Despite progress since the Paris Agreement, a peak in greenhouse gas emissions is only just within sight – and time is fast running out to stay below 1.5C of human-caused global warming since the preindustrial era.
As a result, almost all pathways that keep 1.5C within reach now involve a temporary “overshoot”.
This term refers to a period where the best estimate of warming exceeds 1.5C, until temperatures are brought back below the limit by removing carbon dioxide (CO2) from the atmosphere.
While this idea is growing in prominence, there have only been limited efforts to understand what it would mean to breach the 1.5C limit, even if this is only during a temporary period of overshoot.
In a new Nature paper, we present the findings of a three-year Horizon Europe-funded project, looking at what overshoot means for emissions, temperatures, climate impacts and adaptation.
Our results show that overshooting 1.5C comes with significant uncertainty in terms of warming outcomes, climate impacts and associated risks. For example, climate uncertainty means that what is referred to as a 1.5C “pathway” carries a notable risk of much greater levels of warming.
In order to hedge against the risk of higher-than-expected warming, the world would need to develop substantial capacity for “net-negative” CO2 emissions. This could be used to reverse a temporary overshoot and reduce long-term risks, if warming is no more extreme than expected.
Even so, overshoot would come with irreversible consequences for humans and ecosystems, our research finds, such as rising sea levels and ecosystem loss.
Overshoot overconfidence
The Intergovernmental Panel on Climate Change (IPCC) has been key to shaping our understanding of overshoot scenarios. In its latest sixth assessment report (AR6), the IPCC considered a range of pathways that limit median warming in 2100 to below 1.5C.
The report categorised the pathways according to their probability of breaching 1.5C, but also offered information on the amount of any expected overshoot.
Specifically, the C1 “no or limited overshoot” pathways allow an overshoot of “up to about 0.1C”. The C2 pathways return warming to 1.5C “after a high overshoot” of between “0.1C-0.3C”.
These categorisations give the impression that overshoot can be neatly and confidently constrained – to within a few tenths of a degree – and that in choosing a particular pathway, the countries of the world would have full control over the planetary thermostat.
Crucially, however, the numbers refer only to median warming outcomes. Considering the uncertainties in Earth system feedbacks, it is not possible to rule out much higher peak warming. For example, this could be up to 2.5C under C2 scenarios (at the 95th percentile of all model runs).
If the increase in temperatures is indeed much higher than expected under median warming, or if warming continues even when CO2 emissions reach net-zero, then returning to below 1.5C after an overshoot would require much more CO2 removal than thought.
Even with stringent emissions reductions, we therefore cannot rule out the possibility that reversing a 1.5C overshoot would require the removal of hundreds of billions of tonnes CO2 by 2100.
Indeed, based on the simple climate model FaIR, our findings show that 400GtCO2 of additional removals could be needed to return temperatures to 1.5C by 2100, if warming reaches the 75th percentile of expected levels rather than the median (about 1.7C instead of 1.5C, an outcome with a likelihood of one-in-four).
(This is based on generating more than 2,000 physically plausible climate outcomes for an emission pathway that limits median warming to around 1.5C and achieves net-zero CO2 by around mid-century, without the need for net-negative emissions thereafter.)
To reach 400GtCO2 of removals by 2100 would mean taking nearly 10GtCO2 out of the atmosphere every year after global CO2 emissions reach net-zero. For comparison, current removals amount to around 2GtCO2 per year, from all sources.
The 400GtCO2 of removals that could be needed to deal with higher-than-expected warming is similar to the amount of removals that is typically being relied on in 1.5C pathways, assuming median levels of warming in response to a given level of emissions.
This is shown in the figure below, where the first row illustrates the range of cumulative CO2 removal needed to return temperatures to below 1.5C by 2100, depending on how sensitive the climate is to a given level of emissions. The bottom two rows show removals in C1 “no or limited overshoot” and C2 “high overshoot” 1.5C pathways, assuming a median warming response.
Our findings imply the world may therefore need a “preventive” capacity to remove hundreds of billions of tonnes of CO2 by 2100, to hedge against the risk of higher-than-expected warming.
Moreover, given the political, economic, sustainability and other constraints on the speed and scale at which CO2 removal can be scaled up, it therefore may not be possible to rely on removals to compensate for a failure to reduce emissions in other parts of the economy.
Irreversible impacts
If warming is no more severe than expected under median outcomes, then preventive CO2 removal capacity could be used to steadily reduce temperatures after overshoot.
This could be an important way to minimise long-term climate risks following overshoot.
For example, for every 100 years of overshoot above 1.5C, our findings show that there would be an additional 40cm of sea-level rise by 2300. There would be similarly irreversible consequences for the world’s frozen ecosystems, such as permafrost and peatlands.
In addition, overshoot increases the risk of crossing irreversible climate “tipping points”.
These findings show that even if a global temperature overshoot is reversed, the temporary breach of the 1.5C limit would still come with some irreversible consequences.
Peak and decline
Our study offers a framework for minimising the risks associated with higher-than-expected warming and potentially irreversible climate impacts after temperature overshoot.
Instead of the current categories of mitigation pathway, which focus on peak warming and end-of-century temperatures – apparently with a high level of precision – our paper suggests “peak and decline” (PD) scenarios that allow us to consider a wide range of plausible climate outcomes.
These scenarios aim to achieve a peak in warming, followed by sustained temperature reductions during a period of at least several decades. Global greenhouse gas (GHG) emissions would need to decline towards net-zero CO2 to achieve temperature peaking, followed by net-negative CO2 emissions to enter a long-term decline.
The “peak” is determined by how fast emissions are reduced in the near term, towards reaching net-zero CO2 emissions. This determines the maximum cumulative CO2 emissions of a pathway and therefore the level and timing of peak warming. Importantly, the stringency of non-CO2 GHG emission reductions will also strongly affect peak warming.
The pace of global temperature “decline” after the peak – and therefore the ability to reverse a temporary exceedance of a target limit – depends on the level of net-negative CO2 emissions that can be achieved.
In PD “overshoot” pathways (PD-OS), warming exceeds 1.5C before returning to that level and staying there into the future. These are similar to PD pathways, but the carbon budget, timing of net-zero CO2 and amount of CO2 removal depends on the length, level and timing of overshoot.
In PD “enhanced protection” pathways (PD-EP), warming is kept as low as possible and gradually reversed over time, to minimise climate risks. They entail stringent, rapid cuts in GHG emissions, achieving net-zero CO2 as soon as possible and using sustainable levels of CO2 removal to reduce warming over time, potentially reaching net-zero or even net-negative GHGs.
These pathways are illustrated in the figure below, where the 1.5C limit is shown as a horizontal dotted line, and the different peak and decline pathways are contrasted with a scenario in which temperatures continue to increase, despite reaching net-zero CO2.
Our findings suggest that a peak and decline “enhanced protection” pathway would offer the best way to hedge against the uncertainties and minimise the risks around overshoot and the response of the climate system. This would entail two actions from countries worldwide.
First, it would mean reducing emissions as fast as possible to slow down temperature increase, reduce peak warming, and reduce the dependency of needing large amounts of CO2 removals to even achieve net-zero CO2 emissions.
Second, it would mean rapidly scaling up global capacity for CO2 removal to hedge against high-risk outcomes from stronger than expected climate feedback.
The scale of preventive removal capacity that we estimate could be needed, is only just achievable within sustainable limits. If some removal capacity is used to compensate for a failure to rapidly reduce emissions, then it would not be available to manage higher-than-expected warming.
Overall, our paper reinforces the idea that earlier emissions reductions are the best way to minimise far-reaching climate risks in the 21st century and beyond.
The post Guest post: How to minimise the risks from overshooting the 1.5C limit appeared first on Carbon Brief.
Guest post: How to minimise the risks from overshooting the 1.5C limit
The United Nations Secretary-General and foreign ministers from the UK, France and Spain have blamed the deadly wildfires engulfing Europe on climate change, using the disaster to renew calls for faster cuts to greenhouse gas emissions.
António Guterres told journalists on Friday that the “climate crisis is in overdrive”, adding that global heat seen so far is just a “warm up act” as a phenomenon known as El Niño intensifies “adding fuel to a planet already on fire”.
A new World Meteorological Organisation (WMO) report published on Friday predicts that the weather pattern will grow into a “strong event” between now and October, increasing the risk of higher than normal temperatures across much of the world and disrupted rainfalls.
“That risks shattering every seasonal record – and driving even more severe effects worldwide,” Guterres said.
El Niño builds on top of an already warming world, driven primarily by the burning of fossil fuels. A WMO scientist, who did not want to be named, told journalists that all the heatwaves and other climate impacts seen so far this year are “before the effects of El Niño are really kicking in at a global scale”.
Fossil fuellling the fires
Fires have broken out across much of Europe but are threatening the most people in the south-west of France near Bordeaux and in Central Spain near Madrid. Nearly a quarter of a million people have been evacuated in France with hundreds of homes destroyed while in Spain 80,000 people have had to leave their homes and at least 13 died in one village.
A scientific study published on Friday by the World Weather Attribution group found that man-made climate change made deadly fires in France twice as likely and those in Spain twenty times more likely. Smaller fires in the UK were not analysed by the study.
UN Climate Change leader Simon Stiell blamed fossil fuels for the fires, as well as storms in Chile and heatwaves in North America and Japan in recent weeks. “The climate alarm is blaring”, he said on Wednesday.
Guterres criticised new fossil fuel production projects and fossil fuel subsidies for causing hardship across the world. Discussing his speech, a senior UN official – who did not want to be named – said the subsidies amounted to trillions of US dollars a year and criticised pension funds and institutional investors, including insurance companies, for continuing to invest in fossil fuel projects.
Asked why world leaders and the public are not prioritising climate action, Guterres said they are distracted by wars in Ukraine, the Middle East, Sudan and elsewhere and sometimes forget “other aspects that are a sometimes even more dangerous threat”.
Also the fossil fuel industry and “some countries” are campaigning to pretend that climate change does not exist, he said, adding that the UN should be more active in “naming the situations as they are and the responsibilties as they are and mobilising the public opinion”.
After meetings in Paris and Madrid earlier in the week, the UK’s new foreign minister Ed Miliband issued joint statements with his French and Spanish counterparts – Jean-Noël Barrot and José Manuel Albares Bueno – calling on the world to reduce its dependence on fossil fuels.
They promised to do more to reduce emissions and protect their people and encouraged other governments to do the same.
The UK-French statement called on governments to publish UN climate plans, known as nationally determined contributions (NDCs), which are aligned with the Paris Agreement’s goal to limit global average temperatures to 1.5C above pre-industrial levels.
According to Climate Action Tracker, only three countries – the UK, Nigeria and Norway – have submitted NDCs with 2035 emissions reduction targets which are compatible with 1.5C. Fifty-two countries – including Egypt, Vietnam and Argentina – have yet to submit an NDC at all.
Defending science
Beyond action on emissions, the ministers also intervened in an ongoing dispute over the timing of the Intergovernmental Panel on Climate Change’s (IPCC)’s next flagship assessment.
Miliband and Barrot’s statement said they “underline the importance” of scientific report feeding into governments’ next global stocktake of progress on climate action in two years’ time, calling it a “critical input” to that process.
The timing of this report has been a contentious issue in government negotiations at the IPCC and at June’s climate talks in Bonn. While a group of nations calling themselves the “friends of science” want the report before the stocktake, others like Saudi Arabia and India have argued that this would make the report of a worse quality and less inclusive of developing countries’ scientists.
Science ‘under attack’ from fossil fuel interests at UN climate talks
The UK-Spanish statement weighed in less explicitly on this issue but said that they “recall the importance of scientific evidence and acknowledge the work of the IPCC in this respect.”
The British and French ministers said they would seek to accelerate reductions of emissions in methane, a particularly potent greenhouse gas, at COP31 in November. They encouraged governments “to work jointly to develop a marketplace for fossil fuels with near-zero methane intensity.”
Methane leaks from oil, gas and coal production are a major contributor to global warming. Over a 20-year period, methane traps around 80 times more heat than carbon dioxide.
The UK and Spanish statement emphasised the importance of supporting the Global South and underlined the need to mobilise sustainable financing “at scale with the challenge we face”. The previous UK government, in which Miliband was energy minister, cut climate finance to developing countries to pay for increases in military spending.
The UK government led by new Prime Minister Andy Burnham has yet to outline any major changes to climate finance in its two weeks in power but has announced it will convert some finance from grants to loans in order to free up money to subsidise bus travel in England.
More adaptation needed
Guterres said that “it is time to stop treating each disaster as an isolated tragedy and recognise the systemic risk that is unfolding before our eyes.” A recent study found that three-quarters of UK media reports about the British June heatwave did not mention climate change.
As well as reducing emissions, the UN Secretary-General called for measures to adapt vulnerable people to extreme heat. Specifically, he said that buildings should be built and retrofitted for extreme heat and that every city and country should have heat-health action plans and early warning systems. Over 250 cities have joined the UN’s ‘beat the heat’ initiative, he said.
The Portuguese diplomat called for governments and employers to do more to protect their workers from heat, criticising global fashion brands for not setting heat standards for the factories that supply them. “No one should have to risk their life to earn a living,” he said.
The post UN chief warns climate crisis “in overdrive” as El Niño threatens to fuel the fire appeared first on Climate Home News.
UN chief warns climate crisis “in overdrive” as El Niño threatens to fuel the fire
Climate Change
‘Ride the wave of momentum’: Australia announces once-in-a-decade Marine Parks Network review
In response to the federal government announcing its once-in-a-decade review of Australia’s Marine Parks Network, the following lines can be attributed to Elle Lawless, Senior Campaigner at Greenpeace Australia Pacific:
“Greenpeace Australia Pacific welcomes today’s announcement that the Albanese Government will review Australia’s Commonwealth Marine Parks Network. This is a rare, once-in-a-decade opportunity to strengthen our marine parks and ban industrial fishing in Australia’s marine protected areas.
“Australians would be appalled to know that more than half of Australia’s Marine Parks Network currently allows for extractive industries, like longlining, bottom trawling and oil and gas mining. These so-called ‘protected’ areas were designed to safeguard our beloved ocean wildlife and underwater ecosystems – that is what Australians expect. Damaging industrial industries should not be given a free pass to trawl, fish, drill or extract from our marine parks.”
“With the first Ocean COP just around the corner, and off the back of Australia’s move to ratify the Global Ocean Treaty earlier this year, the Australian government has a unique opportunity to ride the wave of this momentum and solidify itself as a true global ocean leader.
“Greenpeace Australia Pacific is calling for industrial activities to be banned from our protected waters and for at least 30% of Australia’s ocean to be protected as ocean sanctuaries. This review presents a rare opportunity to create more ocean sanctuaries, true blue havens where ocean life can recover, thrive and repopulate the surrounding waters.”
—ENDS—
‘Ride the wave of momentum’: Australia announces once-in-a-decade Marine Parks Network review
In recent days, prominent climate sceptics and rightwing commentators have shared charts on social media incorrectly implying that Europe is having its “quietest” year for wildfires in 2026.
These include Dr Matthew Wielicki, a former University of Alabama geochemist and self-described “professor in exile”, who was recently appointed by the Trump administration to lead the US Global Change Research Program.
However, these charts paint a misleading picture as they are skewed by encompassing the entirety of Russia in the data – including the vast plains of Siberia.
These charts also use data that include fires that are deliberately lit to manage cropland, which is a declining practice across much of Europe.
In this factcheck, Carbon Brief shows that the area burned by wildfires across the European Union in 2026 is second only to 2022 for this time of year.
The latest data from the European Forest Fire Information System (EFFIS) also shows that France has set a new modern record for area burned and Spain’s wildfire season is among the worst on record.
The fires have displaced more than a third of a million people across south-western Europe, while an impending heatwave has also raised fears of the fires worsening in the coming days.
‘Quietest year’
On 27 July, as wildfires raged across multiple European countries, former Conservative peer and climate-sceptic commentator Matt Ridley posted on Twitter that “2026 is the quietest year for wildfires in Europe by some distance”.
Ridley, who sits on the academic advisory council of the Global Warming Policy Foundation (GWPF), a UK-based climate-sceptic lobby group that refuses to reveal the sources of its funding, was responding to an article by Daily Telegraph columnist Tim Stanley.
Stanley’s column, headlined: “Climate change is real – and the right needs to get serious about it”, warned:
“This is no longer a matter of speculation: the wildfires of Europe, pitiless and persistent, are the way we live now.”
Ridley included a chart from Our World In Data, showing the cumulative area burned by wildfires by week for Europe. The chart puts 2026 as having the smallest area for this time of year in a dataset going back to 2012.
Ridley’s post was widely shared by prominent rightwing figures – including Richard Tice, deputy leader of the hard-right, climate-sceptic Reform UK party, former Conservative cabinet minister Jacob Rees-Mogg and multiple commentators.
Separately, Wielicki also shared a chart on Twitter to imply that wildfires in Europe are declining. Wielicki has previously claimed that the “science is not settled on climate change”.
The charts posted by Ridley and Wielicki both use data from the Global Wildfire Information System (GWIS). The GWIS category for “Europe” encompasses all the countries on the continent and includes the whole of Russia.
As a result, Russia accounts for about 74% of the area included in the GWIS definition of “Europe”.
Wildfires in Russia typically account for 80-90% of the burned area in the GWIS Europe dataset. In 2026, fires in Russia are substantially below average. Therefore, including Russia in this comparison creates the false impression that wildfire activity across Europe is unusually low.
Dr Calum Cunningham, a research fellow at the University of Tasmania’s Fire Centre, says that such claims are “highly misleading”, noting that “they rely on aggregating fire activity across an enormous and climatically diverse region”. He tells Carbon Brief:
“A relatively quiet season in Russia can easily mask an exceptionally active season in France or Spain. If the analysis is focused on the regions actually experiencing the current fires, the picture is very different.
“The reality is that western Europe has experienced an extraordinary sequence of climate conditions this year.”
In contrast, the EFFIS provides a subset of wildfire data specifically for the area covered by the 27 nations of the EU, which, therefore, excludes Russia.
Another difference between the two datasets is that GWIS monitors all fires – including those on agricultural land that are intentionally set alight. The burned area as measured by GWIS contains significant cropland area.
By contrast, EFFIS uses land-cover data and other information to filter specifically for forest fires.
Looking at the EU-only data from EFFIS reveals that Europe is far from having its “quietest” year. The bloc’s burned area, as of 29 July, is almost 435,000 hectares (ha) – second only to 2022 for this time of year.
Notably, Wielicki has actually continued to post charts based on GWIS data, even after acknowledging that “includ[ing] all of Russia, including vast areas of Siberia…isn’t a good proxy for Europe”.
French fires
Even looking at EU-wide data misses the scale of this year’s wildfires for some individual countries.
The chart below shows the surge in burned area in France since mid-July.
For much of the first half of the year, the country was having a wildfire season that was only slightly above average in terms of total burned area. However, a notable uptick began in the first week of July.
The third week of the month saw France break its previous cumulative annual record by more than 19,000ha. That gap has widened as the fires continue to burn; as of 29 July, the cumulative burned area in France during 2026 was nearly 24,700ha above the previous record.
The fires in France follow a record-breaking June heatwave that “dried out vegetation across the region, allowing fires to spread quickly”, wrote the New York Times.
On 27 July, French president Emmanuel Macron called a “crisis cabinet meeting” in order to address the fires “ravaging several areas of south-west France”, said France 24.
More than 220,000 people have been evacuated due to the Gironde fire, west of Bordeaux, in “what may be France’s largest peacetime evacuation”, reported the Associated Press.
In the Conversation, Cunningham and two other University of Tasmania researchers write that evacuation orders “protec[t] human lives, but makes it more likely houses and other structures will burn if there’s no one to defend them”. They add:
“There is little doubt climate change has made France and Spain’s wildfires worse. They represent yet another reason to redouble our efforts to tackle climate change and stabilise our climate.”
Central Spain scorched
While Spain’s fire season has not broken records in the same way that France’s has, it is on track to be among the worst since EFFIS began reporting data in 2006.
The chart below shows the rapid increase in burned area in Spain since 8 July. The latest data from EFFIS reveal that, as of 29 July, Spain has almost matched its previous record at this point in the year. It is also nearly five times the average area burned for this time of year.
In Spain, the wildfires have been concentrated in the central part of the country, near Madrid.
BBC News reported that the fires outside the capital have burned “an area more than twice as large as the city itself”.
Nearly 90,000 people were forced from their homes in central Spain by the fires, said the Associated Press.
Pedro Sánchez, Spain’s prime minister, called the fires a “painful expression” of climate change.
Meanwhile, the UK, French and Spanish governments have issued joint statements this week in response to the fires. The UK/Spain statement begins:
“This summer’s wildfires demonstrated that climate change was now a national security emergency facing Europe and threatening our way of life.”
Related
The post Factcheck: No, Europe is not having its ‘quietest’ year for wildfires appeared first on Carbon Brief.
Factcheck: No, Europe is not having its ‘quietest’ year for wildfires
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