1/6 I am thrilled to announce that I have moved to @UChicago to lead a new initiative on Climate Systems Engineering. See news story. This thread addresses some obvious questions.

news.uchicago.edu/story/david-ke… 2/6 Q1-Why does this matter? The UChicago initiative is distinct in that it started with a wide-ranging faculty consultative process that led to a strategic choice by university leadership to pursue research in this area.

1/ Why not commercialize solar geoengineering?

Motivated by silly commercial stuff that bubbled up this year, this thread provides a few reasons why commercializing solar geoengineering is a terrible idea.

Bouquets, brickbats, or additional arguments most welcome. 2/ An example that just got some ink. More examples near end-of-thread. technologyreview.com/2022/12/24/106…

1/ Two pivotal illustrations of climate progress.

One: The flow of money to decarbonization has tripled to 0.75% of GDP in a decade

Two: Per capita emissions have peaked and total emissions will peak soon 2/ One: Decarbonization requires replacing the high-emissions energy infrastructure with a zero-emissions alternative.

flow of $$ --> clean infrastructure is a stronger measure of climate action than the flow of pledges --> mediasphere.

1/ Is every $ on CCS a waste? Enough folks asked me about this to tempt me to tweet.

Fair cop that CCS 1.0--CCS as a path to low carbon electricity – was overhyped by folks including me.

nytimes.com/2022/08/16/opi… 2/ Why were we wrong? Solar & wind got cheap (👏) fast and CCS cost were high.

But Harvey & House look only backward. Yet if you issued bids to procure large volumes of low-carbon cement today CCS would be the cheapest way to supply it. Similar for steel and some chemicals.

1/ What if we regret not geoengineering?

Fear of overconfidence dominates thinking about SRM.

Scenario A: we believe SRM works and come to rely on it by underinvesting in emissions cuts, removal, and adaptation 2/ Fan & shit will then intersect if SRM turns out to be ineffective and risky.

Techno-hubris is dangerous. It's wise to fear overconfidence.

1/ Q: What is the value of research on solar geoengineering?

A: If research reduced uncertainty by 1/3 by 2030 it would be worth ~4 $trillion.

This thread explores why that crazy number that is both wrong and meaningful.

Our watch our 4 min video: player.vimeo.com/video/714634132 2/ Nerdy thread follows -- tune in tomorrow for a more political thread about opposition to research and regret about not geoengineering.

1/4: 3 new papers on solar geoengineering research and policy released today in Science: 2/4: Ted Parson's Editorial "Geoengineering: Symmetric precaution", @parson_ted
DOI: 10.1126/science.abj1587

1/6 What's the least bad way to cool the planet?

My first try comparing carbon removal (CDR) and solar geoengineering (SG) is out as a 1,750 word Guest Essay in @nytopinion.

nytimes.com/2021/10/01/opi… 2/6 My hunch: SG may allow cooling over a human lifetime with less environmental risk and less social disruption than CDR.

1/9 What’s the use of Integrated Assessment Models?

A rambling thread motivated by my recent paper with Mariia Belaia and Juan @jmorenocruz

Optimal Climate Policy in 3D: Mitigation, Carbon Removal, and Solar Geoengineering 2/9 What’s new? First IAM to analyze temporal tradeoffs between mitigation, SG and CDR producing yields first version of Shepherd’s “napkin diagram” from an optimization model. Abstract below. Paper here: worldscientific.com/doi/epdf/10.11…

1/13 Johnathan Foley @GlobalEcoGuy says "Solar Geoengineering: Ineffective, Risky, and Unnecessary".

Well, 2 out of 3 ain't bad. But, before we get to which 2, let's consider his arguments. globalecoguy.org/solar-geoengin… 2/13 Foley opens with a common ad hominem attack, claiming that folks who argue for SG research do so because they are "unwilling to accept" that the tools to cut emissions are at hand so they want to "counteract climate change *instead of* addressing its underlying causes"

1/5 How to improve models used for solar geoengineering?

New @AGU_Eos paper by the steering committee of the Geoengineering Modeling Consortium (GMRC) What's GMRC? We are a science community consortia anchored at NCAR

eos.org/science-update… 2/5 GMRC aims to identify weaknesses in geophysical models used for solar geoengineering and then develop collaborative efforts to improve the models.

Our next event (May 5th) is on the NAS report that will be released Thursday
cgd.ucar.edu/projects/gmrc/

1/13 Is solar geoengineering like nuclear weapons?

In critiquing the SCoPEx experiment Ray Pierrehumbert @ClimateBook compared our work to helping North Korea get nuclear weapons.

So, time for thread #2 debunking solar geoengineering's BS mountain

https://twitter.com/ClimateBook/status/1359126915404230657

2/13 This is not personal. Ray, you are an amazing scholar & human. In the early '90s helped me on meridional energy transport. We have enjoyed dinners talking about shared love of the northern wilds. I am jealous of your musical ability, and wish to count you a friend.

1/7 Geoengineering droughts?

Thread #1 debunking solar geoengineering's BS mountain

Search geoengineering & drought, you get's ~0.5 million google hits and 1,696 news articles in Nexis starting with a 1991 Newsweek article.

Must be some facts underneath? 2/7 The '91 Newsweek article reported that US National Academy has endorsed research on solar geoengineering. It mentioned drought as a climate risk and geoengineering as an uncertain and potentially risky way to ameliorate such risks. Other '90s articles have a similar take.

1/n A $100m carbon removal @xprize cool! But folks who care about climate should ask some hard questions.

Virgin Earth Challenge $25m prize launched in '07 by @richardbranson. Original prize terms were nonsensical: required a $ bn business to win so the $25m would be meaningless

https://twitter.com/xprize/status/1358780911370842114

2/n the Virgin (VEC) prize revamped the terms to say winners had to have pathway to giga scale commercial #CDR, but terms remained deeply ambiguous.

On the plus side, VEC helped us raise funds and attention when I was working to found @CarbonEngineer in '09.

1/3 Cheap intermittent solar power can make carbon-neutral hydrocarbons: high-energy fuels that are easy to store and use. My 12 min talk at Royal Society #CodexTalks describes a low-risk fast path to industrial-scale solar-fuels 2/3 Background: Carbon-Neutral Hydrocarbons keith.seas.harvard.edu/publications/c…. Recent work on renewable hydrogen nature.com/articles/s4156…. H2 will win in some markets, but it has many disadvantages as a fuel. The big $$$ is getting to H2, once there, why not go to hydrocarbons with DAC?