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As 2024 passes its midpoint, the global climate continues to push into uncharted territory.

Carbon Brief’s analysis indicates a 95% probability that this year will surpass 2023 as the warmest year on record in the Copernicus/ECMWF ERA5 dataset.

This projection emerges amid a series of climate extremes that have marked the first half of 2024.

In the latest “state of the climate” quarterly update, Carbon Brief assesses the first full six months of 2024 and finds:

  • The first six months of 2024 have each set new temperature records, extending an already remarkable streak of 13 consecutive record-breaking months dating back to 2023.
  • On 22 July, the world experienced its highest absolute global daily temperature on record, reaching a scorching 17.15C.
  • The heat has been felt globally, with 63 countries experiencing their warmest June on record. Over the past 12 months, a staggering 138 countries have recorded their hottest temperatures ever.
  • July 2024 is very likely to be the first time in 13 months without a new record, coming in cooler than July 2023. However, it will still be more than 0.2C warmer than any July prior to 2023.
  • With El Niño fading and modest La Niña conditions potentially developing later this year, it is unlikely that the extreme monthly temperature records set in the second half of 2023 will be surpassed in 2024.
  • Antarctic sea ice extent has fallen to near 2023’s record lows in recent weeks, reflecting the broader trend of polar sea ice loss.

Record warm first half of the year

Global temperatures set a new record for each of the first six months of 2024, extending what was already a string of seven record setting months in 2023.

All in all, each of the last 13 months has been the warmest since records began in the mid-1850s.

The figure below shows how global temperature so far in 2024 (purple line) compares to each month in different years since 1940 (with lines coloured by the decade in which they occurred) in the Copernicus/ECMWF ERA5 surface temperature dataset.

Temperatures for each month from 1940 to 2024 from Copernicus/ECMWF ERA5. Anomalies plotted with respect to a 1850-1900 baseline. Chart by Carbon Brief.

Temperatures for each month from 1940 to 2024 from Copernicus/ECMWF ERA5. Anomalies plotted with respect to a 1850-1900 baseline. Chart by Carbon Brief.

Global temperatures in the latter half of 2023 exceeded prior records by at least 0.3C, peaking in September when 2023 surpassed the previous September record by 0.5C. While 2024 has continued to set records, the margins have been smaller:

  • January to April 2024: About 0.1C above previous records (set in 2016)
  • May 2024: About 0.2C above the previous record (set in 2020)
  • June 2024: About 0.15C above the previous record (set in 2023)

It is important to note that June 2024 is being compared to the already high temperatures set in 2023. Compared to the last major El Niño event in 2016, June 2024 was about 0.4C warmer.

The figure below shows the margin by which global temperatures were set in each of the prior 13 record-setting months.

Margin by which new monthly temperature records have been set over the past 13 months. Using data from Copernicus/ECMWF ERA5. Chart by Carbon Brief.

Margin by which new monthly temperature records have been set over the past 13 months. Using data from Copernicus/ECMWF ERA5. Chart by Carbon Brief.

In this latest quarterly state of the climate assessment, Carbon Brief analyses records from five different research groups that report global surface temperature records: NASA, NOAA, Met Office Hadley Centre/UEA, Berkeley Earth and Copernicus/ECMWF.

The figure below shows the annual temperatures from each of these groups since 1970, along with the average over the first six months of 2024. (Note: at the time of writing, June data was not yet available for the Hadley/UEA record.)

Annual global mean surface temperatures from NASA GISTEMP, NOAA GlobalTemp, Hadley/UEA HadCRUT5, Berkeley Earth and Copernicus/ECMWF (lines), along with 2024 temperatures so far (January-June, coloured dots). Anomalies plotted with respect to the 1981-2010 period, and shown relative to pre-industrial based on the average pre-industrial temperatures in the Hadley/UEA, NOAA and Berkeley datasets that extend back to 1850. Chart by Carbon Brief.

Annual global mean surface temperatures from NASA GISTEMP, NOAA GlobalTemp, Hadley/UEA HadCRUT5, Berkeley Earth and Copernicus/ECMWF (lines), along with 2024 temperatures so far (January-June, coloured dots). Anomalies plotted with respect to the 1981-2010 period, and shown relative to pre-industrial based on the average pre-industrial temperatures in the Hadley/UEA, NOAA and Berkeley datasets that extend back to 1850. Chart by Carbon Brief.

The globe, as a whole, has warmed more than 1C since 1970, with strong agreement between different global temperature records. However, there are larger differences between temperature records further back in time (particularly pre-1900) due to sparser observations and a resulting greater sensitivity to how gaps between measurements are filled in.

All show that the average global temperature for 2024 so far is higher than any prior annual record. However, annual temperatures may end up being a bit lower than those of the first six months of the year, as El Niño conditions have faded and a mild La Niña event is likely to develop later in the year.

The last two years – 2023 and 2024 – stand out as substantially warmer than any prior year in the temperature record. The chart below shows a heat map of daily global average temperatures in the Copernicus/ECMWF ERA5 dataset, with temperatures shown by colours ranging from blue (-2C) to red (+2C), with the pre-industrial average (1850-1900) set to 0C. The figure below shows each day since 1940 in the dataset.

Heat map of daily temperatures for each day from 1940 to present (21 July 2024) from Copernicus/ECMWF ERA5.
Heat map of daily temperatures for each day from 1940 to present (22 July 2024) from Copernicus/ECMWF ERA5. Anomalies plotted with respect to a 1850-1900 baseline. Chart by Carbon Brief.

A summer of temperature extremes

While global average surface temperature changes are an important indicator of long-term climate change, any month or year will have important regional warm or cool patterns in different parts of the world.

June 2024 saw particularly warm temperatures over much of South America, the southern US and Mexico, northern Africa, western Europe, central Asia and the Middle East among other regions.

The figure below shows the difference between temperatures in June 2024 and the baseline period of 1951-80, taken from Berkeley Earth (using their high-resolution temperature dataset). Red, orange and yellow shading indicate areas that have been warmer than average, while blue shows areas that have been cooler.

Global surface temperature anomalies for June 2024 compared to a 1951-80 baseline period.
Global surface temperature anomalies for June 2024 compared to a 1951-80 baseline period. Figure from Berkeley Earth.

In total, 63 countries, mostly in Africa and South America, had their warmest national-average June on record. These included Brazil, Bulgaria, Cambodia, Colombia, Egypt, Ethiopia, Ghana, Greece, Israel, Ivory Coast, Jordan, Kenya, Lebanon, Libya, Nepal, Romania, Saudi Arabia, Somalia, South Africa, South Korea, Sudan, Syria, Turkey, Venezuela and Yemen.

The figure below shows which portions of the Earth’s surface experienced record high temperatures (deep red shading) in June 2024. It is noteworthy that almost no location on the planet experienced record cold temperatures.

Locations setting record warm temperatures in June 2024 based on data back to 1850. Figure from Berkeley Earth
Locations setting record warm temperatures in June 2024 based on data back to 1850. Figure from Berkeley Earth

Zooming out to the past 12 months (July 2023 to June 2024), 138 countries saw all-time records broken. This includes much of Central and South America, Canada, Africa, Europe, China, the Middle East and south-east Asia. Only an anomalous patch of east Antarctica saw record cold temperatures.

Locations setting record warm temperatures in the 12-month period from July 2023 to June 2024 compared to past July-June periods in data back to 1850.
Locations setting record warm temperatures in the 12-month period from July 2023 to June 2024 compared to past July-June periods in data back to 1850. Figure from Berkeley Earth

Very likely to be the warmest year on record

With half the year of data now available, Carbon Brief has determined that there is now an approximately 95% chance that 2024 will beat 2023 and be the warmest year on record, based on Copernicus/ECMWF’s ERA5 dataset. (Berkeley Earth separately estimated a 92% chance in their June update.)

By looking at the relationship between the first six months and the annual temperatures for every year since 1970 – as well as El Niño-Southern Oscillation conditions for the first six months of the year and projections for the remaining nine months – Carbon Brief has created a projection of what the final global average temperature for 2024 will likely turn out to be.

The analysis includes the estimated uncertainty in 2024 outcomes, given that temperatures from only the first half of the year are available so far.

The chart below shows the expected range of 2024 temperatures using the Copernicus/ECMWF global atmospheric reanalysis product (ERA5) – including a best-estimate (red) and year-to-date value (yellow). Temperatures are shown with respect to the pre-industrial baseline period (1850-1900).

Annual global average surface temperature anomalies from the Copernicus/ECMWF global atmospheric reanalysis product (ERA5) plotted with respect to a 1850-1900 baseline. To-date 2024 values include January-June. The estimated 2024 annual value is based on the relationship between the January-June temperatures and annual temperatures between 1970 and 2023. Chart by Carbon Brief.

Annual global average surface temperature anomalies from the Copernicus/ECMWF global atmospheric reanalysis product (ERA5) plotted with respect to a 1850-1900 baseline. To-date 2024 values include January-June. The estimated 2024 annual value is based on the relationship between the January-June temperatures and annual temperatures between 1970 and 2023. Chart by Carbon Brief.

Carbon Brief’s projection suggests that 2024 is very likely to be the warmest year on record, with a central estimate of 1.57C.

This is true even if – as the projection implicitly assumes – the remaining months in 2024 are below the records set in 2023. Because the first six months of the year were so warm – around 1.63C above pre-industrial levels – the second half of the year would have to be relatively cool (below 1.3C) for the year as a whole to not exceed 2023.

It is worth repeating that an individual year hitting 1.5C above pre-industrial levels is not equivalent to the 1.5C limit within the Paris Agreement. This limit refers to long-term warming, rather than an individual year that includes the short-term influence of natural fluctuations in the climate, such as El Niño. Even including data through to the present day, long-term global temperatures (excluding year-to-year variability) are unlikely to exceed 1.5C until the late 2020s or early 2030s.

The figure below shows Carbon Brief’s estimate of 2024 temperatures using ERA5, both at the beginning of the year and once each month’s data has come in. The central estimate remained relatively unchanged until June, after which it increased a bit as the month turned out a bit warmer than the model anticipated. The uncertainty has diminished with each additional month of data, as there are fewer remaining months in 2024 to substantially change the results.

Carbon Brief’s projection of global temperatures at the start of the year, and after January, February, March, April, May, and June ERA5 data became available. Chart by Carbon Brief.

Carbon Brief’s projection of global temperatures at the start of the year, and after January, February, March, April, May, and June ERA5 data became available. Chart by Carbon Brief.

There is reason to expect that global temperature anomalies will modestly decline over the remainder of the year as El Niño fades away and moderate La Niña conditions potentially develop. The figure below shows a range of different forecast models for ENSO for the rest of this year, produced by different scientific groups. The values shown are sea surface temperature variations in the tropical Pacific – the El Niño 3.4 region – for overlapping three-month periods.

El Niño-Southern Oscillation (ENSO) forecast models for overlapping three-month periods in the Niño3.4 region (December, January, February – DJF – and so on) for the remainder of 2024.
El Niño-Southern Oscillation (ENSO) forecast models for overlapping three-month periods in the Niño3.4 region (December, January, February – DJF – and so on) for the remainder of 2024. Credit: Image provided by the International Research Institute for Climate and Society, Columbia University Climate School

There is a mix of projections across models, with many of the dynamical models expecting very modest La Niña conditions (<-0.5C Niño 3.4 sea surface temperature – SST – anomaly) to develop by October, while most of the statistical models expect ENSO-neutral conditions to persist.

July on track to end the record monthly streak

Global surface temperatures have set a 13-month streak of monthly records from June 2023 and June 2024. However, with more than two thirds of July temperature now available, it is looking increasingly likely that July 2024 will break that streak, coming in as the second warmest on record after July 2023.

The figure below shows daily temperature anomalies from the Copernicus/ECMWF ERA5 record for 2024 (purple line), 2023 (red line) and 1940-2022 (grey lines). It highlights that July 2024 has been at or below 2023 temperatures for all but the past few days.

Daily global temperature anomalies from 1940 to present (22 July 2024) from Copernicus/ECMWF ERA5, with daily values for each year plotted as a separate line. The colours indicate 2024 (purple), 2023 (red) and all other years (grey). Anomalies plotted with respect to a 1850-1900 baseline. Chart by Carbon Brief.

Daily global temperature anomalies from 1940 to present (22 July 2024) from Copernicus/ECMWF ERA5, with daily values for each year plotted as a separate line. The colours indicate 2024 (purple), 2023 (red) and all other years (grey). Anomalies plotted with respect to a 1850-1900 baseline. Chart by Carbon Brief.

Current global temperature anomalies are back in record territory as of 22 July, at around 1.7C above pre-industrial levels. 

This is still well below the anomalies of 2C or more briefly hit in late 2023 and early 2024. However, because the current temperature anomalies align with the warmest week of the year for global surface temperatures, they have resulted in a new record for absolute global temperatures. This is shown in the figure below, which features daily absolute global temperatures from the Copernicus/ECMWF ERA5.

Daily global absolute temperatures from 1940 to present (22 July 2024) from Copernicus/ECMWF ERA5, with daily values for each year plotted as a separate line. The colours indicate 2024 (purple), 2023 (red) and all other years (grey). Chart by Carbon Brief.

Daily global absolute temperatures from 1940 to present (22 July 2024) from Copernicus/ECMWF ERA5, with daily values for each year plotted as a separate line. The colours indicate 2024 (purple), 2023 (red) and all other years (grey). Chart by Carbon Brief.

The prior daily absolute temperature record was 17.08C, set in early July 2023. This was exceeded both by 22 July (at 17.09C) and 22 July (at 17.15C). 

While these daily absolute temperature records are not that climatically meaningful (and are only available in reanalysis data) – anomalies give a better sense of actual changes that are occurring – they nonetheless represent a symbolic milestone.

To determine where July 2024 temperatures will ultimately end up, Carbon Brief used a statistical model that extrapolates the final monthly temperatures based on the first 22 days of the month in all prior Julys since the ERA5 record began in 1940. 

The figure below shows the expected range of July 2024 temperatures (black error bars) alongside a best-estimate (red diamond). Temperatures are shown with respect to the pre-industrial baseline period (1850-1900).

July global average surface temperature anomalies from the Copernicus/ECMWF global atmospheric reanalysis product (ERA5) plotted with respect to a 1850-1900 baseline. The estimated 2024 July value is based on the relationship between the first 21 days of the month and the final monthly temperatures between 1940 and 2023. Chart by Carbon Brief.

July global average surface temperature anomalies from the Copernicus/ECMWF global atmospheric reanalysis product (ERA5) plotted with respect to a 1850-1900 baseline. The estimated 2024 July value is based on the relationship between the first 21 days of the month and the final monthly temperatures between 1940 and 2023. Chart by Carbon Brief.

Here, Carbon Brief estimates that there is a very likely (>95%) chance that July 2024 comes in as the second-warmest July on record after 2023. However, it will still be quite warm, at more than 0.2C warmer than any July prior to 2023.

The extreme heat the world experienced in the latter half of 2023 makes setting new records over the remainder of the year less likely.

Low Antarctic sea ice extent

Antarctic sea ice extent spent much of early 2024 at the low end of the historical 1979-2010 range, though it has not quite exceeded record lows experienced in 2023.

However, in recent weeks Antarctic sea ice extent has rapidly dropped, and is now only modestly above 2023 levels.

Arctic sea ice extent has also spent most of this year at the low end of the historical range.

The figure below shows both Arctic and Antarctic sea ice extent in 2024 (solid red and blue lines), the historical range in the record between 1979 and 2010 (shaded areas) and the record lows (dotted black line). Unlike global temperature records (which only report monthly averages), sea ice data is collected and updated on a daily basis, allowing sea ice extent to be viewed up to the present.

Arctic and Antarctic daily sea ice extent from the US National Snow and Ice Data Center. The bold lines show daily 2024 values, the shaded area indicates the two standard deviation range in historical values between 1979 and 2010. The dotted black lines show the record lows for each pole. Chart by Carbon Brief.

Arctic and Antarctic daily sea ice extent from the US National Snow and Ice Data Center. The bold lines show daily 2024 values, the shaded area indicates the two standard deviation range in historical values between 1979 and 2010. The dotted black lines show the record lows for each pole. Chart by Carbon Brief.

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What Is the Economic Impact of Data Centers? It’s a Secret.

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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.

What Is the Economic Impact of Data Centers? It’s a Secret.

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GEF raises $3.9bn ahead of funding deadline, $1bn below previous budget

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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”.

    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.

    Santa Marta conference: fossil fuel transition in an unstable world

    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.

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

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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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