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
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.”
-ENDS-
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.
-ENDS-
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
Climate Change
GREENPEACE GAS PROTEST DAY TWO: Activists spend first night on Woodside’s Scarborough gas platform, “in this for the long haul”
- NEW footage and photos available here and on Instagram – more being uploaded today.
- Interviews available with campaigners on board the Rainbow Warrior on request.
Greenpeace Australia Pacific activists have slept overnight on Woodside’s Floating Production Unit and dropped a massive 12×14-metre banner reading “Stop Woodside’s Dirty Gas. Save Scott Reef”.
Two activists have set up temporary hanging tents on the South East pillar, while the other two returned to the Rainbow Warrior late yesterday afternoon, after fulfilling their initial role. The activists will occupy the platform for as long as possible.
The environmental advocacy group is peacefully protesting Woodside’s plans to drill for oil and gas at Scott Reef as part of its Browse proposal.
Sakyo Noda, one of the Greenpeace Australia Pacific activists, said: “As a Japanese person living in Australia, I feel incredibly passionate about stopping Australia’s gas exports to Asia.
“Despite what the gas industry tells us, Australia’s gas is not helping to decarbonise Asia. It is simply not true. We shouldn’t be allowing fossil fuel companies like Woodside to extract new fossil fuels, let alone at extraordinary places like Scott Reef”.
Aboard the Rainbow Warrior, Geoff Bice, WA Campaign Lead at Greenpeace Australia Pacific, added, “Everyone is in good spirits. We’re in it for the long haul.”
Links:
Photos and video of Scott Reef here
Audio and footage of yesterday’s press conference here
Content and live updates will be uploaded to a live blog and Instagram
In-person interviews in Perth with David Ritter, CEO of Greenpeace Australia Pacific, can be organised. Dial-in, SimSat and Zoom interviews with Geoff Bice, WA Campaign Lead at Greenpeace Australia Pacific, currently aboard the Rainbow Warrior, can be organised.
Greenpeace delivers 47 metre-long petition with half a million signatures to Woodside HQ following major gas protest
