I don’t know how many people still check out this blog. I’m planning on shutting it down next year, before I have to renew my hosting contract. I’ve been busy “getting my shit together” so to speak, so I haven’t felt like blogging much lately.
But I feel like explaining something. Long ago, there was a debate about climate sensitivity: When the amount of carbon dioxide in the atmosphere doubles, how much does the Earth warm? There have always been widely varying estimates, but the scientific consensus eventually settled at 3 degree Celsius, with a large uncertainty bar.
Since then, it’s been starting to look like the field of climatology in general has been stuck on an erroneously low estimate of climate sensitivity. Sabine Hossenfelder explains it in this video:
The Earth’s real sensitivity, is likely well above 4 degree Celsius. James Hansen estimates it at 4.5, or 4.8 based on paleoclimatology. He wrote at the beginning of this year, that 2025 will tell us what the answer really is: Are the lower estimates of 3 degree Celsius correct, or are we looking at something much higher?
He wrote:
An “acid” test of our interpretation will be provided by the 2025 global temperature: unlike the 1997-98 and 2015-16 El Ninos, which were followed by global cooling of more than 0.3°C and 0.2°C, respectively, we expect global temperature in 2025 to remain near or above the 1.5°C level. Indeed, the 2025 might even set a new record despite the present weak La Nina.
And well, here’s the temperature for 2025 so far:
It’s not looking good guys. The Hansen “acid test”, is looking borderline acidic:
Hansen’s “acid-test” is borderline acidic at the moment, with the global anomaly for 2025 year-to-date at 1.464°C above the pre-industrial baseline and rising, currently about 0.135°C below the anomaly for 2024.
The Climate 8-ball is dissolving.https://t.co/PXY91fr7Ju pic.twitter.com/oSCBNh1yRD
— Prof. Eliot Jacobson (@EliotJacobson) October 27, 2025
But it’s November that’s looking really nasty so far. It’s increasingly looking like global warming has accelerated.
Here you have a graph with the best fitting linear trend, I added the last two red dots myself, for 2024 and 2025.
You can clearly see now that we’re on the purple line and we’re not returning to the old green trend.
Assuming the current trend of accelerated warming holds, this is what we’re looking at:
That’s 3 degree Celsius, by 2060.
Now what you have to comprehend, is that all these climate agreements being made at COP30 in Brazil right now, all these emission agreements, this whole idea of keeping warming below 1.5 degree Celsius, with some temporary overshoot, all of that, is all based on the idea that everything I just showed you is just bullshit and global warming is not accelerating.
Bill Gates suddenly becoming a hero of low status white males, by now telling everyone to stop worrying about climate change? Also based on the idea that climate sensitivity is a modest 3 degree per doubling.
But the temperature anomaly the past few days, is looking pretty nasty. It’s hinting at 2025 becoming the second hottest year ever, despite a La Niña.
It’s hard to say what the real climate sensitivity number is, because we don’t really know how much warming is currently being hidden by toxic air pollution. If a lot of warming is currently being hidden, then sensitivity is high. Nobody quite knows for sure how much the air pollution contributes to the formation of clouds that block sunlight thereby keep the Earth cool.
Yes, that’s basically what determines what our future looks like.
Blocking the sun is a bad idea
For what it’s worth, it doesn’t look like blocking the sun through geo-engineering is a good idea either. I’ll explain why.
Techno-optimists want to block the sun to save us from climate change. They point to stratospheric aerosol injection, as a solution that occurs naturally during volcanic eruptions.
The typically suggested example is the 1991 eruption of Mount Pinatubo. It was originally thought to reduce temperatures by 0.5 degree Celsius globally, by blocking sunlight. These estimates turn out to be wrong however, as natural variability was not sufficiently corrected for.
Newer studies find much lower estimates. This study finds a peak of 0.28 degree Celsius. This study finds a peak of just 0.1 to 0.15 degree Celsius temperature reduction in the area between the arctic and the Antarctic.
So why does this matter? Well, we know what the effects of the Pinatubo eruption were on our world. The chlorine from the eruption increased the hole in the ozone layer and the creation of cloud condensation nuclei in the stratosphere allowed massive rainfall that led to the most destructive floods ever recorded in the United States. It’s also held responsible for a massive flood in Eastern China.
Effects on crop yields by blocking sunlight seem to have been quite significant however. The estimate here suggests a 9% reduction in maize yield and a 5% for other staple crops, as a consequence of the eruption.
So look at it this way: If you cause a giant collapse in agricultural yields by blocking the sun, with just a 0.1 degree Celsius temperature reduction to show for it, then you’re better off not blocking the sun.
The idea that blocking the sun is going to help us deal with climate change, is basically based on outdated science. The newer science suggests that blocking the sun will have far bigger negative effects than positive effects.
This is what I felt like sharing today, hope you found it interesting.