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Ali Duffey

@aliduffey.bsky.social

200 followers 570 following 91 posts

Climate science, solar geoengineering, arctic change PhD student at University College London

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Ali Duffey @aliduffey.bsky.social · 8d

love this chart. It's too late for 1.5, but the fight for 2C is very much still alive

Zeke Hausfather @hausfath.bsky.social · 8d

Yep, while there is a growing literature on emissions and climate outcomes under current policy scenarios (and we can more firmly rule out things like 5x more coal by 2100 globally), current policies represent neither a ceiling nor floor on future emissions: journals.sagepub.com/doi/10.1177/...

Reposted by Ali Duffey

Marie Le Conte @youngvulgarian.marieleconte.com · 19d

wrote about this last year and sure I wasn't in any way the only one but imo people voting for populist politics in the 21st century *is* a sign that they do just have too much faith in institutions, as opposed to not enough - they want to have their little tantrum but assume things will just hold

Ali Duffey @aliduffey.bsky.social · Sep 9

The evidence we have, though, suggests SAI is not like these other ideas, being instead logistically feasible, effective and quite cheap.

We could be wrong on all three of these, of course, but honest debate about geoengineering demands that we grapple with that evidence

Ali Duffey @aliduffey.bsky.social · Sep 9

The SAI section bends over backwards to try to fit it into the same mould as the others (logistically difficult, expensive, and ineffective), but in doing so makes some surprising errors as well as being one-sided.

Ali Duffey @aliduffey.bsky.social · Sep 9

But the idea that further research into these is a waste of resources is crazy to me, when i think about what is at stake here.

Yes sea-curtains sound difficult, but so does building a sea-wall around Bangladesh.

Ali Duffey @aliduffey.bsky.social · Sep 9

Similarly for the ice sheet interventions. While those working on these have been the first to ackowledge that they are profoundly ambitious ideas, the Siegert et al study is a valuable and welcome critical perspective to help understand how and why these ideas would face challenges.

Ali Duffey @aliduffey.bsky.social · Sep 9

My impression is that sea-ice thickening and the ice sheet interventions are somewhere between implausible and just unlikely. The potential for sea-ice thickening to meaningfully impact global climate is often exaggerated, though, and its good to call this out

Ali Duffey @aliduffey.bsky.social · Sep 9

Glass beads for sea-ice albedo modification has always been an implausible idea - here's me in 2023 writing as much. I welcomed the decision of the Arctic Ice project folks to wind down their activities.

www.arcticiceproject.org/the-project/

agupubs.onlinelibrary.wiley.com/doi/full/10....

Ali Duffey @aliduffey.bsky.social · Sep 9

Not all geoengineering proposals are plausible, and we shouldn't waste time and resources on the implausible ones.

Siegert et al look at 5 (really, 6): sea-ice thickening, sea-ice albedo modification, sea-bed curtains, basal water removal from ice sheets, CDR via ocean fertilization, and SAI

Ali Duffey @aliduffey.bsky.social · Sep 9

Is this a crisis or not? Are tipping point risks serious or not?

Net zero is non-negotiable, but climate impacts are here, and all plausible emissions scenarios see us pass 1.5C.

If now is not a reasonable time to explore radical ideas, when would be?

Damian Carrington @dpcarrington.bsky.social · Sep 9

Polar #geoengineering dismissed as “unimaginably expensive” and “dangerous”

Giant underwater curtains and artificial ice thickening diverts attention from cutting fossil fuel burning, climate scientists argue - but proponents disagree

#climatecrisis
Story by me
www.theguardian.com/environment/...

Polar geoengineering dismissed as ‘unimaginably expensive’ and ‘dangerous’

Underwater curtains and artificial ice thickening divert attention from cutting fossil fuel use, says group of climate scientists

www.theguardian.com

Reposted by Ali Duffey

Jack Blackburn @hackblackburn.bsky.social · Aug 4

One of the all-time great test matches. One of the all-time great series.

Topsy-turvy, up and down and, in the end, perfectly balanced. Can't say fairer than that.

Reposted by Ali Duffey

Hannah Ritchie @hannahritchie.bsky.social · Jul 14

The Guardian will publish scary headlines about ice sheet and AMOC collapse on a Friday, then stuff like this on a Monday: www.theguardian.com/commentisfre...

How are people supposed to navigate this? Is climate change an urgent problem, or not?

Ed Miliband would let a turbine farm destroy Brontë country. We need net zero, but at what cost? | Simon Jenkins

Of course the climate crisis must be confronted, but history, tranquility and beauty must also count for something, says Guardian columnist Simon Jenkins

www.theguardian.com

Ali Duffey @aliduffey.bsky.social · Jul 14

"some experts are sceptical"..

New Scientist has been poor on distinguishing serious and unserious climate intervention ideas recently. There isn't even a peer-reviewed paper making the case for this yet!

Ali Duffey @aliduffey.bsky.social · Jul 12

Yeah, the conspiracy theories are growing in a very scary way

Ali Duffey @aliduffey.bsky.social · Jul 11

A very good if somewhat strange watch.

not very informative on risk-reward tradeoffs for solar geo though

Ali Duffey @aliduffey.bsky.social · Jul 11

@eaterofsun.bsky.social might be of interest

Ali Duffey @aliduffey.bsky.social · Jul 11

..and is why a framing of SRM as an "in case of emergency break-glass" type intervention can be misleading

Ali Duffey @aliduffey.bsky.social · Jul 11

BUT, once things are already tipped, SRM might not be able to get you back - we assessed "reversibiility" as ineffective or only partially effective for many important systems.

This shouldn't be surprising - this behaviour is part of what makes these things "tipping points"

A long table summarising the main findings of the paper

Ali Duffey @aliduffey.bsky.social · Jul 11

the slight less TLDR version is that SRM likely reduce the strength of driving factors for tipping in a range of systems, generally by reducing temperature but in some cases by restoring other climatic drivers too

Ali Duffey @aliduffey.bsky.social · Jul 11

here's the paper
esd.copernicus.org/articles/16/...

The interaction of solar radiation modification with Earth system tipping elements

Abstract. The avoidance of hitting tipping points has been invoked as a significant benefit of solar radiation modification (SRM) techniques; however, the physical science underpinning this has thus f...

esd.copernicus.org

Ali Duffey @aliduffey.bsky.social · Jul 11

Given this context, I'm delighted to share a new review on the solar geoengineering and earth system tipping points. Its a long read including ice sheets, AMOC, coral reefs, Amazon dieback and various others..

TLDR: solar geo probably helps avoid tipping, but a lot more research is needed

Prof. Stefan Rahmstorf @rahmstorf.bsky.social · Jul 9

New Scientist has a report on a controversial issue discussed last week at the #GlobalTippingPoints conference in Exeter: will we need solar radiation interference as a desperate measure, as politicians are failing to phase out fossil fuels?
www.newscientist.com/article/2487...

Geoengineering could avoid climate tipping points, but not if we delay

Putting aerosols in the stratosphere to reflect sunlight could prevent the shutdown of key ocean currents, but only if it is done soon, a computer model suggests

www.newscientist.com

Reposted by Ali Duffey

DSG @sgdeliberation.bsky.social · Jul 7

New opportunity: Become a DSG Fellow and contribute to building critical expertise on solar geoengineering governance. Early- or mid-career and working in climate science, policy, ethics, law, or humanities with an interest in SRM? Apply now: www.sgdeliberation.org/our-work/res...

Ali Duffey @aliduffey.bsky.social · Jul 7

The intro to this paper of mine last year has some potentially useful refs on the hydrological response to SRM, particularly on seperating the fast and slow responses to CO2

iopscience.iop.org/article/10.1...

This may all be somewhat tangential to your argument though..

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iopscience.iop.org

Ali Duffey @aliduffey.bsky.social · Jul 7

My thinking was that G1 has unchanged global mean temp, but a different spatial pattern (cooler tropics, warmer poles, amongst other things), as well as the extra GHGs and less sunlight.

Kravitz 2015 describes the CMIP6-era GeoMIP experiments gmd.copernicus.org/articles/8/3...

...

GMD - The Geoengineering Model Intercomparison Project Phase 6 (GeoMIP6): simulation design and preliminary results

gmd.copernicus.org

Ali Duffey @aliduffey.bsky.social · Jul 6

Awesome! The G1 GeoMIP experiment might be a nice additional test case?

Also, small typo on line 86 (two 'η_uniform's)