Dan Miller
@danmiller999.bsky.social
ClimateTech VC. Postings on climate change, CDR, SRM, climate policy & pinball. Host of Climate Chat on YouTube: https://www.youtube.com/@climatechat/streams
While impressive, this is not a massive eruption like 1991's Mt. Pinatubo, which put about 20 million tons of SO2 into the stratosphere. The estimates I've seen for this eruption are ~2% of that.
November 26, 2025 at 10:07 PM
While impressive, this is not a massive eruption like 1991's Mt. Pinatubo, which put about 20 million tons of SO2 into the stratosphere. The estimates I've seen for this eruption are ~2% of that.
To have a global cooling effect, a volcanic eruption needs to be massive. The last massive one was Mt. Pinatubo in 1991.
November 24, 2025 at 3:05 AM
To have a global cooling effect, a volcanic eruption needs to be massive. The last massive one was Mt. Pinatubo in 1991.
Well, we certainly don't have safeguards in place for 2ºC & beyond warming! The status quo is no longer an option. When you think about the risks of geoengineering, compare it to the risks of 2~3ºC warming + tipping points. One of them is "not compatible with an organized global community."
November 23, 2025 at 5:55 AM
Well, we certainly don't have safeguards in place for 2ºC & beyond warming! The status quo is no longer an option. When you think about the risks of geoengineering, compare it to the risks of 2~3ºC warming + tipping points. One of them is "not compatible with an organized global community."
While solar geoengineering has risks, the risks of *not* doing it are far, far greater.
Climate change does not get better when we finally stop emissions. If we are (really) lucky, temps will stop rising but sea levels won't stop rising. We are on track for 2+ºC in the 2030s & tipping points.
Climate change does not get better when we finally stop emissions. If we are (really) lucky, temps will stop rising but sea levels won't stop rising. We are on track for 2+ºC in the 2030s & tipping points.
November 22, 2025 at 3:25 PM
While solar geoengineering has risks, the risks of *not* doing it are far, far greater.
Climate change does not get better when we finally stop emissions. If we are (really) lucky, temps will stop rising but sea levels won't stop rising. We are on track for 2+ºC in the 2030s & tipping points.
Climate change does not get better when we finally stop emissions. If we are (really) lucky, temps will stop rising but sea levels won't stop rising. We are on track for 2+ºC in the 2030s & tipping points.
It's not a prerequisite. If you wait until FF companies are abolished, you will certainly trigger major tipping points that will cause massive harm that cannot be abated or reversed.
I want to abolish FF companies too. But I want a survivable climate for our children after that eventually occurs.
I want to abolish FF companies too. But I want a survivable climate for our children after that eventually occurs.
November 14, 2025 at 9:00 PM
It's not a prerequisite. If you wait until FF companies are abolished, you will certainly trigger major tipping points that will cause massive harm that cannot be abated or reversed.
I want to abolish FF companies too. But I want a survivable climate for our children after that eventually occurs.
I want to abolish FF companies too. But I want a survivable climate for our children after that eventually occurs.
"not give another tool" = discourage
SRM will certainly reduce warming while FF companies exist & that is happening right now since we are doing accidental SRM on a massive scale since FF emissions produce aerosols... 10~20X what is needed for purposeful SRM.
SRM will certainly reduce warming while FF companies exist & that is happening right now since we are doing accidental SRM on a massive scale since FF emissions produce aerosols... 10~20X what is needed for purposeful SRM.
November 14, 2025 at 6:08 PM
"not give another tool" = discourage
SRM will certainly reduce warming while FF companies exist & that is happening right now since we are doing accidental SRM on a massive scale since FF emissions produce aerosols... 10~20X what is needed for purposeful SRM.
SRM will certainly reduce warming while FF companies exist & that is happening right now since we are doing accidental SRM on a massive scale since FF emissions produce aerosols... 10~20X what is needed for purposeful SRM.
Again, you are saying we need harm from FF emissions in order to abolish FF companies. So you are saying that you accept (unnecessary) harm to the Global South in order to provide the impetus to abolish FF companies.
Otherwise, do SRM (& reduce harm) *and* abolish FF companies!
Otherwise, do SRM (& reduce harm) *and* abolish FF companies!
November 14, 2025 at 6:04 PM
Again, you are saying we need harm from FF emissions in order to abolish FF companies. So you are saying that you accept (unnecessary) harm to the Global South in order to provide the impetus to abolish FF companies.
Otherwise, do SRM (& reduce harm) *and* abolish FF companies!
Otherwise, do SRM (& reduce harm) *and* abolish FF companies!
Huh? If we decide to implement SAI, what will delay us by decades? We need ~200 planes with larger wings & engines. We could have that in 5 years (& we can do experiments with existing, smaller planes). Once deployed, cooling happens immediately (though we will ramp it up slowly).
November 14, 2025 at 6:00 PM
Huh? If we decide to implement SAI, what will delay us by decades? We need ~200 planes with larger wings & engines. We could have that in 5 years (& we can do experiments with existing, smaller planes). Once deployed, cooling happens immediately (though we will ramp it up slowly).
So you are saying reducing harm with SRM allows FF to continue. Why not reduce harm *and* abolish FF companies?
November 14, 2025 at 5:56 PM
So you are saying reducing harm with SRM allows FF to continue. Why not reduce harm *and* abolish FF companies?
SRM lowers the heat & reduces harm & helps prevent or delay tipping points.
How does doing SRM prevent you from abolishing FF companies? I don't follow your logic. It seems like you are saying we need the harm to occur in order to abolish FF companies.
How does doing SRM prevent you from abolishing FF companies? I don't follow your logic. It seems like you are saying we need the harm to occur in order to abolish FF companies.
November 14, 2025 at 5:53 PM
SRM lowers the heat & reduces harm & helps prevent or delay tipping points.
How does doing SRM prevent you from abolishing FF companies? I don't follow your logic. It seems like you are saying we need the harm to occur in order to abolish FF companies.
How does doing SRM prevent you from abolishing FF companies? I don't follow your logic. It seems like you are saying we need the harm to occur in order to abolish FF companies.
While you delay SRM in order to encourage FF companies to reduce emissions, many people in the Global South & elsewhere will suffer & many will die from climate impacts. Plus, if you delay SRM, that will lead to tipping points such as AMOC collapse & there is no recovery from that.
November 14, 2025 at 5:28 AM
While you delay SRM in order to encourage FF companies to reduce emissions, many people in the Global South & elsewhere will suffer & many will die from climate impacts. Plus, if you delay SRM, that will lead to tipping points such as AMOC collapse & there is no recovery from that.
Huh? We can implement policies to overcome the Tragedy of the Commons, as we do for CFCs, asbestos & 1000s of other things. If we let everyone do what they want, we certainly will fail. We need leadership to implement policies that get everyone to support survival.
November 12, 2025 at 9:18 PM
Huh? We can implement policies to overcome the Tragedy of the Commons, as we do for CFCs, asbestos & 1000s of other things. If we let everyone do what they want, we certainly will fail. We need leadership to implement policies that get everyone to support survival.
All you are saying is that we will continue to not take climate actions seriously & we will let FF companies do as they please. If we continue to choose to fail, we will. But serious climate action includes CDR, SRM & phase out of FF.
November 12, 2025 at 7:25 PM
All you are saying is that we will continue to not take climate actions seriously & we will let FF companies do as they please. If we continue to choose to fail, we will. But serious climate action includes CDR, SRM & phase out of FF.
Actually, SRM *decreases* emissions because warming causes emissions (as a feedback). So using SRM not only stops temperature overshoot, it reduces the amount of CDR needed to get back to a safe temperature.
youtube.com/live/NfCATLY...
youtube.com/live/NfCATLY...
Sunlight Reflection Methods Can Reduce Overshoot & Emissions, with Peter Irvine
YouTube video by Climate Chat
youtube.com
November 12, 2025 at 7:22 PM
Actually, SRM *decreases* emissions because warming causes emissions (as a feedback). So using SRM not only stops temperature overshoot, it reduces the amount of CDR needed to get back to a safe temperature.
youtube.com/live/NfCATLY...
youtube.com/live/NfCATLY...
I’d like to interview you about SLR on Climate Chat!
November 12, 2025 at 2:11 AM
I’d like to interview you about SLR on Climate Chat!
Do you use IPCC models for future climate or measured CERES data for EEI and implied ECS? I assume if we hit 2°C in the 2030s instead of 2050, that impacts SLR.
November 12, 2025 at 2:10 AM
Do you use IPCC models for future climate or measured CERES data for EEI and implied ECS? I assume if we hit 2°C in the 2030s instead of 2050, that impacts SLR.
I’m interviewing Eric Rignot this Sunday on Climate Chat about accelerating melting of WAIS. He might have something to add to this discussion.
November 12, 2025 at 2:07 AM
I’m interviewing Eric Rignot this Sunday on Climate Chat about accelerating melting of WAIS. He might have something to add to this discussion.
If we reduce CO2 emissions by 50 GT/year ("net-zero") that only reduces the increase in cumulative emissions by 1.9%/year (50 Gt / 2600 Gt). In other words, CO2 is already too high & *only* reducing emissions, at this point, is not enough to maintain a safe climate for our children.
November 12, 2025 at 1:24 AM
If we reduce CO2 emissions by 50 GT/year ("net-zero") that only reduces the increase in cumulative emissions by 1.9%/year (50 Gt / 2600 Gt). In other words, CO2 is already too high & *only* reducing emissions, at this point, is not enough to maintain a safe climate for our children.
We can have massive CO2 removal if we (governments) are willing to pay for it. It won't happen via voluntary removal credits.
If we continue to choose to fail, we will. If we choose to succeed, the plan will include emissions phase out, CDR, and SRM.
If we continue to choose to fail, we will. If we choose to succeed, the plan will include emissions phase out, CDR, and SRM.
November 12, 2025 at 1:16 AM
We can have massive CO2 removal if we (governments) are willing to pay for it. It won't happen via voluntary removal credits.
If we continue to choose to fail, we will. If we choose to succeed, the plan will include emissions phase out, CDR, and SRM.
If we continue to choose to fail, we will. If we choose to succeed, the plan will include emissions phase out, CDR, and SRM.
Also see Hansen's 2007 letter on Scientific Reticence and SLR where he discusses how & why the scientific process (& scientists) underestimates SLR:
www.giss.nasa.gov/pubs/docs/20...
SLR might not get to multimeter this century but we should assume the worst & hope for the best.
www.giss.nasa.gov/pubs/docs/20...
SLR might not get to multimeter this century but we should assume the worst & hope for the best.
www.giss.nasa.gov
November 12, 2025 at 1:13 AM
Also see Hansen's 2007 letter on Scientific Reticence and SLR where he discusses how & why the scientific process (& scientists) underestimates SLR:
www.giss.nasa.gov/pubs/docs/20...
SLR might not get to multimeter this century but we should assume the worst & hope for the best.
www.giss.nasa.gov/pubs/docs/20...
SLR might not get to multimeter this century but we should assume the worst & hope for the best.