A record-breaking amount of new offshore wind capacity has been secured at the UK’s latest auction for renewable energy projects.
Five fixed-foundation projects, amounting to 8.25 gigawatts (GW), secured fixed-price “contracts for difference” (CfDs) to supply electricity for an average of £91 per megawatt hour (MWh).
Additionally, two floating offshore wind projects with a combined capacity of 192.5 megawatts (MW) won contracts, securing a “strike price” of £216/MWh.
This new capacity, totalling 8.4GW, marks a significant increase from last year’s sixth auction, when 5.3GW had been secured as part of a bounce back from the “failed” fifth round.
While the latest auction saw offshore wind prices rising by around 10% since the previous round, analysis suggests that the outcome will, nevertheless, be roughly “cost neutral” for consumers.
Contrary to simplistic and misleading comparisons made by some opposition politicians and media commentators, this is because CfD payments would be balanced by lower wholesale costs.
The government welcomed the “stonking” results, saying that it put the country “on track” to reach its 2030 targets for clean power, create jobs and bring new investment.
Below, Carbon Brief looks at the auction results, what they mean for bills and the implications for the UK’s target of “clean power by 2030”.
- What happened in the seventh CfD auction round?
- What does the record offshore-wind auction mean for bills?
- What does AR7 mean for reaching clean power by 2030?
What happened in the seventh CfD auction round (AR7)?
The UK government announced the results of the seventh auction round (AR7) for new CfDs on 14 January 2026, hailing the outcome as a “historic win”.
The CfD scheme was introduced in 2014 and offers fixed-price contracts to generators via a “reverse auction” process. The first auction was held in 2015.
Projects bid to secure contracts to sell electricity at a fixed “strike price” in the future.
If wholesale prices are lower than this set amount, the project receives a payment that makes up the difference.
However, if the market prices are higher than this level, then the project pays back the difference to consumers. For example, according to a report from thinktank Onward, between November 2021 and January 2022, CfD projects paid back £114.4m to consumers.
For the seventh auction round, the results have been split into two, as part of reforms to help expedite the process for offshore wind. As such, the publication of results on 14 January covers fixed-foundation offshore wind and floating offshore wind.
A second set of results will be released between 6-9 February 2026, covering technologies including large-scale solar and onshore wind.
A total of 17 fixed-foundation offshore wind projects totalling 24.8GW of capacity were competing for contracts at this auction, meaning many have missed out.
Still, a record 8.4GW of offshore wind secured contracts, making it the biggest ever offshore wind auction in Europe, according to industry group WindEurope.
This includes 8,245 megawatts (MW) of fixed-foundation offshore wind and 192.5MW of floating offshore wind, which, collectively, will generate enough to power more than 12m homes.
As such, there was an increase of more than 3GW in offshore wind capacity compared to the sixth allocation round, as shown in the chart below.
(The 2.4GW Hornsea 4 scheme, which had been awarded a CfD at the previous auction round, went on to be cancelled in May 2025, with developer Ørsted citing cost inflation.)
This follows on from the “fiasco” of the fifth allocation round in 2023, where no offshore-wind projects secured contracts due to the limit on prices set by the government.
Carbon Brief analysis suggests that the capacity secured in the latest auction will generate around 37 terawatt hours (TWh) of electricity each year, around 12% of the nation’s total demand.
With onshore wind and solar results still to come, this means that projects with CfDs will generate some 135TWh of power by the time they are all completed, or nearly half of current demand.
When the current Labour government took office in 2024, a number of changes were made to encourage offshore wind capacity bids. This included separating the technology from solar and onshore wind into a separate “pot”, an allowance for “permitted reduction” projects in AR6 and a significant increase to the “budget” for the auction overall.
Since then, there have been continued reforms to help meet the government’s target of decarbonising power supplies by 2030. (See: What does AR7 mean for clean power by 2030.)
This includes extending the contracts from 15 years to 20 years, relaxing eligibility requirements related to planning consent and legislating to allow the secretary of state for energy – currently, Ed Miliband – to see anonymised bid information ahead of setting a final budget for that technology.
Initially, the government set a total budget of £900m for fixed-foundation offshore wind projects and £180m for floating offshore wind.
The budget for fixed-foundation offshore wind projects was then raised to £1,790m.
(Note that the “budget” is a notional limit on the amount of CfD levies that can be added to consumer electricity bills. This does not come from government coffers and – as explained below – it does not translate into an equivalent increase in consumer costs, because CfD projects also reduce wholesale electricity prices, which make up the bulk of bills.)
Ahead of the auction, the maximum “administrative” strike price was set at £113/MWh for offshore wind and £271/MWh for floating offshore wind.
The four winning fixed-foundation offshore wind projects in England and Wales secured a strike price of £91.20/MWh in 2024 prices and the one in Scotland £89.49/MWh, as shown in the table below. This comes out at a blended average of £90.91/MWh.
| Projects (fixed-foundation) | Capacity (MW) | Owners | Strike price (2024 prices) | Delivery year (phase one) |
|---|---|---|---|---|
| Awel y Mor | 775 | RWE, SWM, Siemens Financial Services | £91.20/MWh | 2030/31 |
| Dogger Bank South | 3,000 | RWE, Masdar | £91.20/MWh | 2030/2031 |
| Norfolk Vanguard East | 1,545 | RWE | £91.20/MWh | 2029/2030 |
| Norfolk Vanguard West | 1,545 | RWE | £91.20/MWh | 2028/2029 |
| Berwick Bank | 1,380 | SSE Renewables | £89.49/MWh | 2030/2031 |
The two floating offshore-wind projects will see a strike price of £216.46/MWh, shown below.
| Projects (floating) | Capacity | Owners | Strike price (2024 prices) | Delivery year (phase one) |
|---|---|---|---|---|
| Pentland | 92.5 | CIP, Eurus Energy, Hexicon | £216.46/MWh | 2029/2030 |
| Erebus | 100 | TotalEnergies, Simply Blue Energy | £216.46/MWh | 2029/2030 |
These prices are around 19% below the maximum level set ahead of the auction – a figure that had been cited by opposition politicians as “proof” that the round would be a “bad deal” for consumers.
Successful projects include RWE’s Awel Y Mor (775MW), the first Welsh project to win a CfD contract in more than a decade.
Dogger Bank South in Yorkshire and Norfolk Vanguard in East Anglia – which will be two of the largest offshore windfarms in the world – at 3GW and 3.1GW, respectively – both secured contracts.
Additionally, Berwick Bank in the North Sea became the first new Scottish project to win a CfD since 2022. At 4.1GW, the project being developed by SSE Renewables is the largest planned offshore-wind project in the world.
The projects are located around the UK, which is expected to ease grid connections. Nick Civetta, project leader at Aurora Energy Research, noted in a statement:
“83% of the capacity connects in areas of high power demand and greater network capacity, lowering the cost of managing the system.”
In terms of companies, German developer RWE has dominated the auction outcome, with 6.9GW of the capacity being developed overall.
What does the record offshore-wind auction mean for bills?
The auction results arrive at a moment of intense interest in energy bills, which remain significantly higher than before the global energy crisis in 2022.
The government, along with much of the energy industry, said the new offshore wind projects would lower bills, relative to the alternative of relying on more gas.
Meanwhile opposition politicians and right-leaning media used misleading figures to argue that gas power is cheap or that the new offshore wind projects would add large costs to bills.
Broadly speaking, there is some evidence to suggest that electricity bills will rise over the years to 2030 – largely as a result of investment in the grid – before starting to decline.
However, this is the case whether the UK pushes forward with its efforts to expand clean power or not – and is mainly dependent on the timing of electricity network investments and the price of gas.
At the same time, electricity demand is starting to rise as the economy electrifies – as shown in the figure below – and many of the UK’s existing power plants are nearing the end of their lives.
This means that new electricity generation will be needed, whether from offshore wind, gas-fired power stations or from other sources.
Adam Berman, director of policy and advocacy at industry group Energy UK, said ahead of the auction that renewables were the “cheapest” source of new supplies.
Similarly, Pranav Menon, senior associate at consultancy Aurora Energy Research, tells Carbon Brief that the key question is how to meet rising demand most cost-effectively. He says:
“Here, it is quite clear that the answer is renewables (up to a certain price and volume), given that new-build gas is much more expensive…(even after accounting for costs and intermittency for renewables).”
The government said that the price for offshore wind secured through AR7 was “40% lower than the cost of building and operating a new gas power plant”. It added:
“Britain has taken a monumental step towards ending the country’s reliance on volatile fossil fuels and lowering bills for good, by delivering a record-breaking offshore wind result in its latest renewables auction.”
In a similar vein, Dhara Vyas, head of Energy UK said in a statement that the results would “deliver lower bills”. She added:
“Today’s auction results will deliver critical national infrastructure that will strengthen our energy security and deliver lower bills, as well as provide jobs, investment and economic growth right across Great Britain.”
These statements rely on updated government estimates of the cost of different electricity-generating technologies, published alongside the auction results.
They also rely on two studies published by Aurora and another consultancy, Baringa, both commissioned by renewable energy firms involved in the auction.
The government’s new cost estimates reflect the inflationary pressures that have hit turbines for gas-fired generation, as well as offshore wind supply chains.
Carbon Brief analysis of the latest and previous figures suggests that the government thinks the cost of building a gas-fired power station has more than doubled. (Reports from the US point to even steeper three-fold increases in gas turbine costs.)
As such, building and operating new gas-fired power stations would be relatively expensive, at £147/MWh, according to the government. (This assumes the gas plant would only be operating during 30% of hours in each year, in line with the current UK fleet.)
While the offshore wind prices secured in AR7 are around 10% higher than in AR6, at £91/MWh, they would still be considerably lower than the cost of a new gas plant.
However, these figures for new gas and for offshore wind in AR7 do not reflect the wider system costs of keeping the electricity grid running at all times.
In late 2025, Baringa concluded that a strike price of up to £94.50/MWh for up to 8GW of offshore wind would be “cost neutral”. This does not include system balancing costs, which the study argues are relatively modest for each additional gigawatt of capacity.
Carbon Brief understands that, when taking this into account, the “cost neutral” price for further offshore capacity would be reduced by a few pounds. This implies that the AR7 result at £91/MWh is likely to be in or around the “cost-neutral” range, based on Baringa’s assumptions.
Also, in late 2025, Aurora concluded that new offshore wind could be secured at “no net cost to consumers”, provided that contracts were agreed at no more than £94/MWh.
In contrast to Baringa’s work, this study is based on what an Aurora press release describes as a “total system cost analysis”. This means it takes into account the cost of dealing with the variable output of offshore wind, such as system balancing and backup.
In an updated note following the results of the auction, Aurora said that it would “generate net consumer savings of just over £1bn up to 2035”. This is relative to a scenario where no offshore wind had been procured at the latest auction.
(In its pre-auction analysis, Aurora pointed to a reduction in consumer electricity bills of around £20 per household per year by 2035, relative to relying on more gas power instead.)
Writing on LinkedIn, Aurora data analyst Ivan Bogachev said that this was the case, even though it might appear to be “counterintuitive”. He added:
“Moreover, AR7 projects are primarily clustered in areas which see few network constraints, limiting any contribution to higher balancing costs.”
In contrast, Conservative shadow energy secretary Claire Coutinho and right-leaning media commentators cited misleading figures to claim that the auction was “locking us in” to high prices.
Coutinho has repeatedly cited a figure for the cost of fuel needed to run a gas-fired power station in summer 2025 – some £55/MWh – as if this is a fair reflection of the cost of electricity from gas.
However, this excludes the cost of carbon, which gas plants must pay under the UK emissions trading system and the “carbon price support”. It also ignores the cost of building new gas-fired capacity, which as noted above has soared in recent years.
Dr Callum McIver, a researcher at the UK Energy Research Centre (UKERC) and research fellow at the University of Strathclyde, tells Carbon Brief that “you can’t credibly strip out the cost of carbon” and that the £55/MWh figure is not an “apples-to-apples” comparison with the AR7 result.
McIver says that a fairer comparison would be with a new-build gas plant, which, according to the latest DESNZ cost of generation report, would come in at £147/MWh – and would remain at £104/MWh, even if the cost of carbon is ignored.
UKERC director Prof Robert Gross, at Imperial College London, tells Carbon Brief that Coutinho’s £55/MWh figure for gas is “unrealistically low” because it is below current wholesale prices, which averaged around £80/MWh in 2025.
Gross adds that, as well as ignoring carbon pricing, the figure is also for “existing and not new gas stations, which we will need and which will need to recover much increased CAPEX [capital cost]”.
Another factor often not taken into account by those criticising the price of renewable energy contracts is that these projects reduce wholesale prices, as noted in Aurora’s modelling.
Separate analysis published by the Energy and Climate Intelligence Unit (ECIU) thinktank finds that wholesale power prices would have been 46% higher in 2025 – at £121/MWh rather than £83/MWh – if there had been no windfarms generating electricity.
This is because windfarms push the most expensive gas plants off the system, reducing average wholesale prices. This is a well-known phenomenon known as the “merit order effect”.
What does AR7 mean for reaching clean power by 2030?
Offshore wind is expected to be the backbone of the UK’s electricity mix in 2030, making the stakes for this CfD auction particularly high.
Under the National Energy System Operator’s (NESO) independent advice to the government, half of electricity demand will be met by offshore wind by 2030. It says this requires between 43GW and 51GW of generating capacity from the technology.
This advice informed the government’s action plan for meeting 100% of electricity demand with clean power by the end of the decade, which also sets a target of 43-50GW of offshore wind.
Currently, the UK has around 17GW of installed offshore wind capacity, leaving a gap of 27-34GW to the government’s target range.
A further 10GW of capacity already had a CfD prior to the latest auction, excluding the cancelled Hornsea 4 project. The additional 8.4GW contracted in AR7 means the remaining gap to the minimum 43GW end of the government’s range is just 7GW, as shown below.
Speaking to journalists after the auction results were announced, Chris Stark, who is head of “Mission Control” for clean power 2030, told journalists that securing 8.4GW in AR7 put the UK on track for its targets. He added:
“The result today actually takes us now to within touching distance of the goals that we set for 2030 – more to come on that, as I mentioned, with the onshore technologies and the storage projects up and down this country.
“But this is, I think, a real endorsement for the steps that Ed Miliband has taken to bring about that goal of clean power by 2030, it will bring huge benefits to people here in the UK.”
There remain a number of challenges with the delivery of these offshore-wind projects – including securing a grid connection – that could threaten delivery before 2030.
Writing on LinkedIn, Bertalan Gyenes, consultant at LCP Delta, says that with a third of the new capacity set to deliver before 2030, a “swiftly delivered and ambitious [allocation round eight] would put DESNZ within touching distance of its targets”. However, he adds:
“The job is not over yet, the windfarms need to be connected, the network upgraded, consenting pipelines de-clogged – there can be no more delays and certainly no cancellations like what we had seen with Hornsea 4 after last year’s auction.”
McIver wrote on LinkedIn that the auction result “takes us into the goldilocks zone that just about keeps CP30 targets alive, if AR8 can similarly deliver”. He added:
“OK, looking at delivery years [for the contracted projects], maybe we’re aiming for roughly CP33 [clean power by 2033] now? Maybe that would be no bad thing.”
Within the briefing for journalists, Stark highlighted a number of steps undertaken by the government over the past 18 months to ease the challenges around the expansion of the renewable energy sector.
This includes removing “zombie projects” from the queue for connecting projects to the electricity network and announcing £28bn in investment for gas and electricity grids.
As such, the auction results fit within a “host of policies” designed to make the ambitious clean power by 2030 target possible, said Stark.
The second half of the CfD results, covering technologies such as onshore wind and solar, are expected out next month. DESNZ’s action plan set a range of 27-29GW and 45-47GW of capacity for the two technologies, respectively, if the country is to meet its 2030 clean-power target.
The post Q&A: What UK’s record auction for offshore wind means for bills and clean power by 2030 appeared first on Carbon Brief.
Q&A: What UK’s record auction for offshore wind means for bills and clean power by 2030
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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