New paper! How are emissions scenarios 📉 from the IPCC (and other sources) actually used by decision-makers? We asked them, and the results are out just in time for the holidays 🧑‍🎄🤶🧑‍🎄 (with @idasogn.bsky.social & @climansen.bsky.social)

According to the Norwegian National Forest Inventory (NFI), annual tree volume growth continues even in old growth forests. Peak growth is around 40 years, but after 80 years the annual increment stays constant (meaning the volume grows). landsskog.nibio.no

There is a strong relationship between temperature & cumulative CO2 emissions. The relationship is different for CO2 concentration, but approximately linear: * CO2 concentration grows faster than cumulative emissions * Declining CO2 emissions leads to declining concentration rdcu.be/d9Rnm

My pet theory remains that most of the fuss about 2023 was because most of the projections (from late 2022) were wrong since they got El Nino wrong (they thought it was La Nina). It is not easy getting El Nino right either: 2023 is either La Nina or El Nino depending on lags and annualisation.

Hydrogen does not directly warm the climate, but interacts with OH to extend the life of CH4. "More hydrogen means fewer detergents [OH] in the atmosphere, causing methane to persist longer &, therefore, warm the climate longer" phys.org/news/2025-12... Article: www.nature.com/articles/s41...

The Global Carbon Project has just published the most comprehensive Global Hydrogen Budget to date. H2, although not a GHG, has an indirect Global Warming Potential 37 times more potent than CO2. Carbon Brief: www.carbonbrief.org/hydrogen-emi... Research paper: www.nature.com/articles/s41...

An update of the Global Hydrogen Budget. The biggest source of H2 into the atmosphere is oxidation of CH4 and NMVOCs. So if you care about the climate effects of H2, reduce your CH4 emissions... www.nature.com/articles/s41... 1/

[1/3] Before everyone scatters away on holidays, a reminder to people here interested in the history of climate economics and/or the politics of climate modelling about two ongoing calls for papers. One questions futures, the other is history-oriented, take your pick!

"After maturity, forests continue to sequester carbon but more slowly, with increasing storage in deadwood and soil" Obviously... But, I find this discussion on old growth harvests a little weird. "Maturity" is defined as the point of maximum growth, when harvesters want to harvest. 1/

Policy works. How do we know? Because emissions go up when the policy is removed (transport in this case). [Noting, biofuels are allocated zero emissions in GHG emission reporting, on the assumption emissions are captured in LULUCF]

I am preparing my new-years resolutions, and I have an idea for the climate crowd: Stop sloppy climate language! Restrict the use of the term «acceleration» to what should happen to emissions reductions, and stop using it for all things related to climate mitigation. @glenpeters.bsky.social

On day 12 of our #PLOSClimateCountdown, we're highlighting an Essay by @elinlb.bsky.social, @glenpeters.bsky.social and Jale Tosun: "Policy-driven acceleration of climate action" 🔗 journals.plos.org/climate/arti...

Do you have some kids that want to learn about climate change? Or perhaps you want to learn some more, but in a more accessible language? Then check out this Special Collection... kids.frontiersin.org/collections/... 1/

Plenty of figures to choose from. Here are the first six of the 74 on the webpage. They're numbered according to which slide they appear on in the GCB's Powerpoint slidedeck (link on this page), which has a little more interpretation on each one. robbieandrew.github.io/GCB2025/

Has climate policy* worked? There is an argument that CO2 per unit GDP has not accelerated in 50 years (top left). This term is made of two componets: * Energy per GDP (bottom left) which has not changed * CO2 per Energy (top right), this is where the action is 1/

The costs of Direct Air Capture will not fall as much as hoped. "Efforts to reduce carbon emissions should therefore* continue at pace, says the research team." *Therefore is problematic here, as it implies that if DACCS was cheap less reductions are needed. No, no, no. ethz.ch/en/news-and-... 1/

The Nepalese EV transition. In simple terms, brown on this graph is India's share and blue is China's share. The trigger? India effectively halted all imports of petroleum into Nepal in 2015, an "undeclared blockade", which was "masked as constitutional concern". robbieandrew.github.io/carsales/

Anders Opedal (CEO of Equinor) said something wrong here. He said that the IEA said no need for new oil and gas before, now they say more oil and gas needed. This is wrong. The no new oil and gas is if demand drops in line with 1.5C, and always has been. 1/

And if IPCC AR7 is not released until after the GST in 2028, then they will still be using the 2019 number until 2029, when the budget for 1.5°C would have been exceeded... (unless someone comes up with new bigger budgets)

“Most of the things that we need to do for climate change we need to do anyway and we would generally be better off doing those things” @hannahdaly.ie 🎙️ Ep2 of Climate change-off the record out now @ucc.ie @uniofgalway.bsky.social @drclarenoone.bsky.social @roisinmoriarty.com #climateaction

The change in global fossil CO2 emissions in 2025 were rather unusual, particularly for coal & oil. The country level changes are all rather small & often contrast previous years. We project coal to increase, because it is flat everywhere and rising in the US. 1/

Now that we are likely to cross 1.5°C, there is increasing discussion on "overshoot". There is a lot of uncertainties on overshoot, but there is one thing that we are 100% sure about: GHG emissions need to go down >90% in decades for overshoot to be a reality. www.swp-berlin.org/publikation/...

This, by @giacgrassi.bsky.social, remains one of the simplest and best climate visuals

COP31: It's now officially, officially going to Turkey / Australia This 2-page doc sets out the division of labour: Turkey = host and "COP31 president" Australia = "president of negotiations" unfccc.int/sites/def...

This is what Ember's data have for "World", which is a very large share of global electricity generation. Coal is up all of 5 TWh so far in 2025, gas up 19 TWh. Compared to solar up 535 TWh and wind 141 TWh.

The contrast with China is also interesting. Coal generation is also down so far this year in China, but electricity demand is still growing strongly. robbieandrew.github.io/china/

1.5C scenarios are dramatic, but are they useful? Paris puts the control in the hands of countries, with the goal to achieve collective outcomes. Each country needs a transformation pathway that works for them, contributes to collective goals, & makes them stronger. drilled.media/news/cop30-g...

Where are global CO2 emissions heading? Middle-of-the-road? But just because we have followed the SSP2-45, SSP4-60 path for 10 years, does not mean we follow it for the next 70 years. Policy & technology have pushed the world away from the high-end, but 2.7C in 2100 & rising is not a good outcome!

Another way to look at the data:

The atmospheric increase of CH4 has returned to "normal" levels in the last couple of years, after big increases in 2020-2022. The 2020-2022 increases were likely anomalies (COVID, weather), and not a change in trend. gml.noaa.gov/ccgg/trends_...

An interesting snippet of information... Electricity generation from coal in India has dropped in the first 10 months of 2025, with renewables covering for all the growth in electricity use. Noting, growth in electricity use is rather low... More figures: robbieandrew.github.io/india/

I wish there was better news than this headline ⚒️🧪 "Global carbon emissions from fossil fuels are projected to rise by 1.1% in 2025 - reaching a record high" (globalcarbonbudget.org/fossil-fuel-...) + Global Carbon Budget 2025 is out globalcarbonbudget.org/gcb-2025/ + Paper doi.org/10.5194/essd...

Where we are in terms of achieving Paris Agreement temperature goals, where we need to go, and how to get there. Interview with @rishpardikar.bsky.social drilled.media/news/cop30-g...

At #COP30 last week, India highlighted the impossibility of 1.5C and the reliance on CDR for overshoot scenarios. Interview with @glenpeters.bsky.social about Paris Agreement temperature goals, where we need to go and how to get there. drilled.media/news/cop30-g...

As @glenpeters.bsky.social says, we're way off target for any 1.5°C scenario. To see how far off, each of the red/green bars represents the decrease in CO₂ emissions during COVID. Even if we achieved that from now until the end of 2030, we would still miss our 1.5°C target by a significant margin.

Global CO2 emissions are showing signs of levelling, thanks to a slight decline in net land-use change emissions offsetting continued growth in fossil emissions. The trends are way off compared to the 1.5C scenarios with no or low overshoot assessed in the IPCC. Details: bsky.app/profile/glen...

The International Energy Agency (IEA) got plenty of critique for bringing back the Current Policies Scenario (CPS). I think it was a good idea to bring back. Let me explain why... 1/

The most common question I was asked by journalists: "was there anything that surprised you"? "Well, no, because I work on this everyday". Now I have found the surprise... Carbonation, the uptake of CO2 in cement, has turned a corner because cement production is dropping!

My fear is scientists will just sit by & be complicit. Saying you are for 1.5C or net zero is not ambition. If rich country GHG or CO2 emissions are not dropping at >5% per year, they are not remotely consistent with 1.5C, nor net zero in a reasonable time frame. Scientists need to point this out.

The 2025 update of the Global Carbon Budget is out.​​ While fossil CO2 emissions rise again and carbon sinks are weakened by climate change, deforestation emissions are down and many countries decarbonise their energy. No global emissions peak yet though. theconversation.com/the-worlds-c...

For the fossil CO₂ component, we also have revisions, which are documented in the standalone report here: zenodo.org/records/1741...

It is worth a reminder that each year we revised the carbon budget in all years, not just the last year www.carbonbrief.org/analysis-fos... This year we had a rather big adjustment in land-use change emissions, including the change in carbon density due to CO2 fertilisation, etc. rdcu.be/ePDDS

"I would want to see emissions going down for several years before I would stand up on a building top and shout that emissions have peaked" Please take note of my wise words... www.nature.com/articles/d41...

"...it's virtually impossible not to cross 1.5 degrees now. It's just not possible to turn the ship around so fast" @glenpeters.bsky.social Listen now: overshootpod.com

The thing that amazes me most about this figure is not the progress that we made from the blue line "where we were going", but that everyone seems to be having heart failure that the IEA made a scenario where emissions are flat, instead of falling 20% in 25 years... www.axios.com/2025/11/13/c...

If CO2 emissions go to zero in 2050 (top), the sinks (green) will bring atmospheric CO2 back down (middle), & temperature will stabalise at ~1.7°C (bottom). Going to zero today will keep us <1.5°C Constant emissions leads to 2.6°C, rising rapidly thereafter. www.nature.com/articles/s41...

Kina er verdens største utslippsnasjon, verdens største forbruker av kull og verdens største utbygger av fornybar energi. Kina er både verst og best. Så hva er status for Kinas klimaomstilling? Hør og lær: www.energiogklima.no/podkast/stat...

📢Global Carbon Budget 2025📢 Fossil CO2 emissions continue to rise in 2025 while the terrestrial carbon sink recovers to pre-El Niño strength. The key findings are covered in two reports this year: * ESSDD (preprint): essd.copernicus.org/preprints/es... * Nature: www.nature.com/articles/s41... 1/

Published today in Earth System Science Data: The Global Carbon Budget 2025 essd.copernicus.org/preprints/es...

🚨 The Global Carbon Budget 2025 has just been released and I actively contributed for the first time 😍