Cutting emissions in line with the 1.5C warming limit, rather than following current climate policies, could curb long-term sea level rise by 64cm, a new study says.
The research, published in Nature Climate Change, projects how much sea level rise will be unavoidable – or “locked in” – by the year 2300, due to emissions over the coming decades.
According to the authors, 29cm of global average sea level rise is already in the pipeline due to the emissions that were released up to the year 2020.
Following current climate policies until the year 2090 will “lock in” an additional 79cm of sea level rise for the year 2300, the study finds.
However, reducing emissions in line with 1.5C would cut this additional sea level rise to 15cm.
The analysis shows that “if we reduce emissions rapidly in the coming decades, there is a clear path to limiting the legacy of sea level rise”, the lead author of the study tells Carbon Brief.
The study also explores regional sea level rise, showing that Pacific small-island nations will face some of the highest rates of sea level rise.
A scientist not involved in the research tells Carbon Brief that the paper “exposes a deep inequity” between nations, arguing that this makes “ambitious” action to cut greenhouse gas emissions “not just a climate necessity, but a climate-justice imperative”.
‘Locked in’
Average global sea level has risen by more than 20cm since 1900, driven mainly by human-caused climate change through thermal expansion of the ocean and the melting of glaciers and ice sheets.
Rising seas are already threatening to wipe out small-island nations, jeopardising the security, livelihoods and cultures of people who live in these areas. Meanwhile, coastal regions around the world are facing more frequent flooding, erosion and saltwater intrusion.
The authors of the new study explain that emissions released over the coming decades will affect global sea levels for hundreds of years. This is because the oceans and ice sheets respond slowly to past and present warming, they note.
The authors call this “locked in” or “committed” sea level rise.
The study explains that sea level projections are generally based on 21st century emissions pathways, but notes that “late-century emissions then dominate the longer-term sea-level response and mask the impact of near-term emissions”.
In contrast, this study assesses the impact of emissions both early and late in the 21st century – including past emissions and those projected to occur under different emissions pathways. The research investigates how much sea level rise will be locked in by the year 2300 through these emissions.
According to the authors, 29cm of global average sea level rise, compared to 1995-2014, is already locked in due to the emissions that were released up to the year 2020.
Rising seas
The study uses emulators – simple climate models with lower time and computational costs than full-scale Earth system models – to model how much sea level rise will be locked in by 2300 due to 21st century emissions.
The authors chose five emissions pathways and ran multiple model runs where they simulated sudden stops in emissions at the end of each decade for each pathway. This allowed them to isolate the emissions just until these dates.
For example, modelling a sudden drop in emissions in the year 2050 allows the authors to calculate how much sea level rise over the next two centuries is driven solely by human-caused emissions released over the next two decades.
The authors use five emissions pathways:
- SSP1-1.9: A very-low emissions reductions pathway “consistent with” the Paris Agreement’s 1.5C limit
- SSP1-2.6: A “low” emissions pathway consistent with 2C of warming
- SSP2-4.5: A “current climate policy-like trajectory”
- SSP3-7.0: A “high” emissions pathway
- SSP5-8.5: A “very-high emissions” pathway
The left-most panel shows how much additional sea level rise is locked in for the year 2300 due to emissions produced between 2020 and 2030. The next three panels show the results for emissions produced between 2020 and 2050, 2070 and 2090, respectively.
The plot shows that higher levels of greenhouse gas emissions lock in more sea level rise for the year 2300.
The authors find that, under the SSP2-4.5 “current climate policies” scenario, human-produced greenhouse gas emissions over 2020-50 will lock in an additional 29cm of sea level rise by the year 2300. This number grows to 79cm when including emissions out to 2090 under this scenario.
Meanwhile, under the scenario consistent with the 1.5C limit, only 15cm of additional sea level rise will be locked in by 2090.
This means that efforts to cut greenhouse gas emissions over the coming decades could curb long-term sea level rise by an extra 64cm.
The study authors say that their results “reinforce how every increment of additional peak warming from cumulative emissions irreversibly increases sea level rise”.
Dr Alexander Nauels is a science adviser at Climate Analytics and lead author on the study. He tells Carbon Brief that the world is “already committed to a really substantive amount of sea level rise” and stresses that this must be considered in terms of “adaptation, planning and risk management”.
However, he adds, “if we reduce emissions rapidly in the coming decades, there is a clear path to limiting the legacy of sea level rise that we would produce in the coming decades”.
Dr Catia Domingues, is a researcher at the UK’s National Oceanography Centre and was not involved in the study. She tells Carbon Brief that the study’s methodology is “clever and necessary”. She adds:
“[The study] clearly shows how the emissions from just the next 30 years, under current climate policies, will write an irreversible chapter for centuries to come, locking in significant sea level rise on their own.”
Warming levels
The authors also calculate the committed sea level rise at different warming levels.
The chart below plots sea level rise against warming level for every scenario and time period used in the study. It highlights how higher levels of warming commit the world to ever higher seas.
Committed sea level rise by 2300 at different warming levels, under SSP1-1.9 (light blue), SSP1-2.6 (dark blue), SSP2-4.5 (yellow), SSP3-7.0 (red) and SSP5-8.5 (dark red) pathways. Circles, X’s, squares and crosses indicate data points for 2030, 2050, 2070 and 2090 respectively. The green and blue lines show the 1.5C and 2C temperature thresholds. Source: Nauels et al (2025).
The authors note that the relationship between global temperature and committed sea level rise to 2300 is not “linear”, noting that the amount of sea level rise that is locked in by warming accelerates as global temperatures rise.
The authors explain that this is due to a “non-linear increase in ice mass loss in a warmer world” – in other words, physical feedbacks mean that higher levels of warming could see disproportionately large increases in ice losses.
Nauels tells Carbon Brief many sea level processes, such as ice-sheet responses, are still not “fully understood”. This means that when looking out to 2300, there can be “large uncertainties” in results, he adds.
Nevertheless, he argues that it is “still very important to explore the longer-term sea level response, because of the huge risk that is attached to it”.
Inequity
The main findings of the study focus on global average sea level rise. However, the authors note that sea level rise is not consistent across the world, with some regions facing faster rates of sea level rise than others.
This is largely due to ocean currents, driven by wind, warming, evaporation and rainfall, which push large masses of water around the planet. It is also caused by the bumpy, non-uniform surface of the earth.
To show these differences, the authors also selected a handful of coastal regions to study.
Nauels tells Carbon Brief that the study authors decided to focus on a handful of regions that “diverge” from the average global trend.
For example, they find that Pago Pago – the capital of American Samoa, which is made up of a string of coastal villages – will experience greater committed sea level rise than the global average.
On the other hand, Oslo is experiencing “land uplift” and actually shows a drop in sea level under the lowest warming scenario.
The NOC’s Domingues tells Carbon Brief that the study “exposes a deep inequity” between nations. She adds:
“This makes ambitious mitigation not just a climate necessity, but a climate-justice imperative.”
The post Rapid emissions cuts would avoid 64cm of ‘locked in’ sea level rise by 2300 appeared first on Carbon Brief.
Rapid emissions cuts would avoid 64cm of ‘locked in’ sea level rise by 2300
The head of the United Nations has launched an initiative aimed at holding artificial intelligence companies accountable for their exploding environmental impacts, including their carbon emissions, the amount of water and land used for data centres, and the energy they consume.
During a speech at London Climate Action Week on Tuesday, António Guterres noted that AI can accelerate climate solutions, among other key challenges, and said its potential must be harnessed.
“But AI is also hungry for land, water and power,” he emphasised, adding that the data centres needed to run AI models already consume more electricity than most countries.
The UN Secretary-General repeated a call he first made in July 2025 for all big AI companies to commit to power every data centre with renewable energy by 2030.
Some tech firms have announced they are sourcing or building out clean energy to run their hubs, but growing power demand is also contributing to gas-fired generation in the US, according to data from Global Energy Monitor.
The International Energy Agency (IEA) estimates that data centres are set to more than double the emissions from the electricity they use between 2024 and 2030 in a high-growth scenario. But AI’s use could lead to far larger reductions in the energy sector through efficiency gains if adopted widely.
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‘No more hidden costs’
Proposing the new “AI Environmental Transparency Initiative” on Tuesday, Guterres also urged big AI firms companies to measure and publicly disclose the full environmental impact of their systems, including their carbon, water, and land footprints.
“No more hidden costs. No more shifting the burden onto those least able to bear it. It is time to come clean,” he said in a major speech on responding to the world’s twin climate and energy crises. “If AI is to help build a better future, it must be honest about what it costs us now.”
A report issued earlier this month by the UN University Institute for Water, Environment and Health noted that most current assessments of AI’s environmental cost focus on carbon emissions from training models. But, it added, this misses a substantial part of the picture.
Every kilowatt-hour of electricity for AI also carries a water footprint, from cooling and generation, and a land footprint, from infrastructure and supply chains, it said.
Explainer: Will AI data centres make or break the energy transition?
The report estimated that AI data centres globally could consume 945 terawatt-hours of electricity annually by 2030 – more power than all but five countries and roughly twice France’s 2025 consumption.
Offsetting this carbon footprint by 2030 would require growing some 6.7 billion trees over 10 years, it calculated. Producing power for the data centres would consume water equal to the basic needs of 1.3 billion people in sub-Saharan Africa for a year and take up land of more than 14,500 square kilometers, roughly twice the Jakarta metropolitan area.
The European Union said earlier this month it will develop minimum energy-efficiency standards for both new and existing data centres, with a “needs assessment” due by 2027, Reuters reported. It’s also planning a sustainability label for data centres, covering criteria including water use and clean energy supply – but that has been delayed.
US community push-back
Asked after his speech what the response had been, the UN chief said “we’ll see”, without giving more details.
But, he argued that, in his view, the push for transparency “is perfectly reasonable and even positive for the AI industry, because eventually some people will say that they consume much more than they really do”. “I think the truth is essential,” he added.
Concerns about the environmental impacts of AI and the infrastructure needed to run the technology have led to growing opposition in some communities, especially in the US.
This month, Monterey Park in Los Angeles County was the first city in the United States to enact a citywide prohibition on data centres through a voter-approved ballot measure. The developers behind a proposed centre in the area had already pulled the project in April amid an increasingly hostile local environment and regulatory uncertainty.
The vote that stopped a data center: US communities query resource-hungry AI
According to nonprofit Data Center Watch, around $64 billion-worth of data centre projects nationwide were delayed or blocked between May 2024 and March 2025 as communities pushed back against them.
Industry lobby groups argue that data centres can provide economic benefits in their host communities. According to the US-based Data Center Coalition, which represents big operators and developers, data centres generate tax revenue, support construction and technical jobs, and provide infrastructure needed for cloud computing, scientific research and AI development.
The industry has also challenged claims that data centers necessarily raise electricity costs for households.
Force for good?
The UN chief said benefits can be few in the places that are home to the data centre, while “communities are often left in the dark about the environmental impact of the infrastructure rising around them”.
Guterres said companies have an “obligation” to be clear and open about the services they are offering but also the level of resources they require.
“Transparency is essential for the decisions that communities must make – and transparency is essential even for the future of artificial intelligence, and to make sure that artificial intelligence is essentially a force for good,” he told an audience of climate professionals in London
A senior UN official told journalists ahead of Tuesday’s announcement that the AI industry has started to talk about and disclose some of their impacts, but those efforts are not yet comprehensive enough.
The hope is that the new initiative will “encourage the industry to come together and take further action on it”, the official said.
The post UN asks AI companies to reveal full environmental impacts appeared first on Climate Home News.
Phillipe Ciais has spent almost four decades researching the planet’s carbon cycle – and the ways in which humans have been impacting its balance.
Based at the Laboratoire des Sciences du Climat et de l’Environnement (LSCE) on the outskirts of Paris, Ciais (pronounced “see-es”) has been listed as an author on more than 1,300 peer-reviewed studies.
In fact, analysis of Carbon Brief’s Cosmos database reveals that – by some distance – he is the most highly cited climate scientist in the world.
In a wide-ranging interview, he discusses:
The post Prof Philippe Ciais: The world’s most highly cited climate scientist appeared first on Carbon Brief.
https://www.carbonbrief.org/prof-philippe-ciais-the-worlds-most-highly-cited-climate-scientist/
Climate Change
Cited 23 June 2026: Project Cosmos launch | Science ‘under attack’ at Bonn | Emissions inequality
Welcome to Cited, your essential guide to new climate research.
In the news
SCIENCE ‘UNDER ATTACK’: Climate Home News reported that “dozens” of countries called out “coordinated attacks” aimed at “undermining the role of climate science” at UN climate talks in Bonn, Germany, last week. According to the outlet, the countries said that UN decision-making had to remain based on the “best available science”, including the reports of the Intergovernmental Panel on Climate Change. One negotiator said that India and Saudi Arabia “opposed calls in draft texts to encourage scientific work on scenarios that would minimise the magnitude and duration of any overshoot of 1.5C”, the article noted. For more, read Carbon Brief’s summary of the negotiations.
REPORT OPPOSITION: “Oil industry allies” in the US are targeting a report on extreme weather attribution, due to be published by the National Academies of Sciences, Engineering and Medicine, according to Politico. The outlet reported that the “heightened scrutiny – which involves a secretive opposition research group scouring scientists’ emails – has prompted two people to leave the 15-person panel tasked with producing the report”. Separately, the Guardian reported that the Trump administration has “reversed its decision” to dismantle the Ocean Observatories Initiative, a $368m deep-sea observation system.
SUPER EL NIÑO: BBC News reported that the US National Oceanic and Atmospheric Administration announced that El Niño had “officially begun”. Forecasts suggest the event could be among the “strongest ever recorded”, it added. Meanwhile, a “vigorous debate” is taking place about whether climate change is making the El Niño phenomenon more intense, according to the New York Times. The outlet explained that some scientists see the run of “comparatively strong” El Niño events in recent decades as an indication that “climate change is supercharging El Niño”. However, it added that “others say there is no clear evidence to support that theory”.
Research picks
Water
- Global sea level rise has nearly tripled the number of days since the 1970s when coastal water levels have surpassed average tide gauge readings | Science Advances
- As the Arctic warms, increased iceberg activity could “reshape” deep-sea habitats and “elevate” navigational hazards as maritime traffic expands | Nature
- Sea level rise has quadrupled the frequency of extreme coastal sea-level events since the year 1900 | Nature Climate Change
Inequality
- The top 10% of consumers are responsible for $1.7-5.7tn of environmental damage each year, surpassing international climate and biodiversity financing gaps | Communications Sustainability
- Calculating an individual’s emissions based on their asset ownership suggests that wealthier people are responsible for an even higher share of global greenhouse gas emissions than indicated by past studies | Nature Climate Change
- A plan that places equity at the “centre” of climate adaptation efforts in cities is needed to address the “stark disparities” between “affluent” and “disadvantaged” urban communities’ ability to prepare for extreme heat | PLOS Climate
Extremes
- In the western US, 42% of burned area over 2001-24 occurred during, and immediately following, heatwaves | Science Advances
- “Hot-to-wet” whiplash events have become more frequent across Australia over the past century, with south-eastern Australia emerging as a hotspot | Journal of Climate
- Rapid urbanisation, combined with more intense rainfall from tropical cyclones, have increased people’s exposure to “extreme” rainfall from tropical cyclones across China | Journal of Hydrometeorology
Captured
One billion additional people face at least one day of “extreme heat stress” every year compared to the 1970s, according to research published in Nature Climate Change.
The chart shows changes in “strong” (top), “very strong” (middle) and “extreme” (bottom) heat stress, defined as a “universal thermal climate index” above 32C, 38C and 46C, respectively. The grey bar shows the percentage of the global population exposed to at least one, 30 or 90 days of heat stress in 1970. The light and dark blue bars show the number of additional people experiencing heat stress over 2015-24 due to population growth and rising global temperatures, respectively.
10%
Equivalent damage to the UK’s GDP caused by climate change if global warming reaches 4C by 2100, according to new research in Nature Climate Change. The study estimates a range of 2-20%.
Spotlight
Introducing: Project Cosmos
Carbon Brief explains how it built a major new database of climate science research and unveils a new ranking of the 500 most highly cited publications, authors and institutions in climate science.
This week, Carbon Brief launched Project Cosmos – the world’s largest and most complete database of climate change research.
The database features more than 1.8m academic papers, books and reports, capturing the vast body of human knowledge about climate change that has accumulated over more than a century of academic study.
The climate science “universe” is based on reports from the Intergovernmental Panel on Climate Change (IPCC), which are recognised as the world’s most authoritative summaries of the latest climate science.
Since its first report was published in 1990, humanity’s knowledge about human-caused climate change has ballooned. The IPCC has published six sets of reports in total – each one longer than the last.
In total, IPCC reports reference more than 100,000 other papers, books and reports. This is the core of our climate science universe. Carbon Brief then built on this core, by looking at four other sources of data. Read more about how the Cosmos database was created here.
Every single publication in the Cosmos database is linked to at least one other through references. Visualising these links reveals a “galaxy” of references. In the image above, each colour and cluster reveals different topics and densities of research. Explore the galaxy in an interactive map here.
Cosmos 500
As part of an initial wave of preliminary analysis to demonstrate the scope of the Project Cosmos database, Carbon Brief has ranked the 500 most highly cited publications, authors and institutions in the database.
The most highly cited climate scientist is Prof Philippe Ciais, who has spent almost four decades researching the planet’s carbon cycle – and the ways in which humans have been impacting its balance. Carbon Brief recently interviewed Ciais in Paris.
The US tops the tables for the most highly-cited authors and institutions. Almost half of the 500 most highly-cited authors are from US institutions. This raises particular concerns for the future of climate science, as American climate scientists and institutions are coming under attack under the Trump administration.
Experts from global south countries account for only 4% of all authors in the Cosmos 500. China stands out as the most highly-cited global south country. Meanwhile, only 10% of authors in the Cosmos 500 are women.
There are many possibilities for future avenues of research using the Cosmos database. Over time, the database could be used to reveal, for example, how interest in different areas of climate science has changed over time, plus identify potential knowledge gaps and, thus, opportunities for future research.
Carbon Brief invites researchers – including academics, journalists and analysts – to submit their own proposals for co-authored studies, literature reviews and analytical projects.
Preprints to watch
Carbon Brief’s pick of new papers still going through peer review
- Regional reductions in aerosol emissions can “temporarily amplify” the likelihood of record-breaking heat events | Environmental Research: Climate
- Analysis of Reddit posts suggests the Fridays for Future movement has created “wider awareness” of global warming by drawing attention to climate change and “climate actions” | npj climate action
- Periods of simultaneous low wind and solar power generation, known as “renewable energy droughts”, will “intensify progressively” as the planet warms | Nature portfolio
Noticeboard
- 28-30 June: Seventh global conference on climate and sustainable development goal synergies, Bangkok, Thailand
- 29 June-1 July: Exeter climate conference, Exeter, UK
- 29 June-1 July: National Academy of Sciences hybrid workshop on seabed critical mineral resources, Irvine, US
- 30 June: Submission deadline for abstracts for MedCLIVAR conference, scheduled for 21-25 September in Limassol, Cyprus
- 30 June: Application deadline for postdoctoral position in ice-ocean interactions at the Physics Laboratory of Ecole Normale Supérieure de Lyon | Salary: €3,071-4,714 per month. Location: Lyon, France
- 30 June: Submissions open for abstracts for the pan-African conference on environment, climate change and health, scheduled for 21-24 October in Nairobi, Kenya
- 8 July: Application deadline for position as research officer in climate science and law at the Grantham Research Institute | Salary: £43,277-51,714. Location: London, UK
- 10 July: Application deadline for position as associate or senior editor at Nature Water | Salary: Unknown. Location: Shanghai, Beijing or Milan
Cited is researched and written by Cecilia Keating, Robert McSweeney, Ayesha Tandon, Daisy Dunne and Dr Giuliana Viglione.
Please send tips, feedback and upcoming climate research to cited@carbonbrief.org
This is an online version of Carbon Brief’s fortnightly Cited email newsletter. Subscribe for free here.
The post Cited 23 June 2026: Project Cosmos launch | Science ‘under attack’ at Bonn | Emissions inequality appeared first on Carbon Brief.
Cited 23 June 2026: Project Cosmos launch | Science ‘under attack’ at Bonn | Emissions inequality
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