Even passing 1.5C of global warming temporarily would trigger a “significant” risk of Amazon forest “dieback”, says a new study.
Dieback would see large numbers of trees die, shifting the lush rainforest into a dry savannah.
The research, published in Nature Climate Change, assesses the impact of “overshooting” the aspirational goal of the Paris Agreement on the Amazon and Siberian forests.
Overshoot would see warming surpass 1.5C above pre-industrial levels in the coming decades, before being brought back down before 2100 through large-scale carbon dioxide removal.
Using hundreds of climate-model simulations, the authors assess the influence of the “sensitivity” of the climate – a measure of the planet’s temperature response to a given increase in atmospheric CO2.
Across all simulations where global warming in 2100 surpasses 1.5C, 37% show “some amount of dieback”, the study says.
However, the risk increases further in the long term, with “55% of simulations exhibiting dieback by 2300”.
One author tells Carbon Brief that the study highlights that overshooting 1.5C leaves forest ecosystems “exposed to more risk than [they] need to be”.
The findings show that “we can’t afford complacency”, he warns.
Warming pathways
As the planet warms, there is an increasing risk that parts of the Earth system will cross “tipping points” – critical thresholds that, if exceeded, could push a system into an entirely new state.
For example, a seminal 2022 study warned that five tipping elements – including the collapse of the West Antarctic ice sheet and abrupt permafrost thaw – are already within reach, while others are becoming increasingly more likely as temperatures rise.
One way to limit warming to 1.5C by the end of the century involves initially overshooting the threshold. However, research published last year warns that the longer the 1.5C threshold is breached – and the higher the peak temperature – the greater the risk of crossing tipping points.
The new study uses modelling to investigate the risks of overshoot for the Amazon and Siberian forests.
The paper considers three illustrative mitigation pathways taken from the Intergovernmental Panel on Climate Change’s (IPCC) mitigation report from its sixth assessment cycle, which was published in 2022.
Gregory Munday is an applied scientist at the UK Met Office Hadley Centre and lead author on the study. He tells Carbon brief that the authors selected “optimistic” pathways that “each have different relationships to the Paris Agreement goals”.
For each scenario, the authors assess a range of different climate sensitivities – a measure of the planet’s temperature response to a given increase in atmospheric CO2. The average outcome of each pathway is:
- The “renewables” scenario shows a future with reduced emissions and a heavy reliance on renewable energy, which keeps warming below 1.5C by 2100.
- The “negative emissions” pathway shows a world in which warming initially overshoots the 1.5C threshold, but extensive use of carbon removal sees warming drop back below 1.5C before 2100.
- The “gradual strengthening” pathway illustrates a strengthening of climate policies implemented in 2020, with rapid reductions mid-century and a reliance on net-negative emissions by the end of this century. This pathway sees global average temperatures reach 1.8C by 2100.
The authors run the emissions pathways through a simple climate “emulator” model, which calculates the global temperatures associated with each emission pathway.
The charts below show cumulative CO2 emissions (left), atmospheric CO2 concentration (middle) and changes in global average surface temperature compared to the pre-industrial level (right), for the renewables (green), negative emissions (purple) and gradual strengthening (yellow) pathways until the year 2300.
The authors then use a different modelling framework to project the impacts of each emissions scenario.
Study author Dr Chris Jones leads the UK Met Office Hadley Centre’s research into vegetation and carbon cycle modelling and their interactions with climate. He tells Carbon Brief that the new study is the first application of this modelling framework, which he describes as a “rapid response tool”.
He says the tool was developed to “rapidly look at a range of climate outcomes, both global and local, for new scenarios”, adding that it provides a “pretty good approximation” of what traditional global climate models would do.
Munday adds that the framework is able to produce results within days or weeks, rather than taking “months and months”.
Finally, the authors use land surface model JULES to assess forest health under the different scenarios. Overall, the authors produce 918 simulations each of Amazon and Siberian forest health.
Forest health
The authors assess forest health using two metrics. The first is the forest growth metric “net primary productivity”, a measure of the rate that energy is stored as biomass by plants, which can indicate forest productivity. The second metric, forest cover, is a way of measuring the forest’s long-term response.
The models show that rising CO2 levels causes net primary productivity to increase, due to the CO2 fertilisation effect, driving more rapid forest growth. Conversely, many of the impacts of climate change, such as increased heat and changes to rainfall patterns, can be detrimental to forests, damaging or killing trees.
To identify the impacts of overshooting 1.5C on the Amazon and Siberian forests, the authors compare the “renewables” and “negative emissions” pathways. Both of these scenarios reach a similar global average temperature by the year 2100, but the former does so without overshoot, while the latter overshoots 1.5C before temperatures come back down.
The maps below show the difference in net primary productivity in the Amazon (left) and Siberian forests (right) between the two scenarios in the year 2100. Brown shading indicates that net primary productivity was higher in the non-overshoot scenario, while blue indicates that it was higher in the overshoot scenario.
The maps show that “large areas of both Amazonian and Siberian forest show reduced net primary productivity” by 2100 due to overshoot, compared to a scenario with no overshoot, the paper says.
‘High-risk zones’
From the three pathways, the authors generate 918 simulations of future climate and corresponding Amazon forest health.
The authors use these results to identify which future temperature and rainfall conditions result in net forest “dieback”. This is when large numbers of trees die, shifting the rainforest into a dry savannah.
The plots below show which simulations result in Amazon dieback by the year 2100 (left) and 2300 (right), for different amounts of rainfall and temperature levels in the year 2100. Each graph is divided into four sections – hot and wet (top right), hot and dry (bottom right), cold and wet (top right) and cold and dry (bottom right). These sections are based on average regional temperature and rainfall in the year 2100.
Coloured dots indicate scenarios that see forest dieback. These are coloured by pathway, for renewables (green), negative emissions (purple) and gradual strengthening (yellow). Grey dots indicate scenarios without Amazon dieback. The red lines indicate “high-risk climatic zones”, above which there is “a significant risk of dieback”.
The study finds that most Amazon dieback scenarios happen in hot, dry conditions, the authors note.
Across all simulations where warming in 2100 is above 1.5C, 37% show “some amount of dieback” the study says. However, in these model runs, the risk increases further in the long term, the study notes, with “55% of simulations exhibiting dieback by 2300”.
Prof Nico Wunderling is a professor of computational Earth system science at the Potsdam Institute for Climate Impact Research and was not involved in the new research. He tells Carbon Brief it is significant that, according to this study, the Amazon will face impacts from climate change below the tipping point threshold of 2-6C, as assessed in the landmark 2022 tipping points paper.
The authors also carry out this analysis for Siberian forests. Instead of a drop in tree cover, they find a change in the composition of trees. Munday tells Carbon Brief that the vegetation shifts “from grassy surface types to lots more trees and shrubs” in a process called “woody encroachment”.
Woody encroachment can have significant negative impacts on terrestrial carbon sequestration, the hydrological cycle and local biodiversity.
“The Siberian forest is probably committed to a long-term, and possibly substantial, expansion of tree cover,” the authors write.
High-risk scenarios
The greatest uncertainty in this study comes from the spread of climate sensitivities, Munday tells Carbon Brief.
He elaborates:
“This means that although we simulate the impacts from extremely optimistic mitigation scenarios, there is a chance that the Earth’s climate sensitivity is much higher than we expect, and so, small but significant risks of short- and long-term forest ecosystem impacts exist in spite of the choice of these strong-mitigation scenarios.”
In other words, if climate sensitivity is higher than expected, forests could face harmful impacts even under low emissions scenarios.
Dr David McKay – a lecturer in geography, climate change and society at the University of Sussex – is the lead author of the 2022 study. He tells Carbon Brief that the new paper “shows the value in focusing not just on model averages, but also exploring a wide range of possible futures to capture potential ‘low probability, high impact’ outcomes”. He adds:
“[The study shows] how negative emissions to reduce warming might help restabilise these forests in future if we do overshoot 1.5C, but as such large-scale CO2 removal remains hypothetical, we shouldn’t assume we can rely on this in practice.”
However, McKay also notes some uncertainties in the models used. Mckay tells Carbon Brief that the vegetation model used in this study doesn’t include fire and “has some limitations around soil moisture stress and vegetation in the tundra”. These are “likely important for resolving potential tipping points in these biomes”.
Therefore, he adds, the study “doesn’t show how regional tipping points could potentially further amplify and lock-in these future forest shifts, even with negative emissions”.
Dr David Lapola is researcher at the University of Campinas in Brazil and was not involved in the study. He also warns that vegetation models provide a “poor representation of how CO2 may affect these forests directly”. Lapola argues that scientists must “collect field data to make any new advancement with models”.
Nevertheless, Lapola tells Carbon Brief that studies such as this will be “extremely useful” for the IPCC’s upcoming seventh assessment cycle, which will include a dedicated chapter on tipping points and other “low-likelihood high impact events” for the first time.
Study author Jones tells Carbon Brief that overshooting 1.5C leaves forest ecosystems “exposed to more risk than [they] need to be”. The findings show that “we can’t afford complacency”, he warns.
The post ‘Significant’ risk of Amazon forest dieback if global warming overshoots 1.5C appeared first on Carbon Brief.
‘Significant’ risk of Amazon forest dieback if global warming overshoots 1.5C
A landmark conference hosted by Colombia and the Netherlands will aim to lay the foundations for renewed talks on transitioning away from fossil fuels at COP31, though organisers say it remains unclear what concrete outcomes it will deliver.
The First Conference on the Transition Away from Fossil Fuels will take place in April in the city of Santa Marta, on Colombia’s Caribbean coast, where first-moving countries, states and cities will seek to restart last year’s stalled push for a global roadmap away from coal, oil and gas.
Bastiaan Hassing, head of international climate policy for the Dutch government, told an online briefing last week that the “most obvious” impact of the conference would be for its hosts to report back to the UN climate summit on what was agreed in Santa Marta.
“Ideally, but this is also more complicated, we discuss with each other (at COP) what next steps we could take in the implementation, for instance, of paragraph 28 of the COP decision in Dubai, which talks about the global transition away from fossil fuels,” Hassings said.
He noted that there are many options for how the conference can influence UN talks on implementing the global transition away from fossil fuels, but the exact possibilities would depend on the outcome of the talks. “Rest assured that we will be looking into this,” he added.
At last year’s COP30, a bloc of 80 countries, including small island states, as well as some Latin American, European, and African countries, called for the creation of a roadmap to transition away from fossil fuels.
But major oil and gas producers and consumers blocked the initiative in Belém. As a compromise, Brazil’s COP presidency promised to draft proposals for two voluntary roadmaps: one to end deforestation and another to guide the transition away from fossil fuels.
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Brazil has launched consultations seeking input for those plans, asking governments and stakeholders about technological and economic barriers, climate justice considerations and examples of best practice. Last week, COP30 president André Corrêa do Lago told Brazilian media that he would hold discussions on his roadmap proposal at the Santa Marta conference.
Colombia’s environment minister Irene Vélez Torres told reporters last week that “this is the moment to be honest about the challenges involved in transitioning away from fossil fuels”.
“It is not easy. It involves commitments from both the Global North and South. It involves interests and tensions at the subnational level,” she added. “Yet none of this diminishes its urgency or the need to reach agreements at the international multilateral level”.
Process to end fossil fuels
Vélez Torres said she hoped the Santa Marta meeting would help establish an ongoing process to advance discussions that often stall in the formal UN negotiations, where decisions are made by consensus and fossil fuel producers resist stronger language.
“This is the first conference, and we want it to be followed by another. We also want to establish a technical secretariat to sustain these debates,” said Vélez Torres, who added that the initiative would be “articulated with [the] COP30 and COP31” presidencies.
Colombia has been one of the few fossil fuel-producing countries that pledged to halt all new coal, oil and gas exploration. The move triggered backlash from industry and political opponents – with former president Iván Duque calling the decision “political and economic suicide”. The South American country depends on fossil fuels for about 10% of fiscal revenues and 4% of GDP, according to the International Monetary Fund (IMF).
Organisers of the Santa Marta conference said they expect between 40 and 80 high-level representatives from governments, both at national and subnational levels. Colombian president Gustavo Petro is expected to participate, and invitations have been extended to California governor Gavin Newsom and Dutch prime minister Rob Jetten.
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No turning back
The conference comes amid renewed volatility in global energy markets. As the US and Israel’s war in Iran disrupts oil and gas supplies and threatens to cause severe global economic damage, analysts say governments should seek to reduce their dependency on fossil fuels through investments in renewables and energy efficiency.
The upcoming Santa Marta conference should build momentum to plan that transition away from fossil fuels and signal that “there is no turning back”, said Peter Newell, professor of international relations at the University of Sussex and one of the main proponents of a fossil fuel non-proliferation treaty.
“Its outcomes, which might include a declaration on key principles and next steps (for the fossil fuel transition), should give renewed vigour to efforts within the UN climate negotiations to drive the agenda forward,” Newell said.
Because major fossil fuel producers have effectively “vetoed” discussions on a fossil fuel phase-out at COPs, he added, willing countries must move forward independently with initiatives like the Santa Marta conference.
Andreas Sieber, head of political strategy at the NGO 350.org, agreed that the push away from fossil fuels is “both necessary and economically inevitable”, adding that a conference on phasing out fossil fuels would have been “unthinkable just five years ago”.
Countries moving forward
COP30 host Brazil has taken the lead in developing its own national roadmap away from fossil fuels, which President Luiz Inácio Lula da Silva requested his government to draft late last year. The roadmap is expected to be formally developed this year.
The plan – expected to include a dedicated energy transition fund – was initially due in February but has not yet been made public as ministers continue technical discussions.
In Europe, governments have also stepped up efforts to curb fossil fuel use following the energy shocks triggered by Russia’s invasion of Ukraine and the conflict in the Middle East.
Leo Roberts, a fossil fuel transition analyst at the climate think tank E3G, said the recent surge in gas prices linked to the Iran conflict reinforces the case for accelerating the transition to boost energy security and protect people from price shocks.
“Hopefully, Santa Marta is able to really demonstrate that not only is there momentum at the international sphere through the COP30 roadmap process, but there’s huge momentum away from fossil fuels in the real world,” he said.
The post New summit in Colombia seeks to revive stalled UN talks on fossil fuel transition appeared first on Climate Home News.
New summit in Colombia seeks to revive stalled UN talks on fossil fuel transition
Nick Dearden is the director of Global Justice Now.
The US push for nations to join a club that would coordinate the trade of critical minerals outside China signals a giant shift in Washington’s vision for how to govern the global economy But it will, unfortunately, also hinder the clean energy transition.
Critical minerals such as lithium, nickel, copper and rare earths are needed to manufacture clean energy technologies such as solar panels, wind turbines and batteries on which the transition from fossil fuels to clean energy depends.
But these minerals also have applications for a wide range of advanced technologies, not least military equipment and digital infrastructure. In recent years, AI deployment and the build out of data centres have become the primary political justification for mineral extraction.
No US official mentioned clean energy technologies as they promoted the new minerals club in Washington last month. Instead, the trading bloc aims to break China’s dominance over mineral supply chains and ensure US access to the resources it needs for digital and military sectors.
Analysis by Global Justice Now found that almost one in five of the 33 minerals that the UK identified as critical in 2024 are not needed to achieve the International Energy Agency’s decarbonisation pathways. A further 15 play only a very small role and only seven require significant production increases for the clean energy transition.
Prioritise minerals for the energy transition
The urgency of addressing climate change means we must prioritise the use of minerals to rapidly and equitably wean the global economy off coal, oil and gas while reducing resource overconsumption in the Global North. The US approach could make this prioritisation a lot harder.
For Washington, this isn’t about addressing climate change, but America’s ever deepening rivalry with China, a renewable energy superpower. In contrast, Donald Trump has called climate change “a hoax” and overseen unprecedented climate deregulation in favour of fossil fuels.
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The minerals trading bloc risks diverting mineral resources towards carbon-intensive military and technology build-up in the US, which is directly at odds with the need to use these resources to manufacture clean energy technologies.
What’s more, for the green transition to be just, fair and equitable, resource-rich governments must be able to refine and add value to their resources, creating jobs and economic development in the process. But Trump’s trading bloc is intended to tell “partner” countries what role they should play in the global mineral supply chains to best serve US interests.
Serving US interests rather than clean energy
Countries with the smallest and least developed economies stand to lose out.
More than a dozen countries have signed bilateral deals with the Trump administration. The terms of the deals appear to get better the richer a country is.
At the poorer end is the deal with DRC – an outright piece of imperialism with one-sided obligations that override the country’s mineral sovereignty by giving the US first dibs on a range of strategic mining sites and the energy needed to power these sites.
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In the middle, Malaysia committed to facilitate American involvement in its mineral sector and refrain from banning or imposing quotas on exports of raw minerals to the US. This risks restricting the development of Malaysia’s refining capacities, making value addition harder.
At the top end is the UK, which has signed a deal that includes a commitment to streamline mineral permitting, but appears more focused on facilitating financial services to members of the trading bloc.
Wherever countries sit in the pecking order, the agreements signed with the US limit governments’ strategic sovereignty over their resources and stifle their ability to create a more sustainable economy which meets people’s needs.
Tools for a way forward
There is some hope, however. Trump’s mineral trading bloc would operate with profoundly different rules than the neoliberal trade deals, which we have become used to.
Some of its components – like price floors and state ownership – have not been seen in trade deals for a long time. In the right hands, these tools could help governments plan, coordinate and prioritise a globally just green transition and break away from the ‘market knows best’ logic which has long locked poorer countries into low-value exports of raw materials.
If governments work together, outside the coercive US trade bloc, to adopt some of these tools and policies, they might be able to draw local benefits from their mineral wealth and build a genuinely fair and equitable trade in transition minerals.
The post The US’s critical minerals club threatens an equitable clean energy transition appeared first on Climate Home News.
The US’s critical minerals club threatens an equitable clean energy transition
Climate Change
Greenpeace urges governments to defend international law, as evidence suggests breaches by deep sea mining contractors
SYDNEY/FIJI, Monday 9 March 2026 — As the International Seabed Authority (ISA) opens its 31st Session today, Greenpeace International is calling on member states to take firm and swift action if breaches by subsidiaries and subcontractors of The Metals Company (TMC) are established. Evidence compiled and submitted to the ISA’s Secretary General suggests that violations of exploration contracts may have occurred.
Louisa Casson, Campaigner, Greenpeace International, said: “In July, governments at the ISA sent a clear message: rogue companies trying to sidestep international law will face consequences. Turning that promise into action at this meeting is far more important than rushing through a Mining Code designed to appease corporate interests rather than protect the common good. As delegations from around the world gather today, they must unite and confront the US and TMC’s neo-colonial resource grab and make clear that deep sea mining is a reckless gamble humanity cannot afford.”
The ISA launched an inquiry at its last Council meeting in July 2025, in response to TMC USA seeking unilateral deep sea mining licences from the Trump administration. If the US administration unilaterally allows mining of the international seabed, it would be considered in violation of international law.
Greenpeace International has compiled and submitted evidence to the ISA Secretary-General, Leticia Carvalho, to support the ongoing inquiry into deep sea mining contractors. This evidence shows that those supporting these unprecedented rogue efforts to start deep sea mining unilaterally via President Trump could be in breach of their obligations with the ISA.
The analysis focuses on TMC’s subsidiaries — Nauru Ocean Resources Inc (NORI) and Tonga Offshore Mining Ltd (TOML) — as well as Blue Minerals Jamaica (BMJ), a company linked to Dutch-Swiss offshore engineering firm Allseas, one of TMC’s subcontractors and largest shareholders. The information compiled indicates that their activities may violate core contractual obligations under the United Nations Convention on the Law of the Sea (UNCLOS). If these breaches are confirmed, NORI and TOML’s exploration contracts, which expire in July 2026 and January 2027 respectively, the ISA should take action, including considering not renewing the contract.
Letícia Carvalho has recently publicly advocated for governments to finalise a streamlined deep sea mining code this year and has expressed her own concerns with the calls from 40 governments for a moratorium. At a time when rogue actors are attempting to bypass or weaken the international system, establishing rules and regulations that will allow mining to start could mean falling into the trap of international bullies. A Mining Code would legitimise and drive investment into a flagging industry, supporting rogue actor companies like TMC and weakening deterrence against unilateral mining outside the ISA framework.
Casson added: “Rushing to finalise a Mining Code serves the interests of multinational corporations, not the principles of multilateralism. With what we know now, rules to mine the deep sea cannot coexist with ocean protection. Governments are legally obliged to only authorise deep sea mining if it can demonstrably benefit humanity – and that is non-negotiable. As the long list of scientific, environmental and social concerns with this industry keeps growing, what is needed is a clear political signal that the world will not be intimidated into rushing a mining code by unilateral threats and will instead keep moving towards a moratorium on deep sea mining.”
—ENDS—
Key findings from the full briefing:
- Following TMC USA’s application to mine the international seabed unilaterally, NORI and TOML have amended their agreements to provide payments to Nauru and Tonga, respectively, if US-authorised commercial mining goes ahead. This sets up their participation in a financial mechanism predicated on mining in contradiction to UNCLOS.
- NORI and TOML have signed intercompany intellectual property and data-sharing agreements with TMC USA, and the data obtained by NORI and TOML under the ISA exploration contracts has been key to facilitating TMC USA’s application under US national regulations.
- Just a few individuals hold key decision-making roles across the TMC and all relevant subsidiaries, making claims of independent management ungrounded. NORI, TOML, and TMC USA, while legally distinct, are managed as an integrated corporate group with a single, coordinated strategy under the direct control and strategic direction of TMC.
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