Robin Lamboll

Is it time to aim for 1.7°C as the new limit for global warming? With the world on the cusp of passing 1.5°C of warming, scientists are turning their attention to defining a new limit for temperature rises – but not everyone agrees that we should

If 1.5°C warming is the safety line and 2°C the cliff edge, how far into the danger zone can we go?

@joerirogelj.bsky.social and @robinlamboll.bsky.social say we need a clearer, stricter upper limit, around 1.7°C, to guide policy beyond 1.5°C

The question: how close to the edge is too close?

Mele Wedding Customs Intro In 2024 I attended the wedding of my cousin Serah, from the South Pacific nation Vanuatu. Vanuatu has a huge cultural and linguistic diversity, with its 80 islands containing over 130 languag…

Last summer I visited my cousin's wedding in Vanuatu, an intricate and fascinating event which involved a fairly high fraction of all living speakers of the endangered language Mele. I've written a description of events here: scienceisshiny.wordpress.com/2025/07/21/m...

We're within 3 years of reaching a critical climate threshold. Can we reverse course? A report published in June found that the world only has three years before it crosses the 1.5 C climate target. So what should we do now?

Here's a little article on what the very small carbon budget means about 1.5C and what happens after we get there. www.livescience.com/planet-earth...

I'll be at Scenarios Forum in Leeds from tonight - let me know if you want to meet up to discuss things!

More frequent & intense heatwaves are already having a measurable effect on the UK's economy. Workers' health is not sufficiently protected, affecting productivity & putting pressure on health services.
We need adaptation + investment in a low-carbon economy & an equitable transition to net zero.

⚠️Global warming caused by humans is advancing at 0.27°C per decade – the highest rate since records began.

This is one of the indicators updated every year by over 60 international scientists in the annual Indicators of Global Climate Change report – published today. doi.org/10.5194/essd... /1

In case anyone is confused by the different headlines on carbon budgets today, the Guardian's 2 years value is based on a 66% chance, the 3 years comes from a 50% chance.

3. Questions and answers are more useful than lectures, so save extra time for that (you will have to repeat bits of your lecture in the Q+A anyway).

4. Be clear about your own ignorances, particularly regarding local affairs.

1. When in person, assume good faith during any first exchange, but also show your work (put sources, etc.) - don't assume they will assume your good faith.
2. Minimise discussion of models. Climate change is immediately obvious from measurements and people (rightly) distrust models.

Over the weekend I talked to people at Elmbridge's citizen's assembly, giving an introduction to climate change suitable for a general audience which included several climate change skeptics. I thought I'd share some principles I work from when giving these sorts of talks:

🧪 Lead author Hamish Beath explains our paper with a system for evaluating scenarios for climate action in a thread here:

Dr Eleonora Moratto will show us how ballet can be used to tell science stories at the Great Exhibition Road Festival! Featuring nature and climate research by her, @mattcscience.bsky.social, @morenamills.bsky.social and me! www.greatexhibitionroadfestival.co.uk/event/dancin...

I think that's about right. If we reach net zero by 2050, aerosols will be low (unless we emit them on purpose) and it ~doesn't matter when they drop for peak temp. If we keep emitting CO2, aerosol drop matters for temporary temperature.

Depends on the drop, but atmospheric concentrations aren't held fixed, so I don't think it's a useful conversion. But for any conversion to GtCO2, the whole point of a budget is it doesn't matter when you emit the CO2. Almost all paths to net zero feature a drop in aerosols at some point.

I'll be doing poetry with the deeply evocative Fiona Broadhurst at Homebrew Poetry next Wednesday. It will be the last instance of Homebrew for a while, so if you've been meaning to visit now is a good time to go! www.eventbrite.com/e/homebrew-p...

Differences between carbon budget estimates unravelled - Nature Climate Change Estimates of carbon budgets compatible with limiting warming to below specific temperature limits are reviewed, and reasons underlying their differences discussed along with their respective strengths...

If you're going to exceed 2C eventually, dropping aerosols gets the warming sooner, but if you want to avoid 2C it only matters if it happens before or after other things peak.
I will make the moderately strong claim that exceedance budgets have no policy use-cases. www.nature.com/articles/ncl...

I think I see the miscommunication here - you are considering the timing of pathways that will surely exceed 2C and keep going (exceedance budgets), whereas I am considering whether pathways do or don't exceed 2C (avoidance budgets), where the timing of aerosol forcing dropping doesn't matter.

Only if the persistence time overlaps with the time of crossing that boundary (to first order). For 2C and aerosols that's clearly not true, aerosols persist for ~weeks and we're not crossing 2C in weeks with or without them, so you can essentially ignore current emissions. Methane is more complex!

Pretty much, yes. As the time-dependence of CH4/aerosol impact is shorter, it is less problematic to use this than it would be for CO2, though clearly not optimal.

But the calculations are all based on the old database, and don't substantially update until there's a new one. We could harmonise db before calcing results, but since this isn't really what the models indicated, it would mostly be an investigation into the vagaries of the impacts of harmonisation.

Substantial reductions in non-CO2 greenhouse gas emissions reductions implied by IPCC estimates of the remaining carbon budget - Communications Earth & Environment Current best estimates of the remaining carbon budgets to meet the Paris Agreements goals assume substantial reductions in methane and other non-CO2 greenhouse gases, and failure to achieve these redu...

There is no non-CO2 budget; our other paper has approximate emissions reductions in non-CO2 gases implied by CO2 budget (www.nature.com/articles/s43...), but emissions time for these isn't approximately irrelevant in the same way, so "budget" metaphor doesn't apply. The calculation doesn't use ECS.

What is "carbon debt" and who is responsible for overshooting climate targets? A short blog: granthaminstitute.com/2025/04/09/w...
based on research in
www.pnas.org/doi/10.1073/... (with @setupelz.bsky.social, @cjsmith.be, @gidden.bsky.social, @wimthiery.bsky.social, @joerirogelj.bsky.social etc.)

Guest post: How to apportion ‘net-zero carbon debt’ if global warming overshoots 1.5C - Carbon Brief Our findings show that some regions, such as western Europe and North America, will accrue net-zero carbon debt as soon as 2030.

NEW – Guest post: How to apportion ‘net-zero carbon debt’ if global warming overshoots 1.5C | @setupelz.bsky.social @robinlamboll.bsky.social @wimthiery.bsky.social @gidden.bsky.social @cjsmith.be @shonali-p.bsky.social

Read here:

Call for start-ups. Apply now! Deadline: 05 May 2025

Turn your green idea into a successful startup - get the knowledge and skills you need! You have a green idea or business to take to the next level. Perfect, you should enter! Don’t worry if you don’t have a business plan just yet, or if your idea is still on the back of a napkin. Be sure to apply before the UK deadline on 5 May.

ClimateLaunchpad is the world’s largest green business ideas competition. Our mission is to unlock the world’s cleantech potential that addresses climate change. We fill a gap in developing a pipeline of early-stage climate ventures and provide a platform for those ideas to flourish.

Got a green idea? Gain skills to see if it can evolve into a successful startup - apply now for Climate Launchpad!

Don’t worry if you don’t have a business plan just yet, or if your idea is still on the back of a napkin.

Apply before the UK deadline on 5 May ➡️ climatelaunchpad.org/application-...

Slamden - the UK's only Sober Metal Poetry Slam Support independent record shops and purchase your ticket to Slamden - the UK's only Sober Metal Poetry Slam from Raven records today!

This Friday I'm headlining Slamden (sober metal poetry)!
ravenrecordshop.com/product/slam...
At the same time, the lovely @beesmade.bsky.social will be launching her new book online:
www.eventbrite.co.uk/e/allographi...
I wrote a poem inspired by a poem of hers: stepawaymagazine.com/archives/5627

📢 New paper w/ G. Ganti @robinlamboll.bsky.social L. Grant @cjsmith.be @shonali-p.bsky.social @joerirogelj.bsky.social K. Riahi @wimthiery.bsky.social @gidden.bsky.social

We examine a forward-looking measure to guide collective efforts in the era of climate overshoot: net-zero carbon debt.

🧵

Rich nations ignore past pollution to claim climate plans are 1.5C-compatible Campaigners and scientists said historic responsibility means rich countries should prioritize cutting emissions in their climate plans

I gave a few comments for this article in terms of the alignment of government promises with the 1.5C target: www.climatechangenews.com/2025/03/12/r...

@geeknproud42.bsky.social

RealClimate: How will media report on this new AMOC study? RealClimate: I’ve been getting a lot of media queries about a new paper on the AMOC, which has just been published. In my view this large media interest is perhaps due to confusing messages conveyed i...

There is a new study out in Nature about the Atlantic overturning circulation. I will be curious to see the media reporting on this. If you wonder why, read my blog article on it! 🌊
www.realclimate.org/index.php/ar...

The future is green: The economic opportunities brought by the UK’s… The net zero economy has become a significant driver of growth and innovation in the UK, achieving remarkable growth over recent years.

"every £1 of value generated by the net zero economy creating an additional £1.89 in the wider economy... for every job supported by net zero businesses, a further 2.5 jobs are supported in the wider economy."
eciu.net/analysis/rep...