Cold-blooded sea creatures seeking refuge from warming ocean waters may find themselves at increasing risk of deadly cold shocks due to changes in ocean currents, new research warns.
Climate change is pushing species to higher latitudes in an attempt to stay within their range of comfortable temperatures, but this migration can come with unforeseen consequences.
The new study, published in Nature, documents a mass mortality event in March 2021 that saw at least 260 dead sea creatures wash up on the shores of South Africa.
Using satellite data, ocean observations and data on the movements of bull sharks, the researchers link the event to a sudden influx of cold water coming up from the deeper ocean.
They also show that such events have been increasing in frequency over the past three decades and forecast that this trend may continue into the future as the world continues to warm.
One of the study authors tells Carbon Brief that “we predict this is going to become a more regular phenomenon and could impact a lot of different species”.
Marine migration
As the Earth warms, many species that are able to do so are migrating to higher latitudes, allowing them to maintain their place within their “thermal niche” – the set of temperatures at which they can comfortably survive.
Nowhere is this effect more pronounced than in the global oceans, where there are fewer barriers to migration than there are on land. On average, highly mobile marine species have been moving polewards by nearly 60km per decade since the 1950s, according to the latest report on climate impacts from the Intergovernmental Panel on Climate Change (IPCC).
But this migration comes with its own risks.
These shifting ranges due to climate change can introduce species to new, unfamiliar stressors – such as shipping lanes or fisheries, says Dr Natalie Posdaljian, a bioacoustician at Scripps Institution of Oceanography in La Jolla, California, who was not involved in the study.
One of these risks is what the researchers describe as a temperature “bait and switch” – where creatures seeking warmer waters can instead be trapped by a sudden cold event. Posdaljian tells Carbon Brief that the new study is the first time that she’s seen evidence of this hazard.
Mass mortality
On 2 March 2021, dead sea creatures started washing up on the south-eastern shores of South Africa between Port Elizabeth and East London. In all, more than 250 individual organisms and 82 separate species were found, including large, migratory species such as manta rays and bull sharks.
In deducing what had happened, the team of researchers examined the temperature data in the days leading up to the event. Using satellite and other observational data, they found that the temperature of the surrounding ocean had dropped by up to 9.2C in less than 24 hours.
The cold event persisted for seven days and had “severe physiological consequences” for the marine organisms there, including hypothermia, malfunction and death, the paper says.
Similar cold shocks have previously occurred in south-eastern South Africa, dating back to at least 1989 and affecting a wide array of creatures, according to the study. But this instance was “probably the biggest cold-water shock [mass mortality event]” ever recorded, Dr Ryan Daly, a marine scientist at the Oceanographic Research Institute in Durban, South Africa, tells Carbon Brief. Daly is one of the authors of the new study.
The influx of cold water was due to a process called “upwelling”, which carries cold, nutrient-rich water from the ocean depths to its surface.
The study identifies three factors that make rapid upwelling events likely to happen: strong currents interacting with the continental shelf, strong winds blowing from the east to the west and meanders in the current. Such winds occur predominantly during the southern hemisphere’s summer, between October and April. They often act as a harbinger of temperature drops occurring in the coming 0-72 hours, the study notes.
All three of these factors are characteristic of both the south-eastern coast of South Africa and the eastern coast of Australia, where strong currents known as the Agulhas and the East Australian Current, respectively, run up against the continental shelf.
‘Trapped’
Dr Camrin Braun, an ocean ecologist at the Woods Hole Oceanographic Institution in Massachusetts, finds it surprising that even large, migratory species such as rays and bull sharks were killed by the cold snap. Braun, who was not involved in the new research, tells Carbon Brief that these animals “can move really far and really fast”.
Daly says that this surprised the research team as well. But it’s possible, he says, that the onset of the cold temperatures was quick enough and large enough that the animals got “trapped” instead of being able to escape.
To underscore this, the researchers use data on bull shark movements and ocean temperatures from tags attached to sharks before, during and after the event.
They find that the sharks consistently demonstrate “attempted avoidance” of lower temperatures – moving closer to the surface while swimming through upwelling areas and only travelling at deeper depths once they reach warmer waters.
The team also observe one shark taking up residence in a sheltered bay during one upwelling event to escape the cold waters. The researchers write that these actions “probably represent behavioural strategies to avoid/survive intense temperature declines”.
On its own, the shark-movement data is “kind of limited” and does not “make a very convincing case”, Braun says. But combining it with other data “really up[s] the ante on the importance” of the research, he adds.
Climate patterns
The researchers also look at several decades’ worth of sea surface temperature and wind data to understand whether these upwelling events are changing in frequency or intensity.
They identify clear increasing trends in the proportion of winds that favour upwelling events across three sites in South Africa. (Previous research has shown a similar increase in such winds in south-eastern Australia.)
Then, for the three South African sites and three Australian sites, they compare temperature data from three locations: “inshore”, defined as between 0-15km from the shore, “midshelf”, which is 15-30km from the shore and “offshore” – located within the warm “core” of the current. The inshore and midshelf locations fall within the upwelling zone, but the offshore ones do not.
If, as they hypothesised, upwelling events were becoming more frequent, the number of cold events inshore would increase over time, while the number of such events offshore would stay the same. Similarly, an upwards trend in the intensity of cold snaps would be revealed in the inshore and midshelf, but not the offshore, data.
The chart below shows that the proportion of upwelling-favourable winds (top left) at three sites in South Africa has been steadily increasing since the “upwelling season” – the period of upwelling-favourable winds stretching from October to April – of 1988-89.
The other three charts show increasing trends in the number of cold events (top right), the average intensity of cold events (bottom left) and the average rate of onset of such cold events (bottom right) for a single site, Port Alfred, over the same period. All three characteristics increase over time for the inshore (blue) and midshelf (pink) locations, but not the offshore (green) one, supporting the idea that the cold snaps are linked to upwelling.
These increases persist over long enough time periods, the authors argue, to be clear evidence of long-term trends, rather than natural variation. Furthermore, the study points to previous research – dating back more than 30 years – that shows evidence of climate change increasing upwelling intensity due in part to increasingly strong winds driven by the land warming faster than the ocean.
This trend analysis is one of the most valuable contributions of the new study, Posdaljian says. She tells Carbon Brief:
“It’s often hard to be able to have that kind of concrete evidence about how something could be increasing in intensity or frequency over time.”
The idea that climate change could lead to an increase in cold snaps may seem counterintuitive. But those increased temperatures “mean more energy in the climate [system] too”, Daly says. He explains:
“This wind-driven upwelling, linked to climate change, is essentially an extreme event – just like we might have more flooding and stronger cyclones and hurricanes.
“If you think about equivalent on land, that might be fires being fuelled by more intense wind. It takes an existing natural phenomenon and basically supercharges that to become [more] intense.”
He adds:
“Going forward, we predict that this is going to become a more regular phenomenon and could impact a lot of different species.”
The researchers “did a really good job of creating this foundational understanding” of how such cold events could hit marine ecosystems in future, Posdaljian says.
Looking ahead, she adds that she would like to see more work focusing on projecting future trends in cold snaps and perhaps even being able to predict them. She tells Carbon Brief:
“A lot of these animals are not just dealing with one stressor from climate change…We can’t necessarily mitigate these [extreme events], but what we can do is maybe reduce the other stressors that we can control.”
The post Climate change ‘bait and switch’ threatens sharks and rays appeared first on Carbon Brief.
Climate Change
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China has said that hydrogen is a key “future industry”, important to both its energy transition and its industrial policy.
Hydrogen frequently goes through hype cycles, most recently driven by rising oil and gas prices due to the conflict in the Middle East.
Yet, even in China, the world’s largest producer and consumer of the fuel, hydrogen remains expensive and inefficient to produce.
This is especially the case for “green” hydrogen derived from renewables.
Moreover, there is limited supporting infrastructure and there is little incentive to use hydrogen over other energy sources.
As a result, uptake in China of hydrogen as an alternative fuel remains low.
Nevertheless, these challenges echo the early circumstances of another key clean-energy technology – electric vehicles (EVs).
In China, EVs benefited from a policy environment that included consistent signals of support, financial aid and the development of supporting infrastructure.
Many similar policies are now being deployed – and in some cases improved upon – to support the development of China’s hydrogen industry.
This article examines China’s approach to developing hydrogen and how its evolving industrial policy could make the fuel viable.
How is China using hydrogen and where does it come from?
Electrification and rising installations of solar and wind power have been the biggest drivers of China’s decarbonisation story so far. However, how China will address the more energy-intensive, hard-to-electrify segments of its economy remains an open question.
Hydrogen is seen by some in China as a potential solution for reducing emissions in a range of “hard-to-abate” industries, from steel and chemicals to aviation and shipping.
The country is the world’s foremost producer and consumer of hydrogen. It produced 36.5m tonnes of the gas in 2024, with maximum production capacity standing at 50m tonnes that year.
It also consumed nearly a third of the world’s hydrogen in 2024, as shown below.
Most of China’s production capacity is in regions with potential for high demand, such as Shandong, Inner Mongolia, Shaanxi, Ningxia, Shanxi and other provinces with significant heavy industry.
In 2024, the vast majority of China’s hydrogen – around 78% – was produced using fossil fuels, predominantly coal and gas, as shown in the figure below.
Another 21% was produced as an industrial by-product, while only 1% – just 320,000 tonnes – was derived from renewable-powered electrolysis of water.
One study found that, for every kilogram of hydrogen produced, 38.6kg of carbon dioxide (CO2) is emitted if the hydrogen is produced using coal-fired power. Hydrogen made through coal gasification results in 28.5kg of CO2 for every kilogram of hydrogen, while gas-based hydrogen creates 13kg of emissions.
By contrast, one kilogram of renewables-based hydrogen results in 0.5kg of CO2.
The International Energy Agency (IEA) calculates that hydrogen and hydrogen-based fuels could help China avoid close to 16bn tonnes of CO2 cumulatively by 2060 – but only if it comes from low-carbon sources.
The biggest reductions, it adds, would come from heavy industry, particularly chemicals and steel, with the maritime and shipping sectors also seeing some benefit.
Currently, around half of the hydrogen produced in China is used in synthetic ammonia and methanol production.
Ammonia is primarily used to manufacture fertiliser and is seen as a possible fuel technology for shipping. Methanol is used as a fuel for the transport industry, as well as for heating.
Another quarter of China’s current hydrogen usage is consumed by the oil refining and coal-to-chemical sectors. The remaining amount is used in other industries, including transport, heating and metallurgy.
What are the barriers to scaling up hydrogen?
Although China is the largest producer and consumer of hydrogen globally, the industry faces several barriers to becoming a viable clean-energy technology.
Agora Energiewende, a thinktank focused on the energy sector, says that, in order to make hydrogen a practical clean-energy solution, China would need to expand the scale and range of its application, as well as improving the conversion efficiency of production and use.
Both BloombergNEF and the IEA highlight the importance of China creating demand for hydrogen, such as through quotas for industrial usage.
Hydrogen “suffers from a relatively large efficiency loss during various conversion processes”, adds Agora. For example, it notes that only around 22% of the energy put into hydrogen fuel-cell electric vehicles (FCEVs) is converted into motion, compared to 73% for battery electric vehicles. Producing hydrogen with renewable energy is also less efficient than coal-to-hydrogen processes.
Cui Chuansheng, technical director at East China Engineering Science and Technology, tells state news agency Xinhua that the variability of wind and solar power often leads to low utilisation of electrolysers, resulting in “efficiency losses”.
Meanwhile, the cost of producing hydrogen – particularly green hydrogen – remains high.
One study placed the cost of hydrogen produced through alkaline water electrolysis (AWE), the most common method for producing green hydrogen in China, at $4-6 per kilogram, compared with $1.20-2.50/kg for steam methane reforming and $1.30-2 for coal gasification.
In some specific cases, such as blending hydrogen with gas, researchers find that hydrogen prices would need to fall to one-third of gas prices to incentivise uptake.
These constraints are all “interdependent”, Kevin Tu, managing director of Agora Energy China, tells Carbon Brief, with the need to ensure “bankable demand” while also reducing costs and developing infrastructure. He adds:
“Without credible offtake in the right sectors, costs will not fall; without lower costs and better logistics, downstream users will not commit.”
The IEA says that green hydrogen “could become cost-competitive by the end of this decade due to low technology costs and cost of capital”.
For now, however, the China Hydrogen Bulletin Substack reports that China’s four listed hydrogen equipment manufacturers all reported significant losses in 2025.
Meanwhile, a senior executive at a Chinese hydrogen company told economic news outlet Jiemian that he expected 40% of companies in the sector to have closed down by the end of 2026, with surviving companies only turning a profit in 2029 at the earliest.
The industry also lacks refueling and pipeline infrastructure. China’s development of a pipeline network for hydrogen remains in its early stages, with around 400km of pipelines currently in operation. By contrast, its long-distance gas network stands at 128,000km. Similarly, storage remains expensive and inefficient, creating a further obstacle to wider uptake.
How is China supporting hydrogen development?
China began considering the use of hydrogen as an energy source in earnest in the early 2000s, to address concerns around pollution and dependence on imported oil for the transport sector.
A clearer signal of its importance came in 2015, when the State Council included the technology in a 10-year national industrial strategy known as the “Made in China” initiative. This pitched hydrogen as a way to contribute to electrification of China’s road-transport system through the development of FCEVs.
Yuki Yu, founder of research firm Energy Iceberg, tells Carbon Brief that, from 2018-2021, hydrogen was treated as a “FCEV and manufacturing technology challenge”.
This has since evolved, she says, given that battery electric vehicles have emerged as the more popular technology.
Shen Xinyi, senior advisor at the Centre for Research on Energy and Clean Air (CREA), agrees, telling Carbon Brief that recent policy documents suggest the aim is now for hydrogen to be targeted at areas where direct electrification is harder, such as hydrogen-based chemicals, hydrogen metallurgy and some heavy-duty transport applications.
This is in line with the “hydrogen ladder”, an analysis of how likely different possibilities for applying hydrogen as a clean alternative are to become significant. The ladder sees significant future use of hydrogen in these hard-to-electrify areas as much more likely than for light vehicles.
Notable policy moves are being made in “three layers”, says Agora’s Tu, which are combining to improve the technology’s chances of scaling up. These are: the “legal and institutional” layer; “application-oriented” policies; and targeted measures to address “practical bottlenecks” at the local level.
One of the documents underpinning this pivot was the “medium- and long-term plan for the development of the hydrogen energy industry (2021-2035)”, issued in March 2022.
According to a report by the National Energy Administration (NEA), the plan is an attempt to develop an “industrial ecosystem” for hydrogen that features “diverse stakeholders, coordinated innovation and clustered development”.
The plan was the first government document to “lay out a long-term vision for China’s hydrogen economy”, unifying a previously disparate policy push into one document, according to the Oxford Institute for Energy Studies, a UK-based thinktank.
Following on from the 2022 plan, the importance of hydrogen as a broad clean-energy solution has been emphasised in a number of policies. These include its classification being changed from a hazardous chemical to an energy carrier in China’s Energy Law, a 2024 action plan to “accelerate” the use of low-carbon hydrogen in industry and a new pilot scheme offering subsidies for projects that achieve specific targets.
The table below sets out the timeline and content of China’s hydrogen-related policies over the past 25 years.
| Policy | Year published | Key features |
|---|---|---|
| 10th five-year plan (2001–2005) | 2001 | Calls for “actively developing” low-emission vehicles, understood to include hydrogen vehicles |
| Made in China 2025 | 2015 | Pledges to “continue to support” development of fuel cell vehicles and “master core technologies” for low-carbon vehicles |
| Notice on implementation of demonstration projects for fuel cell vehicles | 2020 | Creates a dedicated subsidy programme for finding breakthroughs in FCEV core technologies and industrial applications |
| 14th five-year plan (2021-2025) | 2021 | Hydrogen listed as a future industry |
| Medium- and long-term plan for the development of the hydrogen energy industry (2021–2035) | 2022 | Aims to reach 100,000-200,000 tonnes of green hydrogen production [this target has been met]. Also aims to get 50,000 FCEVs on the road by 2025, leading to a “diversified” hydrogen industry by 2035 |
| Opinions on accelerating the comprehensive green transformation of economic and social development | 2024 | Promotes further development of hydrogen production, transport, storage and applications |
| Implementation plan for accelerating the application of clean and low-carbon hydrogen in the industrial sector | 2025 | Outlines tasks to promote use of low-carbon hydrogen to reduce emissions in heavy industries, such as steel and chemicals |
| Energy law | 2025 | Sees hydrogen included in national legislation for the first time, re-classifies it from a hazardous chemical to an energy carrier |
| 15th five-year plan (2026-2030) | 2026 | Again lists as a future industry, and calls for the development of green fuels derived from green hydrogen |
| Notice on the implementation of pilot projects for the comprehensive application of hydrogen energy | 2026 | Provides subsidies to projects to reduce hydrogen costs to 15-25 yuan/kilogram ($2.20-3.67/kg) and help develop a fleet of 100,000 FCEVs |
Key policies in the development of China’s hydrogen sector.
In addition, the NEA said in 2025 that local governments across China had issued more than 560 hydrogen-related energy policies by the end of 2024.
Tu notes that these local policies cover everything from permitting reforms and pipeline planning to exempting FCEVs from paying road toll.
Different provinces across China adopt distinct strategies for developing hydrogen industries, based on local conditions, says the US-based Center on Global Energy Policy, such as energy mix, availability of coal and industrial needs.
However, these local policies and targets are frequently more ambitious than the “conservative” national-level targets, it adds.
Could a new pilot programme boost hydrogen’s prospects?
A new pilot programme, announced in March 2026, aims to commercialise the country’s hydrogen industry by funding projects to reduce the cost of the fuel to 15-25 yuan/kilogram ($2.20-3.67/kg) by 2030, as well as other targets.
Unlike the 2020 subsidies, which focused on FCEVs, the new programme reaffirms China’s interest in a broader series of sectoral applications for hydrogen, including in clean heating, production of low-carbon iron and steel, and production of “green fuels” and other chemicals.
This new pilot is the “strongest financial instrument ever released for China’s green hydrogen application” in terms of creating a comprehensive hydrogen policy that covers a broad swathe of the economy, supporting it with financial backing and targeting application scenarios, Yu says.
However, she argues that strict grant caps – 240m yuan ($35m) per project and 1.6bn yuan ($235m) per selected region across only five regions – limited the overall funding scale available to the industry.
Energy Iceberg has calculated that only around 60-70 projects nationally could receive funding under the current rules, out of more than 670 active green hydrogen proposals in China.
Shen agrees that the pilot programme is significant and that it will expand the use of hydrogen in China’s climate strategy, particularly green hydrogen.
She notes a provision that “explicitly states that coal-based ammonia and methanol projects cannot be labelled as ‘green’ ammonia or methanol”, suggesting that policymakers are increasingly paying attention to the “integrity” of definitions for hydrogen and hydrogen-derived fuel.
The “real value” of the pilot scheme, says Tu, is that it focuses on developing “integrated city-cluster ecosystems linking supply, transport, infrastructure and end-use demand”, rather than only supporting individual projects.
This “should help identify viable business models, accelerate cost discovery and concentrate support on applications with stronger scale potential”, as well as boost investor confidence, adds Tu.
However, he continues that the broader effect it will have on boosting production of hydrogen will “depend on how quickly the selected clusters can translate the programme into real offtake and lower delivered hydrogen prices”.
How does this compare to China’s EV policy push?
The debate around the viability of hydrogen is reminiscent of critiques of EVs.
Until recently, EVs were seen as too expensive for consumers, inefficient and challenging to use without supporting infrastructure. As a result, many western automakers chose to temper their focus on EVs, while continuing to develop internal combustion engines.
However, China has managed to develop a competitive EV industry with products that top global sales.
Part of the playbook that spurred China’s success on EVs included consistent policy signalling in favour of the technology, including mentions in high-level documents and committing resources to building charging infrastructure.
“The defining features of China’s industrial-policy success are its persistence and adaptability,” says Kyle Chan, fellow at the Brookings Institution, adding that “long before the technology and economics of EVs and batteries were proven, China was making long-term investments and policy bets [in the sectors]”.
More tangible measures included direct and indirect subsidies and policy support in the shape of favourable loan rates and low-cost land. One estimate by US-based thinktank the Center for Strategic and International Studies (CSIS) pegs the amount of support allocated to the EV industry between 2009-2023 at $230.9bn.
This coupled with the success of private Chinese manufacturers in creating innovative, nimble companies that “forc[ed] policymakers to adapt”, as well as growing links between the automotive and information technology industries, according to a separate CSIS report.
But this progress on EVs also reportedly came with significant fraud. In 2016, one investigation found that 33 companies were involved in subsidy fraud totalling 9.2bn yuan ($1.3bn).
(It should also be noted that profitability in the industry lags far behind the average for downstream industrial sectors, according to the Hong Kong-based South China Morning Post, which says that “only a handful” of nearly 50 EV makers have reported profits.)
Being the subject of an industrial policy push alone does not guarantee success, states CSIS. It says the strength of the EV industry “was neither inevitable nor the result of a single master plan” and that China’s aims to develop globally-competitive industries in areas such as commercial aviation remain unaccomplished.
China’s approach to hydrogen has been markedly different.
Instead of offering blanket subsidies, the fuel cell demonstration programme it established in 2020 focused on performance-based rewards.
To avoid the subsidy issues seen in the solar and EV industries, the ministry of finance deliberately chose this indirect funding model, says Yu.
However, Yu argues, the programme did not work as well as hoped, due to the funding ceiling and the siloed attempts made by different regional governments to develop hydrogen ecosystems .
But Chinese policy thinking is becoming more selective and pragmatic for hydrogen compared with EVs, says Shen. She says:
“Electrification remains the primary decarbonisation pathway [for road transport], while hydrogen is increasingly positioned for applications where direct electrification is more difficult.”
Tu echoes this, adding that China is “clearly moving toward a more supportive policy environment for hydrogen”.
But its approach is “unlikely to replicate the EV story one-for-one”, he adds.
China’s concerted hydrogen push is also unlikely to echo the EV story at a global level, according to the IEA.
In terms of green hydrogen, around 60% of global electrolyser manufacturing capacity is currently in China, prompting concerns from the EU about a repeat of China’s global dominance in the solar and EV sectors.
However, the IEA says, electrolysers made in China “might not supply other markets at scale in the short term”, due to difficulties transporting the bulky technology globally, expectations that costs will only fall gradually, uncertainty around global demand and questions over how well Chinese electrolysers perform against global alternatives.
China’s industrial focus on hydrogen is centred more on domestic use, Shen argues. “It is less about near-term export competitiveness and more about building domestic industrial ecosystems,” she says.
The post Q&A: Can China turn hydrogen into its next clean-energy industry? appeared first on Carbon Brief.
Q&A: Can China turn hydrogen into its next clean-energy industry?
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