The rate at which atmospheric CO2 is increasing is now outpacing the pathways set out by the Intergovernmental Panel on Climate Change (IPCC) that limit global warming to 1.5C.
This is what the latest data shows from the Mauna Loa observatory in Hawaii, where measurements of CO2 levels in the atmosphere have been collected for more than 60 years.
In 2024, the rise in atmospheric CO2 was one of the fastest on record.
Emissions of CO2 and other greenhouse gases from human activity have so far caused human-caused global warming to reach about 1.3C above pre-industrial levels.
If warming is to be limited to 1.5C, as set out in the Paris Agreement, the build-up of CO2 and other greenhouse gases in the atmosphere will need to slow to a halt and then go into reverse.
And, yet, the rise in atmospheric CO2 concentrations is still showing no signs of slowing.
Pathways to 1.5C
The third working group report of the IPCC’s sixth assessment report (AR6), published in 2022, presented a set of seven “illustrative pathways” that highlight how different mitigation choices across major economic sectors translate into future greenhouse gas emissions and global temperatures.
In the three most-ambitious pathways, global warming has a 50% chance of either staying below 1.5C, or overshooting it by only 0.1C (for up to several decades) before then returning to below 1.5C:
- Shifting pathways (IMP-SP): Illustrates mitigation in the context of a broader shift towards sustainable development, including by reducing inequality and with a phase-out of fossil fuels.
- Low demand (IMP-LD): Illustrates a strong emphasis on energy-demand reductions, and with a phase-out of fossil fuels.
- Renewables (IMP-Ren): Illustrates a future with a heavy reliance on renewable energy.
As the table below shows, the build-up of atmospheric CO2 in these three scenarios slows from the 2010s average of 2.41 parts per million per year (ppm/year) to 1.33-1.79ppm/year in the 2020s.
It then slows still further and goes into reverse either in the 2030s or 2040s – in other words, the level of CO2 in the atmosphere actually begins to fall.
| Decade | Projected average CO2 rise (ppm/year) in scenarios limiting global warming to1.5C | ||
| C1-IMP-LD | C1-IMP-REN | C1-IMP-SP | |
| 2020s | 1.33 | 1.75 | 1.79 |
| 2030s | -0.14 | 0.13 | 0.57 |
| 2040s | -0.53 | -0.46 | -0.7 |
| 2050s | -0.65 | -0.61 | -0.41 |
Large CO2 rise in 2024
Yet, not only are atmospheric CO2 concentrations still rising, the rate of rise is accelerating.
The build-up of CO2 in the atmosphere has been monitored at the Mauna Loa observatory in Hawaii since 1958.
As illustrated by the iconic Keeling Curve below, the increase has been accelerating over the decades (blue line) due to ongoing emissions of CO2 from burning fossil fuels and changing land use.
So while the curve needs to rapidly bend in the other direction to hold warming to 1.5C (light red line), the rate of rising CO2 marches onwards and upwards.
chart
Monthly CO2 concentrations at Mauna Loa from observations up to 2024 (blue) and the IPCC C1-IMP-SP scenario consistent with limiting global warming to 1.5C (light red). Also shown is the Met Office forecast for 2025 (red).
The table below sets out decadal averages of the annual rise in CO2 concentrations at Mauna Loa. The first half of the 2020s has seen an average CO2 rise of 2.58ppm/year, which is 44-94% higher than it needs to be to track the IPCC 1.5C-compatible scenarios.
| Decade | Observed average CO2 rise (ppm/year) |
|---|---|
| 1960s | 0.86 |
| 1970s | 1.22 |
| 1980s | 1.58 |
| 1990s | 1.55 |
| 2000s | 1.91 |
| 2010s | 2.41 |
| 2020s (2020-2024) | 2.58 |
In fact, the annual rise of 3.58ppm/year between 2023 and 2024 at Mauna Loa was the fastest on record.
The global average, which has been monitored by satellite since 2003, also showed a large rise last year – and, at 2.9ppm/year, this was the second largest on record after 2015-16.
(While the rise at Mauna Loa mirrors the global rise over long periods, in the short term it can also be affected by localised effects, such as fires upwind or in the same hemisphere, before the CO2 disperses more evenly across the globe.)
Global CO2 emissions were also at a record high in 2024, but a further key factor was that natural land carbon “sinks” were substantially weaker, allowing more of the emitted CO2 to remain in the atmosphere.
At least some of this weakening of land carbon sinks was associated with the El Niño conditions in the first part of the year. El Niño events shift weather patterns around the globe, leading to hotter, drier conditions in many parts of the tropics. This means that vegetation grows less well and more carbon is released from decay in soils and from wildfires, leading to land ecosystems removing less carbon from the atmosphere than usual.
With the El Niño now subsided and conditions shifting more towards the opposite pattern of La Niña, natural land carbon sinks can be expected to recover again, at least to some extent.
As a result, in our Met Office forecast of the CO2 rise at Mauna Loa, we predict a slower rate of rise between 2024 and 2025 than between 2023 and 2024. The projected increase is 2.26ppm (with an uncertainty range of ±0.56ppm) – slightly slower than it would have been without the effects of La Niña.
However, even this is still too fast to stay on track with the IPCC 1.5C-compatible scenarios. This is highlighted in the chart below, which shows the annual change in CO2 levels at Mauna Loa since 1995 (blue lines) and how our forecast for 2025 (red point) exceeds a pathway consistent with 1.5C (grey plume).
Faster rise than expected
The specific reasons for the very large increase in CO2 in 2024 are not yet completely clear, although weaker land carbon sinks appear to be implicated.
We had forecast the 2023-24 CO2 rise at Mauna Loa to be 2.84ppm (±0.54) – faster than the average of the previous decade due to the El Niño. We had also highlighted the possibility that it could be the fastest annual rise on record.
However, the actual CO2 rise of 3.58ppm was even faster than expected. This was above the upper limit of our uncertainty range, which should include the forecast value 95% of the time.
Although carbon emissions from fossil fuel burning and deforestation were also at a record high in 2024, this does not fully explain the shortfall in our forecast.
Our forecast method uses the global emissions from the previous year as one of the inputs. The emissions in 2024 were estimated to have been 11.3bn tonnes of carbon (GtC), slightly higher than the 2023 value of 11.1GtC used in our forecast.
This 0.2GtC difference is equivalent to about 0.09ppm of CO2 in the atmosphere. So, even if we had used the larger value in our forecast, the observed rise would still have been beyond our uncertainty range.
Therefore, the origin of the discrepancy must be related to natural carbon sinks, which must have been even weaker than the expected weakening that occurred as a result of the 2023-24 El Niño.
Weaker land carbon sinks
Scientists had already established that land carbon sinks were exceptionally weak in 2023, with very high temperatures worldwide playing a part in this.
2024 was then even hotter than 2023 – and indeed was the first calendar year where warming exceeded 1.5C above pre-industrial levels. It can be expected that the climatic conditions this warmer year once again led to weaker global land carbon sink.
Both North and South America saw high temperatures and exceptionally severe fires in 2024, including in regions not normally affected by El Niño such as Canada, and extending beyond the season of El Niño influence.
Global fire emissions were estimated as 1.6-2.2GtC over January-September 2024, 11-32% above the 2014-23 average for the same months.
Moreover, fire emissions in the northern hemisphere were 0.5-0.6 GtC per year, which was 26-44% above the average of 2014-23. Since Mauno Loa is in the northern hemisphere, this may explain why the local rise there was even larger than the global average.
A portion of these fire emissions may already be accounted for in the above estimate of land-use emissions, but it is not possible to quantify this. Nevertheless, widespread fire activity likely contributed to the large rise in atmospheric CO2 concentrations in 2024. Further analysis is needed to quantify the size of this contribution.
Climate change itself may have played a role in enhancing fire emissions. For example, human-caused warming made the “unprecedented” wildfires that spread across Brazil’s Pantanal wetlands in June 2024 between four and five times more likely.
Although land carbon sinks are generally increasing as a result of rising CO2, Earth system model projections have long indicated that ongoing global warming would reduce this effect, leading to a greater proportion of human-caused emissions remaining in the atmosphere.
Calculations suggest that this has already been occurring in recent years, so a key question is whether the last two years have seen an acceleration. If natural carbon sinks weaken more than already expected, this would further increase the difficulty of slowing the rise in atmospheric CO2 concentrations.
Alternatively, there are a number of historical years for which our CO2 forecast procedure gives almost as large departures between predictions and outcomes as for 2024. For example, 2003 saw a large rise at Mauna Loa despite not being an El Niño year, due to large fires in Siberia. It will therefore be important to see whether there is a higher-than-expected rise in CO2 in 2025, or whether the large exceedance in 2024 is a temporary phenomenon.
With global warming ongoing, extremely high temperatures will continue to occur more frequently and severely, so events such as those seen in 2023 and 2024 could play an ever more important role in the global carbon cycle.
The contribution of fires attributed to climate change is consistent with model simulations which suggest that global fire activity will already be weakening land carbon sinks. Further monitoring of the global carbon cycle will help to reveal whether this is indeed the case.
The post Met Office: Atmospheric CO2 rise now exceeding IPCC 1.5C pathways appeared first on Carbon Brief.
Met Office: Atmospheric CO2 rise now exceeding IPCC 1.5C pathways
Saturday, 17 October 2026
7.18 AM AWST
Hi folks! We’re joining you live from the Rainbow Warrior where we will be providing you with updates as our four activists continue scaling and occupying Woodside’s gas platform. The activists are peacefully protesting against Woodside’s latest gas expansion plans, the Browse project, which would see up to 57 toxic wells drilled at Scott Reef.
“Right now our activists are scaling Woodside’s massive Floating Production Unit. They are scaling the South-East pillar and the underside of the Helideck. They’ll be setting up camp soon and have plenty of provisions with them – so stick around!”
5:45 AM AWST
Our RHIBS are in the water! We’ve deployed our four activists and our ship crew on our small fast boats, headed to the gas platform. We’re carrying crew and equipment, plenty of food, all of our safety climbing gear, some big banners, cameras and a whole lot of heart… someone even has something to read after they get settled in.
5:26 AM AWST
Before sunrise activists prepared to launch RHIBS from the Rainbow Warrior.
Looking for a front seat view?
You can follow along with the Live Rainbow Warrior bow cam here!
Looking for more?
Follow us on Instagram for a peek behind the scenes and hear from our Rainbow Warrior crew.
Live blog: Greenpeace activists occupy Woodside gas project to save Scott Reef
Climate Change
Greenpeace activists climb and occupy Woodside’s Scarborough gas project calling on the Australian government to “Stop Woodside’s Dirty Gas” and “Save Scott Reef”
PERTH, Saturday 17 October 2026 — Four Greenpeace Australia Pacific activists are scaling and occupying a Floating Production Unit at Woodside’s Scarborough gas project off the coast of Western Australia, displaying banners reading: “Stop Woodside’s Dirty Gas. Save Scott Reef.”
- Photos and video available here and here. More will be uploaded throughout the day.
- Content and live updates will be uploaded to a live blog and to Instagram
Early this morning at 05:45 AWST, Greenpeace Australia Pacific activists launched from the Rainbow Warrior, Greenpeace’s flagship vessel, scaling and attaching 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.
Woodside has since confirmed it has initiated a temporary shut down of the FPU.
Greenpeace Australia Pacific is occupying the gas platform in peaceful protest of Woodside’s plans to drill for oil and gas at Scott Reef as part of its Browse proposal.
David Ritter, CEO at Greenpeace Australia Pacific, said: “Greenpeace Australia Pacific is taking action today to expose the unacceptable risk to Scott Reef posed by Woodside’s plans.
“Australians love our oceans. Woodside’s reckless Browse gas proposal would turn the magnificent Scott Reef into an industrial gas zone. Woodside wants to drill up to 57 toxic wells around Scott Reef, Australia’s largest oceanic reef, home to nesting green sea turtles, and endangered species like pygmy blue whales and the dusky sea snake; it is a place like nowhere else on Earth.
“Woodside has an alarming track record of oil spills, incidents and environmental neglect, and can’t be trusted with our oceans. 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 coasts to protect our oceans.
“There’s no future in new gas projects. Our future is in secure homegrown renewable energy, green industry and exports, where communities and places like Scott Reef are protected — there’s no future in dirty gas shipped offshore.
“The prospect of drilling for oil or gas on the Great Barrier Reef would be considered absolute madness today, but that is exactly the decision before the government: save Scott Reef or risk its destruction at the hands of a gas corporation.”
From aboard the Floating Production Unit, Dr Chris Holden, Greenpeace Australia Pacific activist said: “As a doctor, when I see new fossil fuel projects like Woodside’s Browse project being put forward, I can’t help but think about the impact this is going to have on the health of our communities and planet, and feel a sense of duty to act.
“Not only will this project do irrevocable harm to nature at Scott Reef, it will have a terrible impact on our climate, putting all of our lives at risk.
“On the Rainbow Warrior I’m carrying a copy of the 2025 Lancet countdown report, which warns that health impacts of climate change are worsening, with millions dying needlessly each year due to fossil fuel dependence, growing emissions, and failure to adequately adapt.
“With warnings like this from the leading global health professionals, our government simply can’t allow fossil fuel projects like Woodside’s Browse project to go ahead. It is their duty to do what is in the best interest of our communities.”
Almost half a million people have signed a petition calling on the government to Save Scott Reef and Woodside’s Browse gas project.
-ENDS-
Notes:
- Dial-in, SimSat and Zoom interviews with Geoff Bice, WA Campaign Lead at Greenpeace Australia Pacific, currently aboard the Rainbow Warrior, can be organised separately
Media contact:
Greenpeace Australia Pacific media team on +61 406 231 892 or +61 407 581 404
The board of the Fund for Responding to Loss and Damage (FRLD) will decide on Thursday on whether to “provisionally set aside” $20 million for Nepal to deal with some of the effects of the climate-driven flood it suffered in August.
The motion, seen by Climate Home News, has been drafted by a group of board members from both developed and developing countries and so is likely to pass easily at the fund’s first-ever extraordinary board meeting on October 22.
It invites the government of Nepal to submit a proposal for how to use the money, with the board then deciding at one of its regular board meetings whether to approve the proposal or not.
While Nepali officials have described $20 million as merely “symbolic” in the face of the $4.8 billion estimated costs of recovery and reconstruction, it would be the first time the new FRLD – agreed in 2022 months after devastating floods in Pakistan – has set aside money for a specific disaster.
Until now the fund has only taken requests through a single call for proposals, launched at COP30 in Belém last November, that gave countries six months to submit requests.
Most of the 180 projects the FRLD is currently considering are designed to help countries avoid damage from future climate disasters, for example by strengthening responses to floods in Bangladesh and Lagos.
The draft decision says Nepal’s proposal will serve as a pilot for how funding requests can be submitted outside of the fund’s current timetable. That could let governments seek funds quickly after a climate disaster strikes, rather than waiting for the next call.
This arrangement would set the fund apart from other United Nations funds designed for climate adaptation or cutting emissions like the Green Climate Fund.
Climate campaigners from Fill the Fund said the draft decision is “a real step forward” as it is “the first time this Fund has moved to respond to a specific disaster”.
Too little, too late
The FRLD was agreed by governments at COP27, set up and operationalised at COP28 in 2023 but has yet to award any money. The 180 funding requests it is currently considering would cost around $2.8 billion, but it only has $350 million to allocate.
The United Nations Secretary-General António Guterres has described the amount of money available in the fund as “ridiculously small” and Fill the Fund said $20 million “is a meaningful signal but it is a drop against an ocean of need”.
A glacial rock and ice collapse sent a torrent of water and debris through Nepal and the Chinese-administered region of Tibet on August 26. It killed more than 1,400 people, left thousands more missing and destroyed homes, bridges, roads and hydropower plants. Nepal’s finance and environment ministers quickly appealed to the FRLD board for funds, saying that “time is of the essence”.
Their call was followed swiftly by a letter from developing country FRLD board members urging the board’s co-chairs to organise an extraordinary meeting to allocate funds to Nepal.
But developed countries initially called for an informal consultation rather than a full board meeting. It took a further 45 days for the board’s co-chairs to organise an extraordinary board meeting for October 22 and to draft a motion for adoption.
Fill the Fund called for a permanent way of the fund rapid responding to disasters as “Nepal should not have required historic letters, an informal drafting group and the Fund’s first-ever extraordinary meeting simply to unlock an emergency response. The next country cannot wait two months and a bureaucratic marathon. Speed must be built in, not improvised.”
The post UN’s loss and damage fund set to give Nepal $20m for flood recovery appeared first on Climate Home News.
UN’s loss and damage fund set to give Nepal $20m for flood recovery
