More than 1,000 operations at NHS hospitals were cancelled due to heat during the UK’s record May and June heatwaves, Carbon Brief can reveal.

This includes 167 orthopaedic surgeries, such as knee and hip replacements, as well as heart, eye and skin cancer operations.

At least 10 emergency surgeries – those for “life-threatening” conditions – had to be cancelled because of the record-breaking heat, according to the investigation.

Carbon Brief sent freedom-of-information (FOI) requests to 140 NHS trusts to investigate the impact of heatwaves on operations being cancelled in England and Wales.

Areas with the most operations cancelled due to heat include Surrey and Sussex, south Essex and parts of London – all regions experiencing among the highest temperatures.

High temperatures can threaten patient safety by stopping the ventilation systems used in theatres from working, increasing the risk of infection, experts tell Carbon Brief.

Less than half of the NHS trusts provided details of heat-related surgery cancellations – and Carbon Brief understands that many hospitals do not routinely record this information.

Carbon Brief’s figure is therefore likely to be a significant underestimate, but still provides an unprecedented insight into a surgical system “poorly prepared” for heatwaves and the impact on patients.

Overheating operations

The record-breaking heatwaves that have repeatedly struck the UK in 2026 – amplified by climate change – have already been linked to thousands of deaths.

High temperatures can lead to all sorts of health complications and worsen respiratory, cardiovascular and kidney diseases.

Extreme heat also threatens healthcare systems. News outlets have reported on the NHS “struggling”, as it faces record A&E demand, hospital wards reaching “unsafe” temperatures and equipment failing due to heat.

Among these reports was coverage of hospitals being forced to cancel operations, or even abandon them midway through, as surgical theatres became intolerably hot.

To investigate this problem, Carbon Brief sent FOI requests to the 140 NHS trusts and health boards in England and Wales responsible for hospitals with surgical theatres.

They were asked about all the operations that were cancelled due to extreme heat during the May and June heatwaves, when “amber” and “red” heat warnings were in place.

In total, 59 trusts and health boards responded with details of 1,110 heat-related cancellations across the 17-day period covering 22-28 May and 18-27 June.

(Of the 63 trusts that responded but did not provide details of heat-related disruption, many said that they simply did not record this data, rather than stating that heat was not a problem. See Methodology for more details.)

The map below shows the location of these cancelled surgeries, which cover everything from routine hernia operations to heart surgeries.

Surrey and Sussex Healthcare NHS Trust reported the most cancellations – 140 in total – all in the surgery unit at Crawley Hospital. This hospital was in one of the hottest parts of the country in June, with temperatures approaching 36C.

Other hotspots for cancellations include south Essex, Dudley in the West Midlands, south Wales and parts of London. Many of the hardest-hit hospitals were in southern England, where temperatures were highest.

Of the trusts that provided full datasets of all surgery cancellations in the period, around 7% were heat-related. This data illustrates how heat is placing more strain on an already stretched NHS, adding to existing issues such as staff shortages and lack of beds.

Nearly all of the cancelled surgeries were “elective”, meaning they were scheduled in advance and not immediately life-saving. Nevertheless, the list of cancellations includes at least eight heart operations and seven skin-cancer removals.

There were also 10 “emergency” operations cancelled due to heat in surgical theatres. Another 18 surgeries had to be abandoned mid-way through.

Dr Dmitri Nepogodiev, a public health researcher focusing on surgery at the University of Birmingham, says hospitals will always prioritise “time-sensitive, life-threatening” surgeries.

Nevertheless, he tells Carbon Brief that every cancellation can cause significant “distress” and harm to patients’ quality of life, adding:

“Behind all of these statistics…are real people who have probably already been waiting a long time.”

Each dot in the graphic below indicates a cancelled surgery. Of the 596 for which trusts provided details, 167 are orthopaedic surgeries, such as knee and hip replacements.

Eye surgeries, gynaecological and urological surgeries are also among the most frequently cancelled, broadly reflecting how common such procedures are.

Richard Egan, an endocrine surgeon and a national clinical director within NHS Wales, notes the knock-on effects of cancelling surgeries for several days during heatwaves. He tells Carbon Brief:

“That’s a significant impact on waiting lists…For every week that patients are waiting on a waiting list, their condition could get worse and deteriorate.”

‘Increased risks’

When providing specific reasons for cancellations, most NHS trusts simply indicated that surgical theatres were “too hot and humid”.

Sometimes, this was accompanied by comments about “risk of infection” or “overheating for both patients and staff”.

There are several reasons why it can get “too hot” for operations to take place, but the main one is that the complex ventilation systems installed in theatres can stop working above a certain temperature, explains Dr Ed Robinson, an NHS anaesthetist. He tells Carbon Brief:

“An operating theatre is a very tightly engineered clinical environment. There are quite complicated ventilation systems, which dilute airborne contaminants, remove fumes from different [medications] and anaesthetic gases.

“We have generalised airflow systems that make the air in theatre flow outwards to adjacent areas, so pathogens and fumes get carried away from the patient into non-clinical areas. When it gets to a certain heat, those systems can fail.”

These systems are also responsible for controlling heat and humidity levels inside theatres, says Robinson.

When the systems fail, it is not possible to guarantee patient safety, he continues, meaning surgeries may need to be cancelled.

Although most hospitals simply stated that it was “too hot” for operations to take place during the heatwaves, there were 48 cases where staff specified that this was due to air conditioning or ventilation units that were either broken or unable to sustain appropriate temperatures.

Tim Lane, a urological surgeon and president of the Royal College of Surgeons of England (RCS England), tells Carbon Brief that heat places “extra physical strain” on patients:

“Extreme heat can increase risks and make it harder to deliver care under the conditions clinicians would consider ideal.”

If air in operating theatres is too humid, excess moisture can condense on surgical implements and transmit infections, he says.

Extreme heat and humidity inside theatres can also pose a risk to staff having to wear heavy protective clothing. Robinson explains:

“Staff are usually wearing PPE [personal protective equipment]. If it’s orthopaedics, they will be wearing ‘leads’ a lot of the time. This is because they will be doing lots of X-rays, and there’s no time to descrub and rescrub every time.

“So if the ventilation system is not working, you’re going to overheat [and] that’s going to affect your ability to concentrate and perform a safe operation. You just wouldn’t start under those conditions.”

There are also “certain pieces of equipment and medications” that are not “validated to be used outside of certain ranges of temperature”, he says.

This includes specialised “cement” used to secure hip and knee replacements, which can set too quickly at higher temperatures, according to Lane.

‘Poorly prepared’

Following the record-breaking heat of 2022, one study found that surgical services in the UK were “poorly prepared for heatwaves”.

Based on staff surveys, the study concluded that ambient temperatures “could not be controlled” in two-fifths of NHS operating theatres.

With hospitals once again under significant pressure this summer, health secretary Yvette Cooper told the Guardian that the NHS “has to make sure we are preparing for summer pressures now in the same way we prepare for winter”.

Nepogodiev notes that the problem of extreme heat extends from increased patient numbers to staff shortages, which can be the result of a range of wider factors such as heat-related train cancellations. He tells Carbon Brief.

“There isn’t a single magic solution because it’s a kind of complex, multifactorial challenge – so it also underlines the importance of broader preparedness.”

Egan, who is investigating ways to prepare surgical theatres for extreme heat, says the response so far has been “ad hoc”. He suggests it may be possible to continue with less risky operations, even at higher humidity levels.

As it stands, many NHS hospitals are old and not designed for increasingly extreme temperatures.

Government advisers at the Climate Change Committee (CCC) have recommended that all healthcare buildings should work to “maintain safe and appropriate temperatures” by 2035.

The UK’s national adaptation programme already says NHS England will work to “adapt NHS infrastructure to extreme weather events and overheating risks”, by incorporating adaptation measures into plans for new buildings.

However, years of underinvestment have left many sites with what the King’s Fund thinktank calls “deteriorating buildings” and “outdated technology”.

Following the extreme heat this summer, the government has announced £32m from a £1.5bn spending programme for projects that strengthen hospitals’ “resilience to extreme heat, including improved “cooling and ventilation systems”.

RCS England president Lane tells Carbon Brief that heat-related surgical cancellations underline the need for investment in hospitals, ventilation systems and modern equipment:

“NHS staff work incredibly hard to adapt, often reorganising services and finding practical solutions to keep care running, but resilience alone cannot compensate indefinitely for outdated infrastructure or sustainability.”

Methodology

Carbon Brief contacted 140 NHS trusts and health boards in England and Wales, only including those that perform surgical procedures. Mental health trusts, community trusts and other specialist trusts were therefore excluded.

These requests covered the periods 22-28 May 2026 and 18-27 June 2026, when heatwaves affected much of England and Wales.

At the time of filing the FOIs, these were the two periods when the UK Health Security Agency (UKHSA) had issued “amber” or “red” heat-health alerts across much or all of England. There were also comparable weather warnings in place across Wales for some of this time.

(Scotland and Northern Ireland were excluded from the analysis, on the basis that they did not experience such extreme heat.)

The FOI requests asked for details of all surgical procedures – both elective and emergency – that were cancelled during this period. Specifically, the requests also asked trusts to state which cancellations were related to extreme heat. Of these, 59 provided details of surgeries that were cancelled due to heat.

Of the remaining 63 that responded to the FOI requests, only a few stated explicitly that there were no surgeries cancelled due to heat. Most either said that they did not record this information, or provided lists with standard cancellation reasons that may – or may not – indicate heat as a factor, such as “failure of equipment”. The remaining 19 did not respond to the request by the time of publication.

NHS trusts and health boards responded to Carbon Brief’s FOI requests in a large variety of ways, reflecting the inconsistent way in which heat-related cancellations are recorded.

Among those that disclosed data, some provided all the information requested while others only provided parts. Some would not provide exact numbers when the number of cancellations was five or less. In those cases, Carbon Brief assumed that two surgeries had been cancelled. (This assumption accounts for fewer than 50 of the 1,110 cancellations.)

The full dataset is available here, with details of all the surgeries cancelled and the reasons given for their cancellations.

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The post Revealed: More than 1,000 NHS operations cancelled due to record UK heatwaves appeared first on Carbon Brief.

Revealed: More than 1,000 NHS operations cancelled due to record UK heatwaves

What a week! Our Pacific team is back from Palau and the 55th Pacific Islands Forum Leaders Meeting, and preparing for the next big moment in our campaign for Pacific climate justice — the Pacific Pre-COP.

So grab a cuppa as we take stock of what unfolded in Palau and what it means for the voyage ahead.

Keeping 1.5°C Alive

Immediately before leaders sat down for their negotiations, the UN Environment Program dropped a bombshell report confirming the world is set to overshoot the all-important goal of limiting warming to 1.5°C.

Limiting warming to 1.5°C is a non-negotiable survival line for Pacific communities. Every year above 1.5°C will increase irreversible harms to communities in the Pacific and around the world. The task now is to minimise the magnitude and duration of any temperature overshoot, and to return warming to 1.5°C as soon as possible.

The good news — there is a path back to 1.5°C. But it’s going to demand the very best of humanity, and all of us working together.

As a person from the Pacific, I know our communities will not quietly accept these dire warnings of climate overshoot as our fate; we are already living and fiercely resisting this reality every single day. With every increment of warming, our lands, our livelihoods, and our island homes are threatened, but the Pacific’s resolve only grows stronger.

Shiva Gounden, Head of Pacific, responds to the UNEP Limiting Overshoot report

Australia, get it together

In just two months, Australia will be chairing the world’s global climate negotiations — a role it has pledged to undertake in meaningful partnership with the Pacific. It’s a major responsibility, at a critical moment in the world’s response to the climate and energy crisis, and one that requires a focussed, all-of-government effort from Australia.

So you can imagine our shock at the start of the week, as images appeared of Australian Minister for Resources Madeleine King celebrating the first extraction of gas from the giant Beetaloo Basin, alongside Chief Minister of the Northern Territory Lia Finocchiaro. Needless to say, the image of the two leaders laughing as they turned on Australia’s largest gas tap, amid the still unfolding flood disaster in Nepal-Tibet, will not age well. Skip to Thursday, and the news came that the Australian Government had approved an expansion of one of Queensland’s largest coal mines. This was the 37th new, expanded or extended fossil fuel project approved by the Albanese Government since it was elected, and the second year in a row that Australia has approved a major fossil fuel expansion during the Pacific Islands Forum.

This is not the allyship that the Pacific has been promised from Australia, the largest member of the Forum, or the leadership the world needs. Expanding fossil fuel production is utterly incompatible with our moral, legal and scientific imperative to limit warming to 1.5°C.

Australia is not doing enough. Australia is a major producer of fossil fuels. We all know fossil fuels are the primary driver of the climate crisis. The very least a country like Australia should be doing is stopping future expansion, and it’s not doing that.

Ralph Regenvanu, Minister for Climate Change, Vanuatu

We need all hands, all heart, all minds, in this fight together

Moemoana Schwenke, Pacific Climate Campaigner

Powering up the Blue Pacific

On the bright side, the week helped bring the vision of a Fossil Fuel Free Pacific one step closer to reality.

Nowhere on Earth are the perils of fossil fuel dependence and the opportunities of renewable energy clearer than in the Pacific, where countries currently spend up to 25% of GDP on fuel imports, and renewables truly are the path to greater energy security, affordability and sovereignty.

Tuesday saw the launch of a 100% Renewable Blue Pacific Investment Prospectus, designed to attract more than $2 billion in investment to advance the vision of a Fossil Fuel Free Pacific.

Protecting our oceans

While sometimes called ‘small island states’ owing to their small land area and population, Pacific island countries are far better understood as ‘large ocean states’. If you were to divide Tuvalu’s ocean area by its population, you’d find that Tuvaluans are responsible for around 250x more ocean per person than Australians.

Pacific islanders are the world’s ocean protectors, and right now are in a fight to protect the ocean floor from deep sea mining. This year our team, led by Rae Bainteiti, hosted a moving talanoa on deep sea mining, with diverse perspectives grounded in Pacific values.

Greenpeace has been working hard to encourage more Pacific governments to join the call for a moratorium on deep sea mining, so that this destructive new industry can be stopped before it gets fully underway.

The voyage ahead

Earlier this week, a large crowd of Greenpeace staff and volunteers gathered on the dock to bid fair winds to our campaign ship Oceania as she set sail for Fiji and next month’s Pacific Pre-COP.

Hot on the heels of the Pacific Islands Forum, the Pacific Pre-COP is the next crucial moment in our voyage towards the year’s global climate negotiations (COP31) in Antalya. It is a unique opportunity to amplify Pacific leadership, and to ensure that the core priorities of keeping 1.5°C alive, accelerating the transition away from fossil fuels, and ensuring communities can access the financial support they need, are high on the agenda for COP31.

Holding the line: From Palau to Fiji

Extreme heat is one of the deadliest climate hazards, but no two heatwaves are the same.

Heat extremes that happen outside of the peak summer months are often more dangerous because they can catch people off guard.

Heatwaves that hit during the spring or the first heatwave of the summer are riskier because people’s bodies are not yet accustomed to the heat and cooling strategies, such as air conditioning or public cooling centres, might not be available.

On the other hand, heatwaves that happen in the autumn, after a long summer season of heat exposure, can place further strain on bodies and local infrastructure that are already under stress.

As the climate changes and global temperatures rise, research has shown that heatwaves are becoming more frequent, intense and lengthy.

Our study, published in AGU Advances, is the first to measure whether the timing of extreme heat during the calendar year is changing around the world.

We find that, in more than half of the world, extreme heat events are spreading into the “shoulder seasons”, but doing so unevenly – in other words, they tend to creep more into autumn or spring, depending on the location.

Defining heat seasons

Meteorological summer is often assumed to be the warmest three-month period of the year. It is simplistically defined as June to August in the northern hemisphere and December to February in the southern hemisphere.

However, extreme heat seasons vary from place to place and do not always neatly map on to these defined periods.

Our study, therefore, goes beyond traditional definitions of seasons and instead focuses on “local heat seasons”. We define these as the three consecutive months when extreme heat events happened most often in the 1980s.

From this starting point, our research looks at how extreme heat is creeping into the two-month periods before and after a local heat season. We call these periods “shoulder seasons”.

This flexible definition of heat and shoulder seasons allows us to measure how the timing of extreme heat has changed over time.

Specifically, we look at the percent of annual heat days that occurred in the heat season and shoulder seasons at each location on Earth and measure how those relative shares have shifted over the last 45 years.

For our analysis, we use climate data from 1980-2024 from the MERRA2 reanalysis dataset. To ensure our results were robust, we repeated the process using ERA5 reanalysis data. 

We picked the 1980s as our baseline decade as it was the start of the common time period between the two reanalysis datasets. We compared this to climate data in the decade between 2015-24. 

Comparing these two time periods – the opposite ends of our datasets – allowed us to register a larger magnitude change and account for cumulative effects of climate change.

We consider measures of both dry and humid heat, as each has distinct impacts. Dry heat tends to be more dangerous to plant and ecosystem health, while humid heat is more strenuous for humans.

We use the dry-bulb temperature and wet-bulb globe temperature as our measures of dry and humid heat, respectively.

Created in the 1950s by the US military, wet-bulb globe temperature has a long history as an international standard used for outdoor sports and occupational hazard monitoring. It combines measurements of temperature, humidity, wind speed and solar radiation.

Changing heat seasons

Our research finds that, in the 1980s, extreme heat around the world was closely confined to a single heat season. For example, some 93% of the world’s land area experienced more than 80% of extreme dry-heat days during its traditional dry-heat season.

Surprisingly, this was even true in the tropics, where there is much less of a seasonal swing in temperatures.

We also show that extreme dry- and humid-heat seasons are often different from one another, typically offset by one month. This is especially true in places influenced by monsoon systems, such as north-western Mexico and central India, where the extreme dry-heat season precedes the extreme humid-heat season.

But, the edges of these extreme heat seasons are starting to blur.

Extreme heat events are spreading out significantly in the calendar year in more than half of global land areas.

This extension of the extreme dry- and humid-heat seasons means that dangerous heat has started to creep into the shoulder seasons – but not equally so.

The maps below show how, in western Europe, southern Africa and north-western India, a larger fraction of each year’s extreme heat events are happening in the months before the historical dry- and humid-heat seasons. These regions are shaded in green.

On the other hand, in much of the US, eastern China, northern Africa and eastern Europe, extreme heat events are increasing in frequency in the months after the traditional heat seasons. These regions are shaded in purple.

Boosting existing seasons

It is possible that these observed changes have a straightforward – and somewhat simple – explanation.

In many regions, one shoulder season – spring or autumn – is warmer than the other. One hypothesis we explored was whether a simple step up in daily heat across the calendar year makes it more likely for extreme heat days to occur in one shoulder season over the other.

Our research shows that things are not so simple.

To investigate, we created a new, “synthetic” timeseries in order to identify the impact of annual average warming. To do this, we took the baseline 1980s timeseries and “shifted up” the data by the average change in local dry or humid heat between the first and last 10 years of our dataset (1980-89 compared to 2015-24).

We find that, in most locations, intensifying the baseline seasonality in a given location by warming evenly over the course of the year explains the changes in extreme heat timing within the traditional heat season.

However, annual average warming alone cannot explain the uneven changes in how extreme heat is occurring in the shoulder seasons.

As such, we conclude there must be other factors at play.

Long-term changes in seasonal precipitation and soil moisture – whether drying or moistening – could be contributing.

There could also be potential links to land-use changes, such as agricultural intensification or increased irrigation. Natural fluctuations in regional climates, caused by phenomena such as the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation, could also be playing an important role.

To tease out the contributions of each of these drivers, scientists will need to conduct more regionally-focused studies.

Managing hazards

The expansion of extreme heat events into the shoulder seasons indicates that key protections, such as heat early warning systems and the establishment of cooling centres, may be needed outside the traditional summer months.

Further research is also required to look into whether the overlap of extreme heat with other seasonal hazards is increasing.

For example, we find that, throughout much of the US, there is a larger expansion of the heat season into the autumn than the spring. In the western US, extreme heat which stretches later into the year could increase the overlap between the extreme heat and wildfire seasons.

Meanwhile, a similar extension of the heat season into the autumn in the eastern US could increase the overlap between the extreme heat and Atlantic hurricane seasons.

Understanding how the intersection of these seasonal hazards is changing is essential for developing targeted climate adaptation strategies, given that multiple hazards happening at once or in quick succession are much more dangerous than when they happen in isolation.

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The post Guest post: How extreme heat is ‘creeping’ from summer into autumn and spring appeared first on Carbon Brief.

Guest post: How extreme heat is ‘creeping’ from summer into autumn and spring