Glen Peters
banner
glenpeters.bsky.social
Glen Peters
@glenpeters.bsky.social

Energy, emissions, & climate
CICERO Center for International Climate Research, Oslo, Norway
https://cicero.oslo.no/en/employees/glen-peters

Glen Vecchione is an American composer, lyricist, poet, and writer. With David Dusing he co-authored the music and lyrics to the musical The Legend of Frankie and Johnny. He is the author and illustrator of several non-fiction books for children and young adults; many of them written on science related topics or on children's games. He has also published poetry for adults in several literary journals. Under the pseudonym Glen Peters he wrote the novel Where the Nights Smell Like Bread. .. more

Environmental science 41%
Economics 22%
Pinned
📢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/

That took a while. Glad it is finally out!
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)
Analysing the use of emissions scenarios in practice - npj Climate Action
npj Climate Action - Analysing the use of emissions scenarios in practice
www.nature.com

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

In case you were wondering what it looks like if you use annual CO2 emissions and not cumulative...

(If you turn you head to the side, and use a mirror, you can think of atmospheric CO2 as a proxy for time, then the emissions looks like emissions as a function of time)

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

Yes, that is correct (and was sort of my point). They collect loads of information up until (harvest) maturity, disaggregating into five maturity / harvest classes, but provide no disaggregation past harvest maturity. It is a harvest dominated system, all questions have the same answer: harvest.

Reposted by Richard Betts

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...
Overlooked hydrogen emissions are heating Earth and supercharging methane, research finds
Rising global emissions of hydrogen over the past three decades have added to the planet's warming temperatures and amplified the impact of methane, one of the most potent greenhouse gases, according ...
phys.org
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...
Hydrogen emissions are ‘supercharging’ the warming impact of methane - Carbon Brief
The warming impact of hydrogen has been “overlooked” in projections of climate change, authors of the latest “global hydrogen budget” say.
www.carbonbrief.org

The aggregated temperature effect of H2 is of the order 0.01-0.05C, depending on scenario. This is relatively small, but does not mean H2 is the best energy carrier.

We did not look at H2 substitution in the energy system, that would require different modelling tools.

4/

The climate impacts of H2 depend strongly on the background CH4 emissions.

While it is obviously important to reduce hydrogen leaks, reducing CH4 reduces the production of H2 by oxidation.

We should reduce CH4 emissions anyway, but the H2 effect is yet another reason.

3/

There are lots of natural sources of H2, and these are generally stable.

H2 from production leaks is quite small, but growing. H2 from fossil fuel use is small and declining.

But, H2 from CH4 oxidation is increasing, as CH4 is increasing.

2/
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!

Reasonable points...

Anyway, it is rather disappointing there is so little literature on old growth forests. The fact there is so much confusion and uncertainty on this issue is disappointing, and I would say largely a framing issue based on the way forest modelling and reporting work.

6/6

The article above says as much, but it seems to struggle to say it. Though, it seems to be quite some literature supporting old growth forests taking up carbon for a variety of reasons. (obviously, much less than maximum growth at maturity).

5/

We expect growth to slow down after harvest "maturity" (this does not imply they should be harvested), but we we don't really know what the steady state of an old growth forest is (100s of years after maturity) because they don't really exist.

4/

The real question is whether "old growth forests" reach a state of 'carbon neutrality' after some hundreds of years.

The problem is these forests don't really exist, as they were hacked down years ago. The old growth forests that exist are often of low quality (ie, not valuable for harvest).

3/

I think there would be unanimous agreement that forests continue to take up carbon after "maturity", though, I think many in the forest sector try to imply that they stop taking up carbon. Therefore they *must* be harvested.

Well, no, forests take up carbon long after harvest "maturity".

2/

"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/

Looks like next year will be quite the revision too...

As an aside, Swedish LULUCF has made quite the recovery...

This will be unrelated to the biofuels, as I would assume most of those are sourced outside of Sweden?

It seems there has been a substantial revision in the Swedish LULUCF (right is from last years emission reporting).
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]

Reposted by Glen P. Peters

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...

Though, they are the same sort of models. They just might discuss in a little more detail.