Glen Peters

"It is the model with the most scenarios that has the largest influence on 1.5°C scenario findings. Individual studies have only a small or negligible impact on most findings," says @idasogn.bsky.social

cicero.oslo.no/en/articles/...

It is possible to make narratives where it makes sense. Maybe technology develops and we have scalable free fusion in 50 years, and so the overshoot part is easy. I just think it is more relevant to look at the consequences of 2.5C, then look at what is different going from 2.5 to 2.0C.

Sure, a valid point. But the assumption is "urgent action doesn't happen now, but it will suddenly happen in 20 years". So we are irrational for the next 10-20 years, then suddenly, we are all rational. I think that future is rather unlikely. It is more likely we just have a warmer world.

Graph showing: Avoided emissions from passenger cars in Norway

My estimates of how much Norway's CO₂ emissions have been reduced as a result of EVs, PHEVs, and biofuels.
robbieandrew.github.io/EV/

Yes, it is amazing. Tesla is quite established in Norway, they often have good deals and cut prices if sales drop, and have good charging infrastructure. Then they probably discount the extra baggage of the owner (if they even care)...

Do you know how many people die each year from air pollution from coal power plants, even before we talk about climate?

Actually, I made a thread on this. You will see on the C2 and C3 scenarios, there are some with delay. Often they are "don't do anything to 2025 or 2030, then go crazy on mitigation". This will also give you an idea of the mapping of current trends. bsky.app/profile/glen...

I wonder how important this is for people buying Tesla's. If they were undecided between a Tesla and a non-Tesla, but then found the deal was so good with the Tesla?

Yes, but there was criteria. They had to have emissions and trends within a certain range. So if you had a scenario with peak emissions in 2010, it would not be included, for example. So all scenarios would have been made from 2015 or later, in general.

Nothing wrong with a conference, etc, I am just a little on the picky side.

4/4

There is also this weird 1.5C aspect. The only way to 1.5C is with overshoot. But the people most focused on 1.5C are also those more sceptical that OS works, whether CCS/CDR will scale, etc. Which would imply 1.5C is deader than dead. But, no keep focussing on OS to keep 1.5C alive?

3/

I guess this is a framing / priority type question. I would put the fine ruler over the time from now to peak, and not put a fine ruler over the decline phase. There are interesting science questions, for sure, but I am not sure they are the most important questions.

2/

Yes. Which is all ok. But the conclusion is still the same. Urgent action. If OS works, then we need urgent action. If OS fails, then we need urgent action. If we have tipping points, limits on CDR, etc, etc, then we need urgent action.

1/

Yes, many of these models have been around for decades. This paper looked at some of the older generation of scenarios www.nature.com/articles/s41...

Though, in the figure above, all the models have been "harmonised" to have the correct emissions in 2020.

I remain perplexed why there is so much focus on overshoot, other then scientific curiosity (guilty as charged). All the analysis has the same implication, immediate short term reductions. But alas, lets see if we can do overshoot by 2500...

Surely the short term science is more relevant?

Bekrefter: Fortsatt null rente på ny Tesla Forlenger kampanjene.

It would be interesting to know how Tesla sales relate to the incentives. In terms of "amount of car per NOK", Tesla must remain hard to beat I would think? You just have to accept Musk...

Incentives: www.tv2.no/broom/fortsa...

They have trade in offers, but when I looked at this a few years ago it was far better (say 100,000 nok better) to sell private. Though, Tesla gives very good incentives, so this changes. Currently 0% interest, 36 months. If you pay 5% on a house loan, then better 500,000 nok at 0%...

Thanks. And very interesting...

The median is biased... Before using statistics, you should make sure the sample is representative. Yes? We finally have a new paper out which looks at this question for scenarios assessed in the IPCC Sixth Assessment Report...

Based on a paper with @idasogn.bsky.social, see LinkedIn post also www.linkedin.com/pulse/median...

Figure showing reductions by scenario, group by each model. REMIND has nearly 100% reductions with 41 scenarios. AIM has around 60% reduction with 4 scenarios. Other models in between. There are 97 scenarios in total. So the median, used by IPCC, is very close to the REMIND median. Take out remind, instead of IPCC reporting 95% reductions by 2050, it would instead report something like 83%. There would be therefore greater reductions in oil and gas, to compensate.

How much must coal go down by 2050?

Well, it depends on the model...

AIM has small reductions & few scenarios, REMIND has high reductions & many scenarios. Statistics presented in IPCC therefor give high reductions. Without REMIND, reductions lower (red line with R)

www.nature.com/articles/s41...

Does the rest of the table to the right have the YTD for the same period in 2024? That would be interesting, how does 2025 compare to 2024?

It is hard to know. They were very concerned we were being critical of REMIND, as it has the most scenarios. If we had of dealt with that issue, it may have resolved other issues. They also wanted a complete solution to the problem, whereas we were mainly outlining the problem.

I am pondering whether I should post on Twitter...

Or you could set up an anonymous chat system, so you could discuss with a reviewer(s). As often issues are more misunderstandings, can be solved in minutes.

In 2025 you could probably jump on Zoom, sort it out in an hour, and save both authors and reviewers weeks of work and months of waiting. People will say they don't have time for a call, but then, they will spend far longer re-reviewing.

Yes, not sure how to solve that one... Many of the issues I imagine could be solved with a Zoom chat. A part of the problem is that you could spend days / weeks redoing things to appease the reviewer, but you don't know if it will. Then you wait more months for the review response.

Yes, the 43% part. Without REMIND, that would have been 50%. So it depends on the models selected. There are ways around it. Eg, give a range, and explain the consequences if at the low or high end of the range. "Lower reductions by 2030 mean deeper and more expensive reductions later"

Yes, and this is the key strength of IAMs. Though, they end up being used to say "for <1.5C, emissions need to go down x%, coal y%, etc", and that becomes the focus of policy, instead of answering the question you posed.

I should have put "reviewer #2", as I think they might have been another number...

Influence of individual models and studies on quantitative mitigation findings in the IPCC Sixth Assessment Report - Nature Communications The paper analyses the impact of the uneven representation of models and studies on key mitigation findings in the IPCC Sixth Assessment Report. It finds that the model with the most scenarios has a considerable influence on several findings.

New paper with @glenpeters.bsky.social in Nature Communications today. We show how models and studies with a lot of scenarios in the IPCC scenarios database have a large impact on key findings, including emissions reductions, net-zero GHG year, and coal, gas, and oil consistent with 1.5°C.