Many pathways to staying below 1.5C delay deep cuts in carbon dioxide (CO2) emissions and rely instead on huge amounts of CO2 removal (CDR) later this century.
Land-based CDR is used extensively in the 1.5C pathways presented by the Intergovernmental Panel on Climate Change (IPCC) and also features heavily in the climate plans of many governments and businesses.
Yet the large-scale deployment of land-based CDR could come with major challenges. These include significant ecological and societal risks – particularly to biodiversity loss, food security, freshwater use and human rights, among others – which have not been comprehensively assessed.
In our new paper, published in Science, we assess the level of sustainability risks that could be triggered by the use of various different land-based CDR techniques, such as bioenergy with carbon capture and storage (BECCS) and afforestation and reforestation (A/R).
We show that risks are triggered at much lower levels of deployment than previously thought. Moreover, many of the “Paris aligned” 1.5C pathways presented by the IPCC would exceed the CDR sustainability limits defined by our evaluation.
CDR deployment in mitigation pathways
Many mitigation pathways assessed by the IPCC envisage large deployments of CDR throughout the 21st century.
This is significant because, although the IPCC is not “policy prescriptive”, these pathways – and the policy options within them – strongly shape the “solution space” as seen by policymakers when considering how to meet the goals of the Paris Agreement.
The use of CDR is particularly widespread in the pathways labelled by the IPCC as “1.5C with high overshoot”. In these pathways, emissions cuts are not fast enough to avoid breaching the carbon budget for 1.5C and global temperatures temporarily overshoot the 1.5C limit, before extensive use of CDR brings temperatures down later this century.
Within these pathways, CDR is deployed up to 2050 to help compensate for a slower transition away from fossil fuels, to reduce net emissions. When emissions reach net-zero, CDR is being used to counterbalance large remaining residual emissions. Beyond this point, it is used to draw-down global temperature after exceeding 1.5C.
This type of pathway is typified by the IPCC’s “Neg” illustrative mitigation pathway. Here, – some 5.1bn tonnes of CO2 (GtCO2) is taken out of the atmosphere using CDR in 2050 and 15.1GtCO2 in 2100.
In this pathway, one of five outlined in the IPPC’s sixth assessment report (AR6), primary energy from fossil fuel drops only 36% below 2020 levels by 2050 and 73% by 2100, relative to 2020.
This CDR and emissions profile is in sharp contrast to the IPCC’s “Ren” pathway – which relies on rapid scale-up of renewable energy – primary energy from fossil fuel falls 85% by 2050 and 95% by 2100, relative to 2020. (IMP-Ren)
This means that this renewable energy pathway has much lower reliance on CDR, which is only used to take 2.6GtCO2 out of the atmosphere in 2050 and 3GtCO2 in 2100.
Sustainability limits
The large amounts of land-based CDR in many of the pathways assessed by the IPCC come with significant implications in terms of sustainability, with the potential for serious impacts on human livelihoods and food security.
Yet the IPCC report does not comprehensively assess the environmental feasibility of the scenarios, nor their associated sustainability risks. Nor does it put a figure on the scale of CDR that could be deployed without triggering major impacts.
To address this gap, we quantified the sustainability limits to the widespread deployment of BECCS, A/R and “nature-based” CDR, which includes limited reforestation, forest restoration, reduced forest harvest and agroforestry.
To do so, we draw from recent studies that give greater attention to the ecological, biological and societal impacts of land-based CDR.
Based on these studies, we calculated the levels of CDR deployment that would trigger “low”, “medium”, “high” and “very high” risks for sustainability. These risk levels are colour-coded from green through to dark red, for each type of land-based CDR in the figure below.
Reading from left to right, the figure shows increasing levels of CDR deployment in terms of GtCO2 removed per year. The grey bar shows the range of “technical mitigation potential” for each technique, as currently assessed by the IPCC. The upper end of this is the largest amount that could theoretically be deployed, if barriers to rapid scale-up, constraints on feasibility and sustainability risks are not taken into account.
The figure shows that sustainability risks start well below the technical mitigation potential.
For BECCS, the IPCC reports an average technical potential of 5.9GtCO2 per year. Yet we find that deploying more than 1.2GtCO2 of BECCS per year would tip over from “low risk” into “medium” or higher risk levels.
(This figure is based on BECCS plants capturing a “medium” share of their associated CO2 emissions, below 70%. For a “low” capture rate below 50%, the low-risk threshold drops to just 0.7GtCO2 per year.)
Correspondingly, BECCS would cross the high sustainability risk threshold (shown in red) if used to remove 1.3GtCO2 with a low capture rate – or 2.8GtCO2 with a medium rate.
Even these limited levels of BECCS assume significant bioenergy policy reforms that governments have not yet addressed. These include addressing gaps in emissions accounting and ensuring bioenergy is not causing deforestation, either directly or indirectly.
For A/R, the IPCC average technical potential is 3.9GtCO2 a year. Our research shows that associated sustainability risks remain low or medium below 3.8GtCO2 per year, with high risks beyond that point.
We find that nature-based CDR (which includes limited reforestation) carries the lowest sustainability risks. Deployment would trigger high risks beyond 5.1GtCO2 a year (including 3.8GtCO2 per year of non-monoculture reforestation).
Having defined risk levels for each type of CDR, we then mapped those indicators onto the amount of CDR deployed in each of the IPCC’s five “illustrative mitigation pathways” (IMPs).
(These pathways are: gradual strengthening of climate policy, GS; widespread use of CDR, Neg; low energy demand, LD; shifting pathways towards sustainable development, SP; and heavy use of renewables, Ren.)
Our results, illustrated in the table below, show that the three pathways that limit warming to 1.5C with limited to no overshoot are able to do so without greatly overstepping our sustainability risk thresholds.
In contrast, Neg limits warming in 2100 to 1.5C with high temperature overshoot, but exceeds high and even very high sustainability risk thresholds. The GS pathway only limits warming to 2C and still carries significant levels of sustainability risks.
Reading the table from top to bottom, the first set of rows list the change in CO2 emissions, energy demand and fossil fuel use in 2050 and 2100.
The second set of rows show the amount of each type of CDR deployed in 2050 and 2100, colour-coded according to our sustainability risk levels.
The third set of rows show the amount of land needed for CDR deployment – the land footprint. Again, these are colour-coded according to our sustainability risk levels.
Notably, our findings show that the amount of land needed for CDR in the Neg pathway could reach 7.2m square kilometres in 2050 and 13.3m square kilometres in 2100. For comparison, the land area of the US is just 9.1m square kilometres.
Risk assessment
Our findings suggest there is an urgent need to consider sustainability risks when choosing between different mitigation pathways.
One way to do this would be to define a “sustainable CDR budget”, as the amount of CDR that could be deployed sustainably across all CDR methods.
While our research only considered land-based CDR, alternative CDR options are also likely to come with sustainability and deployment risks, which could limit their potential. These include direct air carbon capture and storage (DACCS) or ocean-based CDR.
Another option would be for scientists to identify Paris-aligned scenarios that do not overstep sustainability limits. Our research suggests that this could be a key priority for the IPCC’s seventh assessment cycle, as well as integrating environmental risks and feasibility throughout the IPCC’s work.
Moreover, our findings suggest that delaying fossil fuel cuts, in the hope that emissions can be drawn down later this century using CDR, would come with high sustainability risks.
If, on the other hand, countries wish to account for biodiversity considerations alongside climate goals, while still limiting temperatures to 1.5C, then they would need to follow a mitigation pathway with more rapid cuts in fossil fuel use, our research suggests.
Many of these pathways include behaviour changes and reductions in energy demand.
Countries could take up our findings in their next nationally-determined contributions (NDCs) under the Paris Agreement, due in 2025. For example, they could address sustainability risks by setting separate, transparent targets for CDR, in addition to headline emissions goals.
They could also aim to limit their reliance on CDR – and its corresponding land footprint – in order to avoid climate actions that have negative consequences for their national biodiversity plans under the global biodiversity framework (NBSAPs).
The post Guest post: Heavy use of CO2 removal would trigger high sustainability risks appeared first on Carbon Brief.
Guest post: Heavy use of CO2 removal would trigger high sustainability risks
An Lambrechts is a biodiversity politics expert at Greenpeace International with extensive experience in biodiversity-related multilateral negotiations. She is the head of the Greenpeace delegation at the Convention on Biological Diversity (CBD) COP17 happening in Yerevan, Armenia.
In 2022, COP15 delivered the landmark Kunming-Montreal Global Biodiversity Framework to halt and reverse biodiversity loss by 2030. With COP17 starting in Yerevan, we are now halfway to the deadline, and according to the first Global Review of progress, countries are not on track to meet the biodiversity targets, and implementation must accelerate fast.
One of the main findings of the Global Review is that funding falls far short of the scale needed to halt and reverse nature loss. But the crisis facing the world’s biodiversity is not an absolute scarcity of capital – it is a profound public policy distortion.
The global economy currently spends roughly $30 destroying nature for every single dollar invested in its protection. According to a report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, a staggering $2.4 trillion is spent in public subsidies for fossil fuels, agriculture and water use, while global investment in biodiversity conservation and restoration stands at a mere $220 billion.
Countries urged to ramp up “insufficient” nature policies at COP17
Yet, discussions about how to close the biodiversity finance gap continue to claim that salvation lies in mobilising private capital, scaling offsets and “derisking” investments in nature. This is a fundamental misunderstanding of both the nature of ecological stewardship and of the global financial architecture.
Biodiversity conservation is not a speculative investment portfolio – it is the foundation of human survival. The health of our planet is a non-monetisable, non-excludable public good. Expecting profit-seeking private capital to protect nature perpetuates the structural drivers of ecosystem destruction in the first place.
But if private market mechanisms cannot save biodiversity, where will the necessary public resources come from?
Money going to the wrong places
The answer lies in recovering the vast public wealth currently drained by cross-border tax abuse, financial secrecy and corporate impunity. Finance and environment ministers meeting in Yerevan must give a strong political signal that, to avert ecological breakdown, countries need to take swift action to reform global tax rules, eliminate harmful public subsidies and cancel unsustainable sovereign debts for the public revenues to end up where they belong.
Extractive sectors such as industrial agriculture, fishing, timber and mining continue business-as-usual, often heavily subsidised by public treasuries, while voluntary carbon and biodiversity offset markets pose a serious risk to nature conservation. Offset schemes have delivered only a negligible fraction of the funding needed to preserve ecosystems, allowing industries to continue with their destructive business-as-usual practices.
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In advanced economies, public funding often actively undermines biodiversity. In Europe, over €5.3 billion in public subsidies is funnelled annually into intensive forest biomass harvesting under renewable energy directives, degrading primary forest ecosystems and undermining long-term climate resilience. Pleading with private investors to fill a “finance gap” while pouring billions into ecological destruction is an exercise in futility.
Developing countries struggle with debt burden
For developing countries, reliance on private finance is further compounded by a crushing sovereign debt crisis. In 2024, public debt in developing economies reached record levels, with net interest payments alone absorbing $921 billion. A record 61 developing countries now spend more than 10% of government revenue on foreign debt service, with many climate-vulnerable nations spending twice as much servicing external debt as they receive in climate and biodiversity finance combined.
This burden acts as a structural driver of ecosystem destruction. Under pressure from external creditors and international financial institutions to avoid default and secure foreign exchange, governments are routinely forced into austerity measures and pushed to expand raw commodity exports into pristine biomes.
Comment: World Bank and IMF should lead the financial system in responding to the climate crisis
The current negotiations for a United Nations Framework Convention on International Tax Cooperation (UNFCITC) also offer a way forward. An estimated $492 billion in tax revenue is lost every year to offshore tax havens. Multinational corporations account for around $348 billion of this total by shifting profits away from the countries where real economic extraction and environmental degradation occur.
In the mining sector alone, developing nations lose tens of billions annually to corporate tax dodging. Furthermore, international financial secrecy shields environmental criminals, with illicit financial flows from illegal logging draining between $51 billion and $152 billion annually.
At COP17, leaders must seize the opportunity to build a bridge between the two conventions and enhance cooperation. Governments must put the world on a firm path to securing predictable, sufficient, sovereign public finance for biodiversity conservation. It’s the only path to a restorative, rights-based future for people and the planet.
The post Protecting nature is a public duty, not a Wall Street profit opportunity appeared first on Climate Home News.
Protecting nature is a public duty, not a Wall Street profit opportunity
Climate Change
Greenpeace delivers 47 metre-long petition with half a million signatures to Woodside HQ following major gas protest
Greenpeace delivers 47 metre-long petition with half a million signatures to Woodside HQ following major gas protest
PERTH, Monday 19 October 2026 — Dozens of Perth community members delivered a giant petition, signed by almost half a million people, to Woodside’s corporate headquarters this morning, calling on the government to save Scott Reef from Woodside’s reckless Browse gas proposal.
Dressed in sea creature costumes and hats, supporters carried one of Australia’s biggest environmental petitions to Woodside’s headquarters, and a local choir performed a ‘Scott Reef’ rendition of Angie McMahon’s iconic cover of ‘Reckless’ by Australian Crawl.
On the sidelines of the Perth Global Citizen Now event, it comes following a two day-long protest at Woodside’s Scarborough gas platform that saw activists scale and occupy the Floating Production Unit calling to “Stop Woodside’s Dirty Gas” and “Save Scott Reef”. The activists were taken from the platform by police helicopter on Sunday afternoon.
David Ritter, CEO at Greenpeace Australia Pacific, said: “Less than a day after two Greenpeace Australia Pacific activists were arrested for their peaceful protest at Woodside’s Scarborough gas platform to save Scott Reef, we are here again with another message to Woodside: half a million of us do not want your dirty gas at Scott Reef.
“Community pressure on Woodside is rising. Today we are here to show Woodside that they can’t ignore half a million people who want Scott Reef protected, not turned into an industrialised gas zone.
“Woodside can’t be trusted with our oceans. Woodside’s plans to drill up to 57 toxic wells at Scott Reef, Australia’s largest oceanic reef, putting endangered pygmy blue whales at risk, and jeopardising a nesting ground for unique green sea turtles.
“We Australians love our oceans and this is an opportunity for our governments to do the right thing, to reject Woodside’s reckless drilling plans, and save Scott Reef.”
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Media contact
Kate O’Callaghan on +61 406 231 892 or Emma Sangalli on +61 431 513 465
Climate Change
Greenpeace Australia Pacific activists in police custody after two-day protest against Woodside’s Browse gas project at Scott Reef
PERTH, Sunday 18 October 2026 — Two Greenpeace Australia Pacific activists are in police custody after occupying a gas platform at Woodside’s Scarborough gas project, in peaceful protest of the fossil fuel corporation’s plans to drill for oil and gas at Scott Reef.
NEW footage and photos of the peaceful protest available here and on Instagram
The activists used specialised climbing equipment to scale and attach themselves to a Floating Production Unit (FPU), a key piece of gas processing infrastructure at the Scarborough gas field over 200km off the coast of Exmouth, at around 05:45am AWST on Saturday and proceeded to occupy the platform for two days, displaying banners reading “Stop Woodside’s Dirty Gas. Save Scott Reef.”
Special police forces landed a helicopter on the FPU at around 11:30am AWST. The activists safely removed themselves from their equipment before being taken into police custody around 1:00pm AWST. At the time of writing, no charges have been laid.
David Ritter, CEO at Greenpeace Australia Pacific, said: “It takes guts and conviction to do what our activists have done, peacefully protesting Woodside’s reckless gas plans at Scott Reef.
“Woodside’s plans to drill up to 57 toxic wells at Scott Reef are outrageous. If allowed to go ahead Woodside would turn Scott Reef, Australia’s largest oceanic reef, home to nesting green sea turtles and elusive pygmy blue whales, into an industrial gas zone. Around half a million people have called on our governments to stop Woodside and to save Scott Reef.
“Our activists are highly trained and experienced in these activities. West Australia has a proud history of peaceful, democratic protest at sea, to protect our oceans from environmental threats. From whaling in Albany in the seventies, to Woodside’s threat to Scott Reef today, there’s more than fifty years of history, of Greenpeace taking action off WA’s coast to protect the places we love.
“Peaceful protest has long been part of what has given us so many of the things that are great about Australia and is part of the fabric of our democracy and our national identity.”
“The right to peaceful protest is fundamental to a healthy democracy. From Australia to the Arctic and the Amazon, Greenpeace has been peacefully protesting for more than 50 years to expose the biggest environmental threats around the world. We will not be silenced by corporations like Woodside who actively try to stop everyday people from speaking out against their reckless plans.
“Woodside’s reckless proposal to drill at Scott Reef is an unacceptable risk to Scott Reef and to the climate, which our government should emphatically reject.”
Speaking from the Rainbow Warrior, Captain of the Rainbow Warrior Hettie Geenen, said:
“It felt powerful watching from the Rainbow Warrior as these brave activists scaled Woodside’s enormous and imposing gas infrastructure, which has no place at Scott Reef. We are all out here because we feel an urge to act, in the face of Woodside’s grave threat to Scott Reef and to our climate. Now we ask for the Australian government to act too, and reject Woodside’s reckless Browse project.
“Just before this peaceful protest, the Rainbow Warrior sailed to Scott Reef, where our whole crew got to witness the magic of an untouched, healthy reef ecosystem full of marine life. It was my second time visiting Scott Reef with the Rainbow Warrior. When you see Scott Reef up close and witness its magic first hand, it is impossible not to feel driven to try and protect it.”
The activists sailed to Scarborough on the Rainbow Warrior, Greenpeace’s flagship vessel, which is in the region campaigning to protect Australia’s oceans, including Scott Reef.
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Media contact
Greenpeace Australia Pacific media team in Perth on +61 406 231 892 or +61 407 581 404 or email media.au@greenpeace.org