Extreme weather events, such as heavy rainfall, flooding and heatwaves, have been described as the “new normal” for China.
The country lost almost 12bn yuan ($1.65bn) due to heavy rainfall and floods in April – “the worst in 10 years”. In June, dozens of people were killed and some 33 rivers in China “exceeded warning levels”. The floods in Guilin, capital city of Guangxi province, were the largest in the area since 1998.
It has been less than a year since the Beijing meteorological service recorded 745mm of rain in just five days during July 2023 – roughly the same amount the city usually receives in the whole month.
The province surrounding Beijing, Hebei, also had heavy rainfall at the same time. In July 2023, the county of Lincheng recorded more than one metre of rain, twice its annual average.
In July 2021, Hebei’s neighbouring province Henan had a “one-in-a-thousand-year” rainstorm.
While China has issued more policies to improve its emergency response system and infrastructure, the increasing number of extreme weather events continues to pose challenges.
In this Q&A, Carbon Brief looks at the reasons for China’s recent floods, how the country is adapting and whether it will need to re-examine and future-proof its flood defence systems.
- What are the reasons behind the recent floods?
- What role does human-caused climate change play?
- How is China adapting to increasingly frequent flooding?
- How effective are these measures?
- What can China learn from other cities?
What are the reasons behind the recent floods?
There are various factors behind the frequent heavy rain and flooding in recent years.
Dr Oliver Wing, honorary research fellow at the school of geographical sciences, University of Bristol, tells Carbon Brief that “on the whole, we expect a warming world to be a wetter world due to the Clausius-Clapeyron relationship”.
This relationship dictates that the air can generally hold around 7% more moisture for every 1C of temperature rise, meaning rainfall is likely to be heavier in a warmer climate.
Wing notes that “for sub-daily rainfall, we are seeing even greater scaling than this relationship would suggest. This makes surface water flooding in cities [more likely] due to short-duration, intense, localised rainfall increase”.
In addition, he says, “warming is inducing a rise in sea levels in most places, meaning storm surges have a higher baseline from which to inflict damage”.
In China, “higher than normal temperatures” were behind frequent heavy rainfall in southern coastal provinces, such as Guangdong and Guangxi, since April, says Zheng Zhihai, chief forecaster at the National Climate Centre of the China Meteorological Administration (CMA), and reported in China Daily.
Zheng adds that the El Niño-Southern Oscillation – a natural climate cycle that entered its warmer El Niño phase in mid-2023 – was partly to blame because it raised sea surface temperatures and directed vast amounts of water vapour from the South China Sea and the Bay of Bengal towards southern China.
Dr Faith Chan, head of the school of geographical sciences at the University of Nottingham Ningbo China, tells Carbon Brief that the rainfall pattern in Guangdong during this April was quite similar to the intensive rainstorm on 6-8 September in 2023 after Typhoon Haikui.
Specifically, the intense rainfalls were generated by the low-pressure moist current from the south-east and south Asian monsoon pattern crashing into another low-pressure rain belt from the Philippines and the west Pacific.
Typhoon Haikui had hit Hong Kong with the worst storm in 140 years and caused some of the heaviest rains in the provinces of Guangdong and Fujian.
While these intense rainstorms, in a meteorological sense, are not unusual, they are happening more closely to one another owing to the warming world, Chan says.
Large-scale heavy rainstorms typically occur three times on average in April – the onset of a monsoon season. But, this year, China has been battered by at least eight regional extreme rain events in the month alone, all happening in quick succession.
River floods are commonly seen in the affected regions, such as Chongqing and Hunan. Identifying the causes can be more complicated for river floods in general, says Wing:
“There are many modulating factors. Drier soils in a warming world may enable the land to absorb the increased rainfall, thereby mitigating any flood hazard increase. Many floods are not driven by intense rainfall, but are driven by snowmelt or low-intensity, long-duration rain falling on saturated soils. For this reason, it is not reasonable to extrapolate that increased rainfall in a warming world will lead to increased fluvial flooding.”
Chan says natural reasons “of course” enhanced the wetness, “but human-induced climate change led to the greenhouse effect and caused sea temperature to rise, which caused more storms and low-pressure rain belts. That is a fact”.
Wing agrees that “the thermodynamic impact” of human-led climate change increases the rainfall associated with storms. But, he adds:
“What we do not understand well is how anthropogenic climate change has altered the dynamics of the climate system, and where and how this either compounds or dampens the thermodynamic response.”
What role does human-caused climate change play?
Many studies have found that warmer sea surface temperatures are supercharging high-impact, back-to-back extreme rains.
The sixth assessment report (AR6) from the UN’s Intergovernmental Panel on Climate Change (IPCC) also says that human-induced climate change caused by greenhouse gas emissions contributes to ocean warming and “is likely the main driver of the observed global-scale intensification of heavy precipitation over land regions”.
In east and central Asia, under 1.5C of global warming, extreme annual daily rainfall (Rx1) and five-day accumulated rainfall (Rx5) events are projected to increase by 28% and 15%, respectively, relative to 1971-2000, according to AR6.
Similarly, it says that in China’s urban agglomerations, “an increase in global warming from 1.5C to 2C is likely to increase the intensity of total precipitation of very wet days 1.8 times and double maximum five-day precipitation”.
Prof Yang Chen of the Chinese Academy of Meteorological Sciences at the CMA tells Carbon Brief that human-caused intensification of heavy rainfall over China had been even larger than expected. He explains:
“Human-caused intensification of heavy precipitation over monsoonal China is markedly larger than expected from increases in atmospheric moisture due to warming, because of stronger feedback between latent heat releases and ascending motion within wetter storms in a warmer climate.”
Such feedback, he adds, is particularly evident in eastern China compared to other regions of similar latitudes.
A recent study in Nature also anticipates storm activity over China to become more frequent and intense as a result of warming. By the end of the 21st century, the annual average frequency of tropical cyclones on the east coast of China is anticipated to increase by 16% compared to the present day, according to the study.
Apart from climate change that is caused by human activities, poorly designed and constructed cities, as well as subsidence – caused by groundwater extraction, the weight of buildings as result of urban growth, urban transportation systems and mining activities – could also amplify floods.
Dr Kevin Smiley, assistant professor from the department of sociology of Louisiana State University tells Carbon Brief:
“Climate change is increasing the severity and frequency of extreme weather. Extra rainfall induced by climate change can be the difference between a building’s parking lot hosting puddles on a rainy day compared to floodwaters crossing the threshold of the building and causing thousands of dollars of damages.
“It’s always important to remember: climate change is anthropogenic, so this increased risk also has human-caused roots.”
How is China adapting to increasingly frequent flooding?
China has built a number of large water projects to prevent flooding, such as the south-north water transfer projects in the Yangtze river that was launched in 2002.
In the most recent “national water network construction planning outline” published by the State Council – China’s top administrative authority, the equivalent of central government – constructing “national water networks” by 2035 is among the “backbones” of future flood prevention.
The “backbones” in the document also include large hard-engineered structures on the main rivers, such as embankments, flood gates and channelised river networks, to mitigate flood risks.
Meanwhile, a study published in the journal Ocean & Coastal Management found that “nature-based solutions” have also become popular in China. The restoration and conservation of freshwater swamps, mangroves and wetlands along coastlines and river mouths are being used to provide a buffer for tidal and storm surges.
They include the Chongming Island wetland in Shanghai (Yangtze delta) and the Futian and Mai Po wetlands in Shenzhen Bay (Pearl River delta).
Another concept proposed in the planning document is to “accelerate smart development” by using the internet, data and technology to monitor and prevent floods.
The capital Beijing has incorporated data from high-definition cameras, as well as telescopes, radar maps and satellite cloud images to provide real-time hazard updates, which has improved emergency response times.
Ningbo, a port city on China’s east coast, has worked with mobile companies to analyse big data and disseminate information.
The Ministry of Emergency Management said these measures have reduced the number of deaths and missing people as a result of natural disasters by 54% over 2018-22, compared to 2013-17. The death toll continued to fall in 2023 but the number of destroyed buildings and direct economic losses rose by 97% and 13%, respectively, compared with 2018-22 levels.
In 2015, the sponge city programme (SCP) concept was written into a policy document of the Ministry of Housing and Urban-Rural Development. It was promoted across the country and 30 major cities, such as Wuhan (home to 11 million people) and Zhengzhou (home to 10 million people), were chosen to be the pilot cities.
Those sponge cities are designed to collect, purify and re-use at least 70% of the floodwaters through “green-blue facilities”, such as green roofs, permeable pavements and stormwater parks, in urban areas. The overall system was meant to resolve the issues of urban heating, freshwater scarcity and flooding all at once.
China has improved its recovery process too. In Ningbo, for example, flood victims were able to access financial compensation within an hour, using an improved online documentation process during Typhoon In-Fa in 2021.
How effective are these measures?
Chan tells Carbon Brief that China has “done very well in terms of preparation, response and recovery for flood and drought hazards” – the two most destructive types of natural disasters.
“As a global south country,” he says, referring to China as a developing country, “China has done quite well with the SCP [sponge cities programme] and the ecologically enhanced solutions for addressing climate change”.
However, Wing argues that nature-based solutions, such as SCP, can “get saturated quickly” and so “there’s a risk of their role being overstated”. He continues:
“These types of interventions are most effective for rainfall events which occur relatively regularly at low intensities. They will be quickly overwhelmed during the very intense, rare rainfall events (whose probabilities are changing rapidly in a warming world) that cause the most damage and suffering.”
In 2021, a “historically rare” rain and flood, that affected more than 14 million people and killed 398 in Zhengzhou, a showcase sponge city, highlighted the limitations of the SCP in the face of climate change.
SCP is designed to only withstand one-in-30-year rain events, says the Nature study. On top of that, it can create a false sense of security, which encourages more people to move to high-risk areas, leading to an increase in population and assets in exposed areas that require ever-increasing protection in a cycle referred to as a “levee effect”, says Chan.
The levee effect refers to the paradox whereby the construction of a flood-defence levee leads to a lowered perception of flood risks and a greater likelihood of property owners investing in their property, increasing the potential damages should the levee breach.
The effect, according to the Nature paper, is a key challenge in the densely populated Yellow River delta and Pearl River areas, which both face high risks of flooding.
Smiley says:
“Risk is realised when social vulnerabilities intersect with hazards. Vulnerabilities are social. Flood impacts are greater when social vulnerabilities are greater…Social vulnerabilities are uneven. A household with some wealth and good insurance can recover from a flooding event much faster and more successfully than a household living paycheck-to-paycheck.”
The Chinese government has allocated more than one trillion yuan ($138bn) – via a special government bond – to support the vulnerable citizens and reconstruction of areas hit by natural disasters in March this year. More than half of the funds are used for “the construction of water conservancy projects like flood control,” reported state media outlet the Global Times.
But the delivery of financial support has been questioned in the past. When Typhoon Doksuri hit China in 2023, only $2bn out of roughly $25bn in aggregate losses were underwritten, according to global reinsurer Munich Re.
In addition, the construction of those sponge cities has already cost China 1.5-1.8bn yuan ($210-250m) between 2015 and 2018. And maintenance will make this bill even larger.
The authors of the Nature paper suggest that the government should work on integrating fragmented “grey infrastructure” – built structures such as drains, pipework and pumping stations – into existing green-blue facilities, but should not rely on engineered infrastructure alone.
Dr Lele Shu, a researcher at the northwest institute of eco-environment and resources, Chinese Academy of Sciences, tells the Intellectual magazine that “the [impact of] heavy rain at the current rate cannot be mitigated through traditional engineered approaches alone”.
“Everytime there is heavy rain, the damage it causes will make headlines primarily because there are too many people living in the city,” adds Shu.
The lack of coordination between regional governments and municipalities in flood prone areas also often led to fragmented approaches to disaster management.
In the case of the Yangtze and Pearl deltas, there is a lack of delta-wide plans that “systematically zone land and prioritise investments within one unified hydrological system”, the Nature study adds.
Dr Zheng Yan, a researcher at the Research Institute of Eco-civilisation, China Academy of Social Sciences, noted in the aftermath of the 2023 Beijing flood that government bodies often look after their own jurisdiction and aim only to move the problem and divert the floods quickly, which piled pressure on cities in downstream areas.
Smiley says:
“Floodwaters don’t care about human-created boundaries by municipality, district or province. Effective urban design in one locality may lessen flood risk there, but indirectly increase risk elsewhere. Thinking collectively while centering justice means providing spatially extensive and locally attuned solutions that help all recover effectively instead of exacerbating inequalities.”
What can China learn from other cities?
As flooding is a challenge faced by cities across the world, there is a plethora of ideas and technologies that China can draw on.
The Nature paper suggests that the Yangtze and Pearl deltas, for example, could learn from the Ganges-Brahmaputra-Meghna delta and the Mekong delta to “improve their responses to regional challenges such as subsidence and erosion, by using and aligning with the underlying dynamics of the deltas that are rapidly changing in response to climate change and anthropogenic activities”.
Building a resilient society that is “proactive and forward-looking, with adequate capabilities to limit detrimental flooding impacts and timely return to the pre-disaster state” is also advocated by the paper.
Rotterdam, a Dutch delta city of 600,000 people that is surrounded by water on four sides, has built water storage facilities, such as an underground parking garage with a basin the size of four Olympic swimming pools. It has also installed green roofs and facades to absorb rainwater.
Japan has built an intricate network of concrete tunnels and vaults about 14 storeys beneath the Saitama prefecture in the outskirts of Tokyo, Japan’s capital city, that can hold more than 1,000 Olympic pools of rainwater.
Both cities’ underground flood diversion facilities are often used as a prime example of a viable flood defence system for urban cities on the frontline of climate change.
Hong Kong has a similar underground stormwater storage system beneath the sport pitches of the Happy Valley Racecourse, designed to withstand once-in-50-years flood events.
However, Chan says it is difficult to compare flood mitigation measures as each city is very different in terms of geography, demographic, densities and topography.
He tells Carbon Brief:
“But in my opinion, China’s megacities should think about using underground spaces to store the sudden extreme discharge from super intensive rainstorms…Tokyo and Rotterdam are quite wise (in that regard) for using their underground spaces.”
The post Q&A: How China is adapting to increasingly frequent flooding appeared first on Carbon Brief.
Q&A: How China is adapting to increasingly frequent flooding
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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