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
The launch of the Africa Energy Bank (AEB) has been put back yet again, raising doubts about the institution’s future ability to finance fossil fuel projects – its main objective – as global lenders retreat from such investments over climate concerns, experts told Climate Home News.
The bank, which had been billed to launch in September after a series of delays, is now scheduled to begin operations in November, according to the head of the African Energy Chamber, an advocacy body for the continent’s oil and gas sector.
Even as the world aims to transition away from fossil fuels, many African leaders have made clear they want to continue exploring and extracting the continent’s large oil and gas deposits – estimated at around 125 billion barrels of crude and over 600 trillion cubic feet of gas – to boost economic development.
As a group, Africa sided with a number of powerful oil-and-gas producing nations in blocking progress on negotiations to craft a global roadmap to transition away from fossil fuels at last year’s UN COP30 climate talks, although some countries did individually support the proposal.
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Meanwhile, major projects under development across the continent – including the 1,443-km East African Crude Oil Pipeline (EACOP) and Dangote’s 700,000-barrel-per-day Kenyan refinery – show that African governments see oil and gas as playing a significant role in meeting their energy and economic needs for many years to come.
In 2022, at a gathering of the African Petroleum Producers’ Organization (APPO) in oil-rich Angola, ministers from its member states adopted a resolution to create the Africa Energy Bank to finance projects for the production, use and trade of oil, gas and broader energy sources.
African control over energy resources
An article on the APPO website explains that the bank was conceived as a way to overcome “disenchantment” with fossil fuels among “the international community” which it said had crystallised around the “energy transition” concept.
“If Western countries, after having long taken advantage of the energy sources they now revile to develop, can afford the luxury of abandoning them, this is not the case in Africa,” it adds, noting that many of the continent’s economies are still largely dependent on oil and gas revenues.
A separate web page about the bank, also hosted on APPO’s website, says its objectives include financing the exploration, production and refining of oil and gas, as well as supporting member states in transitioning from fossil fuels to cleaner energy sources “while ensuring energy security”.
Said Addi, a former executive with Shell and energy commodities trading house Gunvor, said the new bank was judged necessary because financing for hydrocarbons from many traditional international lenders has become constrained.
In trying to fill this financing gap, Africa is not simply setting up another fund to support oil and gas, he added. “It is also an attempt to give African countries greater control over how their energy resources and infrastructure are financed,” he explained.
Nigeria to host the AEB
The energy bank – a joint initiative of APPO and the African Export–Import Bank (Afreximbank) – has so far suffered several delays and is almost two years behind schedule. The initial plan was to start operations in January 2025, with Nigeria as the host country, but the bank’s opening was delayed to June of that year to allow Nigeria time to finalise the construction of the bank’s headquarters in Abuja.
After the government announced the completion of the offices in late November 2025, a new launch date was set for January 2026, which was moved back to April, June and then September. Now it has shifted again to November, raising concerns that the institution may be losing momentum.
Former Shell executive Addi said that if the capital is eventually paid in, the bank becomes operational and its first projects are commercially credible, then the delays will be regarded as normal teething troubles in setting up a multilateral institution. But, he added, scepticism will be justified if it continues to stall.
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Baron Lamarré, an oil and gas expert and former Petronas oil trader, said that missing “three deadlines in a row is not normal”, and warned that if the timeline slips again, “the story flips from ‘ambitious institution finding its footing’ to ‘good idea that lost momentum before it found any’.”
The Nigerian government, APPO and Afreximbank did not respond to requests for comment by the time of publication.
The funding challenge
The Africa Energy Bank is targeting base capital of $5 billion, with plans to scale up to $120 billion within five years by mobilising private-sector funds. However, it is expected to start operations with initial seed capital of $500 million.
The funding plan is to have the 18 member countries of the APPO contribute $83 million each to the bank as equity for a combined $1.5 billion. Afreximbank, other non-APPO African countries and investors outside the continent are expected to provide the remaining $3.5 billion.
But even the initial $500 million has not been easy to mobilise. In May, APPO Secretary-General Farid Ghezali called on members to deliver on their pledges towards the startup goal before the end of June. But the delays suggest this may not have been met, with experts saying Africa may be finding it difficult to self-fund its oil and gas projects in the absence of international capital.
Lamarré said every extension of the deadline points to the fact that “raising fossil fuel capital in Africa without the majors and their financing networks is brutally hard”.
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Since 2020, Western lenders, export credit agencies and insurers have been in steady retreat from African hydrocarbons, he said, while oil majors are divesting their African assets, handing over fields to smaller local operators whose credit ratings are not high enough to borrow cheaply.
Even capital from China and the Gulf, which has partially filled the gap, cannot match the volume, tenor or pricing that Western investors once offered, Lamarré argued.
“If mobilising the first $500 million of seed capital [for the AEB] has taken this long, that’s the clearest signal yet of how steep the climb to $120 billion looks,” he said, noting that the continent’s energy financing gap is as large as $30 billion-$45 billion per year.
Africa’s investment landscape, meanwhile, has been shifting. While foreign direct investment dropped from a 2024 peak, inflows remained roughly one-third above the continent’s long-term average in 2025, according to the 2026 World Investment Report from UN Trade and Development (UNCTAD). They are concentrated in a few sectors including critical minerals needed for renewable energy technologies, battery manufacturing and advanced industrial production.
At the same time, data on global energy investment from the International Energy Agency (IEA) shows that fossil fuel investment in Africa has declined over the last decade.
“Trojan horse” for fossil fuels
While the Africa Energy Bank struggles to get off the ground, climate campaigners have criticised its primary aim of financing oil and gas on the continent at a time when the world is starting to move away from high-carbon fuels to cleaner alternatives.
Bhekumuzi Dean Bhebhe, founder of Africa Change Lab, described the bank as a “Trojan horse”, arguing that its focus on fossil fuel financing runs counter to the global energy transition and the African Union’s Agenda 2063 goals of sustainable development and inclusive growth.
The energy bank, he warned, “risks locking Africa into a new cycle of debt, dependency and fossil fuel entrenchment”, adding that its financing blueprint does not pave the way for a climate-resilient future. “In truth, it is to deepen the same extractive, carbon-heavy pathways that the continent should be moving away from,” he added.
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Kenya-based climate and energy expert Joab Okanda said the AEB’s plan to finance oil and gas is “a misplaced priority” and it should instead back clean energy in line with the policies of some of Africa’s major export markets like Europe.
In addition, the new bank could struggle to mobilise enough resources to advance large-scale oil and gas projects, he added, noting that its proposed $5-billion initial capital is equivalent to the cost of the East African Crude Oil Pipeline alone.
The AEB’s aim of backing more fossil fuels should be flipped “to support countries that are oil-dependent to start working on their transition plans”, Okanda said.
The post Launch of Africa Energy Bank delayed again in blow to oil and gas hopes appeared first on Climate Home News.
Launch of Africa Energy Bank delayed again in blow to oil and gas hopes
A booklet published by the UK’s opposition Conservative party includes a “cost of net-zero” that appears to have been doubled by a spreadsheet error.
The “common sense” policy document argues that “what people ultimately want is a government competent enough to solve the problems for which it takes responsibility”.
In a section that says “sophisticat[ed]…modelling” should not be a substitute for “political judgement”, the “Right Way” document disparages various estimates of the cost of net-zero.
The Conservative document then claims – incorrectly – that the government’s official adviser, the Climate Change Committee (CCC), had put the cost of net-zero at close to £1tn. It says:
“In 2020, the CCC estimated that its route to net-zero would cost £957bn.”
In fact, the CCC’s 2020 estimate was exactly half this amount – £478bn – and last year it published a revised figure of £108bn, largely as a result of the falling cost of electric vehicles (EVs).
Spreadsheet error
The Conservative party’s erroneous claim appears to stem from another report that had accidentally added up numbers twice, using a spreadsheet published by the CCC in 2020.
The 2020 spreadsheet contains a table listing the additional investments that would be needed to build a net-zero economy, from low-carbon electricity generation through to heat pumps and EVs.
These extra capital expenditures, listed as “CAPEX”, add up to a total of £1.38tn over the 30 years of 2020-50. They are set against operational savings, listed as “OPEX”, of £0.90tn.
Added up over 2020-50, the combined CAPEX and OPEX figures come to a total of £478bn.
In addition to the annual sectoral CAPEX and OPEX figures, the CCC’s 2020 spreadsheet also has a line giving combined totals for each year. It appears that someone has added all of these numbers together, resulting in the savings and costs being counted twice.
This double-counted total for the cost of net-zero amounts to £957bn – as shown in the image below – and it appears to be the source of the claim in the Conservative booklet.
At the time of publication in 2020, the CCC said that the £478bn net cost of net-zero amounted to less than 1% of GDP over 30 years – and that the large investment needed would not only result in savings due to lower fossil-fuel imports, but that it would boost GDP overall, by around 2%.
In 2025, the CCC revised its estimates for investment costs and operating savings to £670bn and £562bn respectively, giving a net total of £108bn over 2025-50, or less than 0.2% of GDP.
Earlier this year,