漫步在有着中国“新能源汽车第一城”之称的深圳街头,你不会错过停放在路边的大量新能源汽车,以及宣传“绿色低碳”生活方式的标语。
深圳是一座紧邻香港的城市,有着1800万人口。这座城市因40多年前成为中国的改革开放试验田而闻名。
如今,它在碳减排方面也走在前列,是中国“低碳城市”建设的“试点”地区之一。
深圳是中国首个将公交车、出租车和网约车全部实现电气化的城市。2024年,深圳新车销量中有约77%为新能源汽车,远高于48%的全国平均水平。
深圳还率先设立了碳排放总量控制机制,推动“能耗双控”向“碳排放双控”转型——这比全国层面出台碳排放总量控制政策更早。

此外,深圳的地方性碳排放权交易市场(ETS)和“绿色债券”也都早于国家层面推出。
尽管深圳在碳减排领域很早就采取了措施,但一些专家对Carbon Brief表示,深圳的政策——这被当地政府称为“深圳模式”——很难在中国其他进行低碳转型的城市复制。
Carbon Brief回顾了深圳在低碳转型方面迄今为止所做的努力,并评估了其减排成效。
电动交通
官方智库中国(深圳)综合开发研究院财税贸易与产业发展研究中心主任韦福雷对Carbon Brief表示,深圳的低碳转型并非一蹴而就,而是建立在早期规划、政府支持和市场驱动相结合的基础上。
深圳的低碳转型始于21世纪初,当时该市的空气重污染天数达到峰值。
BBC新闻2017年的一篇报道称,经过十年的污染治理,深圳的空气污染程度“下降了近一半”。
报道称,这一成果很大程度上源于其“产业基础”的改变,也使深圳成为全国首批“低碳城市”之一。
这一时期,当地官员们制定了“低碳发展”战略,其中包括培育一批“战略性新兴产业”,如“信息通信技术”。这些产业后来为深圳包括新能源汽车行业在内的低碳行业提供了核心技术支持。
例如,目前全球领先的电动汽车巨头比亚迪,正是在这样的背景下诞生于深圳的。
韦福雷指出:“有了这种‘产业基因’,深圳只需把产业链重新梳理一遍,,就能快速满足新能源汽车行业(在2020年代)的新需求。”
尽管人口仅占全国约1%,但2025年深圳地方“两会”上的政府工作报告显示,该市在2024年的新能源汽车产量占到全国的22%。
报告同时称,深圳将在未来一年启动大约100个“气候投融资项目”,计划新增“绿色贷款”约1800亿元人民币(约合240亿美元)。
能源与清洁空气研究中心(CREA)分析师和中国团队负责人沈昕一对Carbon Brief说,深圳地方政府在扶持新兴产业方面经验丰富。
她说:“20年前,风电、太阳能发电,以及电动汽车,都还是需要大量投资和技术研发的新兴行业……当时的失败风险很高,但深圳市政府敢于推出很多创新政策加以扶持。”
新能源汽车企业的迅猛发展带动本地市场中新能源汽车占比持续上升。除了国家层面的补贴,地方政府也在生产和消费两端给予有力支持。
2024年,深圳销售的新车中约77%为新能源汽车,远高于48%的全国平均水平。
此外,深圳还率先实现了本市公交车、出租车和网约车全部电气化,是中国首个做到这一点的城市。
伦敦大学学院(UCL)可持续基建、经济与金融学讲师郑赫然向Carbon Brief指出,“更环保的交通车队”加快了深圳的低碳转型步伐,因为一座城市的低碳转型主要依赖两个关键方面——“交通转型”和“产业脱碳”。
他说:“一个城市在碳减排上的政策工具其实有限,但它可以推动更绿色的交通。比如,伦敦设立了超低排放区,鼓励人们使用公共交通和更清洁的车辆。城市也可以推动产业升级和减排,但这更难做到,因为很少有城市愿意放慢经济增长的步伐。”
郑赫然表示,深圳“与中国一些煤矿城市不同”,在产业转型方面具有“优势”,这使其可以设定“更具雄心”的排放目标。

碳控机制
中国将能源强度和碳强度(即单位国内生产总值GDP的能源使用量和排放量)作为其气候政策的关键指标。
此外,自2016年以来,中国一直实行“能耗双控”机制,即同时控制能源消费强度和能源消费总量。但中国政府已经宣布将在2024年起转向“碳排放双控”机制。
新机制将对二氧化碳排放总量设定约束性上限,并将成为2030年后的主要目标,而2030年前的主要指标——碳强度——将逐渐成为次要目标。
在这一领域,深圳依然是先行者。据“对话地球”(Dialogue Earth)报道,早在2023年,深圳就已成为中国首个明确承诺实行“(碳排放)双控机制”的城市。
为此,深圳市在2023年发布了两份《实施方案》,同时设定了市级碳排放总量控制目标。
与国家层面的方案相比,深圳在进程上更具雄心,其目标是在2025年建立起市级“碳排放双控”机制,并计划于2026年至2030年“全面实施”。
其中一份方案提出:“力争到2028年实现深圳碳市场制造业基本采用碳排放双控方式开展配额分配工作……力争到2030年实现市场调节能力显著提升。”
深圳还计划到2025年底,将能源强度在2020年的基础上降低14.5%,高于同期全国13.5%的目标。
郑赫然表示,深圳的这些目标是“量力而行的”。他解释道:“(就中国整体而言)碳减排主要集中在三个领域——钢铁、水泥和电力。深圳没有大型钢铁或水泥产业,因此只需将重心放在电力领域……而且它也不属于化石燃料城市,不位于供应链上游,无需担心煤炭开采等业务。深圳的产业结构主要以‘高附加值’行业为主,比如科技和新能源汽车,这些行业的碳排放更容易削减。”
“此外,深圳是科技中心,很多高碳排企业已搬到周边城市,比如汕尾。这就是所谓的‘排放外包’,受益于此,深圳的绿色转型面临的障碍更少。”
去年,郑赫然和同事在《自然》杂志上发表了一篇有关中国城市间碳排放外包的研究,指出“一些城市从其他城市的碳减排成果中获得大于其自身的收益”,并建议政策制定者正视其影响。
他还指出,深圳与其他城市相比还有一个“巨大差异”:“深圳拥有自己的核电站”,而这对深圳实现电力转型具有“重要”意义。电力行业是深圳在当前低碳转型中需要着力的最后一环。
低碳能源
根据2021年的一份报告,大亚湾核电站是深圳“最大的本地电力来源”,总装机容量达6.1吉瓦(GW)。
2021年,核电在深圳总发电量中的占比达到35%。
这也拉高了深圳的低碳能源使用水平。2024年,深圳一次能源消费中约47%来自清洁能源。
对深圳而言,核能发电量远超其他并入城市电网的清洁能源来源。市政府在2025年工作报告中提到,当前本地太阳能发电装机容量约为1吉瓦,风电装机并未被提及。
《深圳市应对气候变化“十四五”规划》写道,由于本地能源资源匮乏,加之风电、光伏“受土地和资源限制”,可再生能源的增长空间“有限”。
与此同时,深圳对外来电力的依赖程度也非常高——约七成的用电从外部进口。
这种依赖限制了深圳对电力行业碳排放的掌控,也给本地电网在用电高峰期的调度带来压力。
2024年,中国批准在毗邻深圳的惠州建设更多核电机组。
根据2022年一份研究报告,深圳市政府计划“到2025年将天然气、核能和可再生能源在能源结构中的总占比从当前的77%提升至90%,远高于全国52%的平均水平”。
郑赫然表示,“深圳与邻近的香港非常相似,香港的能源转型也不依赖太阳能和风能的建设”。
他补充说,深圳和香港应充分发挥自身作为“金融城市”的优势,以实现可持续的能源转型。

“绿色金融”
韦福雷表示,深圳一直善于利用“市场机制”,“在政府支持与市场驱动之间”成功找到平衡。其中,企业“担任主力角色,承担了90%的工作”,政府只在必要时出手干预。
在政府干预较少的情况下,深圳早在2013年就成为全国首批建立碳排放权交易市场“试点”的七个省市之一,远早于2021年全国碳市场的上线。
和全国层面的碳市场类似,深圳的本地碳市场并不以绝对排放量为基准,而是根据企业的排放强度(即单位产值的碳排放量),为企业分配可交易的排放配额。
深圳本地的碳排放权交易市场启动时覆盖了全市约38%的碳排放量。国际碳行动伙伴组织(ICPA)在一份报告中指出,这一比例到2020年已经提升至50%,并将进一步扩大。深圳还宣布将从2027年起为碳排放设置“绝对上限”。
(目前,国家层面的碳市场也未设置排放总量上限,但这也将在未来有所改变。)
不过,咨询公司ClearBlue Markets分析师秦炎对Carbon Brief说,虽然深圳碳排放权交易市场的覆盖范围还在扩大,但许多试点地区的碳排放权交易市场正在“收缩”,因为越来越多企业选择退出地方市场,转而加入国家碳市场。
国际碳行动伙伴组织的研究也发现,自2019年深圳碳排放权交易市场“向国家市场过渡”以来,发电已不再被纳入深圳碳排放权交易市场。
尽管如此,秦炎强调,这些地方试点“仍是一个重要的试验田,为国家碳排放权交易市场的成功落地铺平道路。(它们)会继续存在,覆盖中小企业以及国家市场尚未涉及的行业”。
国际碳行动伙伴组织称,截至2022年,深圳的地方碳排放权交易市场涵盖了水利、燃气、供热、制造业和交通等多个行业。
根据《深圳商报》报道,截至2024年,深圳已拥有全国最大的地方碳排放权交易市场,年交易量连续多年居全国首位。
与此同时,深圳也在“绿色金融”领域积极布局,将私人投资引入市场。
2021年,深圳在香港发行了中国首支面向海外市场的“绿色政府债券”,并出台了中国首部地方性“绿色金融法规”。国际绿色金融研究所(International Institute of Green Finance)在一份对该立法的评估中指出,其为规范“绿色市场”提供了“坚实的制度保障”。
相比之下,中国的首支主权绿色债券自2025年4月起才向国际买家发行。
深圳还推出了多种“绿色金融”产品。据官媒《经济日报》报道,2024年上半年,沪深两地交易所内新能源、新能源汽车及其他环保相关行业公司的市值达约4.6万亿元人民币(约合6,330亿美元)。
不过,郑赫然表示,“绿色债券”的效果“很难评估”。他说:“有很多项目,比如污水处理,也可以被归入‘绿色债券’的范畴。”
据官媒中央电视台报道,深圳2021年发行的“绿色债券”涵盖了“普通公办高中建设、城市轨道交通和水治理”等项目。
郑赫然表示,这些项目虽然在一定程度上与提高能效有关,但它们对碳减排的直接影响仍“有限”。
他补充说,市场引导在一座城市的低碳转型中“不可或缺”,但“目前尚无关于绿色金融产品在减排方面能发挥多大作用的研究”。
沈昕一则指出,“金融工具”在支持低碳转型方面仍发挥着重要作用。
她说:“低碳产业的成本往往高于化石燃料相关行业……通过政策支持和金融工具,才能够规模化,成本才能够降下来。”
“深圳模式”
深圳地方政府和媒体将深圳在气候领域取得的成就誉为“深圳模式”,意在其可以被推广到其他地区。
深圳市生态环境局党组成员许化表示,在去年的联合国气候变化大会(COP29)上,这一模式“向世界展示了成果”:“一是持续完善顶层设计,坚持立法先行,构建政策体系……二是聚焦重点领域转型升级……将新能源、安全节能环保等战略性新兴产业纳入重点产业集群,培育赋能……三是坚持开放共享,探索绿色低碳发展新路径。”
许化补充说,深圳的“绿色发展水平走在全国前列”,截至2023年底,深圳的“万元GDP能耗、水耗、碳排放分别降到了全国平均水平的1/3、1/8和1/5”。
不过,沈昕一指出,深圳的发展路径并非完全“可复制”,因为“深圳抓住了时代的机遇”。
她对Carbon Brief说:“比如,深圳的产业链优势和技术工人的聚集,给其高端制造业提供了很好的基础。”
郑赫然也认同这一观点。他认为,深圳只能代表中国一种特定类型的城市。
“深圳就像中国的硅谷,在高端科技领域投入巨大。它只能代表一线城市这一(特定)类别的中国城市,比如北京、上海、广州。中国有三百多个城市,每个城市都面临着独特的转型形势。依赖煤炭的工业城市照搬深圳的做法并不现实。”
与此同时,中国的其他城市也开始探索各自的可持续发展之路。
苏州建成了中国首批低碳工业园区试点之一的苏州工业园区。当地还建立了“市场化碳普惠交易体系”,鼓励居民和中小企业“自愿”参与碳排放交易。
据新华社报道,天津也与新加坡开展合作,“探索城市绿色低碳发展路径”。
沈昕一表示,其他城市必须“因地制宜地制定策略”。这种理念也体现在国务院于2023年发布的《新时代的中国绿色发展》白皮书中。
该文件指出,地方政府要“依托资源环境禀赋和产业发展基础……充分发挥各地区比较优势。”
The post 解读:何为中国城市低碳转型的“深圳模式”? appeared first on Carbon Brief.
Climate Change
COP31 electrification pledge leaves out clean power commitment
COP31’s flagship initiative to accelerate the electrification of the world’s economy has been criticised for failing to include a commitment to produce the power from clean energy.
Governments that sign the voluntary pledge at this year’s UN climate summit will commit to increasing electricity’s share of total energy consumption to 35% globally by 2035 in line “with pathways consistent with keeping 1.5C alive”, the text unveiled by the Turkish presidency on Tuesday says.
While the document says that the electrification goal is “complementary to efforts to expand renewable energy and improve energy efficiency”, governments are not explicitly asked to commit to producing the extra power with clean sources and driving down greenhouse gas emissions.
The text instead says the “use of clean electricity” will vary according to national circumstances. Fossil fuels are not mentioned by name, although the pledge cites the COP28 Global Stocktake decision, which called for “transitioning away from fossil fuels” in energy systems.
COP31 president Murat Kurum said earlier this month that the push to make electrification more “widespread” – through measures like the rollout of electric vehicles and heat pumps – will “automatically” lead to a reduction in the use of fossil fuels.
But many campaigners disagree, criticising the proposed pledge for failing to give an explicit signal on the fossil fuel transition.
Lack of clarity on energy sources
“Let’s not let electrification become the Trojan horse of our times, used to hide new fossil fuel consumption rather than promote renewable energy,” Claire Smith from civil society umbrella group Beyond Fossil Fuels said in reaction to the pledge’s publication.
She added that the commitment will only help address the climate crisis if electrification is powered by a flexible energy system where solar and wind are complemented by enhanced grids and storage.
The pledge’s text says that the electricity goal should be supported by “diverse and sustainable energy sources”, but it stops short of explaining what these sources are.
Alden Meyer, an international climate policy expert and senior associate at think-tank E3G, said the details of the pledge matter to how effective it will be in helping bring planet-heating emissions down.
“It has to be clean, and we haven’t got enough clarity on a guarantee that it will be a decarbonisation move,” he told Climate Home News.
China’s industrial engine starts to break its fossil fuel habit
According to an annual electricity review from energy think-tank Ember, in 2025 renewables edged ahead of coal power for the first time in 100 years. Continued growth in solar and wind pushed the share of renewables above a third of global electricity generation to just under 34%, compared with coal at 33%, it said.
Janet Milongo, energy Transition lead at CAN International, said success cannot be measured simply by how much of the world’s final energy consumption becomes electric.
“We must ask what generates that electricity, who has access to it, who owns the infrastructure, and whether it is helping communities transition away from fossil fuels,” she added.
Electrification alone can’t meet climate goals
Analysis published by the IEA on Tuesday, alongside the pledge, found that it would already be cost-effective to raise electricity’s share of global energy use from 23% today to around 33% with existing technologies, putting the COP31 goal “within striking distance”. Based on current policies, however, the share reaches only about 30% by 2035.
Hitting the 35% target would cut fossil fuel importers’ import bills by around $400 billion a year by 2035, the IEA said. At the higher prices caused by the conflict in the Middle East, that saving rises to more than $500 billion.
Speaking at New York Climate Week on Tuesday, IEA executive director Fatih Birol said the agency’s figures show that in 2026, about 80% of all new power plants built will run on renewables, with a few percentage points coming from nuclear power and the rest from fossils fuels. “So therefore, electrification itself will lead reduction of the [greenhouse gas] emissions,” he added.


However, the IEA warned in its new report that electrification “by itself is not enough” to meet the world’s climate targets. It noted that, if “low-emission” sources of power continue to simply grow in line with current policy scenarios, that would be only just enough to cover the extra demand from electrification, driving a modest decline in emissions.
Matt Webb, associate director of global clean power diplomacy at E3G, said the pledge is a “welcome signal of leadership” and can help COP31 be a “critical moment” for countries to double down on the energy commitments made at COP28.
But to secure the full benefits of electrification, he added, it is essential that we “urgently clean up” by speeding up the rollout of renewables and developing credible national plans to transition away from fossil fuels.
The post COP31 electrification pledge leaves out clean power commitment appeared first on Climate Home News.
COP31 electrification pledge leaves out clean power commitment
Climate Change
As loss and damage fund stalls, Nepal crowdfunds flood relief
People around the world have donated almost $90 million to a government-led campaign to help Nepal recover from its recent devastating Himalayan flood, according to a Nepali climate negotiator, even as the UN chief slammed the tiny amount of money in a new fund to deal with such disasters.
Individuals and companies from Nepal and abroad have chipped in from $5 to “many millions” of dollars to the Prime Minister’s Disaster Relief Fund, Manjeet Dhakal, an advisor to the poorest countries at UN climate talks, told an event on Monday focused on early warning systems.
The prompt and substantial response from the public contrasts with the slower, more limited support that is potentially on offer from the UN’s new Fund for Responding to Loss and Damage (FRLD), set up by governments to compensate developing countries for climate disasters.
Comment: Human security relies on adapting to the world’s new climate reality
Over three weeks have passed since Nepal’s finance and environment ministers asked the FRLD board to take an urgent decision to allocate funding to help Nepal protect people and restore essential services in the wake of the disaster, which caused around 1,450 deaths and left more than 5,000 people missing.
“Time is of the essence,” the ministers wrote in an appeal to the FRLD on August 31, which was swiftly followed by a letter from a group of developing-country board members urging the FRLD board’s co-chairs to organise an extraordinary meeting to come up with a response.
Loss and damage fund hesitates
Yet, despite informal online meetings, the co-chairs have yet to convene a meeting with the power to allocate funds. The board’s next scheduled meeting begins on December 15.
Dhakal said on Monday that the request has “received some positive response, but still there is some discussion ongoing about how to respond to that”.
“If they can’t respond in a timely manner, then is [the fund] fit for purpose in terms of disasters that the world would be facing in the coming years? The scale and intensity of these disasters is increasing,” he said.
With just $820 million pledged to it by rich countries and not all of that yet delivered, the FRLD has earmarked just $350 million to spend in its initial phase and without further contributions could run out of money next year.
Because of these limited funds, and a huge number of requests for funding totalling nearly $3 billion, the FRLD has said it will only give out a maximum of $20 million to each project for now. It has yet to approve funding for any projects.
Dhakal recently told The Nation magazine that this amount was just a “symbolic gesture”. Nepal’s government has estimated the costs of recovery and reconstruction at $4.8 billion, with homes, roads, bridges, hospitals and hydropower stations in the affected area needing to be repaired and rebuilt.
“Ridiculously small” funding
In a speech to the UN General Assembly on Tuesday, the body’s outgoing Secretary-General António Guterres criticised the “ridiculously small” level of funds made available by wealthy governments to the FRLD. Developed countries should “make the loss and damage fund work at scale”, he said.

The Portuguese diplomat told world leaders that when he travelled to Nepal three years ago, he had “sounded the alarm on accelerating glacier melt, warning that the rooftops of the world are caving in”.
“Some dismissed it all as overstating dangers, but as tragic events have shown, impacts are arriving sooner, hitting harder, and spreading further than many anticipated,” he said.
A recent study by scientists with the World Weather Attribution group found that climate change contributed to the rock-ice avalanche which sparked a huge flash flood along a river valley on the Nepal-Tibet border.
Speaking at a separate event in New York on Monday, leading climate scientist Johan Rockström highlighted those findings on the role of global warming in the Himalayan disaster.
“This will be potentially the first poster-child case of a loss and damage invoice, because here we have a proven case of a catastrophe which would not have occurred if it hadn’t been for human-caused climate change,” he said.
The post As loss and damage fund stalls, Nepal crowdfunds flood relief appeared first on Climate Home News.
As loss and damage fund stalls, Nepal crowdfunds flood relief
Climate Change
Explainer: How sea level rise poses an ‘existential threat’ to humans, heritage and nature
For millions of people around the world, rising sea levels are already reshaping economies, livelihoods and cultures.
The world’s oceans are currently rising at a faster rate than at any time in at least the past three millennia, with human influence the “dominant cause” of sea level rise since at least 1970.
At the UN general assembly in New York this week, world leaders are set to adopt a high-level declaration on the “existential threats” posed by sea level rise.
The declaration notes: “Sea level rise is not a distant scenario, but a real and lived experience for many.”
On average, global sea levels rose by 20 centimetres (cm) between 1901 and 2018.
This is due to both the melting of glaciers and ice sheets and the expansion of seawater as it warms, as well as changes in land-water storage.
The rate of the rise has accelerated in recent years, with ocean levels rising 10.6cm since 1993.
Sea level rise can vary locally due to seismic and volcanic activity, groundwater extraction and changes to the Earth’s surface resulting from ice melt.
Under a moderate-emissions scenario, scientists predict that global average sea level will rise an additional 56cm by 2100, relative to a 1995-2014 baseline.
Here, Carbon Brief unpacks some of the key ways that sea level rise threatens both societies and ecosystems.
Cities and coastal communities
Around 770 million people – 10% of the world’s population – are at “acute risk” of negative impacts from sea level rise, according to a report from the UN secretary general released last month.
(The report defines locations at acute risk as those that are less than five metres above the high-tide line.)
The people at risk include the residents of several of the world’s largest cities, including Mumbai and Kolkata in India and Shenzhen and Guangzhou in China. It also encompasses the entire populations of many island nations. (See: Small island developing states.)
There are two ways to consider sea level rise.
Global-average sea level rise is the amount the ocean surface has moved upwards, on average, relative to a baseline.
Relative, or local, sea level rise, is how much the ocean has risen in a given place. This can vary from the global average due to a number of factors, including land motion and ocean circulation, as well as changes to the Earth’s surface, rotation and gravitational pull due to the melting of the ice sheets.
Higher sea levels bring with them myriad dangers for coastal communities: they can increase persistent flooding and inundation, strengthen dangerous storm surges and erode beaches and cliffs. Sea level rise also causes the water table of coastal land to rise, which exacerbates flood risk.
The frequency of 100-year “extreme sea level events” has already increased 12-fold since 1900. These are events where high tides, storm surges and relative sea level rise combine to produce exceptionally high sea levels. Under a moderate-emissions scenario, these events are likely to occur at least annually – and, potentially, even more frequently – in many places by the end of the century.
In addition to damage to homes and other buildings, critical infrastructure – such as water systems and wastewater management projects – is increasingly vulnerable to flooding as a result of sea level rise. Flooding can cut communities off from essential services, such as hospitals and markets, with low-income and other marginalised groups disproportionately affected.
Inland encroachment of seawater leads to the saltwater intrusion and threatens agriculture in low-lying coastal areas.
Vertical land motion can also amplify the risk of rising seas. This includes a shifting of the land in response to seismic or volcanic activity or to land sinking, known as subsidence. The changes in local sea level due to these types of vertical motion can equal or surpass the contributions of climate-driven sea level rise.

Many of the coastal cities experiencing the largest changes in their relative sea level are located in east and south-east Asia. One notable example is Jakarta, Indonesia, which has been sinking by up to 15cm per year over the past decade, due largely to the overextraction of groundwater, which leads to the collapse of underground aquifers.
But even as the risks from sea level rise increase, population growth in coastal areas continues to outstrip that of inland areas. Between 2000 and 2018, the global population grew by slightly more than 23%. The population living within 5km of a coast increased by 28% over that same time.
The associated development of coastal areas means that, even without future sea level rise, global losses from flooding in the world’s largest 136 coastal cities could reach up to $52bn per year by 2050 – up from $6bn in 2005.
In response to the growing threats posed by sea level rise, communities around the world have implemented a number of adaptive actions.

In 2003, the Italian city of Venice began a years-long project to construct three floodgates that could be raised during high tide events to protect the city’s lagoon from the encroachment of the Adriatic Sea. The system was engaged for the first time in October 2020 and then another 48 times in the following two years.
Other communities have opted for less technologically intensive adaptations, including constructing seawalls, restoring mangrove forests and marshes, disincentivising development in high-risk areas and relocating residents, buildings and infrastructure to higher ground or inland areas.
However, existing adaptations may not be sufficient to protect communities. Under a low-emissions scenario, these protections may be breached 10 times as frequently over the next 30 years as they currently are.
Biodiversity and coastal ecosystems
The world’s coastal ecosystems are rapidly being destroyed due to both development and sea level rise.
This combination of pressures is called “coastal squeeze”, where ecosystems that may have otherwise shifted inland in response to sea level rise find their paths blocked by human-made structures.
Coastal squeeze has contributed to the widespread loss of the world’s wetlands.

Globally, nearly 28m hectares of coastal wetlands – including estuaries, tidal flats, mangroves and seagrass – have disappeared since 1970, according to the 2025 “global wetland outlook” report. This is an area equivalent to roughly the size of Ecuador.
Although the report names conversion to agriculture as the largest driver of wetland loss, it notes:
“Climate change is increasingly exacerbating the impact of other drivers on wetlands and human wellbeing through changes in the frequency and intensity of extreme weather events, associated fires, floods and droughts and through sea level rise.”
In the continental US, just 16% of coastal wetlands are migrating inland at rates that exceed local sea level rise. Nearly three-quarters of sites are moving at rates that do not outpace sea level rise, while 11% are submerging.
Low-lying islands are particularly threatened by sea level rise, due to their large amounts of coastline relative to their land areas. At the same time, islands are often “hotspots” of biodiversity, with many home to species found nowhere else in the world. More than 20% of the Earth’s known plant species are found only on islands.
A 2013 study modelled the impact of different amounts of sea level rise on 10 island biodiversity hotspots, comprising nearly 4,450 individual islands. It found that in a future with one metre of sea level rise, around 6% of the island habitat area would be completely submerged, while more than 11% of the hotspot islands would see their land area reduced by at least half. This could put dozens of species at risk of extinction, the study said.

In 2024, researchers documented the first known extirpation, or local extinction, of a plant species in the US due to sea level rise. Hurricanes and storm surges – amplified by sea level rise – began to kill off the only US population of the Key Largo cactus in the 2010s.
The remaining cacti suffered from soil erosion and saltwater intrusion and the final remaining specimens were removed in 2021 in an effort to cultivate them in greenhouses. (Other Caribbean islands, including Cuba, do still have surviving populations of the cactus.)
As native flora and fauna are diminished or even eliminated by rising sea levels, coastal ecosystems may become vulnerable to colonisation by invasive alien species, further harming biodiversity.
And as coastal communities are forced to relocate due to sea level rise, there are knock-on effects for biodiversity as they develop on new lands. These secondary biodiversity impacts are likely to be particularly prevalent in south-east Asia, due to the large number of people living in low-lying areas who may be forced to migrate due to sea level rise.
Small island developing states
Sea level rise poses an “acute and disproportionate” threat to small island developing states, says the recent UN report. It adds:
“Even under moderate scenarios, rising seas will render many low-lying coastal zones and small island developing states increasingly uninhabitable without extraordinary adaptation.”
Climate change is already resulting in loss and damage to small island nations, which are particularly vulnerable to both climate change in general and sea level rise specifically.
This vulnerability is in large part due to the geography of these countries. Several small island Pacific states are made up of atolls – ring-shaped coral or sandy islands that encircle lagoons. These often have average elevations of 1-2 metres above sea level and maximum elevations of 3-5 metres above sea level.

Some modelling evidence has shown that reef islands can grow vertically in response to sea level rise, as waves washing over the islands transport sediment from the ocean onto the surface. However, the strength of such waves would likely make these islands unsuitable for building on.
Other research has shown that Pacific islands respond in many different ways to rising sea levels, with “complex” outcomes, both positive and negative.
In addition, most of the small-island nations in the Pacific Ocean are located in a region where relative sea level rise from the melting of the Antarctic ice sheet is projected to be 11-33% higher than the global average rise in 2100 – regardless of emissions scenario.
The effects of this higher-than-average sea level rise is already evident.
In 1999, Kiribati lost two small, uninhabited islands to the rising seas. Several uninhabited islands in the Solomon Islands had vanished by 2014, while a further six islands had been severely eroded by the ocean, necessitating the relocation of some communities.
In addition, most small island developing states are located in parts of the ocean that are often hit by tropical cyclones. Sea level rise can enhance storm surge, leading to greater destruction during such storms.
However, small island developing states are also vulnerable “because they lack the means to address the impacts on their own”, reads the UN report.
According to the UN, these countries will require up to $6bn annually by 2035 in order to adapt to climate change. However, they received just $1.2bn in public adaptation finance in 2022-23.

Currently, small island developing states experience “expected” annual climate damages of $1.64bn due to coastal flooding, equivalent to 0.13% of their cumulative GDP. But, even if warming were limited to 1.5C above pre-industrial temperatures, these annual damages are projected to grow to $24bn.
In the international policy arena, questions have arisen over what should happen to island nations’ maritime boundaries as their land is enveloped by the sea. This is because maritime holdings, such as exclusive economic zones, are determined based on a country’s land borders.
However, a 2025 report by the UN International Law Commission considered the legal implications of sea level rise. It concluded that international law allows for countries’ borders to stay the same, “notwithstanding changes to the coastline as a result of climate change-related sea level rise”. It also noted:
“There is a need to develop legal and practical solutions to better protect persons affected by sea level rise, including those who remain in situ and those who are internally or externally displaced by it.”
Other small islands also face similar issues in their exposure to threats posed by sea level rise.
Coral reefs
Coral reefs are among the ecosystems that are most vulnerable to climate change.
They are also being visibly affected already – almost entirely due to ocean warming. Even though these ecosystems are completely submerged to begin with, they are also impacted by sea level rise.
As the ocean rises, the water over shallow ecosystems deepens.
The effects of this are twofold. Deeper water reduces the temperatures experienced by reefs. This can act as a buffer against marine heatwaves and global ocean warming.
At the same time, the increased depth reduces the amount of light that can reach the coral communities, which can impact their survival.
In addition, sea level rise-assisted erosion will add more sediment to the near-shore waters. These particles can settle on corals, impeding their ability to feed and reproduce, as well as interfering with photosynthesis by the zooxanthellae algae that live symbiotically with corals. Together, this leads to slower coral growth and increased stress on reefs.
So far, reefs in some parts of the world have been able to “keep pace” with sea level rise, growing vertically at accelerated rates and therefore maintaining suitable levels of light availability.
However, modelling has shown that few reefs have the capacity to continue to maintain their distance from the surface under a moderate-emissions scenario.

As coral reefs degrade, the seafloor below them can wear away. This erosion is contributing to greater apparent levels of sea level rise on coral reefs in the Caribbean, as well as the US states of Florida and Hawaii.
Sea level rise may also have the ability to spur reef growth in shallow environments previously thought to be uninhabitable for corals. In Sanya Bay in the northern South China Sea, sea level rise since the mid-1980s has allowed for the recolonisation of a reef that had been dormant for more than five millennia.
But the opportunities for such recolonisation are far outstripped by the loss of coral elsewhere. Since 1980, the world has lost nearly 10% of its coral cover due to climate change-induced ocean warming. The UN declaration reads:
“Every fraction of a degree of global warming increases the risks to coral reefs.”
Heritage sites
Throughout human history, many societies developed along rivers and coastlines, due to the abundance of food and ease of transportation. However, their proximity to the sea means that many of these sites are now at risk of being damaged or destroyed by sea level rise.
Cultural heritage includes “physical sites, living heritage, traditional lands, burial grounds, underwater cultural heritage, archaeological and sacred sites and culturally significant coastal landscapes”, according to the UN sea level rise report.

Several studies have mapped the cultural and natural heritage sites that are most at risk from flooding and erosion due to sea level rise.
There are 49 Unesco world heritage sites located at low elevations along the coast of the Mediterranean Sea. Nearly every one of these is already at risk from erosion or severe flooding events – 42 face issues with erosion, while 37 are at risk from a 100-year flood event. Both of these risks will increase over the remainder of the century as sea levels continue to rise.
The locations at risk include the archaeological sites of the ancient cities of Carthage in present-day Tunisia and Ephesus in Turkey, the ruins of Pompeii and Herculaneum in Italy and the medieval Cathedral of St James in Šibenik, Croatia.
The sea level rise associated with warming of 3C above pre-industrial temperatures would impact nearly one-fifth of all Unesco cultural world heritage sites. The sites at risk include Japan’s Hiroshima Peace Memorial, South Africa’s Robben Island, Chile’s Rapa Nui and the Sydney Opera House. Many of these become vulnerable at lower levels of global warming.

In Africa, 56 out of 284 cultural and natural heritage sites already face threats from flooding or erosion due to sea level rise. This number is expected to nearly triple – to 191 threatened sites – by 2050 under a moderate-emissions scenario. However, mitigating emissions could reduce the number of very-highly exposed sites – those with at least 75% of their area vulnerable – by one-quarter.
Globally, there are 386 Unesco heritage sites along the coast that are, at most, 20 metres above sea level and are therefore potentially affected by coastal erosion and flood hazards.
These threatened sites include 289 cultural heritage sites and 91 natural heritage sites, as well as six “mixed” sites that are recognised for both their cultural and natural significance.
The UN declaration calls for action to mitigate damage to significant sites, saying:
“Protection, preservation and documentation of cultural heritage is a priority.”
The post Explainer: How sea level rise poses an ‘existential threat’ to humans, heritage and nature appeared first on Carbon Brief.
Explainer: How sea level rise poses an ‘existential threat’ to humans, heritage and nature
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