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China Briefing handpicks and explains the most important climate and energy stories from China over the past fortnight.
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Key developments
China’s role at COP29 and beyond
‘COOPERATIVE’ COP: China’s “role” at the COP29 climate talks, which concluded over the weekend in Baku, Azerbaijan, was “markedly different to previous years”, with its negotiators being “unusually cooperative”, according to an anonymous “chief negotiator” for a “powerful” country quoted by BBC News. Bloomberg cited sources “close to the Chinese delegation” explaining that “Chinese officials moved to soothe angry delegations from India, Saudi Arabia, Africa and the small island group” during the tense final plenary. It added that China’s delegation head Zhao Yingmin, who is also the vice minister of the Ministry of Ecology and Environment (MEE), held “one-on-one conversations with delegates in the final hours to warn things would be worse without COP29’s finance agreement”. COP29 president Mukhtar Babayev wrote in the Guardian that China “coordinat[ed] their response to the negotiations…with the G77 group”. Babayev also claimed that “the Chinese were willing to offer more [climate finance] if others did so too”. (For more on China’s role at COP29, see the Spotlight.)
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GLOBAL CALLS: As concerns over the US’s future role loomed over the two-week summit, UN climate chief Simon Stiell said the world “will need China’s continued leadership” to meet climate goals, Politico reported. This was echoed by South Africa’s environment minister, who said China “has an opportunity to lead the global fight against climate change”, according to Bloomberg. BBC News quoted Jonathan Pershing, program director of environment at the William and Flora Hewlett Foundation, saying that, should China become the de-facto leader at future COPs, it “won’t lead from the front, like the US and Europe”, but instead would “discreetly interven[e] to unblock disputes…behind closed doors”.
CHINA’S REACTION: In response to Stiell, Politico quoted Zhao saying: “China has contributed in addressing climate change. But, in the future, China will do our best to contribute more.” Zhao also said in an interview with business news outlet 21st Century Herald that China will be “the backbone of the global response to climate change”. Nevertheless, Chinese climate envoy Liu Zhenmin told Beijing News that “people expect China and the EU to work together to fill this gap [of US leadership], which is a very good wish, but, in practice, it is very difficult”. (Read more in the Spotlight below.) China’s foreign ministry noted that agreements at COP29 demonstrated global “willingness” to address climate change, although it added that developed countries should “effectively fulfil their obligations and responsibilities”, Shanghai-based news outlet the Paper said. A commentary in the party-affiliated People’s Daily under the nom de plume “Heyin”, which is used for articles expressing the view of party leadership on international affairs, said COP29 “consolidated the momentum” of the global energy transition, adding that “no matter how the [geopolitical] climate changes, China’s determination…to actively address climate change will remain unchanged”. Elsewhere, an editorial in the state-run newspaper China Daily argued COP29 was an “unusual climate diplomacy success” as it broke “the long-standing multilateral negotiations stalemate over climate financing”.
New China research
EARLY PEAK: Meanwhile, on the sidelines of COP29, an assessment by research institute the Centre for Research on Energy and Clean Air (CREA) of China’s energy transition in 2024 found that the clean energy industry “continued to exceed forecasts”, but that spiking energy consumption meant record additions served only to “stabilise emissions, not to push them down”. It added that 52% of experts surveyed by CREA expected China’s coal consumption to peak by 2025 and 44% believe China’s carbon emissions have already peaked or will peak by 2025.
POLLUTING PROVINCES: Al Gore-backed research institute Climate Trace released a report finding that Shanghai was the world’s “most polluting” city, Fortune said. It added that “seven states or provinces spew more than 1bn metric tonnes of greenhouse gases [per year]”, six of which are in China – the exception being Texas.
POWER SYSTEM REFORM: The International Energy Agency also presented a report at COP29 examining the “evolving flexibility requirements of China’s power system” during its energy transition, finding that “non-fossil resources, such as hydropower, battery storage and demand response, could fulfil nearly 60% of [China’s] short-term flexibility needs by 2030”, according to a press statement.
‘INSUFFICIENT’ SPEED: The 2024 Global Carbon Neutrality Progress Report, released by Beijing’s Tsinghua University, evaluated progress in 151 countries that have set carbon neutrality targets. The report said that developing countries have higher “ambitions” and willingness to reduce emissions than developed countries. However, it added that the “current speed of renewable energy development globally is insufficient” to meet the target of tripling renewable energy capacity by 2030 – a goal set at COP28 in an effort to limit global warming to 1.5C.
Xi at APEC and G20
SUNNIER CLIMES: As his subordinates hashed out details in Baku, President Xi Jinping’s attendance of the APEC economic leaders’ meeting in Peru and G20 summit in Brazil “fuelled expectations that China will continue championing…better global governance”, China Daily said, adding that during APEC Xi “emphasised the importance of innovation, openness, green development and inclusive growth”. Xi also inaugurated Peru’s Chancay port – built by a Chinese company – as Beijing “look[s] to further tap into resource-rich Latin America”, Reuters reported. At the G20 summit, Xi noted the importance of supporting developing countries in “responding to…climate change, biodiversity loss and environmental pollution”, state news agency Xinhua said. China also signed 37 agreements with Brazil, according to the Associated Press, which included specific agreements on mining, solar and nuclear power.
UK-CHINA TIES: In the first high-level meeting between the UK and China since 2018, UK prime minister Keir Starmer told Xi that the UK “would like to engage with Beijing on areas such as trade, the economy and climate”, Reuters reported. Starmer told the UK House of Commons that the two countries need to “work together on challenges such as climate change and delivering growth”, adding that he and Xi “agreed a new dialogue on these issues, which [UK chancellor Rachel Reeves] will take forward with vice premier He [Lifeng] in Beijing” next year, according to a transcript of his remarks.
‘Disorderly expansion’ of solar factories targeted
RAISING REQUIREMENTS: China’s Ministry of Industry and Information Technology (MIIT) raised minimum capital requirements for construction and expansion of solar-manufacturing projects, the Hong Kong-based South China Morning Post said, adding that MIIT also urged manufacturers to limit projects that are “merely meant to increase capacity”. Lin Boqiang, director of Xiamen University’s China Energy Policy Research Institute, told business news outlet Yicai the move will “control the disorderly expansion of production capacity”.
LOWERING REBATES: China’s finance and tax bodies also “announced a reduction in the export tax rebate” for solar products, “squeezing profit margins” and possibly leading to companies “increasing export prices”, PV Magazine reported, in what may be “part of a longer-term strategy”. Finance news outlet Wall Street CN noted that rebates for batteries will also shrink, but that manufacturers will still have a “price advantage in overseas markets”.
EXPERT VIEWS: Liu Shijin, former vice-president of the Development Research Centre (DRC) and chief advisor at the China Council for International Cooperation on Environment and Development (CCICED), said in a speech covered by Yicai that “overcapacity” is a “normal process of market competition”, adding that the government should avoid “disturbing” industries through “administrative intervention and unfair competition”, and instead encourage market expansion by “accelerating the shift from dual-control of energy consumption to dual-control of carbon emissions”.
Spotlight
COP29: How China approached the UN climate talks in Baku
As ever at COPs, a key question was how the world’s current largest annual emitter, China, would approach the talks. This year, with Donald Trump being reelected as the US president, more expectations fell on China to step up and do more.
In this article, Carbon Brief summaries some of the key points China made at COP29. This is a summary of “China at COP29” in Carbon Brief’s in-depth summary of the event’s key outcomes.
China arrived at the COP29 UN climate talks in Baku with the fifth-largest delegation, continuing its recent trend of major showings at the annual summit.
At the high-level opening of the talks, China’s vice premier Ding Xuexiang – who is president Xi Jinping’s “special representative” at COP – declared that his country had “provided and mobilised project funds of more than 177bn yuan ($24.5bn) for developing countries’ climate response” since 2016.
This was the first time China used the language of climate finance to talk about its overseas aid. It quickly drew attention to Beijing’s intentions and levels of ambition for climate finance.
Kate Logan, director of the China climate hub at the Asia Society Policy Institute (ASPI), wrote on Twitter that this placed China “on the same order – if not higher than – many developed countries’ efforts” on climate finance.
Dialogue Earth reported that Beijing has contributed more than $30bn to global climate finance since the launch of its “Belt and Road Initiative”, putting China “on a par with the UK, to become the joint fifth-largest provider of climate finance after Japan, Germany, the US and France”.
However, entering week two, China’s stance on climate finance remained firm – it said it would not agree to make any compulsory contributions, including to the new climate finance goal (NCQG) that was being negotiated at the summit.
China’s new climate envoy Liu Zhenmin, replacing Xie Zhenhua, told the Paper, a Shanghai-based outlet, that paying for the NCQG was “their business”, referring to developed countries.
During the closing stages of COP29, Xia Yingxian, director of the department of climate change of the Ministry of Environment and Ecology, said that a serious climate finance offer from developed countries was the “master switch and golden key” to a deal in Baku.
Liu was also quoted by state-run newspaper China Daily, saying China is “not obliged to contribute to the post-2025 climate financing target that is expected to be announced during COP29”.
At the closing plenary, Carbon Brief heard Zhao Yingmin, head of Chinese delegation and the vice minister of the Ministry of Ecology and Environment (MEE), saying that developed countries’ NCQG commitments were still “fall far short of meeting the needs of developing nations” and that developed countries’ “financial obligations must be further clarified”.
Nevertheless, China said it remained open to multilateral cooperation on climate change.
Chen Zhihua, deputy director of China’s National Centre for Climate Strategy and International Cooperation, told Carbon Brief that Donald Trump being reelected as the US president “certainly is a big thing that people talk about and [we] have concerns about how things will turn out”.
He added: “It will have big impacts, but China won’t change its strategy – we will cooperate with whoever for global cooperation on climate change.”
Wen Hua, deputy director-general of the Department of Resources Conservation and Environmental Protection at China’s top planner the National Development and Reform Commission (NDRC), said at another event attended by Carbon Brief: “China is willing to take a more active role in global climate governance.”
Throughout COP29, China strongly identified itself as a developing country. China, together with the G77 group of developing counties, rejected an initial draft for the NCQG framework. According to BBC News, they wanted “public grants of $500bn per year”.
At the South-South Cooperation on Climate Change forum hosted by China, Carbon Brief heard Huang Runqiu, minister of the MEE, saying that the world needs multilateral cooperation on combating climate change, but that “green trade barriers” prevent better cooperation, especially for developing countries.
Wang Can, director of the department of environmental planning and management at Beijing’s Tsinghua University, explained to Carbon Brief that the “green trade barriers” are “bans and tariffs…mainly from the US” on renewable technology products.
Both Chinese academics and multiple senior officials expressed their desire for international cooperation on energy transition at COP29.
For example, Wen called the energy transition “fundamental” for China at an event hosted by the country’s COP29 pavilion.
China also stated some of its specific targets and actions for addressing climate change, such as the latest emissions standards for coalbed methane introduced by Liu at a methane summit held during COP29.
Regarding China’s next NDC, an anonymous scholar told Carbon Brief that shifts in the new pledge could lie in “adjusting the timeline of [the] ‘dual-carbon’ goal”, which currently targets a peak in emissions “before 2030” and carbon neutrality “by 2060”. (For more views, see Carbon Brief’s “Experts: What to expect in China’s climate pledge for 2035.”)
China has already adjusted its “dual-carbon” goal from “achieving carbon peak by 2030” to “before 2030”. Bai Quan, director of the Energy Research Institute of the Academy of Macroeconomic Research (AMR), a government-affiliated “national high-end thinktank”, told Carbon Brief that while “we would love to try our best…we can’t rule out all possibilities to peak even earlier than planned”.
(Read Carbon Brief’s full-length interview with Bai and his colleague Lyu Wenbin.)
Captured
China’s historical carbon dioxide (CO2) emissions within its borders are now higher than the 27 member states of the EU combined, new Carbon Brief analysis found, although it is “still far behind” and “unlikely to ever overtake” the US total. The analysis – which was covered by the New York Times under the headline: “China’s soaring emissions are upending climate politics” – noted that when viewed on a per-capita basis, using 2024 figures, China’s contribution is “just 227tCO2 per capita, less than a third of the 682tCO2 for people in the EU27”.
Watch, read, listen
PROGRESS UPDATE: China Water Risk published an analysis of China’s progress towards its carbon targets and its “potential” to accelerate its shift away from coal.
MINERAL TRANSITION: The China-Global South Podcast, aired by the Sinic Podcast Network, discussed “Indonesia’s uncomfortable position squeezed between China and the US in the race to dominate transition mineral supply chains”.
KEYNOTE: The South China Morning Post interviewed Ma Jun, founder of the Beijing-based Institute of Public and Environmental Affairs (IPE), on prospects for future US-China climate diplomacy and China’s path to carbon neutrality.
MEXICAN STANDOFF: The electric vehicle-focused newsletter Dunne Insights assessed why Chinese car exports to Mexico have spiked in recent months, and how it might be “pressured” by the US and Canada to respond.
88
The number of extreme weather events in China that had their “severity or likelihood” increased by climate change, out of a total of 114 attribution studies covering the country, according to Carbon Brief analysis. The figures come from Carbon Brief’s updated “attribution map”, which covers every attribution study published since the method was developed in 2004. The map includes more than 600 studies, with China making up 16%. More than 70% of the China-focused studies were published in the past four years, significantly higher than average.
New science
npj Climate and Atmospheric Science
The number of heat-related diabetes deaths in Chinese cities is expected to increase by the end of the century as a result of global warming, a new study warned. The authors predicted deaths due to extreme heat over 2010-2100 in 32 “major” Chinese cities. They projected that under the low warming SSP1-2.6 scenario, the heat-attributable fraction of diabetes deaths will rise from 2.3% in the 2010s to 4.6% in the 2090s. Under the high warming SSP5-8.5 scenario, the fraction could rise to 19.2% in the 2090s, they added.
Communications Earth & Environment
Electric vehicles in China have nearly a 12% reduction in CO2 as compared to internal combustion engines, according to new research. Researchers carried out a life-cycle analysis of internal combustion engines, plug-in hybrid vehicles and battery EVs in each of China’s provinces. They found that while battery EVs reduced CO2 and nitrogen oxide emissions, they had higher emissions of sulphur dioxide and particulate matter. The authors wrote that “improving technological progress and optimising electricity mix will greatly assist in achieving emissions reduction”.
China Briefing is compiled by Wanyuan Song and Anika Patel. It is edited by Wanyuan Song and Dr Simon Evans. Please send tips and feedback to china@carbonbrief.org
The post China Briefing 28 November 2024: How China approached COP29; Xi cuts energy deals in South America; Solar’s ‘disorderly’ expansion appeared first on Carbon Brief.
The past three years have been exceptionally warm globally.
In 2023, global temperatures reached a new high, after they significantly exceeded expectations.
This record was surpassed in 2024 – the first year where average global temperatures were 1.5C above pre-industrial levels.
Now, 2025 is on track to be the second- or third-warmest year on record.
What has caused this apparent acceleration in warming has been subject to a lot of attention in both the media and the scientific community.
Dozens of papers have been published investigating the different factors that could have contributed to these record temperatures.
In 2024, the World Meteorological Organization (WMO) discussed potential drivers for the warmth in a special section of its “state of the global climate” report, while the American Geophysical Union ran a session on the topic at its annual meeting.
In this article, Carbon Brief explores four different factors that have been proposed for the exceptional warmth seen in recent years. These are:
- A strong El Niño event that developed in the latter part of 2023.
- Rapid declines in sulphur dioxide emissions – particularly from international shipping and China.
- An unusual volcanic eruption in Tonga in 2022.
- A stronger-than-expected solar cycle.
Carbon Brief’s analysis finds that a combination of these factors explains most of the unusual warmth observed in 2024 and half of the difference between observed and expected warming in 2023.
However, natural fluctuations in the Earth’s climate may have also played a role in the exceptional temperatures, alongside signs of declining cloud cover that may have implications for the sensitivity of the climate to human-caused emissions.
An unusually warm three years
Between 1970 and 2014, average surface temperatures rose at a fairly steady rate of around 0.18C per decade.
Set against this long-term trend, temperature increases during the period from 2015 to 2022 were on the upper end of what would be expected.
The increases seen in 2023, 2024 and 2025 were well outside of that range.
The high temperatures of the past three years reflect a broader acceleration in the rate of warming over the past decade.
However, the past three years were unusually warm, even when compared to other years in the 2010s and 2020s.
Record-breaking warmth in 2023 meant that it beat the prior warmest year of 2016 by 0.17C – the largest magnitude of a new record in the past 140 years.
The year 2024 then swiftly broke 2023’s record, becoming the first year where average global temperatures exceeded 1.5C above pre-industrial levels.
The 10 months of data available for 2025 indicates that the year is likely to be slightly cooler than 2023 – though it is possible it may tie or be slightly warmer.
The figure below shows global surface temperatures between 1970 and 2025. (The figures for 2025 include uncertainty based on the remaining three months of the year.)
It includes a smoothed average based on temperature data for 1970-2022 that takes into account some acceleration of warming – and then extrapolates that smoothed average forward to 2023-25 to determine what the expected temperature for those years would have been. (This follows the approach used in the WMO’s “state of the global climate 2024” report.)
This approach calculates how much warmer the past three years were than would be expected given the long-term trend in temperatures.
It shows that 2023 was around 0.18C warmer than expected, 2024 was a massive 0.25C warmer and 2025 is likely to be 0.11C warmer.
Researchers have identified a number of potential drivers of unexpected warmth over 2023-25. Here, Carbon Brief looks at the evidence for each one.
A weirdly behaving El Niño event
El Niño is a climate pattern of unusually warm sea surface temperatures (SSTs) in the tropical Pacific that naturally occurs every two to seven years. Strong El Niño years generally have warmer global temperatures, with the largest effect generally occurring in the months after El Niño conditions peak (when SSTs reach their highest levels in the tropical Pacific).
A relatively strong El Niño event developed in the latter half of 2023, peaking around November before fading in the spring of 2024.
This event was the fourth-strongest El Niño ever recorded, as measured according to SSTs in the Niño 3.4 region in the central tropical Pacific. However, it was notably weaker than the El Niño events in both 1998 and 2016.
This can be seen in the chart below, which shows the strength of El Niño events (red shading) since the 1980s. (The blue shading indicates La Niña events – the opposite part of the cycle to El Niño, which results in cooler SSTs in the tropical Pacific.)
(It is worth noting that measuring the strength of El Niño events is not entirely straightforward. Other tools used by scientists to monitor changes to El Niño – such as the US National Oceanic and Atmospheric Administration’s (NOAA’s) multivariate ENSO index – show the 2023-24 event was much weaker than indicated in the Niño 3.4 dataset.)
Global surface air temperatures tend to be elevated by around 0.1-0.2C in the six months after the peak of a strong El Niño event – defined here as when SSTs in the Niño 3.4 region reach 1.5C above normal.
The figure below shows the range of global temperature change for the 12 months before and 22 months after the peak of all 10 strong El Niño events since 1950. The light line represents the average of past strong El Niño events, the dark blue line the temperature change observed during the 2023-24 event and the shaded blue area the 5-95th percentile range.
The figure shows the 2023-24 El Niño was quite unusual compared to other strong El Niño events since 1970. Global temperatures rose to around 0.4C above expected levels – which is on the high side of previous El Niños.
The heat also came early, with high temperatures showing up around four months before the El Niño event peaked. This early heat is unlike any other El Niño event in modern history and is one of the reasons why 2023’s global temperatures were so unexpectedly warm.
Global temperatures remained elevated for a full 18 months after the El Niño peaked, well after conditions in the tropical Pacific shifted into neutral conditions – and even after mild La Niña conditions developed at the end of 2024 and into early 2025.
This figure does not explain how much of this unusual heat was actually caused by El Niño, compared to other factors, but it does suggest that El Niño behaviour alone does not fully explain unusually high temperatures in recent years.
Based on the historical relationship between El Niño and global temperatures, Carbon Brief estimates that El Niño contributed a modest 0.013C to 2023 temperatures and a more substantial 0.128C to 2024 temperatures, albeit with large uncertainties. (See “methodology” section at the end for details.)
However, it is possible that this 2023 estimate is too low. There are some suggestions in the literature that 2023-24 El Niño’s early warmth may have been caused by the rapid transition out of a particularly extended La Niña event. There are indications that temperatures have spiked in similar situations further back in the historical temperature record.
Falling sulphur dioxide emissions
Sulphur dioxide (SO2) is an aerosol that is emitted into the lower atmosphere by the burning of coal and oil. It has a powerful climate cooling effect – Carbon Brief analysis shows that global emissions of SO2 have masked about one-third of historical warming.
Global SO2 emissions have declined around 40% over the past 18 years, as countries have increasingly prioritised reducing air pollution, including through the installation of scrubbers at coal plants.
These declines have been particularly concentrated in China, which has seen a 70% decline in SO2 emissions since 2007. In addition, a rule introduced for international shipping in 2020 by the International Maritime Organization (IMO) has resulted in an 80% decline in the sulphur content of shipping fuel used around the world.
The decline of SO2 emissions is shown in the figure below.
Shipping in particular has been suggested as a potential culprit for recent temperatures, given that ships emit SO2 over oceans where the air tends to be cleaner and so emissions have a bigger effect.
Seven of the eight studies that have explored the temperature impact of the IMO regulations have suggested a relatively modest effect, in the range of 0.03-0.08C. However, one study – led by former NASA scientist Dr James Hansen – calculated a much stronger effect of 0.2C that would explain virtually all the unusual warmth of recent years.
The figure below shows Carbon Brief’s estimate of the global average surface temperature changes caused by the low-sulphur shipping fuel rules, using the estimates produced by all eight studies. The central estimate (dark blue line) is relatively low, at around 0.05C, but the uncertainty range (light blue shading) across the studies remains large.
Overall, Carbon Brief’s analysis finds that around 0.04C of warming over 2020-23 and 0.05C of warming over 2020-24 can be attributed to SO2 declines from shipping and other sources.
However, this approach might slightly overstate the effects of SO2 on the exceptional temperatures of the past three years, as shipping and other SO2 declines would have had some effect on 2021 and 2022 as well.
It is also worth noting that the total effects of SO2 declines on global temperatures have been considerably larger and are estimated to be responsible for around one-quarter of all warming since 2007.
However, these SO2 decreases occurred over a long period of time and do not clearly explain the recent spike in temperatures.
An unusual volcanic eruption in Tonga
In early 2022, the Hunga Tonga-Hunga Ha’apai underwater volcano erupted spectacularly, sending a plume 55km into the atmosphere. This was by far the most explosive volcanic eruption since Mount Pinatubo erupted in 1991.
This was a highly unusual volcanic eruption, which vaporised vast amounts of sea water and lofted it high into the atmosphere. Overall, around 146m metric tonnes of water vapour ended up in the stratosphere, which is the layer of the atmosphere above the troposphere.
Water vapour is a powerful greenhouse gas. While it is short-lived in the lower atmosphere, it can stick around for years in the stratosphere, where it has a significant warming effect on the climate.
The figure below shows the concentration of water vapour in the stratosphere between 2005 and mid-2025. It shows how the 2022 eruption increased atmospheric concentrations of the greenhouse gas by around 15%. More than half the added water vapour has subsequently fallen out of the upper atmosphere.
Most early studies of the Hunga Tonga-Hunga Ha’apai volcano focused specifically on the effects of stratospheric water vapour. These tended to show strong warming in the lower stratosphere and cooling in the middle-to-upper stratosphere, but only a slight warming effect on global surface temperatures of around 0.05C.
Hunga Tonga-Hunga Ha’apai had much lower sulphur emissions than prior explosive eruptions, such as Pinatubo and El Chichon. However it put 0.5–1.5m tonnes of sulphur into the stratosphere – the most from an eruption since Pinatubo.
Studies that included both sulphur and water vapour effects tend to find that the net effect of the eruption on surface temperatures was slight global cooling, concentrated in the southern hemisphere.
By using the estimates published in a 2024 study published in Geophysical Research Letters, which used the FaIR climate emulator model, Carbon Brief estimates that the Hunga Tonga-Hunga Ha’apai eruption cooled global surface temperatures by -0.01C in 2023 and -0.02C in 2024.
This suggests that the eruption was likely only a minor contributor to recent global surface temperatures.
A stronger-than-expected solar cycle
The source of almost all energy on Earth is the sun. Over hundreds of millions of years, variations in solar output have a big impact on the global climate.
Thankfully, over shorter periods of time the sun is remarkably stable, helping keep the Earth’s climate habitable for life. (Big changes – such as ice ages – have more to do with variations in the Earth’s orbit than changes in solar output.)
However, slight changes in solar output do occur – and when they do, they can influence climate change over shorter periods of time. The most important of these is the roughly 11-year solar cycle, which is linked with the sun’s magnetic field and results in changes in the number of sunspots and amount of solar energy reaching Earth.
The figure below shows a best-estimate of changes in total solar irradiance since 1980, based on satellite observations. Total solar irradiance is a measure of the overall amount of solar energy that reaches the top of the Earth’s atmosphere and is measured in watts per metre squared.
The 11-year solar cycle is relatively modest compared to the sun’s total output, varying only a few watts per metre squared between peak and trough – amounting to around 0.01% of solar output. However, these changes can result in variations of up to 0.1C in global temperatures within a decade.
The most recent solar cycle – solar cycle 25 – began around 2020 and has been the strongest solar cycle measured since 1980. It was stronger than most models had anticipated and likely contributed to around 0.04C global warming in 2023 and 0.07C in 2024.
Putting together the drivers
By combining earlier estimates of different factors contributing to 2023 and 2024 global surface temperatures, about half of 2023’s unusual warmth and almost all of 2024’s unusual warmth can be effectively explained.
This is illustrated in the figure below, which shows the five different factors discussed earlier – El Niño, shipping SO2, Chinese SO2, the Hunga Tonga-Hunga Ha’apai volcano and solar cycle changes – along with their respective uncertainties.
The sum of all the factors is shown in the “combined” bar, while the actual warming compared to expectations is shown in red.
The upper chart shows 2023, while the lower one shows 2024.
It is important to note that the first bar includes both El Niño and natural year-to-year variability; the height of the bar reflects the best estimate of El Niño’s effects, while the uncertainty range encompasses year-to-year variability in global temperatures that may be – at least in part – unrelated to El Niño.
The role of natural climate variability
Large natural variability to the Earth’s climate is one of the main reasons why the combined value of the different drivers of expected warmth in 2023 has an uncertainty range that exceeds the observed warming – even though the best-estimate of combined factors only explains half of temperatures.
Or, to put it another way, there is up 0.15C difference in global temperatures year-on-year that cannot be explained solely by El Niño, human-driven global warming, or natural “forcings” – such as volcanoes or variations in solar output.
The figure below shows the difference between actual and expected warming in the global temperature record for every year in the form of a histogram. The vertical zero line represents the expectation given long-term global warming and the other vertical lines indicate the warming seen in 2023, 2024 and 2025.
The height of each blue bar represents the number of years over 1850-2024 when the average global temperature was that far (above or below) the expected level of warming.
Based on the range of year-to-year variability, temperatures would be expected to spike as far above the long-term trend as they did in 2023 once every 25 years, on average. The year 2024 would be a one-in-88 year event, whereas 2025 would be a less-unusual, one-in-seven year event.
These likelihoods for the past three years are sensitive to the approach used to determine what the longer-term warming level should be.
In this analysis, Carbon Brief used a local smoothing approach (known as locally estimated scatterplot smoothing) to determine the expected temperatures, following the approach used in the WMO “state of the climate 2024” report.
This approach results in a warming of 1.28C in 2023 and 1.30C in 2024, against which observed temperatures are compared.
Other published estimates put the longer-term warming in 2024 notably higher.
Earlier this year, the scientists behind the “Indicators of Global Climate Change” (IGCC) report estimated that human activity caused 1.36C of recent warming in 2024. They also found a slightly lower overall warming level for 2024 – 1.52C, as opposed to the WMO’s 1.55C – because they looked exclusively at datasets used by IPCC AR6. (This meant estimates from the Copernicus/ECMWF’s ERA5 dataset were not included.)
Based on climate simulations, the IGCC report finds the likelihood of 2024’s warmth to be a one-in-six year event and 2023’s a one-in-four event.
Using the same assumptions as the IGCC, Carbon Brief’s approach calculates that 2024 would be a less-common, one-in-18 year event.
However, the IGCC estimate of current human-induced warming is based on the latest estimates of human and natural factors warming the climate. That means that it already accounts for additional warming from low-sulphur shipping fuel, East Asian aerosols and other factors discussed above.
Therefore, the results from these two analyses are not necessarily inconsistent: natural climate variability (including El Niño) played a key role – but this came in addition to other factors. Natural fluctuations in the Earth’s climate alone would have been unlikely to result in the extreme global temperatures seen in 2023, 2024 and 2025.
A cloudy picture
Even if unusual recent global warmth can be mostly attributed to a combination of El Niño, falling SO2 emissions, the Hunga Tonga-Hunga Ha’apai volcano, solar cycle changes and natural climate variability, there are a number of questions that remain unanswered.
Most important is what the record warmth means for the climate going forward. Is it likely to revert to the long-term average warming level, or does it reflect an acceleration in the underlying rate of warming – and, if so, what might its causes be?
As explained by Carbon Brief in a 2023 article, climate models have suggested that warming will speed up. Some of this acceleration is built into the analysis presented here, which includes a slightly faster rate of warming in recent years than has characterised the period since 1970.
But there are broader questions about what – beyond declining SO2 and other aerosols – is driving this acceleration.
Research recently published in the journal Science offered some potential clues. It found a significant decline in planetary reflectivity – known as albedo – over the past decade, associated with a reduced low-level cloud cover that is unprecedented in the satellite record.
The authors suggest it could be due to a combination of three different factors: natural climate variability, changing SO2 and other aerosol emissions and the effects of global warming on cloud reflectivity.
Natural climate variability seems unlikely to have played a major role in reduced cloud cover, given that it was relatively stable until 2015. However, it is hard to fully rule it out given the relatively short satellite record.
Reductions in SO2 emissions are expected to reduce cloud reflectivity, but the magnitude of the observed cloud reflectivity changes are much larger than models simulate.
Models might be underestimating the impact of aerosols on the climate. But, if this were the case, it would indicate that climate sensitivity might be on the higher end of the range of model estimates, because models that simulate stronger aerosol cooling effects tend to have higher climate sensitivity.
Finally, cloud cover might be changing and becoming less reflective as a result of warming. Cloud responses to climate change are one of the largest drivers of uncertainty in future warming. One of the main reasons that some climate models find a higher climate sensitivity is due to their simulation of less-reflective clouds in a warming world.
The Science study concludes that the 2023 heat “may be here to stay” if the cloud-related albedo decline was not “solely” caused by natural variability. This would also suggest the Earth’s climate sensitivity may be closer to the upper range of current estimates, it notes.
Methodology
Carbon Brief built on work previously published in the IGCC 2024 and WMO state of the global climate 2024 reports that explores the role of different factors in the extreme temperatures in 2023, 2024 and 2025.
The impact of El Niño Southern Oscillation (ENSO) on the temperatures was estimated using a linear regression of the annual mean global temperature anomaly on the Feb/Mar Niño 3.4 index. This resulted in an impact of −0.07C, 0.01C and 0.13C for 2022, 2023 and 2024 respectively (with a 95% confidence interval of ±0.13 ºC).
It is important to note that the uncertainties in the ENSO response estimated here also incorporate other sources of unforced internal (modes of variability in other basins such as AMV), and potentially some forced variability. The bar in the combined figure is labelled “El Niño and variability” to reflect this.
For details on calculations of the temperature impact of shipping and Chinese SO2 declines, see Carbon Brief’s explainer on the climate impact of changing aerosol emissions.
Solar cycle 25 was both slightly earlier and slightly stronger than prior expectations with a total solar irradiance anomaly of 0.97 watts per metre squared in 2023 relative to the mean of the prior 20 years. This resulted in an estimated radiative forcing of approximately 0.17 watts per metre squared and an estimated global surface temperature increase of 0.07C (0.05C to 0.10C) with a one- to two-year lag based on a 2015 study. Thus, the impact on 2023 and 2024 is around 0.04C and 0.07C, respectively (+/- 0.025C). This is a bit higher warming than is given by the FaIR model, as the 2015 study is based on global models that have ozone responses to the UV changes, which amplifies the temperature effects a bit.
The Hunga Tonga-Hunga Haʻapai volcanic eruption added both SO2 and water vapour to the stratosphere (up to 55km in altitude). The rapid oxidation of SO2 to sulphate aerosol dominated the radiative forcing for the first two years after the eruption. As a result, the net radiative forcing at the tropopause was likely negative; −0.04 watts per metre squared and −0.15 watts per metre squared in 2022 and 2023, respectively, implying a temperature impact of -0.02C (-0.01C to -0.03C) calculated using the FaIR model.
The post Analysis: What are the causes of recent record-high global temperatures? appeared first on Carbon Brief.
Analysis: What are the causes of recent record-high global temperatures?
Local officials are often viewed as relatively weak actors in China’s governance structure, largely implementing policies issued from the central level.
However, a new book – “Implementing a low-carbon future: climate leadership in Chinese cities” – argues that these officials play an important role in designing innovative and enduring climate policy.
The book follows how four cities – Shenzhen, Zhenjiang, Xiamen and Nanchang – approached developing low-carbon policies over the course of almost a decade.
It identifies “bridge leaders” – mid-level local bureaucrats who have a strong interest in a specific policy area and who are unlikely to move often between different posts – as key to effective local climate policymaking.
Carbon Brief interviews author Weila Gong, non-resident scholar at the UC San Diego School of Global Policy and Strategy’s 21st Century China Center and visiting scholar at UC Davis, on her research.
The interview has been edited for length and clarity.
- Gong on why cities are important: “Over 85% of China’s carbon emissions come from cities. The majority of Chinese people live in cities, so the extent to which cities can become truly low-carbon will also influence China’s climate success.”
- On what motivates local policymakers: “Mid-level bureaucrats need to think about how to create unique, innovative and visible policy actions to help draw attention to their region and their bosses.”
- On cities as a way to test new policies: “Part of the function of local governments in China is to experiment with policy at a local level, thereby helping national-level officials develop responses to emerging policy challenges.”
- On how local policymakers get results: “Even though we tend to think that local officials are very constrained in terms of policy or financial resources, they can often have the leverage and space to build coalitions.”
- On uneven city-level engagement: “To begin with, all regions received political support if they joined the [low-carbon city] pilot programme. But over the years, different regions have engaged very differently.”
- On the need for ‘entrepreneurial bureaucrats’: “China will always need local officials willing to introduce new legislations or try new policy instruments…For that, it needs entrepreneurial bureaucrats who are willing to turn ideas into actions.”
- On international cooperation: “Even with how geopolitics is really complicating things, many cities continue to have common challenges. For example, collaboration between Shanghai and Los Angeles on green shipping corridors is still ongoing”.
- On the effectiveness of mid-level bureaucrats: “They are creative, they know how to convince their boss about the importance of climate action and they know how that can bring opportunities for themselves and their boss. And because of how long they have worked in one area, they understand the local politics, policy processes and the coalitions needed to provide solutions.”
Carbon Brief: You’ve just written a book about climate policy in Chinese cities. Could you explain why subnational governments are important for China’s climate policy in general?
Weila Gong: China is the world’s largest carbon emitter, so the extent to which global efforts to address climate change can actually reach their goal is largely influenced by China’s efforts.
If you look at the structure of China’s carbon emissions, over 85% of China’s carbon emissions come from cities. The majority of Chinese people live in cities, so the extent to which cities can become truly low-carbon will also influence China’s climate success. That’s why I started to look at this research area.
We tend to think of China as a centralised, big system and a unitary state – state-run and top-down – but it actually also has multi-level governance. No climate action or national climate targets can be achieved without local engagement.
We also tend to think subnational level [actors], including the provincial, city and township levels, are barriers for environmental protection, because they are focused on promoting economic growth.
But I observed these actors participating in China’s low-carbon city pilot programme [as part of my fieldwork spanning most of the 2010s]. I was really surprised to see so many cities wanted to participate in the pilot, even though at the time there was no specific evaluation system that would reward their efforts.
We think of local governments just as implementers of central-level policy. When it comes to issues like climate change and also low-carbon development – in 2010 [policymakers found these concepts] very vague…So I was curious why those local officials would want to take on this issue, given that there was no immediate reward, either in terms of career development or in terms of increasing financial support from the central government.
CB: Could you help us understand the mindset of these bureaucrats? How do local-level officials design policies in China?
WG: The role of different local officials in promoting low-carbon policy is not very well understood. We tend to focus on top political figures, such as mayors or [municipal] party secretaries, because we see them as the most important policymakers.
But that is not entirely true. Those top local politicians are very important in supporting efforts to tackle problem areas…but the focus in my book is the mid-level bureaucrats.
Unlike mayors and party secretaries, mid-level officials tend to stay in one locality for their entire career. That helps us to understand why climate policy can become durable in some places and not others.
Mayors and party secretaries are important for [pushing through policy solutions to problem] issues, but they can also be key barriers for ensuring continuation of those policies – particularly when they change positions…as they tend to move to another locality every three to five years.
Therefore, these top-level officials are not the ones implementing low-carbon policies. That’s why I looked at the mid-level bureaucrats instead.
The conventional understanding of these bureaucrats is that they are obedient and only follow their bosses’ guidance. But actually, when low-carbon policies emerged as an important area for the central government in 2010, opportunities appeared for local governments to develop pilot projects.
Mid-level local officials saw this as a way to help their bosses – the mayors and party secretaries – increase their chances of getting promoted, which in turn would help the mid-level bureaucrats to advance their own career.
Impressing central government officials isn’t really a consideration for these officials…but their bosses need visible or more reliable local actions to show their ability to enforce low-carbon development.
As such, mid-level bureaucrats need to think about how to create unique, innovative and visible policy actions to help draw attention to their region and their bosses.
Secondly, mid-level bureaucrats are more interested in climate issues if it is in the interest of their agency or local government.
For example, Zhenjiang [a city in east China] came to be known as a leader in promoting low-carbon development due to a series of early institutional efforts to establish low-carbon development. In particular, in part because of this, it was chosen for a visit by president Xi Jinping in 2014.
As a result, the city created a specialised agency [on low-carbon development]. This made it one of the first regions to have full-time local officials that followed through on low-carbon policy implementation.
This increased their ability to declare their regulatory authority on low-carbon issues, by being able to promote new regulations, standards and so on, as well as enhancing the region’s and the local policymakers’ reputations by building institutions to ensure long-term enforcement.
Another motivation for many local governments is accessing finance through the pilot programmes. If their ideas impress the central-level government, local policymakers could get access to investment or other forms of financial resources from higher levels of government.
In the city of Nanchang, for example, officials were trying to negotiate access to external investment, because the main central government fund for low-carbon initiatives only provided minimal finance.
Nanchang officials tried to partner with the Austrian government on sustainable agriculture, working through China’s National Development and Reform Commission (NDRC).
It didn’t materialise in the end, but they still created a platform to attract international investment, and gathered tens of millions of yuan [millions of dollars] in central-level support because the fact they showed they were innovating allowed them to access more money through China’s institutional channels.
CB: Could you give an example of what drives innovative local climate policies?
WG: National-level policies and pilot programme schemes provide openings for local governments to really think about how and whether they should engage more in addressing climate change.
The national government has participated in international negotiations on climate for decades…but subnational-level cities and provinces only joined national efforts to address climate issues from the 2010s – starting with the low-carbon city programme.
So we can see that local responses to addressing climate change have been shaped by the opportunities provided by the national government, [who in turn] want more local-level participation to give them successful case studies to take to international conferences.
Local carbon emission trading systems (ETSs) are an example of giving local governments opportunities to experiment.
In my book, I look at the case of Shenzhen, which launched China’s first local ETS. [Shenzhen was one of seven regions selected to run a pilot ETS, ahead of the national ETS being established in 2018.]
Part of the function of local governments in China is to experiment with policy at a local level, thereby helping national-level officials develop responses to emerging policy challenges.
I remember a moment during my field research in 2012, when I was with a group of officials from both the national and local government.
The national government officials asked the local officials to come up with some best practices and solutions, to help them envision what could be done at the national level.
Then there are drivers at the international level, which I think is very interesting.
I observed that the officials particularly willing to take on climate issues usually had access to international training.
During the early stages of subnational climate engagement, organisations such as the German Agency for International Cooperation (GIZ) worked with the NDRC and other national-level agencies to train local officials across the country.
This created more opportunities to help local officials understand what climate change and carbon markets were, and how to use policy instruments to support low-carbon development.
In Shenzhen, local bureaucrats also turned to their international partners to help them design policy.
The city created a study group to visit partners working on the EU ETS and learn how it was designed. They learned about price volatility in the EU ETS and pushed legislation through the local people’s congress [to mitigate this in their own system].
One thing that made the Shenzhen ETS so successful is what I call “entrepreneurial bureaucrats” [who have the ability to design, push through and maintain new local-level climate policies].
Shenzhen’s vice mayor worked with the local people’s congress to push the ETS legislation through. This was the first piece of legislation in China to require compulsory participation by more than 600 local industrial actors. It also granted the local government authority to decide the quotas and scope of the ETS.
These 600 entities also included Shenzhen’s public building sector[, a powerful local interest group].
This shows that, even though we tend to think that local officials are very constrained in terms of policy or financial resources, they can often have the leverage and space to build coalitions – even in China’s more centralised political system – and know how to mobilise political support.
CB: You chose to look at the effectiveness of four cities – Shenzhen, Zhenjiang, Xiamen and Nanchang – in climate policymaking. Why did you choose these cities and how representative are they of the rest of China?
WG: We tend to believe that only economically-advanced areas or environmentally-friendly cities will become champions for low-carbon development…But I was surprised, because Zhenjiang and Nanchang are not known for having an advanced economy, but [they nevertheless built impactful climate] institutions – regulations, standards and legislation that shape individual and organisational behaviours in the long term. I thought they were interesting examples of how local regions can really create those institutions.
Then there was Xiamen, which is seen as an environmentally-friendly city and economically is comparable to Shenzhen when you look at GDP per capita. Xiamen actually did not turn its low-carbon policy experimentation into long-term institutions, instead randomly proposing new initiatives [that were not sustained].
I conducted more than 100 interviews, talking with policy-practitioners inside and outside of government about specific policies, their processes and implementation.
I found that, over the course of eight years, these [cities] showed very different levels of engagement.
Some I categorised into substantive engagement, where the local government delivered on their climate goals. [Shenzhen falls into this category.]
Then there is performative engagement – such as in the case of Nanchang – where the local government was more interested in [using climate policies to] attract external investment and access projects from higher levels of government.
But they were not able to enforce the policies, because impressing higher levels of government became the primary motivation.
Zhenjiang was a case of symbolic engagement. It actually created a lot of institutions, such as a specialised agency and a screening system to ensure new [low-carbon] investment. When I was observing Zhenjiang, from 2012 to 2018, officials recognised they needed to be carbon-constrained.
The problem was that Zhenjiang has a very strong power sector – mainly coal power – which supplies the whole eastern coast. That meant, even though the government was very determined to promote low-carbon policies, they faced [opposition from] very strong local actors – meaning the government could only partially implement the targets they set.
Then there is sporadic engagement, as seen in Xiamen. [The city’s approach to climate policy was incremental and cautious] because of a lack of political support [from officials in Xiamen], as well as local coalitions between key actors. So instead, we find random initiatives being promoted.
This explains the uneven policy implementation in China. To begin with, all regions received political support if they joined the pilot programme. But over the years, different regions have engaged very differently, in terms of the regulations, standards and legislation they have introduced, and whether those were paired with enforcement by a group of trained personnel to follow through on those initiatives.
CB: What needs to be done to strengthen sub-national climate policy making?
WG: It’s very important to have groups of personnel trained on climate policy. Since 2010, when I started studying the low-carbon pilot programme, there were no provincial-level people or agencies fully responsible for climate change. Back then, there was only the [central-level] department of climate change under the NDRC.
By the time I finished the book, provincial-level departments of climate change had been created across all provinces. But almost nothing has been established at the city level, so most city-level climate initiatives are being managed under the agencies responsible for air quality.
That means climate change is only one of those local officials’ day-to-day responsibilities. Only a handful of cities have dedicated staff working on climate issues: Beijing, Shanghai, Zhenjiang, Shenzhen and Guiyang.
Nanchang devised some of China’s first legislation to include an annual [financial] budget for low-carbon development. But when I revisited the city, officials were not actually sure about how and whether that budget was being used, because there wasn’t a person responsible for it.
Therefore, even if there are resources available, they can go unused because local officials at the city level are so busy. If climate policy is not prioritised, or written into their job responsibilities, that can be a challenge for sustaining implementation.
In China’s governance structure, the national government comes up with ideas, and the provincial level transfers these ideas down to local-level governments. City-level governments are the ones implementing these ideas.
So we need full-time staff to follow through on policies from the beginning right up to implementation.
Secondly, while almost all cities have now made carbon-peaking plans, one area in which the Chinese government can make further progress is in data.
China has recently emphasised the need to strengthen carbon-emissions data collection and monitoring. But when I was conducting my research, most Chinese cities had not yet established regular carbon-accounting systems.
As such, inadequate energy statistics and insufficient detail remain key barriers to effective climate-policy implementation.
In addition, the relevant data usually is owned by China’s National Bureau of Statistics (NBS), which does not always share it with other agencies. Local agencies can’t always access detailed data.
When I visited Xiamen, officials told me the local government is now improving emissions monitoring systems. But there should be more systematic and rigorous data collection, covering both carbon emissions and non-CO2 greenhouse gases. Also, much of the company-level data is self-reported, which could affect the accuracy of carbon-emissions statistics.
For continued climate action, it’s also important that the central government ensures that local officials have the institutional support needed to experiment and propose new ideas.
…China will always need local officials willing to introduce new legislations or try new policy instruments – like Shenzhen with its ETS, or establishing new carbon-monitoring platforms.
For that, it needs entrepreneurial bureaucrats who are willing to turn ideas into actions. Ensuring that local governments have the right set of conditions to do this is very important.
CB: What did you find most surprising when researching this book?
WG: That international collaboration is still very important. I found that many officials learnt about climate change through international engagement.
In the current situation, I think international engagement is still very important – particularly given how, even with how geopolitics is really complicating things, many cities continue to have common challenges. For example, collaboration between Shanghai and Los Angeles on green shipping corridors is still ongoing.
That can bring opportunities for continuing climate action at the city level in the face of rising international tensions, as long as national governments give them space to be involved in international climate action.
Another surprise was the factors of what exactly made climate action durable. I was really surprised that many of the cities that I revisited were still involved in the pilot programmes, despite the central government restructuring that shifted the climate change portfolio from the NDRC to the Ministry of Ecology and Environment – which created challenges for the local governments who had to navigate this.
I also thought that the change in mayors for all four cities would lead to climate initiatives falling off the agenda.
But actually, Zhenjiang, Xiamen and Nanchang all maintained their low-carbon initiatives, despite these changes. This showed it isn’t only strong mayors that bring success, but rather a group of trained personnel building and enforcing regulations and standards. So the importance of bureaucrats and bureaucracy in making climate action durable was actually way beyond my initial expectations.
I was also surprised that bureaucrats can be entrepreneurial, even though they work in a centralised system. They are creative, they know how to convince their boss about the importance of climate action and they know how that can bring opportunities for themselves and their boss. And because of how long they have worked in one area, they understand the local politics, policy processes and the coalitions needed to provide solutions.
The post Interview: How ‘mid-level bureaucrats’ are helping to shape Chinese climate policy appeared first on Carbon Brief.
Interview: How ‘mid-level bureaucrats’ are helping to shape Chinese climate policy
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