The Earth’s jet streams play a fundamental role in the speed and direction of weather systems across the world.
This means that they are crucial for understanding extreme weather events and how they will change as the world warms.
Research suggests that upper-level jet-stream winds will accelerate on average as global temperatures rise, but little is known about how their fastest winds – known as “jet streaks” – will change.
In a first-ever study, published in Nature Climate Change, my co-author and I show that fast jet-stream winds will get faster and faster — by around 2% for every degree Celsius the world warms. This means that fast winds will speed up around 2.5 times more than average jet-stream winds.
Furthermore, it means we should anticipate record-breaking jet-stream winds as warming continues.
Our research also reveals that this acceleration occurs because the difference between the density of the air in the tropics and the air at the poles will increase.
While further work will be needed to understand the full impact of our findings, we expect that they will include stronger severe storms and an increase in clear-air turbulence for aircraft passengers.
Fast flowing
The Earth’s jet streams are fast-flowing narrow bands of wind high up in the atmosphere. The fastest jet-stream winds blow from west to east and occur in the upper troposphere, around 10-12 km above the surface.
Jet streams are important because they shape Earth’s surface climate by steering weather systems, and so they can affect where severe weather occurs. For example, the regions around fast upper-level jet-stream winds – called “jet streaks” – have been linked to the occurrence of storms, tornadoes, hail and severe winds.
Jet streams are also key for air travel, providing an ideal tailwind for aircraft. Previous research has established that the average wind speed of the upper-level jet stream increases under climate change. This has the potential knock-on effect of causing more clear-air turbulence for aircraft passengers.
Our research was inspired by reports in 2019 of transatlantic flights breaking speed records. As a result, we set out to find out how climate change will affect fast jet-stream winds.
Little is known about how fast upper-level jet-stream winds – classed as those above the 99th percentile – could change as the world warms. Furthermore, no mechanism has been proposed to explain why fast jet-stream winds would change.
Fast-get-faster response
We started by examining how physics-based climate models project fast jet-stream winds would change. We used models from the sixth Coupled Model Intercomparison Project (CMIP6), which were developed for the latest assessment by the Intergovernmental Panel on Climate Change (IPCC).
In these model projections, we compare daily jet-stream winds that exceed the 99th percentile at the end of the 20th (1980-2000) and 21st (2080-2100) centuries under a very high emissions scenario (SSP5-8.5). We also compare wind speeds for the near-term in an intermediate scenario (SSP2-4.5), which is broadly in line with the trajectory of global emissions today.
Our analysis finds that climate change makes the fastest upper-level jet-stream winds get faster and faster – by about 2% for every degree Celsius the world warms. This means that fast winds will speed up around 2.5 times more than average jet-stream winds.
We refer to this as the “fast-get-faster” response and we find the effect in all seasons of the year.
You can see this in the chart below, which shows the percentage change in the fastest winds at around 12km altitude per degree of warming across different latitudes (from 80 degrees south on the left-hand side to 80 degrees north on the right).
While the fast winds increase at all latitudes, those in the “extratropics” – that is, between around 20 to 60 degrees, where jet streams are found – are the fastest to begin with and thus get the largest boost under climate change.

Percentage changes in fast (>99th percentile) winds at 200 hectopascal (hPa), normalised by the global average change in surface air temperature for each climate model from 80 degrees south to 80 degrees north in latitude. Simulations use SSP5-8.5. The black line indicates the multi-model average and the shading indicates one standard deviation of the response across all the models. Source: Shaw & Miyawaki (2023)
Moist air
In addition to quantifying the “signal” of long-term change, we also provide a physical explanation for why it occurs.
Bridging the gap between simulating the response to climate change using models and understanding the causes helps us justify that this is a signal to take seriously.
The first step we take is to simplify the model to help isolate what physics underlies the signal. When the model is run without ocean currents and without land, we still find the signal.
This suggests that the fast-get-faster signal emerges in a world formed entirely of water. The result implies that the physics of a moist atmosphere is key to explaining the fast-get-faster response.
The second step we take is to use our physical understanding of the jet stream to quantify the connection between moisture and the signal.
The jet stream exists because of the contrast of density between air at the equator, which is warm and light, and air at the pole, which is cold and dense. We connect this contrast to the response of moisture under climate change.
In particular, in today’s climate, tropical air holds more moisture than air at the poles because it is warmer. Climate change exacerbates this contrast because hotter air can hold much more moisture than colder air.
While the air at the poles is warming more rapidly than in the tropics, hotter air can hold so much more moisture than cold air that the overall density difference still increases.
This effect increases the density contrast under climate change, accelerating the jet-stream winds. Importantly, the effect is multiplicative – namely, fast jet-stream winds today that involve a steep density contrast would be boosted much more in the future than slower jet-stream winds that involve a shallower density contrast.
Thus, our results project record-breaking jet-stream winds.
Emerging signal
When we look at the recent past (1980–2022) using reanalysis data – which combines physical observations with model simulations – we do not find that the fast-get-faster signal has yet emerged from the noise of natural variability.
However, all the climate models in our study suggest that a statistically significant fast-get-faster signal will emerge for the extratropics in both the southern and northern hemispheres by the middle of this century.
Specifically, under SSP2-4.5, all climate models project the signal in the southern and northern hemispheres extratropics by 2038 and 2048, respectively. Under SSP5-8.5, this is slightly earlier – by 2035 and 2045, respectively.
This is shown in the figures below, which show the percentage change in fast jet-stream winds, relative to 1980-2000, from 1980 to 2050 in the southern (top) and northern (bottom) hemispheres, excluding the tropics. The lines indicate reanalysis data (black) and climate models projections under SSP2-4.5 (green) and SSP5-8.5 (orange).
The charts on the right-hand side show the trend, per degree of warming, for each model (green and orange) and the reanalysis data (black). Closed and open circles indicate results that are and are not statistically significant, respectively.

Timeseries of percentage changes (relative to 1980-2000) in fast 200hPa jet-stream winds in reanalysis and climate models for different emission scenarios for the southern (top) and northern (bottom) hemisphere extratropics from 1980 to 2050. Data are presented as multi-model average (thick line) with one standard deviation of the response across the models (shading). Right-hand charts show the linear trends of these changes per degree of global warming, where statistically significant trends are indicated by closed circles. Source: Shaw & Miyawaki (2023)
We are now working to better understand the knock-on impacts of these changes in the jet stream for severe weather.
New climate models are allowing scientists to look in greater detail at how extreme weather is – and will – change. Ultimately, unravelling the impacts of climate change on winds at regional scales will help society better prepare for the implications of a warming world.
The post Guest post: Why ‘jet-streak’ winds will get faster as the climate warms appeared first on Carbon Brief.
Guest post: Why ‘jet-streak’ winds will get faster as the climate warms
Climate Change
New panel of climate scientists calls for fossil fuel transition roadmaps
A new panel of experts, bringing together some of the world’s top climate scientists, has called on governments to develop roadmaps for phasing out fossil fuels “anchored in science and justice”.
Launched on Friday in Santa Marta, Colombia, along with a set of 12 initial policy recommendations, the panel’s appeal came ahead of a key ministerial meeting on equitable ways to reduce dependence on coal, oil and gas during next week’s “First Conference on Transitioning Away from Fossil Fuels”.
Sixty countries head to Santa Marta to cement coalition for fossil fuel transition
Presenting the panel’s recommendations in a packed Santa Marta Theatre, Johan Rockström, director of the Potsdam Institute for Climate Impact Research (PIK), said the push for a global transition away from fossil fuels offers “a light in the tunnel” during a “very dark moment” of geopolitical conflict and climate extremes.
“Science is here to serve,” Rockström said. “We’re today launching the Science Panel for the Global Energy Transition (SPGET) as a service, as a global common good for all countries, all sectors, all regions to connect to the best science enabling a transition away from fossil fuels.”
The panel is urging countries to create “whole-of-government” plans to “dismantle legal, financial and political barriers” to the energy transition. Its insights are intended to inform top officials from 57 governments who will gather in Santa Marta for high-level discussions on Tuesday and Wednesday.
Draft roadmap for Colombia
Colombian Environment Minister Irene Vélez Torres said the panel “addresses a longstanding shortcoming” in international climate science, by creating a scientific body dedicated solely to overcoming the world’s reliance on fossil fuels.
“It’s a first-of-its-kind, designed to organise in the next five years the scientific evidence that allows cities, regions, countries and coalitions to take the big leap,” Vélez told the event in Santa Marta.
As an example of how countries can move forward – even when their economies are closely tied to the production and use of dirty energy – a group of European scientists presented a draft roadmap to phase out fossil fuels in Colombia, with inputs from the Colombian government. It will be used as a basis for further consultation in the Latin American nation to define the way forward.
To phase out fossil fuels, developing countries need exit route from “debt trap”
Piers Forster, director of the Priestley Centre for Climate Futures at the University of Leeds and co‑author of the roadmap, said it shows “a clear pathway to economic and societal benefit”, with average annual investment of $10.6 billion producing net economic benefits of $23 billion per year by 2050.
The document says fossil fuels in Colombia can be phased out through energy efficiency measures, coupling renewable generation with energy storage, and switching to electrified transport. But, it adds, the government will need to plan for reduced revenue from fossil fuel exports, which roughly half by the mid-2030s.
“What matters now is moving beyond headline targets to create credible, policy-relevant roadmaps, enabling a just and effective transition,” Forster said in a statement. Brazil is also working on a national roadmap for its own economy, as well as leading a voluntary process to produce a global roadmap.
IPCC hobbled by politics
Currently, the world’s top climate science body – the Intergovernmental Panel on Climate Change (IPCC) – requires countries to sign off on each “summary for policymakers” of its flagship science reports. This has led to a politically fraught process that has increasingly seen some oil-producing governments making efforts to weaken its recommendations.
In a bid to focus scientific debates on the phase-out of fossil fuels, the new SPGET was created based on a mandate from last year’s COP30. It is also meant to come up with scientific recommendations at a faster pace than the IPCC’s seven-year cycle.
Natalie Jones, senior policy advisor at the International Institute of Sustainable Development (IISD), called the new scientific panel “historic”, as it will be “more specific, more targeted and potentially more agile” with its advice on phasing out coal, oil and gas than the IPCC’s exhaustive scientific synthesis reports.
Why the transition beyond fossil fuels depends on cities and collective action
One of the SPGET members, Peter Newell of the UK’s University of Sussex, said “there are many different challenges along the way – and not all of them have to do with lack of evidence”, but the phasing out of fossil fuels “is one part of the story and it’s important to address it”.
The panel will be co-chaired by Cameroonian economist Vera Songwe, PIK’s chief economist Ottmar Edenhofer and Gilberto M. Jannuzzi, professor of energy systems at Brazil’s Universidade Estadual de Campinas. It will be composed of between 50 and 100 scientists divided into four working groups: transition pathways, technological solutions, policies and finance.
Under the 12 insights for the Santa Marta process, the panel recommended banning new fossil fuel infrastructure, mandating “deep cuts” in methane emissions, implementing carbon levies on imports, and de-risking clean energy investments via interventions from central banks, among others.
The post New panel of climate scientists calls for fossil fuel transition roadmaps appeared first on Climate Home News.
New panel of climate scientists calls for fossil fuel transition roadmaps
Climate Change
New loss and damage fund could run out of money next year
Despite not yet paying out any money, a UN-backed fund meant to address the loss and damage caused to developing countries by climate change could face “liquidity issues” by the end of next year, its head warned today.
With ten projects already requesting $166 million in total, the fund’s Executive Director Ibrahima Cheikh Diong warned a board meeting in Zambia that the fund was likely to be “oversubscribed” and should anticipate cashflow problems.
A framing paper prepared by the fund’s secretariat similarly warns that “given the current status of the capitalization of the Fund, there is a risk of the Fund exhausting its capital by the end of 2027, which could result in a loss of operational momentum and expose the FRLD to reputational risk”.
Since governments agreed to set up the fund at UN climate talks in Egypt in 2022, wealthy nations have promised $822 million, but delivered just $449 million.
The fund is expected to approve its first projects at its next board meeting in July. Early proposals submitted include strengthening responses to floods in Bangladesh and the Nigerian city of Lagos, and improving water infrastructure in Jamaica following Hurricane Melissa last year.
Millions not billions
ActionAid Zambia climate justice coordinator Michael Mwansa told the board meeting that he was concerned about “the failure of the Global North governments to deliver on their climate finance obligations, making it largely impossible to scale up [the fund’s initial stage] significantly, if at all”.
“Pledges remain nowhere near the billions and even the trillions needed to address loss and damage to the Global South”, Mwansa added, highlighting reports which found that financing loss and damage could cost developing countries up to $400 billion a year.
The fund’s board discussed its strategy for raising more money at its meeting this week while climate campaigners called, in an open letter, for it to aim to secure $50 billion a year from developed countries starting next year, rising to $100 billion a year by 2031 and $400 billion by 2035.
The World Bank-hosted fund aims to have revenue-raising rounds known as replenishments every four years, with the first in 2027.
Governments have agreed to “urge” developed countries to contribute but only to “encourage” other nations to do so and the fund’s secretariat wants to appoint a “high-level champion” to lead the replenishment team.
The fundraising strategy will be discussed further at the next board meeting in the Philipines in June.
Campaigners’ open letter calls for developed countries to contribute more and for them to introduce taxes on fossil fuel companies, financial transactions, luxury air travel and wealth to raise money for the fund.
“Rich countries must be held strictly accountable for the devastation they have caused,” said Climate Action Network International head Tasneem Essop. “Their failure to fulfil their responsibility to the Loss and Damage Fund is not just an oversight; it is a shameful betrayal of humanity.”
The post New loss and damage fund could run out of money next year appeared first on Climate Home News.
Climate Change
Don’t be so reckless: Hands of Scott Reef
Today, Greenpeace activists disrupted Woodside’s Annual General Meeting, its biggest corporate event of the year, to put the dirty gas corporation’s disastrous plans to drill at Scott Reef front and centre.

While a community rallied outside the shareholder meeting, Greenpeace activists brought the protest inside.
Together, a clear message was sent to Woodside’s executives: keep your hands off Scott Reef.
Inside, a choir of activists performed a ‘Save Scott Reef’ rendition of Angie McMahon’s cover of ‘Reckless’ – a plea to Woodside’s executives, including new CEO Liz Westcott, and shareholders to abandon their reckless plans to drill for dirty gas on the doorstep of a pristine ocean ecosystem.
Several activists were escorted out of the meeting by security while singing and holding up “Hands off Scott Reef” signs that had been smuggled into the room.
Outside, a powerful community gathered in protest, calling on WA and Federal governments to reject Woodside’s Browse project and put our oceans and climate first.
Why are we doing this?
Woodside’s Browse project involves drilling 57 gas wells underneath and around Scott Reef – a critical habitat for rare marine life including pygmy blue whales, green sea turtles and the dusky sea snake.
Gas would be extracted and transported to the Burrup Hub – the most polluting fossil fuel project in Australia. This proposal would industrialise Australia’s largest freestanding oceanic reef system, threatening the marine life that relies on it and the climate.
This project has already been called “unacceptable” by the WA EPA, and has not yet been approved by either the WA or Federal government.
That means our voices matter, now.
Woodside cannot be trusted with our oceans. Together, we can save Scott Reef.
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