火山喷发对科学家及其气候模型构成了根本性挑战。
众所周知,剧烈的火山喷发会导致地表气温突然下降,多次喷发则会在几十年乃至几个世纪的时间尺度上影响气候变率。
当火山喷发将二氧化硫注入平流层时,会形成气溶胶,从而阻挡阳光到达地球表面。
与人类对气候变化的影响不同,后者发生缓慢且可以在各种社会经济情景下被纳入气候模型进行考量。火山喷发具有突发性,这给气候预测带来了挑战。
目前科学家尚无法预测火山喷发的发生时间、地点以及二氧化硫的排放量。
那么,在进行未来气候预测时,如何考虑火山喷发对气候的影响呢?

在我们最近发表于《通讯-地球与环境》(Communications Earth & Environment)的研究中,我们表明火山喷发对全球气温预测的不确定性产生了重大影响。
我们的研究结果发现,如果将偶发的火山喷发纳入气候预测,突破《巴黎协定》所设定的1.5C升温上限的时间会略有延迟,但与此同时,未来几十年也将出现更多快速升温和降温的时期。
气候预测中的火山强迫
气候科学家将火山喷发对气候的影响——主要是通过释放出二氧化硫气体进入大气——称为“火山强迫”(volcanic forcing)。
当前的气候模型在进行未来预测时采用一个恒定的火山强迫值,该值是根据1850年至今的历史平均强迫值计算得出的。
国际耦合模式比较计划(CMIP)也是如此,这项全球模型工作为政府间气候变化专门委员会(IPCC)发布的重要评估报告提供基础数据。
然而,这种方法存在显著局限。
首先,历史平均强迫值无法表示火山爆发的偶发性。
大规模火山喷发呈零星分布——有时好多事件集中发生在某几个十年内,有时两个事件之间则可能相隔上百年。
此外,与数千年尺度的记录相比,从1850年至今的参考时期中,发生过的大规模喷发事件 ——指排放超过3太克(Tg)二氧化硫的喷发事件——相对较少。
最后,早期国际耦合模式比较计划气候模型中所使用的火山强迫重建数据并未包含排放量少于3太克二氧化硫的中小规模喷发。
这是因为这些喷发在1980年卫星时代开始之前大多未被探测到。然而,这些体量较小但发生频率更高的喷发事件,在长期火山强迫中贡献了30%至50%。
采取新方法
传统上,气候科学家认为气候预测中主要存在三种不确定性来源:内部变率、模型不确定性和情景不确定性。
其中,“内部”变率是指气候系统内部自然产生的波动,如厄尔尼诺现象;模型不确定性是指不同气候模型之间结果的差异;情景不确定性则涉及未来几十年全球可能的发展路径。
我们的研究结果表明,火山喷发应被明确视为气候预测中第四个重要的不确定性来源。
为了探究在考虑火山强迫不确定性的情况下,气候预测会发生怎样的变化,我们的研究采用了一种概率方法,这一方法建立在Bethke等人于2017年提出的研究基础之上。
为此,我们构建了“随机强迫情景”,其本质是1000种延续至本世纪末的火山活动可能时间线预测。
这些情景基于冰芯中记录的过去1.15万年火山活动历史,以及卫星观测和地质证据。每个情景都呈现了不同的喷发强度、地点、时间和频率的组合。
(在数学中,“随机”系统是指结果包含随机性或不确定性的系统,因此不可预测;这与“确定性”系统相对,后者的结果可以通过初始条件和一套规则或方程完全预测。)
随后,我们利用2015至2100年期间的随机火上强迫和历史平均火山强迫模拟气候预测,研究共享社会经济路径(SSPs)中三种不同排放情景下的升温变化:低排放情景(SSP1-1.9)、与现行气候政策相符的中等排放情景(SSP2-4.5)、非常高排放情景(SSP5-8.5)。
在这一步中,我们使用了一种称为FaIR的简化气候模型,也称“模拟器”。
通过模拟1000种不同的火山未来情况,我们发现在21世纪未来时期火山喷发所引起的气候不确定性,可能超过同期气候系统本身的内部变率。
我们还发现,到2030年代,火山喷发可能占全球气温预测总不确定性的三分之一以上。
下图中能看到这些结果。图中展示了不同来源对总不确定性的影响。火山为橙色、内部变率为深蓝色、气候模型响应为黄色,未来人类排放情景为绿色。

对1.5C临界值的意义
我们的模拟结果表明,在气候预测中纳入可能的火山活动时间线后,短期内突破《巴黎协定》设定的1.5C升温上限的概率略有下降。
根据不同的排放情景,相较于使用恒定火山强迫的预测,模拟发现超过1.5C升温上限的概率下降了4%至10%。
尽管这一结果听起来似乎令人鼓舞,但未来的火山活动并不能在长期缓和由人类引起的全球变暖。
1815年坦博拉火山的喷发事件就是一个强有力的例证。这次喷发使全球气温平均下降了约0.8C,带来了“无夏之年”,导致欧洲、北美和中国大范围的作物歉收和饥荒。
火山喷发带来的降温效应是短暂的,通常只持续几年,其并不会改变由人类排放所导致的长期变暖趋势。
我们的研究发现,即使考虑多种可能的未来火山活动,在除了最低排放路径以外的所有情景中,全球变暖仍将在几十年内超过1.5C。
即便21世纪火山活动频繁,其对全球变暖的抵消作用也仅占很小一部分——这意味着减排对于实现长期气候目标仍然至关重要。
下方图表展示了在三种排放情景下,使用随机火山强迫(实线)与恒定火山强迫(虚线)时超过1.5C的概率(上图),以及两种强迫方式之间的概率差异(下图)。

十年尺度的气温变率
我们的研究提供的另一个重要发现是:一旦将火山强迫的变率纳入考虑,将更有可能出现极端温暖和寒冷的十年期。
在中等排放情景下,我们发现出现负向十年期趋势——即全球表面温度在某个十年内平均下降——的概率增加了10%到18%。
与此同时,出现极端温暖十年期的概率也随之增加,这反映出火山强迫的变率会同时提高变暖和变冷极端事件发生的可能性。
这一结果凸显了火山喷发如何在十年时间尺度上对全球气温趋势带来显著的波动。
迈向更完善的气候预测
了解火山对气候的影响,对于全面评估农业、基础设施和能源系统在未来所面临的风险至关重要。
使用全面的地球系统模型运行数千种火山情景并不切实际,因为这需要极高的计算资源。但与此同时,当前的方法也存在上文提到的显著局限。
不过,在未来的气候模型工作中,仍有折中方案可行。
即将开展的下一阶段气候建模实验——即CMIP7情景模式比较计划——可以采用更具代表性的“平均”火山强迫基线,这一基线纳入了历史记录中常被遗漏的小型喷发事件的影响。这一偏差现已在用于下一代气候模型模拟的历史火山强迫数据集中得到纠正。
此外,建模团队还应额外运行包含高频和低频未来火山活动的情景,以全面捕捉火山不确定性对气候预测的影响范围。
虽然人类导致的温室气体排放仍是气候变化的主导因素,但若能妥善考虑火山活动的不确定性,将有助于我们获得更全面的未来气候图景及其对社会的潜在影响。
The post 嘉宾来稿:探究火山喷发如何影响气候预测 appeared first on Carbon Brief.
Climate Change
Battle over cleaning up shipping set to resume at London talks
The US is expected to resume its attempt to sink measures for a greener global shipping sector at closed-door talks between governments at the International Maritime Organization (IMO) in early September.
The US and oil-producing allies like Saudi Arabia want to weaken a proposed plan for cleaner fuels that aims to reduce planet-heating emissions from the industry, which relies heavily on dirty bunker fuels. Shipping currently represents 3% of global emissions.
Those that want a softer system are likely to back a Liberian proposal which expert analysis suggests would see emissions fall by only half at most by 2050, far short of the sector’s agreed climate goals.
After several years of debate, governments provisionally agreed in April 2025 on the “Net Zero Framework” (NZF), a series of emissions reduction targets for shipowners, backed up with financial rewards for meeting the targets and fees for missing them.
But in October 2025, after a high-profile intervention from US President Donald Trump and threats of sanctions and visa restrictions, the US convinced a majority of voting nations to postpone the adoption of the NZF for a year.
Ralph Regenvanu, climate minister for the Pacific nation of Vanuatu, called the delay “unacceptable” given the urgency of accelerating climate change.
After a round of low-profile talks in May, the first of three further sets of talks on how to clean up shipping will begin at the IMO’s riverside headquarters in London on Tuesday, culminating in a final public session in November.
Em Fenton, who follows the talks as senior director of climate diplomacy at Opportunity Green, an NGO focused on aviation and shipping, said governments should not be sidetracked by alternative proposals to the NZF, calling them “a distraction from a hard-fought multilateral compromise”.
“If countries want to deliver a just and fair maritime transition, there is really only one choice: back the NZF and stand together in solidarity against those who would tear it apart,” Fenton added.
Five proposals on the table
Governments will discuss five different proposals submitted in advance of next week’s meeting. The most ambitious of these is from the Pacific island nation of Tuvalu, which has proposed a levy on the entirety of a ship’s emissions rather than just those above a certain level, as the NZF envisions.
That had been the original demand of Pacific nations before the NZF was provisionally adopted in April 2025. At the time, Tuvalu’s transport minister Simon Kofe described the NZF as disappointing and not ambitious enough.
For this reason, six Pacific countries abstained in the vote on the NZF. While they supported the original plan for its adoption in October 2025, they have used the delay to push again for more ambition.
John Kautoke, advisor to a group of Pacific nations called 6PAC+, told Climate Home News that the NZF “cannot diminish its already inadequate ambition. If anything, the NZF must increase in ambition if we are going to renegotiate its parameters.”
Analysis by the Institute of Marine Engineering, Science and Technology (IMarEST) suggests that, of the five proposals, only Tuvalu’s would meet the 2030 and 2040 emissions reduction targets for global shipping that were agreed by governments in 2023. Those were for cuts of 20% between 2008 and 2030, 70% by 2040 and then reaching net zero “by or around, i.e. close to 2050”.
Despite this, the UK, Australia, Canada and South Africa have formally proposed that governments adopt the NZF, which won support in a 63-13 vote among governments at the April 2025 talks. Trump’s US walked out halfway through.
According to IMarEst’s analysis, while the NZF proposal will not be enough to meet the industry’s targets, it will reduce emissions more cheaply than the Pacific proposal.
A proposal by Brazil – which fought hard for the NZF last October – suggests tweaking the framework to make meeting targets easier in the short term and harder in the long term.
While this compromise will make it more appealing to the owners of polluting ships and countries that support them, IMarEst estimates it would lead to higher cumulative emissions than either the NZF or Pacific proposals.
The NZF stipulates that fees for high-polluting shipowners should be be put into a Net Zero Fund and used to promote clean shipping fuels and a fairer transition. The Brazilian proposal would delay raising and spending these funds by two years, from 2029 to 2031.
Liberia’s proposal weakens emissions cuts
The US and Saudi Arabia are likely to swing behind a new proposal from Liberia, whose government makes millions of dollars a year selling the right for shipowners to register their vessels in the small West African nation via a US-based company.
This proposal would weaken the emissions reduction targets. IMarEst says it would cut the industry’s emissions at most by a half by 2050, falling far short of the target agreed in 2023 for international shipping to reach net zero “close to 2050”.
It would also replace the NZF’s fees for missing targets with a carbon trading system. As a result, there would be no Net Zero Fund and therefore less money available to incentivise green fuels and make the transition more equitable for poorer nations.
Pacific advisor Kautoke said that, as well as preventing shipping from reaching zero emissions by 2050, Liberia’s proposal would mean the Pacific “will not receive any support to deal with the disproportionately negative impacts created by the cost of the transition”.
“We get a double blow if we adopt the Liberian proposal,” he warned. “We get all the cost of a transition without any support, and we have an industry that continues to burn fossil fuels to an unforeseen point.”
Japanese proposal favours shipowners
Japan has submitted a late proposal to amend the NZF so that shipowners have more control over how the fees they would pay for emitting above a set threshold are spent.
University College London professor Tristan Smith has argued that this change means there will be no central mechanism to incentivise investments in clean fuels. He wrote on LinkedIn that under the system put forward by Japan, shipowners would be able to select which green projects their fees would go to. They could choose their own or those of a sister company or other shipowners, rather than funding broader just transition projects that would benefit marine workers or developing countries hit by rising shipping costs.
Despite its flaws, Smith added that Japan’s proposal “could still get taken seriously by some, given how appealing it may seem to shipowners who have consistently demanded control of revenues, and given how the US and other member states have pushed back against the IMO Net Zero Fund and [greenhouse gas] pricing.”
Tacit or explicit approval?
Next week, governments are expected to make statements saying which proposals – or which aspects of proposals – they prefer. Another set of talks will be held from November 23-27 before a potentially final round from November 30-December 4.
A new framework to tackle shipping emissions could be adopted at those talks if two-thirds of countries that are present and signed up to a regulation called Marpol Annex VI – endorsed by just over 100 states – vote in favour of it, as they did in April 2025.
The US and its allies are also trying to change the rules to make the next stage more difficult. Decisions that have been adopted at IMO meetings usually take effect automatically unless a certain number of countries object within a certain time period decided by governments, a system known as tacit approval.
But the US wants that to require explicit approval instead, so that any new emissions standard would not come into force unless enough governments – representing a certain percentage of the world’s shipping fleet – actively indicate support for it.
Critics say this change would give a small number of countries with large shipping registries the power to block implementation. Liberia has the world’s biggest shipping registry, run by an American company, followed by Panama and the Republic of the Marshall Islands.
Liberia and Panama have supported the US at the talks on the Net Zero Framework. The Marshall Islands has long been one of the most vocal supporters of climate action in shipping but, with its officials and shipping registry income vulnerable to US retaliation, did not sign on to the recent Pacific proposal vowing to strengthen the NZF if it is re-opened.
Brazilian negotiator Adriana de Medeiros Gabinio warned in April that the NZF’s opponents are trying to change the rules by which it comes into force as a “safety net to block” it.
The post Battle over cleaning up shipping set to resume at London talks appeared first on Climate Home News.
Battle over cleaning up shipping set to resume at London talks
Climate Change
Coles, Woolworths failing on deforestation commitments
SYDNEY, Wednesday 26 August 2026 — New 2026 Sustainability Reports released by supermarket giants Coles and Woolworths this week demonstrate the retailers are failing on their commitments to end deforestation in their supply chains.
Adele Chasson, Nature Policy Lead at Greenpeace Australia Pacific said:
“These so-called sustainability reports are revealing. Despite their public commitments in 2024 and 2025, neither Coles nor Woolworths have taken deforestation-linked beef off their shelves. Meanwhile, bulldozers continue to tear up forests and bushland, pushing wildlife closer to extinction and causing mass toxic runoff to flow into the Great Barrier Reef. Millions of native animals like koalas are losing their homes to beef pastures each year, while the big supermarkets put off action.
“Australians would be shocked to know that beef on the shelves of our biggest supermarkets could be pushing threatened species to the brink of extinction. Collectively Coles and Woolworths have made more than $2 billion in profits in the last year, profiting from the destruction of wildlife and precious Australian nature. Coles and Woolworths owe it to shoppers to deliver on their promises and end deforestation in their supply chains now.
“As big beef buyers, Coles and Woolworths have an essential role to play in keeping Australia’s unique forests standing. They can help stop the Great Barrier Reef from being poisoned by runoff and protect iconic forest wildlife by taking deforestation off their shelves. It’s time these big companies put their money where their mouths are and follow through on their promise of sourcing and supplying deforestation-free beef.”
Climate Change
New Zealand moves to protect business with law curtailing climate litigation
New Zealand’s parliament has adopted a controversial new law blocking a whole avenue of climate litigation and shutting down its most advanced corporate lawsuit, which has been blamed by the government for shaking business confidence and investment.
The Climate Change Response (Tort Liability) Amendment Bill, expected to take effect in the coming days after it is formally signed by the Governor-General, prevents all current and future civil claims for climate loss or harm under tort law.
Justice minister Paul Goldsmith said last week that the aim was to give businesses “certainty around their climate change obligations”, noting it would not alter the government’s responsibilities under the Climate Change Response Act 2002 nor business obligations under the Emissions Trading Scheme.
“Our response to climate change is best managed by the Government at a national level and not through piece-meal litigation in the courts,” he added in a statement.
Such litigation, he said, “risks developing a new regime that contradicts the framework Parliament has already enacted” to tackle climate change.
Goldsmith singled out a key domestic climate lawsuit brought by Northland iwi leader and activist Mike Smith against six big companies: dairy firms Fonterra and Dairy Holdings, energy firms Genesis Energy and Z Energy, New Zealand Steel and coal mining firm BT Mining. A seventh original defendant, Channel Infrastructure, was dropped after it permanently decommissioned its Marsden Point oil refinery.
Smith argued that these companies had caused him harm under public nuisance and negligence law, as well as a third breach of a duty to cease contributing to climate change that has yet to be tested domestically. He did not seek financial compensation, instead asking for the companies to immediately stop emitting or contributing to net greenhouse gas emissions.
In one of the most advanced corporate climate accountability lawsuits in the world, a trial had been scheduled for April 2027 after the Supreme Court unanimously allowed the case to continue.
Corporate lobbying in the shadows
Smith described the passing of the bill as “deeply concerning”, particularly as it coincided with the Supreme Court hearing another of his climate lawsuits. In that case, Smith v Attorney-General, he argues that the government’s response to climate change and its impacts on Māori communities in particular breaches rights to life and culture.
“That timing raises profound questions about the separation of powers and the rule of law,” said Smith. “Whatever one’s view of the merits of these cases, it is deeply troubling when parliament intervenes to remove a legal pathway while the courts are actively considering fundamental questions about climate responsibility, rights and the crown’s obligations.”
The bill – which says that no person (including the government) can be found liable in tort for emissions-related climate change effects – followed major lobbying efforts by the companies defending themselves in Smith’s lawsuit. They outlined a proposed legal amendment in a briefing note to the government in 2024.
The centre-right government has been fiercely criticised over its lack of transparency in relation to this lobbying activity. The national ombudsman recently found that the Prime Minister’s Office effectively withheld information requested by the Environmental Law Initiative about meetings, discussions and conversations regarding Smith’s case.
Green groups fail to stop bill
The bill sparked huge concern among environmental campaigners in New Zealand and elsewhere. Greenpeace Aotearoa called it a “shocking abuse of executive power” and the vast majority of submissions to a parliamentary inquiry said it should be rejected.
But in the end, it was adopted with little resistance, moving relatively smoothly through parliament, passing its third reading by 67 votes to 53. Sam Bookman, climate law lecturer at Melbourne Law School, told Climate Home News he was not surprised by this, given that the coalition government has a secure majority.
A complaint has been made to the UN special rapporteur on climate change and human rights by Smith, the National Iwi Chairs Forum Pou Tikanga and youth coalition Climate Clinic Aotearoa over what they see as the government’s heavy-handed approach. Smith is also challenging the new law in yet another lawsuit.
“Pathetic”: New Zealand plans to barely cut emissions between 2030 and 2035
Bookman thinks it “very unlikely” that such a challenge will succeed, noting that New Zealand’s constitution is firmly anchored in parliamentary sovereignty.
But the expert in climate law does not see the bill as the end of legal action in the country, noting that New Zealand has a “sophisticated climate litigation landscape with a growing number of specialist and experienced lawyers and NGOs”.
The country is also approaching its next general election in November, and some opposition parties have pledged to restore access to the courts if elected.
Amanda Larsson, global project lead on agriculture for Greenpeace International, said: “This law deserves to be tested, and I strongly encourage the international climate litigation community to unite and help defend New Zealanders’ fundamental right to hold polluters accountable before this becomes a global blueprint.”
Copycat legislation on the rise
New Zealand’s move is part of a small but growing legislative effort to shut down climate litigation around the world.
In the US, Republican politicians introduced legislation in the House and Senate in April that would shield fossil fuel firms from climate liability lawsuits. Similar laws have already been passed at state level in Tennessee, Utah, Iowa and Louisiana.
The German state of Bavaria has put forward a similar proposal to the Federal Council, aiming to block private climate claims as well as the recognition and enforcement of foreign judgments imposing such liability. There are also proposals to limit available remedies and actions in the Netherlands and Belgium.
UN General Assembly backs “climate obligations” set by world’s top court
Bookman said he expects more efforts to counter climate damages litigation and advised plaintiffs to think about how to respond, including drawing on broader support in opposing them.
“Even though it’s very hard for plaintiffs to win these types of cases, companies are very eager to avoid the expense, embarrassment and political accountability that come even with unsuccessful lawsuits,” he said.
The post New Zealand moves to protect business with law curtailing climate litigation appeared first on Climate Home News.
New Zealand moves to protect business with law curtailing climate litigation
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