of a fair regulatory framework, should be informed of the factual and legal basis of any non-compliance inquiries, understand the procedure being applied, and receive a meaningful opportunity to respond,” said Gerard Barron, CEO of The Metals Company.

        Iridogorgia and bamboo coral pictured around the Johnston Atoll Unit of the Pacific Remote Islands Marine National Monument (Photo: NOAA Office of Ocean Exploration and Research)

        Environmental groups said the ruling allows scrutiny of the companies’ actions to continue.

        Louisa Casson, deep-sea mining campaigner with Greenpeace, said the “entire litigation has been an egregious waste of time and money”, which was part of the industry’s “textbook distraction tactic” meant to delay the consequences of the inquiry.

        “If the inquiry confirms that TMC’s subsidiaries are breaching their contracts, governments must send the strongest possible signal that complicity in unlawful deep sea mining will not be tolerated,” she said.

        While investigation is still ongoing, NORI’s contract is set to expire this week and is up for review. Governments asked the ISA to report back and make “make appropriate recommendations” by the next ISA assembly, its main decision-making body set to take place next week from July 27 to 31.

        The court ordered both the ISA and TMC to submit a report on how they complied with the ruling by August 31, and called on both to “cooperate and refrain from any action that might lead to
        aggravating the dispute”.

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