Connect with us

Published

on

Electric heat pumps are set to play a key role in the UK’s climate strategy, as well as cutting the nation’s reliance on imported fossil fuels.

Heat pumps took centre-stage in the UK government’s recent “warm homes plan”, which said that they could also help cut household energy bills by “hundreds of pounds” a year.

Similarly, innovation agency Nesta estimates that typical households could cut their annual energy bills nearly £300 a year, by switching from a gas boiler to a heat pump.

Yet there has been widespread media coverage in the Times, Sunday Times, Daily Express, Daily Telegraph and elsewhere of a report claiming that heat pumps are “more expensive” to run.

The report is from the Green Britain Foundation set up by Dale Vince, owner of energy firm Ecotricity, who campaigns against heat pumps and invests in “green gas” as an alternative.

One expert tells Carbon Brief that Vince’s report is based on “flimsy data”, while another says that it “combines a series of worst-case assumptions to present an unduly pessimistic picture”.

This factcheck explains how heat pumps can cut bills, what the latest data shows about potential savings and how this information was left out of the report from Vince’s foundation.

How heat pumps can cut bills

Heat pumps use electricity to move heat – most commonly from outside air – to the inside of a building, in a process that is similar to the way that a fridge keeps its contents cold.

This means that they are highly efficient, adding three or four units of heat to the house for each unit of electricity used. In contrast, a gas boiler will always supply less than one unit of heat from each unit of gas that it burns, because some of the energy is lost during combustion.

This means that heat pumps can keep buildings warm while using three, four or even five times less energy than a gas boiler. This cuts fossil-fuel imports, reducing demand for gas by at least two-fifths, even in the unlikely scenario that all of the electricity they need is gas-fired.

Simon Evans on BlueSky (@drsimevans.carbonbrief.org): "Going slow on heat pumps could mean UK consumers having to pay an extra £3bn for imported gas 2026-2030, says Energy UK Says UK govt foot-dragging is "increasing costs for energy customers & hampering future system planning"

Since UK electricity supplies are now the cleanest they have ever been, heat pumps also cut the carbon emissions associated with staying warm by around 85%, relative to a gas boiler.

Heat pumps are, therefore, the “central” technology for cutting carbon emissions from buildings.

While heat pumps cost more to install than gas boilers, the UK government’s recent “warm homes plan” says that they can help cut energy bills by “hundreds of pounds” per year.

Similarly, Nesta published analysis showing that a typical home could cut its annual energy bill by £280, if it replaces a gas boiler with a heat pump, as shown in the figure below.

Nesta and the government plan say that significantly larger savings are possible if heat pumps are combined with other clean-energy technologies, such as solar and batteries.

Chart showing that clean electric tech could save households £1,000 a year, compared to gas boilers
Annual energy bill savings (£) for a typical household from April 2026, by using different clean-energy technologies in comparison with a gas boiler. Source: Nesta analysis, using data from Ofgem, the Centre for Net Zero and an Octopus Energy tariff.

Both the government and Nesta’s estimates of bill savings from switching to a heat pump rely on relatively conservative assumptions.

Specifically, the government assumes that a heat pump will deliver 2.8 units of heat for each unit of electricity, on average. This is known as the “seasonal coefficient of performance” (SCoP).

This figure is taken from the government-backed “electrification of heat” trial, which ran during 2020-2022 and showed that heat pumps are suitable for all building types in the UK.

(The Green Britain Foundation report and Vince’s quotes in related coverage repeat a number of heat pump myths, such as the idea that they do not perform well in older properties and require high levels of insulation.)

Nesta assumes a slightly higher SCoP of 3.0, says Madeleine Gabriel, the organisation’s director of sustainable future. (See below for more on what the latest data says about SCoP in recent installations.)

Both the government and Nesta assume that a home with a heat pump would disconnect from the gas grid, meaning that it would no longer need to pay the daily “standing charge” for gas. This currently amounts to a saving of around £130 per year.

Finally, they both consider the impact of a home with a heat pump using a “smart tariff”, where the price of electricity varies according to the time of day.

Such tariffs are now widely available from a variety of energy suppliers and many have been designed specifically for homes that have a heat pump.

Such tariffs significantly reduce the average price for a unit of electricity. Government survey data suggests that around half of heat-pump owners already use such tariffs.

This is important because on the standard rates under the price cap set by energy regulator Ofgem, each unit of electricity costs more than four times as much as a unit of gas.

The ratio between electricity and gas prices is a key determinant of the size and potential for running-cost savings with a heat pump. Countries with a lower electricity-to-gas price ratio consistently see much higher rates of heat-pump adoption.

(Decisions taken by the UK government in its 2025 budget mean that the electricity-to-gas ratio will fall from April, but current forecasts suggest it will remain above four-to-one.)

In contrast, Vince’s report assumes that gas boilers are 90% efficient, whereas data from real homes suggests 85% is more typical. It also assumes that homes with heat pumps remain on the gas grid, paying the standing charge, as well as using only a standard electricity tariff.

Prof Jan Rosenow, energy programme leader at the University of Oxford’s Environmental Change Institute, tells Carbon Brief that Vince’s report uses “worst-case assumptions”. He says:

“This report cherry-picks assumptions to reach a predetermined conclusion. Most notably, it assumes a gas boiler efficiency of 90%, which is significantly higher than real-world performance…Taken together, the analysis combines a series of worst-case assumptions to present an unduly pessimistic picture.”

Similarly, Gabriel tells Carbon Brief that Vince’s report is based on “flimsy data”. She explains:

“Dale Vince has drawn some very strong conclusions about heat pumps from quite flimsy data. Like Dale, we’d also like to see electricity prices come down relative to gas, but we estimate that, from April, even a moderately efficient heat pump on a standard tariff will be cheaper to run than a gas boiler. Paired with a time-of-use tariff, a heat pump could save £280 versus a boiler and adding solar panels and a battery could triple those savings.”

What the latest data shows about bill savings

The efficiency of heat-pump installations is another key factor in the potential bill savings they can deliver and, here, both the government and Vince’s report take a conservative approach.

They rely on the “electrification of heat” trial data to use an efficiency (SCoP) of 2.8 for heat pumps. However, Rosenow says that recent evidence shows that “substantially higher efficiencies are routinely available”, as shown in the figure below.

Detailed, real-time data on hundreds of heat pump systems around the UK is available via the website Heat Pump Monitor, where the average efficiency – a SCoP of 3.9 – is much higher.

Charts showing that recent heat-pump installations tend to be far more efficient
Number of installations by heat pump efficiency, in the electrification of heat trial (left) and on the website Heat Pump Monitor (right). An efficiency of three means that each unit of electricity delivers three units of heat, on average, across a year. Source: Heat Pump Monitor.

Homes with such efficient heat-pump installations would see even larger bill savings than suggested by the government and Nesta estimates.

Academic research suggests that there are simple and easy-to-implement reasons why these systems achieve much higher efficiency levels than in the electrification of heat trial.

Specifically, it shows that many of the systems in the trial have poor software settings, which means they do not operate as efficiently as their heat pump hardware is capable of doing.

The research suggests that heat pump installations in the UK have been getting more and more efficient over time, as engineers become increasingly familiar with the technology.

It indicates that recently installed heat pumps are 64% more efficient than those in early trials.

Jan Rosenow on BlueSky (@janrosenow.bsky.social): "Well-installed heat pumps installed in the UK today achieve on average a 64% higher efficiency than those during the early trials 15 years ago. It is testament to the brilliant installers and to the technology getting better. More in our recent paper"

Notably, the Green Britain Foundation report only refers to the trial data from the electrification of heat study carried out in 2020-22 and the even earlier “renewable heat premium package” (RHPP). This makes a huge difference to the estimated running costs of a heat pump.

Carbon Brief analysis suggests that a typical household could cut its annual energy bills by nearly £200 with a heat pump – even on a standard electricity tariff – if the system has a SCoP of 3.9.

The savings would be even larger on a smart heat-pump tariff.

In contrast, based on the oldest efficiency figures mentioned in the Green Britain Foundation report, a heat pump could increase annual household bills by as much as £200 on a standard tariff.

To support its conclusions, the report also includes the results of a survey of 1,001 heat pump owners, which, among other things, is at odds with government survey data. The report says “66% of respondents report that their homes are more expensive to heat than the previous system”.

There are several reasons to treat these findings with caution. The survey was carried out in July 2025 and some 45% of the heat pumps involved were installed between 2021-23.

This is a period during which energy prices surged as a result of Russia’s invasion of Ukraine and the resulting global energy crisis. Energy bills remain elevated as a result of high gas prices.

The wording of the survey question asks if homes are “more or less expensive to heat than with your previous system” – but makes no mention of these price rises.

The question does not ask homeowners if their bills are higher today, with a heat pump, than they would have been with the household’s previous heating system.

If respondents interpreted the question as asking whether their bills have gone up or down since their heat pump was installed, then their answers will be confounded by the rise in prices overall.

There are a number of other seemingly contradictory aspects of the survey that raise questions about its findings and the strong conclusions in the media coverage of the report.

For example, while only 15% of respondents say it is cheaper to heat their home with a heat pump, 49% say that one of the top three advantages of the system is saving money on energy bills.

In addition, 57% of respondents say they still have a boiler, even though 67% say they received government subsidies for their heat-pump installation. It is a requirement of the government’s boiler upgrade scheme (BUS) grants that homeowners completely remove their boiler.

The government’s own survey of BUS recipients finds that only 13% of respondents say their bills have gone up, whereas 37% say their bills have gone down, another 13% say they have stayed the same and 8% thought that it was too early to say.

The post Factcheck: What it really costs to heat a home in the UK with a heat pump appeared first on Carbon Brief.

Factcheck: What it really costs to heat a home in the UK with a heat pump

Continue Reading

Climate Change

The 2026 budget test: Will Australia break free from fossil fuels?

Published

on

In 2026, the dangers of fossil fuel dependence have been laid bare like never before. The illegal invasion of Iran has brought pain and destruction to millions across the Middle East and triggered a global energy crisis impacting us all. Communities in the Pacific have been hit especially hard by rising fuel prices, and Australians have seen their cost-of-living woes deepen.

Such moments of crisis and upheaval can lead to positive transformation. But only when leaders act with courage and foresight.

There is no clearer statement of a government’s plans and priorities for the nation than its budget — how it plans to raise money, and what services, communities, and industries it will invest in.

As we count down the days to the 2026-27 Federal Budget, will the Albanese Government deliver a budget for our times? One that starts breaking the shackles of fossil fuels, accelerates the shift to clean energy, protects nature, and sees us work together with other countries towards a safer future for all? Or one that doubles down on coal and gas, locks in more climate chaos, and keeps us beholden to the whims of tyrants and billionaires.

Here’s what we think the moment demands, and what we’ll be looking out for when Treasurer Jim Chalmers steps up to the dispatch box on 12 May.

1. Stop fuelling the fire
2. Make big polluters pay
3. Support everyone to be part of the solution
4. Build the industries of the future
5. Build community resilience
6. Be a better neighbour
7. Protect nature

1. Stop fuelling the fire

Action Calls for a Transition Away From Fossil Fuels in Vanuatu. © Greenpeace
The community in Mele, Vanuatu sent a positive message ahead of the First Conference on Transitioning Away from Fossil Fuels. © Greenpeace

In mid-April, Pacific governments and civil society met to redouble their efforts towards a Fossil Fuel Free Pacific. Moving beyond coal, oil and gas is fundamental to limiting warming to 1.5°C — a survival line for vulnerable communities and ecosystems. And as our Head of Pacific, Shiva Gounden, explained, it is “also a path of liberation that frees us from expensive, extractive and polluting fossil fuel imports and uplifts our communities”.

Pacific countries are at the forefront of growing global momentum towards a just transition away from fossil fuels, and it is way past time for Australia to get with the program. It is no longer a question of whether fossil fuel extraction will end, but whether that end will be appropriately managed and see communities supported through the transition, or whether it will be chaotic and disruptive.

So will this budget support the transition away from fossil fuels, or will it continue to prop up coal and gas?

When it comes to sensible moves the government can make right now, one stands out as a genuine low hanging fruit. Mining companies get a full rebate of the excise (or tax) that the rest of us pay on diesel fuel. This lowers their operating costs and acts as a large, ongoing subsidy on fossil fuel production — to the tune of $11 billion a year!

Greenpeace has long called for coal and gas companies to be removed from this outdated scheme, and for the billions in savings to be used to support the clean energy transition and to assist communities with adapting to the impacts of climate change. Will we see the government finally make this long overdue change, or will it once again cave to the fossil fuel lobby?

2. Make big polluters pay

Activists Disrupt Major Gas Conference in Sydney. © Greenpeace
Greenpeace Australia Pacific activists disrupted the Australian Domestic Gas Outlook conference in Sydney with the message ‘Gas execs profit, we pay the price’. © Greenpeace

While our communities continue to suffer the escalating costs of climate-fuelled disasters, our Government continues to support a massive expansion of Australia’s export gas industry. Gas is a dangerous fossil fuel, with every tonne of Australian gas adding to the global heating that endangers us all.

Moreover, companies like Santos and Woodside pay very little tax for the privilege of digging up and selling Australians’ natural endowment of fossil gas. Remarkably, the Government currently raises more tax from beer than from the Petroleum Resource Rent Tax (PRRT) — the main tax on gas profits.

Momentum has been building to replace or supplement the PRRT with a 25% tax on gas exports. This could raise up to $17 billion a year — funds that, like savings from removing the diesel tax rebate for coal and gas companies, could be spent on supporting the clean energy transition and assisting communities with adapting to worsening fires, floods, heatwaves and other impacts of climate change.

As politicians arrive in Canberra for budget week, they will be confronted by billboards calling for a fair tax on gas exports. The push now has the support of dozens of organisations and a growing number of politicians. Let’s hope the Treasurer seizes this rare window for reform.

3. Support everyone to be part of the solution

As the price of petrol and diesel rises, electric vehicles (EVs) are helping people cut fuel use and save money. However, while EV sales have jumped since the invasion of Iran sent fuel prices rising, they still only make up a fraction of total new car sales. This budget should help more Australians switch to electric vehicles and, even more importantly, enable more Australians to get around by bike, on foot, and on public transport. This means maintaining the EV discount, investing in public and active transport, and removing tax breaks for fuel-hungry utes and vans.

Millions of Australians already enjoy the cost-saving benefits of rooftop solar, batteries, and getting off gas. This budget should enable more households, and in particular those on lower incomes, to access these benefits. This means maintaining the Cheaper Home Batteries Program, and building on the Household Energy Upgrades Fund.

4. Build the industries of the future

Protest of Woodside and Drill Rig Valaris at Scarborough Gas Field in Western Australia. © Greenpeace / Jimmy Emms
Crew aboard Greenpeace Australia Pacific’s campaigning vessel the Oceania conducted a peaceful banner protest at the site of the Valaris DPS-1, the drill rig commissioned to build Woodside’s destructive Burrup Hub. © Greenpeace / Jimmy Emms

If we’re to transition away from fossil fuels, we need to be building the clean industries of the future.

No state is more pivotal to Australia’s energy and industrial transformation than Western Australia. The state has unrivaled potential for renewable energy development and for replacing fossil fuel exports with clean exports like green iron. Such industries offer Western Australia the promise of a vibrant economic future, and for Australia to play an outsized positive role in the world’s efforts to reduce emissions.

However, realising this potential will require focussed support from the Federal Government. Among other measures, Greenpeace has recommended establishing the Australasian Green Iron Corporation as a joint venture between the Australian and Western Australian governments, a key trading partner, a major iron ore miner and steel makers. This would unite these central players around the complex task of building a large-scale green iron industry, and unleash Western Australia’s potential as a green industrial powerhouse.

5. Build community resilience

Believe it or not, our Government continues to spend far more on subsidising fossil fuel production — and on clearing up after climate-fuelled disasters — than it does on helping communities and industries reduce disaster costs through practical, proven methods for building their resilience.

Last year, the Government estimated that the cost of recovery from disasters like the devastating 2022 east coast floods on 2019-20 fires will rise to $13.5 billion. For contrast, the Government’s Disaster Ready Fund – the main national source of funding for disaster resilience – invests just $200 million a year in grants to support disaster preparedness and resilience building. This is despite the Government’s own National Emergency Management Agency (NEMA) estimating that for every dollar spent on disaster risk reduction, there is a $9.60 return on investment.

By redirecting funds currently spent on subsidising fossil fuel production, the Government can both stop incentivising climate destruction in the first place, and ensure that Australian communities and industries are better protected from worsening climate extremes.

No communities have more to lose from climate damage, or carry more knowledge of practical solutions, than Aboriginal and Torres Strait Islander peoples. The budget should include a dedicated First Nations climate adaptation fund, ensuring First Nations communities can develop solutions on their own terms, and access the support they need with adapting to extreme heat, coastal erosion and other escalating challenges.

6. Be a better neighbour

The global response to climate change depends on the adequate flow of support from developed economies like Australia to lower income nations with shifting to clean energy, adapting to the impacts of climate change, and addressing loss and damage.

Such support is vital to building trust and cooperation, reducing global emissions, and supporting regional and global security by enabling countries to transition away from fossil fuels and build greater resilience.

Despite its central leadership role in this year’s global climate negotiations, our Government is yet to announce its contribution to international climate finance for 2025-2030. Greenpeace recommends a commitment of $11 billion for this five year period, which is aligned with the global goal under the Paris Agreement to triple international climate finance from current levels.
This new commitment should include additional funding to address loss and damage from climate change and a substantial contribution to the Pacific Resilience Facility, ensuring support is accessible to countries and communities that need it most. It should also see Australia get firmly behind the vision of a Fossil Fuel Free Pacific.

7. Protect nature

Rainforest in Tasmania. © Markus Mauthe / Greenpeace
Rainforest of north west Tasmania in the Takayna (Tarkine) region. © Markus Mauthe / Greenpeace

There is no safe planet without protection of the ecosystems and biodiversity that sustain us and regulate our climate.

Last year the Parliament passed important and long overdue reforms to our national environment laws to ensure better protection for our forests and other critical ecosystems. However, the Government will need to provide sufficient funding to ensure the effective implementation of these reforms.

Greenpeace has recommended $500 million over four years to establish the National Environment Agency — the body responsible for enforcing and monitoring the new laws — and a further $50 million to Environment Information Australia for providing critical information and tools.

Further resourcing will also be required to fulfil the crucial goal of fully protecting 30% of Australian land and seas by 2030. This should include $1 billion towards ending deforestation by enabling farmers and loggers to retool away from destructive practices, $2 billion a year for restoring degraded lands, $5 billion for purchasing and creating new protected areas, and $200 million for expanding domestic and international marine protected areas.

Conclusion

This is not the first time that conflict overseas has triggered an energy crisis, or that a budget has been preceded by a summer of extreme weather disasters, highlighting the urgent need to phase out fossil fuels. What’s different in 2026 is the availability of solutions. Renewable energy is now cheaper and more accessible than ever before. Global momentum is firmly behind the transition away from fossil fuels. The Albanese Government, with its overwhelming majority, has the chance to set our nation up for the future, or keep us stranded in the past. Let’s hope it makes some smart choices.

The 2026 budget test: Will Australia break free from fossil fuels?

Continue Reading

Climate Change

What fossil fuels really cost us in a world at war

Published

on

Anne Jellema is Executive Director of 350.org.

The war on Iran and Lebanon is a deeply unjust and devastating conflict, killing civilians at home, destroying lives, and at the same time sending shockwaves through the global economy. We, at 350.org, have calculated, drawing on price forecasts from the International Monetary Fund (IMF) and Goldman Sachs, just how much that volatility is costing us. 

Even under the IMF’s baseline scenario – a de facto “best case” scenario with a near-term end to the war and related supply chain disruptions – oil and gas price spikes are projected to cost households and businesses globally more than $600 billion by the end of the year. Under the IMF’s “adverse scenario”, with prolonged conflict and sustained price pressures, we estimate those additional costs could exceed $1 trillion, even after accounting for reduced demand.

Which is why we urgently need a power shift. Governments are under growing pressure to respond to rising fuel and food costs and deepening energy poverty. And it’s becoming clearer to both voters and elected officials that fossil dependence is not only expensive and risky, but unnecessary. 

People who can are voting with their wallets: sales of solar panels and electric vehicles are increasing sharply in many countries. But the working people who have nothing to spare, ironically, are the ones stuck with using oil and gas that is either exorbitantly expensive or simply impossible to get.

Drain on households and economies

In India, street food vendors can’t get cooking gas and in the Philippines, fishermen can’t afford to take their boats to sea. A quarter of British people say that rising energy tariffs will leave them completely unable to pay their bills. This is the moment for a global push to bring abundant and affordable clean energy to all.

In April, we released Out of Pocket, our new research report on how fossil fuels are draining households and economies. We were surprised by the scale of what we found. For decades, governments have reassured people that energy price spikes are unfortunate but unavoidable – the result of distant conflicts, market forces or geopolitical shocks beyond anyone’s control. But the numbers tell a different story. 

    What we are living through today is not an energy crisis. It is a fossil fuel crisis. In just the first 50 days of the Middle East conflict, soaring oil and gas prices have siphoned an estimated $158 billion–$166 billion from households and businesses worldwide. That is money extracted directly from people’s pockets and transferred, almost instantly, into fossil fuel company balance sheets. And this figure only captures the immediate impact of price spikes, not the permanent economic drain of fossil dependence. Fossil fuels don’t just cost us once, they cost us over and over again.

    First, through our bills. Every time there is a war, an embargo or a supply disruption, fossil fuel prices surge. For ordinary people, this means higher costs for energy, transport and food. Many Global South countries have little or no fiscal space to buffer the shock; instead, workers and families pay the price.

    Second, through our taxes. Governments around the world continue to pour vast sums of public money into fossil fuel subsidies. These are often justified as a way to protect the most vulnerable at the petrol pump or in their homes. But in reality, the benefits are overwhelmingly captured by wealthier households and corporations. The poorest 20% receive just a fraction of this support, while public finances are drained.

    Third, through climate impacts. New research across more than 24,000 global locations gives a granular account of the true costs of extreme heat, sea level rise and falling agricultural yields. Using this data to update IMF modelling of the social cost of carbon, we found that fossil fuel impacts on health and livelihoods amount to over $9 trillion a year. This is the biggest subsidy of all, because these massive and mounting costs are not charged to Big Oil – they are paid for by governments and households, with the poorest shouldering the lion’s share. 

    Massive transfer of wealth to fossil fuel industry

    Adding up direct subsidies, tax breaks and the unpaid bill for climate damages, the total transfer of wealth from the public to the fossil fuel industry amounts to $12 trillion even in a “normal” year without a global oil shock. That’s more than 50% higher than the IMF has previously estimated, and equivalent to a staggering $23 million a minute.

    The fossil fuel industry has become extraordinarily adept at profiting from instability. When conflict drives up prices, companies do not lose, they gain. In the current crisis, oil producers and commodity traders are on track to secure tens of billions of dollars in additional windfall profits, even as households face rising bills and governments struggle to manage the fallout.

    Fossil fuel crisis offers chance to speed up energy transition, ministers say

    This growing disconnect is impossible to ignore. Investors are advised to buy into fossil fuel firms precisely because of their ability to generate profits in times of crisis. Meanwhile, ordinary people are told to tighten their belts.

    In 2026, unlike during the oil shocks of the 1970s, clean energy is no longer a distant alternative. Now, even more than when gas prices spiked due to Russia’s invasion of Ukraine in 2022, renewables are often the cheapest option available. Solar and wind can be deployed quickly, at scale, and without the volatility that defines fossil fuel markets.

    How to transition from dirty to clean energy

    The solutions are clear. Governments must implement permanent windfall taxes on fossil fuel companies to ensure that extraordinary profits generated during crises are redirected to support households. These revenues can be used to reduce energy bills, invest in public services, and accelerate the rollout of clean energy.

    Second, we must shift subsidies away from fossil fuels and towards renewable solutions, particularly those that can be deployed quickly and equitably, such as rooftop and community solar. This is not just about cutting emissions. It is about building a more stable, fair and resilient energy system.

    Finally, we need binding plans to phase out fossil fuels altogether, replacing them with homegrown renewable energy that can shield economies from future shocks. Because what the current crisis has made clear is this: as long as we remain dependent on fossil fuels, we remain vulnerable – to conflict, to price volatility and to the escalating impacts of climate change.

    The true price of fossil fuels is no longer hidden. It is visible in rising bills, strained public finances and communities pushed to the brink. And it is being paid, every day, by ordinary people around the world.

    It’s time for the great power shift

    Full details on the methodology used for this report are available here.

    The Great Power Shift is a new campaign by 350.org global campaign to pressure governments to bring down energy bills for good by ending fossil fuel dependence and investing in clean, affordable energy for all

    Logo of 350.org campaign on “The Great Power Shift”

    Logo of 350.org campaign on “The Great Power Shift”

    The post What fossil fuels really cost us in a world at war appeared first on Climate Home News.

    What fossil fuels really cost us in a world at war

    Continue Reading

    Climate Change

    Traditional models still ‘outperform AI’ for extreme weather forecasts

    Published

    on

    Computer models that use artificial intelligence (AI) cannot forecast record-breaking weather as well as traditional climate models, according to a new study.

    It is well established that AI climate models have surpassed traditional, physics-based climate models for some aspects of weather forecasting.

    However, new research published in Science Advances finds that AI models still “underperform” in forecasting record-breaking extreme weather events.

    The authors tested how well both AI and traditional weather models could simulate thousands of record-breaking hot, cold and windy events that were recorded in 2018 and 2020.

    They find that AI models underestimate both the frequency and intensity of record-breaking events.

    A study author tells Carbon Brief that the analysis is a “warning shot” against replacing traditional models with AI models for weather forecasting “too quickly”.

    AI weather forecasts

    Extreme weather events, such as floods, heatwaves and storms, drive hundreds of billions of dollars in damages every year through the destruction of cropland, impacts on infrastructure and the loss of human life.

    Many governments have developed early warning systems to prepare the general public and mobilise disaster response teams for imminent extreme weather events. These systems have been shown to minimise damages and save lives.

    For decades, scientists have used numerical weather prediction models to simulate the weather days, or weeks, in advance.

    These models rely on a series of complex equations that reproduce processes in the atmosphere and ocean. The equations are rooted in fundamental laws of physics, based on decades of research by climate scientists. As a result, these models are referred to as “physics-based” models.

    However, AI-based climate models are gaining popularity as an alternative for weather forecasting.

    Instead of using physics, these models use a statistical approach. Scientists present AI models with a large batch of historical weather data, known as training data, which teaches the model to recognise patterns and make predictions.

    To produce a new forecast, the AI model draws on this bank of knowledge and follows the patterns that it knows.

    There are many advantages to AI weather forecasts. For example, they use less computing power than physics-based models, because they do not have to run thousands of mathematical equations.

    Furthermore, many AI models have been found to perform better than traditional physics-based models at weather forecasts.

    However, these models also have drawbacks.

    Study author Prof Sebastian Engelke, a professor at the research institute for statistics and information science at the University of Geneva, tells Carbon Brief that AI models “depend strongly on the training data” and are “relatively constrained to the range of this dataset”.

    In other words, AI models struggle to simulate brand new weather patterns, instead tending forecast events of a similar strength to those seen before. As a result, it is unclear whether AI models can simulate unprecedented, record-breaking extreme events that, by definition, have never been seen before.

    Record-breaking extremes

    Extreme weather events are becoming more intense and frequent as the climate warms. Record-shattering extremes – those that break existing records by large margins – are also becoming more regular.

    For example, during a 2021 heatwave in north-western US and Canada, local temperature records were broken by up to 5C. According to one study, the heatwave would have been “impossible” without human-caused climate change.

    The new study explores how accurately AI and physics-based models can forecast such record-breaking extremes.

    First, the authors identified every heat, cold and wind event in 2018 and 2020 that broke a record previously set between 1979 and 2017. (They chose these years due to data availability.) The authors use ERA5 reanalysis data to identify these records.

    This produced a large sample size of record-breaking events. For the year 2020, the authors identified around 160,000 heat, 33,000 cold and 53,000 wind records, spread across different seasons and world regions.

    For their traditional, physics-based model, the authors selected the High RESolution forecast model from the Integrated Forecasting System of the European Centre for Medium-­Range Weather Forecasts. This is “widely considered as the leading physics-­based numerical weather prediction model”, according to the paper.

    They also selected three “leading” AI weather models – the GraphCast model from Google Deepmind, Pangu-­Weather developed by Huawei Cloud and the Fuxi model, developed by a team from Shanghai.

    The authors then assessed how accurately each model could forecast the extremes observed in the year 2020.

    Dr Zhongwei Zhang is the lead author on the study and a researcher at Karlsruhe Institute of Technology. He tells Carbon Brief that many AI weather forecast models were built for “general weather conditions”, as they use all historical weather data to train the models. Meanwhile, forecasting extremes is considered a “secondary task” by the models.

    The authors explored a range of different “lead times” – in other words, how far into the future the model is forecasting. For example, a lead time of two days could mean the model uses the weather conditions at midnight on 1 January to simulate weather conditions at midnight on 3 January.

    The plot below shows how accurately the models forecasted all extreme events (left) and heat extremes (right) under different lead times. This is measured using “root mean square error” – a metric of how accurate a model is, where a lower value indicates lower error and higher accuracy.

    The chart on the left shows how two of the AI models (blue and green) performed better than the physics-based model (black) when forecasting all weather across the year 2020.

    However, the chart on the right illustrates how the physics-based model (black) performed better than all three AI models (blue, red and green) when it came to forecasting heat extremes.

    Accuracy of the AI models
    Accuracy of the AI models (blue, red and green) and the physics-based model (black) at forecasting all weather over 2020 (left) and heat extremes (right) over a range of lead times. This is measured using “root mean square error” (RMSE) – a metric of how accurate a model is, where a lower value indicates lower error and higher accuracy. Source: Zhang et al (2026).

    The authors note that the performance gap between AI and physics-based models is widest for lower lead times, indicating that AI models have greater difficulty making predictions in the near future.

    They find similar results for cold and wind records.

    In addition, the authors find that AI models generally “underpredict” temperature during heat records and “overpredict” during cold records.

    The study finds that the larger the margin that the record is broken by, the less well the AI model predicts the intensity of the event.

    ‘Warning shot’

    Study author Prof Erich Fischer is a climate scientist at ETH Zurich and a Carbon Brief contributing editor. He tells Carbon Brief that the result is “not unexpected”.

    He adds that the analysis is a “warning shot” against replacing traditional models with AI models for weather forecasting “too quickly”.

    The analysis, he continues, is a “warning shot” against replacing traditional models with AI models for weather forecasting “too quickly”.

    AI models are likely to continue to improve, but scientists should “not yet” fully replace traditional forecasting models with AI ones, according to Fischer.

    He explains that accurate forecasts are “most needed” in the runup to potential record-breaking extremes, because they are the trigger for early warning systems that help minimise damages caused by extreme weather.

    Leonardo Olivetti is a PhD student at Uppsala University, who has published work on AI weather forecasting and was not involved in the study.

    He tells Carbon Brief that “many other studies” have identified issues with using AI models for “extremes”, but this paper is novel for its specific focus on extremes.

    Olivetti notes that AI models are already used alongside physics-based models at “some of the major weather forecasting centres around the world”. However, the study results suggest “caution against relying too heavily on these [AI] models”, he says.

    Prof Martin Schultz, a professor in computational earth system science at the University of Cologne who was not involved in the study, tells Carbon Brief that the results of the analysis are “very interesting, but not too surprising”.

    He adds that the study “justifies the continued use of classical numerical weather models in operational forecasts, in spite of their tremendous computational costs”.

    Advances in forecasting

    The field of AI weather forecasting is evolving rapidly.

    Olivetti notes that the three AI models tested in the study are an “older generation” of AI models. In the last two years, newer “probabilistic” forecast models have emerged that “claim to better capture extremes”, he explains.

    The three AI models used in the analysis are “deterministic”, meaning that they only simulate one possible future outcome.

    In contrast, study author Engelke tells Carbon Brief that probabilistic models “create several possible future states of the weather” and are therefore more likely to capture record-breaking extremes.

    Engelke says it is “important” to evaluate the newer generation of models for their ability to forecast weather extremes.

    He adds that this paper has set out a “protocol” for testing the ability of AI models to predict unprecedented extreme events, which he hopes other researchers will go on to use.

    The study says that another “promising direction” for future research is to develop models that combine aspects of traditional, physics-based weather forecasts with AI models.

    Engelke says this approach would be “best of both worlds”, as it would combine the ability of physics-based models to simulate record-breaking weather with the computational efficiency of AI models.

    Dr Kyle Hilburn, a research scientist at Colorado State University, notes that the study does not address extreme rainfall, which he says “presents challenges for both modelling and observing”. This, he says, is an “important” area for future research.

    The post Traditional models still ‘outperform AI’ for extreme weather forecasts appeared first on Carbon Brief.

    Traditional models still ‘outperform AI’ for extreme weather forecasts

    Continue Reading

    Trending

    Copyright © 2022 BreakingClimateChange.com