Record-breaking sea temperatures across the Gulf of Mexico have been a key ingredient behind some of the intense hurricanes devastating the region this year.
Last month, Hurricane Helene made landfall on Florida’s “Big Bend” and then stalled over several states to the north dumping “enormous rainfall totals”, resulting in epic flooding which killed at least 220 people.
Just a couple of weeks later, Milton – the ninth hurricane to form in the Atlantic this year and one of the most rapidly intensifying hurricanes on record – has swept this week towards Florida’s Tampa Bay region, threatening communities that are still recovering from Helene’s impact.
A rapid attribution study recently concluded that record-breaking ocean temperatures in the Gulf of Mexico, which helped Hurricane Helene to “spin up”, were made 200-500 times more likely because of human-caused climate change.
Scientists tell Carbon Brief that the same intense ocean heat likely helped to fuel Milton’s behaviour and explains how hurricanes can become more intense in a fast warming world.
How do hot oceans fuel hurricanes?
A hurricane is the name for a tropical cyclone that forms in the Atlantic Ocean or northeastern Pacific Ocean.
Atlantic hurricanes typically first form over the tropical waters of the north Atlantic off the African continent. As the systems travel westwards across the Atlantic, they draw up the warm, moist air that rises from the surface of the ocean, using it to fuel themselves and grow stronger.
As the low-pressure system picks up energy, winds can begin to spin, forming a storm. The warmer the ocean water is, the more energy the storm accumulates and the more quickly it can intensify. Sea surface temperatures of more than 26.5C down to a depth of 50 metres can drive the storm to intensify into a hurricane, once wind speeds exceed 74 miles per hour.
The 2024 Atlantic season runs from the start of June to the end of November and has already seen multiple intense storms, including the powerful Helene and Milton hurricanes, which have struck Florida within just two weeks of each other.
Both hurricanes picked up energy as they travelled over the Gulf of Mexico, which is currently experiencing a marine heatwave.
The graph below shows the extra ocean heat content – a metric that captures the amount of thermal energy stored in the water – for the Gulf of Mexico. For each month, it shows the extra ocean heat, compared with the average amount for that month during 2013-23.
A tropical storm is said to undergo “rapid intensification” if its wind speed increases by at least 35mph over a 24-hour period. Hurricane Milton’s wind speed accelerated faster than all but two previously recorded storms, with more than a 90mph increase in speeds in just 24 hours, ranking it as one of the “strongest” Atlantic storms ever recorded.
A study published in August in the Nature journal Communications Earth & Environment examined hurricanes that form over the Gulf of Mexico. It found that “rapid intensification” is 50% more likely to occur during marine heatwaves.
A rapid attribution study by Climate Central indicates that, over the past two weeks, the record-breaking temperatures in the Gulf of Mexico were made 400-800 times more likely by climate change.
Dr Kevin Reed – a researcher from Stony Brook University in New York – tells Carbon Brief that “Hurricane Milton’s rapid intensification this week is a telltale sign of climate change, which is responsible – in part – for the near-record temperatures in the Gulf of Mexico currently”. He adds:
“Warmer ocean temperatures are leading to more storms that undergo rapid intensification leading to an increase in the proportion of storms that reach major hurricane strength.”
A rapid attribution study from the World Weather Attribution (WWA) service examining Hurricane Helene used a model to investigate its strong winds by analysing storms making landfall within two degrees (120 nautical miles) of Helene. It said:
“By statistically modelling storms in a 1.3C cooler climate, this model showed that climate change was responsible for an increase of about 150% in the number of such storms (now once every 53 years on average, up from every 130 years) and, equivalently, that the maximum wind speeds of similar storms are now about 6.1 m/s (around 11%) more intense.”
The same team is now conducting a rapid analysis on the influence of climate change on Hurricane Milton, which will be released on Friday.
“This is in line with other scientific findings that Atlantic tropical cyclones are becoming wetter under climate change and undergoing more rapid intensification,” the WWA study on Helene finds.
Dr Kerry Emanuel, a professor of meteorology at the Massachusetts Institute of Technology, tells Carbon Brief that “Milton’s behaviour is consistent with predictions that hurricane scientists have made going back at least three decades”.
New normal?
Since 1878, around six to seven hurricanes, on average, have formed in the North Atlantic every year, with only a couple typically making landfall in the US.
The number of Atlantic hurricanes on record has increased over the period 1851-2019. However, some research suggests that more consistent monitoring, rather than a true increase in hurricane numbers, is behind this trend.
There is a clearer trend of increasing hurricane intensity. Research shows that the proportion of tropical cyclones reaching at least category 3 intensity has also risen over the past four decades. Although the study does not confidently link this increase to climate change, it notes that higher sea surface temperatures are likely to contribute.
As Prof Andrew Dessler summarises on his Climate Brink blog, the impact of climate change on the intensity and frequency of tropical cyclones is still not certain. However, he says that “we can have high confidence that climate change will drive more intense hurricanes”.
Meanwhile, studies have shown that the record-breaking 2020 Atlantic hurricane season, when 14 hurricanes were recorded, was partly due to increased sea surface temperatures.
A study published by Nature Communications in 2022 found that human-caused climate change increased sea surface temperatures in the North Atlantic basin by 0.4-0.9C. The authors estimated that this increased “extreme three-hourly storm rainfall rates” and “extreme three-day accumulated rainfall amounts” for Atlantic storms by 11% and 8%, respectively.
Another 2022 study published in Nature Communications found that over the period 1982-2020, climate change-induced increases in sea surface temperatures doubled the probability of “extremely active tropical cyclone seasons”. The 2020 season might have been made twice as likely by ocean surface warming, the authors found.
The post Explainer: How hotter oceans can fuel more intense Atlantic hurricanes appeared first on Carbon Brief.
Explainer: How hotter oceans can fuel more intense Atlantic hurricanes
Drought and heatwaves occurring together – known as “compound” events – have “surged” across the world since the early 2000s, a new study shows.
Compound drought and heat events (CDHEs) can have devastating effects, creating the ideal conditions for intense wildfires, such as Australia’s “Black Summer” of 2019-20 where bushfires burned 24m hectares and killed 33 people.
The research, published in Science Advances, finds that the increase in CDHEs is predominantly being driven by events that start with a heatwave.
The global area affected by such “heatwave-led” compound events has more than doubled between 1980-2001 and 2002-23, the study says.
The rapid increase in these events over the last 23 years cannot be explained solely by global warming, the authors note.
Since the late 1990s, feedbacks between the land and the atmosphere have become stronger, making heatwaves more likely to trigger drought conditions, they explain.
One of the study authors tells Carbon Brief that societies must pay greater attention to compound events, which can “cause severe impacts on ecosystems, agriculture and society”.
Compound events
CDHEs are extreme weather events where drought and heatwave conditions occur simultaneously – or shortly after each other – in the same region.
These events are often triggered by large-scale weather patterns, such as “blocking” highs, which can produce “prolonged” hot and dry conditions, according to the study.
Prof Sang-Wook Yeh is one of the study authors and a professor at the Ewha Womans University in South Korea. He tells Carbon Brief:
“When heatwaves and droughts occur together, the two hazards reinforce each other through land-atmosphere interactions. This amplifies surface heating and soil moisture deficits, making compound events more intense and damaging than single hazards.”
CDHEs can begin with either a heatwave or a drought.
The sequence of these extremes is important, the study says, as they have different drivers and impacts.
For example, in a CDHE where the heatwave was the precursor, increased direct sunshine causes more moisture loss from soils and plants, leading to a drought.
Conversely, in an event where the drought was the precursor, the lack of soil moisture means that less of the sun’s energy goes into evaporation and more goes into warming the Earth’s surface. This produces favourable conditions for heatwaves.
The study shows that the majority of CDHEs globally start out as a drought.
In recent years, there has been increasing focus on these events due to the devastating impact they have on agriculture, ecosystems and public health.
In Russia in the summer of 2010, a compound drought-heatwave event – and the associated wildfires – caused the death of nearly 55,000 people, the study notes.
The record-breaking Pacific north-west “heat dome” in 2021 triggered extreme drought conditions that caused “significant declines” in wheat yields, as well as in barley, canola and fruit production in British Columbia and Alberta, Canada, says the study.
Increasing events
To assess how CDHEs are changing, the researchers use daily reanalysis data to identify droughts and heatwaves events. (Reanalysis data combines past observations with climate models to create a historical climate record.) Then, using an algorithm, they analyse how these events overlap in both time and space.
The study covers the period from 1980 to 2023 and the world’s land surface, excluding polar regions where CDHEs are rare.
The research finds that the area of land affected by CDHEs has “increased substantially” since the early 2000s.
Heatwave-led events have been the main contributor to this increase, the study says, with their spatial extent rising 110% between 1980-2001 and 2002-23, compared to a 59% increase for drought-led events.
The map below shows the global distribution of CDHEs over 1980-2023. The charts show the percentage of the land surface affected by a heatwave-led CDHE (red) or a drought-led CDHE (yellow) in a given year (left) and relative increase in each CDHE type (right).
The study finds that CDHEs have occurred most frequently in northern South America, the southern US, eastern Europe, central Africa and south Asia.
Threshold passed
The authors explain that the increase in heatwave-led CDHEs is related to rising global temperatures, but that this does not tell the whole story.
In the earlier 22-year period of 1980-2001, the study finds that the spatial extent of heatwave-led CDHEs rises by 1.6% per 1C of global temperature rise. For the more-recent period of 2022-23, this increases “nearly eightfold” to 13.1%.
The change suggests that the rapid increase in the heatwave-led CDHEs occurred after the global average temperature “surpasse[d] a certain temperature threshold”, the paper says.
This threshold is an absolute global average temperature of 14.3C, the authors estimate (based on an 11-year average), which the world passed around the year 2000.
Investigating the recent surge in heatwave-leading CDHEs further, the researchers find a “regime shift” in land-atmosphere dynamics “toward a persistently intensified state after the late 1990s”.
In other words, the way that drier soils drive higher surface temperatures, and vice versa, is becoming stronger, resulting in more heatwave-led compound events.
Daily data
The research has some advantages over other previous studies, Yeh says. For instance, the new work uses daily estimations of CDHEs, compared to monthly data used in past research. This is “important for capturing the detailed occurrence” of these events, says Yeh.
He adds that another advantage of their study is that it distinguishes the sequence of droughts and heatwaves, which allows them to “better understand the differences” in the characteristics of CDHEs.
Dr Meryem Tanarhte is a climate scientist at the University Hassan II in Morocco, and Dr Ruth Cerezo Mota is a climatologist and a researcher at the National Autonomous University of Mexico. Both scientists, who were not involved in the study, agree that the daily estimations give a clearer picture of how CDHEs are changing.
Cerezo-Mota adds that another major contribution of the study is its global focus. She tells Carbon Brief that in some regions, such as Mexico and Africa, there is a lack of studies on CDHEs:
“Not because the events do not occur, but perhaps because [these regions] do not have all the data or the expertise to do so.”
However, she notes that the reanalysis data used by the study does have limitations with how it represents rainfall in some parts of the world.
Compound impacts
The study notes that if CDHEs continue to intensify – particularly events where heatwaves are the precursors – they could drive declining crop productivity, increased wildfire frequency and severe public health crises.
These impacts could be “much more rapid and severe as global warming continues”, Yeh tells Carbon Brief.
Tanarhte notes that these events can be forecasted up to 10 days ahead in many regions. Furthermore, she says, the strongest impacts can be prevented “through preparedness and adaptation”, including through “water management for agriculture, heatwave mitigation measures and wildfire mitigation”.
The study recommends reassessing current risk management strategies for these compound events. It also suggests incorporating the sequences of drought and heatwaves into compound event analysis frameworks “to enhance climate risk management”.
Cerezo-Mota says that it is clear that the world needs to be prepared for the increased occurrence of these events. She tells Carbon Brief:
“These [risk assessments and strategies] need to be carried out at the local level to understand the complexities of each region.”
The post Heatwaves driving recent ‘surge’ in compound drought and heat extremes appeared first on Carbon Brief.
Heatwaves driving recent ‘surge’ in compound drought and heat extremes
Greenhouse Gases
DeBriefed 6 March 2026: Iran energy crisis | China climate plan | Bristol’s ‘pioneering’ wind turbine
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Energy crisis
ENERGY SPIKE: US-Israeli attacks on Iran and subsequent counterattacks across the Middle East have sent energy prices “soaring”, according to Reuters. The newswire reported that the region “accounts for just under a third of global oil production and almost a fifth of gas”. The Guardian noted that shipping traffic through the strait of Hormuz, which normally ferries 20% of the world’s oil, “all but ground to a halt”. The Financial Times reported that attacks by Iran on Middle East energy facilities – notably in Qatar – triggered the “biggest rise in gas prices since Russia’s full-scale invasion of Ukraine”.
‘RISK’ AND ‘BENEFITS’: Bloomberg reported on increases in diesel prices in Europe and the US, speculating that rising fuel costs could be “a risk for president Donald Trump”. US gas producers are “poised to benefit from the big disruption in global supply”, according to CNBC. Indian government sources told the Economic Times that Russia is prepared to “fulfil India’s energy demands”. China Daily quoted experts who said “China’s energy security remains fundamentally unshaken”, thanks to “emergency stockpiles and a wide array of import channels”.
‘ESSENTIAL’ RENEWABLES: Energy analysts said governments should cut their fossil-fuel reliance by investing in renewables, “rather than just seeking non-Gulf oil and gas suppliers”, reported Climate Home News. This message was echoed by UK business secretary Peter Kyle, who said “doubling down on renewables” was “essential” amid “regional instability”, according to the Daily Telegraph.
China’s climate plan
PEAK COAL?: China has set out its next “five-year plan” at the annual “two sessions” meeting of the National People’s Congress, including its climate strategy out to 2030, according to the Hong Kong-based South China Morning Post. The plan called for China to cut its carbon emissions per unit of gross domestic product (GDP) by 17% from 2026 to 2030, which “may allow for continued increase in emissions given the rate of GDP growth”, reported Reuters. The newswire added that the plan also had targets to reach peak coal in the next five years and replace 30m tonnes per year of coal with renewables.
ACTIVE YET PRUDENT: Bloomberg described the new plan as “cautious”, stating that it “frustrat[es] hopes for tighter policy that would drive the nation to peak carbon emissions well before president Xi Jinping’s 2030 deadline”. Carbon Brief has just published an in-depth analysis of the plan. China Daily reported that the strategy “highlights measures to promote the climate targets of peaking carbon dioxide emissions before 2030”, which China said it would work towards “actively yet prudently”.
Around the world
- EU RULES: The European Commission has proposed new “made in Europe” rules to support domestic low-carbon industries, “against fierce competition from China”, reported Agence France-Presse. Carbon Brief examined what it means for climate efforts.
- RECORD HEAT: The US National Oceanic and Atmospheric Administration has said there is a 50-60% chance that the El Niño weather pattern could return this year, amplifying the effect of global warming and potentially driving temperatures to “record highs”, according to Euronews.
- FLAGSHIP FUND: The African Development Bank’s “flagship clean energy fund” plans to more than double its financing to $2.5bn for African renewables over the next two years, reported the Associated Press.
- NO WITHDRAWAL: Vanuatu has defied US efforts to force the Pacific-island nation to drop a UN draft resolution calling on the world to implement a landmark International Court of Justice (ICJ) ruling on climate, according to the Guardian.
98
The number of nations that submitted their national reports on tackling nature loss to the UN on time – just half of the 196 countries that are part of the UN biodiversity treaty – according to analysis by Carbon Brief.
Latest climate research
- Sea levels are already “much higher than assumed” in most assessments of the threat posed by sea-level rise, due to “inadequate” modelling assumptions | Nature
- Accelerating human-caused global warming could see the Paris Agreement’s 1.5C limit crossed before 2030 | Geophysical Research Letters covered by Carbon Brief
- Future “super El Niño events” could “significantly lower” solar power generation due to a reduction in solar irradiance in key regions, such as California and east China | Communications Earth & Environment
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured
UK greenhouse gas emissions in 2025 fell to 54% below 1990 levels, the baseline year for its legally binding climate goals, according to new Carbon Brief analysis. Over the same period, data from the World Bank shows that the UK’s economy has expanded by 95%, meaning that emissions have been decoupling from growth.
Spotlight
Bristol’s ‘pioneering’ community wind turbine
Following the recent launch of the UK government’s local power plan, Carbon Brief visits one of the country’s community-energy success stories.
The Lawrence Weston housing estate is set apart from the main city of Bristol, wedged between the tree-lined grounds of a stately home and a sprawl of warehouses and waste incinerators. It is one of the most deprived areas in the city.
Yet, just across the M5 motorway stands a structure that has brought the spoils of the energy transition directly to this historically forgotten estate – a 4.2 megawatt (MW) wind turbine.
The turbine is owned by local charity Ambition Lawrence Weston and all the profits from its electricity sales – around £100,000 a year – go to the community. In the UK’s local power plan, it was singled out by energy secretary Ed Miliband as a “pioneering” project.
‘Sustainable income’
On a recent visit to the estate by Carbon Brief, Ambition Lawrence Weston’s development manager, Mark Pepper, rattled off the story behind the wind turbine.
In 2012, Pepper and his team were approached by the