Leon Simons
@leonsimons.com
Mission: To understand & protect the home planet.
Innovator, climate research & communication, social entrepreneur.
Board member Club of Rome NL
Innovator, climate research & communication, social entrepreneur.
Board member Club of Rome NL
Pinned
Leon Simons
@leonsimons.com
· Jun 6
No one should be surprised when a planet that accumulates heat more than twice as fast starts to see temperatures go up more than twice as fast.
This isn't rocket science, but we do need more of these NASA satellites. 🌍🛰
To keep us from going blind.
bsky.app/profile/leon...
This isn't rocket science, but we do need more of these NASA satellites. 🌍🛰
To keep us from going blind.
bsky.app/profile/leon...
Starting in one hour:
ASK US ANYTHING, before or during Climate Chat later today.
What questions do you have for us?
Please comment here or on YouTube:
www.youtube.com/live/LZTPZOA...
What questions do you have for us?
Please comment here or on YouTube:
www.youtube.com/live/LZTPZOA...
December 14, 2025 at 4:57 PM
Starting in one hour:
There is much more warming in the pipeline than simple models suggest.
Especially regionally.
Observations trump simple models.
Global averaging of (outdated CMIP6) models is pretty much useless with regards to what most people care about:
understanding real world impacts.
Especially regionally.
Observations trump simple models.
Global averaging of (outdated CMIP6) models is pretty much useless with regards to what most people care about:
understanding real world impacts.
December 14, 2025 at 2:53 PM
There is much more warming in the pipeline than simple models suggest.
Especially regionally.
Observations trump simple models.
Global averaging of (outdated CMIP6) models is pretty much useless with regards to what most people care about:
understanding real world impacts.
Especially regionally.
Observations trump simple models.
Global averaging of (outdated CMIP6) models is pretty much useless with regards to what most people care about:
understanding real world impacts.
ASK US ANYTHING, before or during Climate Chat later today.
What questions do you have for us?
Please comment here or on YouTube:
www.youtube.com/live/LZTPZOA...
What questions do you have for us?
Please comment here or on YouTube:
www.youtube.com/live/LZTPZOA...
December 14, 2025 at 1:02 PM
ASK US ANYTHING, before or during Climate Chat later today.
What questions do you have for us?
Please comment here or on YouTube:
www.youtube.com/live/LZTPZOA...
What questions do you have for us?
Please comment here or on YouTube:
www.youtube.com/live/LZTPZOA...
Reposted by Leon Simons
Sunday 12/14 at 10am PT on Climate Chat: Ask Us Anything #2 w/ Dan Miller & @leonsimons.bsky.social. Post questions on the YouTube Live chat or post them below. On YouTube & LinkedIn.
@bikingmzstacey.bsky.social @radsci.bsky.social
#ClimateCrisis #ClimateAction
youtube.com/live/LZTPZOA...
@bikingmzstacey.bsky.social @radsci.bsky.social
#ClimateCrisis #ClimateAction
youtube.com/live/LZTPZOA...
Ask Us Anything #2 with Dan Miller & Leon Simons
YouTube video by Climate Chat
youtube.com
December 13, 2025 at 10:02 PM
Sunday 12/14 at 10am PT on Climate Chat: Ask Us Anything #2 w/ Dan Miller & @leonsimons.bsky.social. Post questions on the YouTube Live chat or post them below. On YouTube & LinkedIn.
@bikingmzstacey.bsky.social @radsci.bsky.social
#ClimateCrisis #ClimateAction
youtube.com/live/LZTPZOA...
@bikingmzstacey.bsky.social @radsci.bsky.social
#ClimateCrisis #ClimateAction
youtube.com/live/LZTPZOA...
Heed the 'Stockdale Paradox':
"You have to, on the one hand, never confuse the need for unwavering faith that you will find a way to prevail in the end.
With on the other hand, the discipline to confront the most brutal facts we actually face.
And we're not getting out of here by Christmas."
"You have to, on the one hand, never confuse the need for unwavering faith that you will find a way to prevail in the end.
With on the other hand, the discipline to confront the most brutal facts we actually face.
And we're not getting out of here by Christmas."
December 12, 2025 at 10:30 PM
Heed the 'Stockdale Paradox':
"You have to, on the one hand, never confuse the need for unwavering faith that you will find a way to prevail in the end.
With on the other hand, the discipline to confront the most brutal facts we actually face.
And we're not getting out of here by Christmas."
"You have to, on the one hand, never confuse the need for unwavering faith that you will find a way to prevail in the end.
With on the other hand, the discipline to confront the most brutal facts we actually face.
And we're not getting out of here by Christmas."
False hope fills me with despair.
It surprised me how many of those who (should) know better have been celebrating the *false* narrative that the Paris agreement has supposedly limited warming to below 2.6°C this century.
Genevieve breaks it down here:
It surprised me how many of those who (should) know better have been celebrating the *false* narrative that the Paris agreement has supposedly limited warming to below 2.6°C this century.
Genevieve breaks it down here:
On the 10th Anniversary of the Paris Agreement, you’re going to hear a lot about the progress we’ve made — people saying we “are” heading to 2.5 degrees heating instead of four.
I deeply regret to tell you that this is complacent misinformation.
🧵
I deeply regret to tell you that this is complacent misinformation.
🧵
December 12, 2025 at 8:05 PM
False hope fills me with despair.
It surprised me how many of those who (should) know better have been celebrating the *false* narrative that the Paris agreement has supposedly limited warming to below 2.6°C this century.
Genevieve breaks it down here:
It surprised me how many of those who (should) know better have been celebrating the *false* narrative that the Paris agreement has supposedly limited warming to below 2.6°C this century.
Genevieve breaks it down here:
Reposted by Leon Simons
Vanmiddag naar het ministerie van klimaat (😉) - ik kreeg een uitnodiging voor een bijeenkomst waar men stilstaat bij 10 jaar klimaatakkoord van Parijs, met sprekers als @heleendeconinck.bsky.social
Benieuwd, vooral hoeveel gevoel voor urgentie ik daar ga bespeuren.
Benieuwd, vooral hoeveel gevoel voor urgentie ik daar ga bespeuren.
🚨10 years after Paris:
As far as the recent past is any indication of the future, I don't expect we will see the 3-year average going down below +1.5°C much ever again...
As far as the recent past is any indication of the future, I don't expect we will see the 3-year average going down below +1.5°C much ever again...
December 12, 2025 at 8:55 AM
Vanmiddag naar het ministerie van klimaat (😉) - ik kreeg een uitnodiging voor een bijeenkomst waar men stilstaat bij 10 jaar klimaatakkoord van Parijs, met sprekers als @heleendeconinck.bsky.social
Benieuwd, vooral hoeveel gevoel voor urgentie ik daar ga bespeuren.
Benieuwd, vooral hoeveel gevoel voor urgentie ik daar ga bespeuren.
Reposted by Leon Simons
🚨10 years after Paris:
As far as the recent past is any indication of the future, I don't expect we will see the 3-year average going down below +1.5°C much ever again...
As far as the recent past is any indication of the future, I don't expect we will see the 3-year average going down below +1.5°C much ever again...
December 11, 2025 at 10:11 PM
🚨10 years after Paris:
As far as the recent past is any indication of the future, I don't expect we will see the 3-year average going down below +1.5°C much ever again...
As far as the recent past is any indication of the future, I don't expect we will see the 3-year average going down below +1.5°C much ever again...
When we build sustainable energy technologies, we know that reality always trumps models.
This 'traditional' electric stove from Ethiopia has a power density of about 17,000 W/m².
Compared to this Earth's Energy Imbalance of 1.4 W/m² doesn't seem much.
But Earth's surface is 510 trillion m².
This 'traditional' electric stove from Ethiopia has a power density of about 17,000 W/m².
Compared to this Earth's Energy Imbalance of 1.4 W/m² doesn't seem much.
But Earth's surface is 510 trillion m².
December 11, 2025 at 5:14 PM
When we build sustainable energy technologies, we know that reality always trumps models.
This 'traditional' electric stove from Ethiopia has a power density of about 17,000 W/m².
Compared to this Earth's Energy Imbalance of 1.4 W/m² doesn't seem much.
But Earth's surface is 510 trillion m².
This 'traditional' electric stove from Ethiopia has a power density of about 17,000 W/m².
Compared to this Earth's Energy Imbalance of 1.4 W/m² doesn't seem much.
But Earth's surface is 510 trillion m².
"But I'd have you know that thes waters of mine
Were once a branch of the River Rhine
When hundreds of miles to the East I went
And England was joined to the Continent"
Rudyard Kipling
We can still find ~12,000 year old wood, washed ashore on our *new* Dutch beaches.
Were once a branch of the River Rhine
When hundreds of miles to the East I went
And England was joined to the Continent"
Rudyard Kipling
We can still find ~12,000 year old wood, washed ashore on our *new* Dutch beaches.
December 11, 2025 at 5:10 PM
"But I'd have you know that thes waters of mine
Were once a branch of the River Rhine
When hundreds of miles to the East I went
And England was joined to the Continent"
Rudyard Kipling
We can still find ~12,000 year old wood, washed ashore on our *new* Dutch beaches.
Were once a branch of the River Rhine
When hundreds of miles to the East I went
And England was joined to the Continent"
Rudyard Kipling
We can still find ~12,000 year old wood, washed ashore on our *new* Dutch beaches.
Reposted by Leon Simons
Based on other lines of evidence, firemaking started likely much sooner even.
I recommend reading the book 'How cooking made us human'
See insightful interview with Richard Wrangham (from before Peterson went apeshit).
youtu.be/BAifu7lu8TU?...
I recommend reading the book 'How cooking made us human'
See insightful interview with Richard Wrangham (from before Peterson went apeshit).
youtu.be/BAifu7lu8TU?...
Primatologist Explains the 1% Difference Between Humans & Apes | Richard Wrangham | EP 249
YouTube video by Jordan B Peterson
youtu.be
December 11, 2025 at 2:22 PM
Based on other lines of evidence, firemaking started likely much sooner even.
I recommend reading the book 'How cooking made us human'
See insightful interview with Richard Wrangham (from before Peterson went apeshit).
youtu.be/BAifu7lu8TU?...
I recommend reading the book 'How cooking made us human'
See insightful interview with Richard Wrangham (from before Peterson went apeshit).
youtu.be/BAifu7lu8TU?...
This malpractice by climate bean counters doesn't get enough attention.
Malpractice by financial accountants will get them fired or worse, while climate accountants get a raise.
www.youtube.com/live/Vcx6Wyj...
Malpractice by financial accountants will get them fired or worse, while climate accountants get a raise.
www.youtube.com/live/Vcx6Wyj...
CO2 Accounting Scam? with Dan Miller & Leon Simons
YouTube video by Climate Chat
www.youtube.com
December 11, 2025 at 12:55 PM
This malpractice by climate bean counters doesn't get enough attention.
Malpractice by financial accountants will get them fired or worse, while climate accountants get a raise.
www.youtube.com/live/Vcx6Wyj...
Malpractice by financial accountants will get them fired or worse, while climate accountants get a raise.
www.youtube.com/live/Vcx6Wyj...
Imagine those 'darn leftists' making lists of forbidden words....
According to a new court filing, the Trump administration has a six-page list of banned words that Head Start locations are forbidden from using when describing their programs.
Among the censored words: "disability," "race," "women," "trauma," "Gulf of Mexico." Short thread with the full list. 🧵
Among the censored words: "disability," "race," "women," "trauma," "Gulf of Mexico." Short thread with the full list. 🧵
December 11, 2025 at 3:26 AM
Imagine those 'darn leftists' making lists of forbidden words....
Reposted by Leon Simons
I’m not asking anyone to agree with Hansen — just to refute him scientifically. So far the pushback is mostly hand-waving about “variability”, even as records fall during La Niña. If his physics is wrong, show where. That’s how science works.
"What we witness now, is scientific reticence on steroids.
Perhaps because IPCC was granted the position of extreme authority.
But in science supreme authority is not granted to anyone.
Galileo proved that."
@drjamesehansen.bsky.social
youtu.be/4-a-qeMyaPE
Perhaps because IPCC was granted the position of extreme authority.
But in science supreme authority is not granted to anyone.
Galileo proved that."
@drjamesehansen.bsky.social
youtu.be/4-a-qeMyaPE
James Hansen: 'What we witness now is scientific reticence on steroids'
YouTube video by Climate Chat
youtu.be
December 10, 2025 at 4:05 PM
I’m not asking anyone to agree with Hansen — just to refute him scientifically. So far the pushback is mostly hand-waving about “variability”, even as records fall during La Niña. If his physics is wrong, show where. That’s how science works.
"What we witness now, is scientific reticence on steroids.
Perhaps because IPCC was granted the position of extreme authority.
But in science supreme authority is not granted to anyone.
Galileo proved that."
@drjamesehansen.bsky.social
youtu.be/4-a-qeMyaPE
Perhaps because IPCC was granted the position of extreme authority.
But in science supreme authority is not granted to anyone.
Galileo proved that."
@drjamesehansen.bsky.social
youtu.be/4-a-qeMyaPE
James Hansen: 'What we witness now is scientific reticence on steroids'
YouTube video by Climate Chat
youtu.be
December 10, 2025 at 2:01 PM
"What we witness now, is scientific reticence on steroids.
Perhaps because IPCC was granted the position of extreme authority.
But in science supreme authority is not granted to anyone.
Galileo proved that."
@drjamesehansen.bsky.social
youtu.be/4-a-qeMyaPE
Perhaps because IPCC was granted the position of extreme authority.
But in science supreme authority is not granted to anyone.
Galileo proved that."
@drjamesehansen.bsky.social
youtu.be/4-a-qeMyaPE
10 years after the Paris Agreement, we have reached a '3-year average global temperature anomaly of +1.5°C in 2 or more datasets'!
And we can't blame El Niño for this, as ENSO was on average negative during this period.
The Paris Agreement was doomed from the start..
And we can't blame El Niño for this, as ENSO was on average negative during this period.
The Paris Agreement was doomed from the start..
December 9, 2025 at 5:46 PM
10 years after the Paris Agreement, we have reached a '3-year average global temperature anomaly of +1.5°C in 2 or more datasets'!
And we can't blame El Niño for this, as ENSO was on average negative during this period.
The Paris Agreement was doomed from the start..
And we can't blame El Niño for this, as ENSO was on average negative during this period.
The Paris Agreement was doomed from the start..
This December to November year was the second warmest on record.
1/
1/
December 8, 2025 at 4:42 PM
This December to November year was the second warmest on record.
1/
1/
This is bad for my mental health!
The sick joke called the Trump administration took the @EPA Climate Indicators website offline on October 10, 'World Mental Health Day'...
I backed up the 800,000 year greenhouse gas graphs and data in the link below, please share!
The sick joke called the Trump administration took the @EPA Climate Indicators website offline on October 10, 'World Mental Health Day'...
I backed up the 800,000 year greenhouse gas graphs and data in the link below, please share!
December 8, 2025 at 2:30 PM
This is bad for my mental health!
The sick joke called the Trump administration took the @EPA Climate Indicators website offline on October 10, 'World Mental Health Day'...
I backed up the 800,000 year greenhouse gas graphs and data in the link below, please share!
The sick joke called the Trump administration took the @EPA Climate Indicators website offline on October 10, 'World Mental Health Day'...
I backed up the 800,000 year greenhouse gas graphs and data in the link below, please share!
'As scientists, we are increasingly being asked to tell the public the truth about the crises we face in simple and direct terms.
The truth is that we are shocked by the ferocity of the extreme weather events in 2023.
We are afraid of the uncharted territory that we have now entered.'
1/2
The truth is that we are shocked by the ferocity of the extreme weather events in 2023.
We are afraid of the uncharted territory that we have now entered.'
1/2
December 8, 2025 at 1:38 PM
'As scientists, we are increasingly being asked to tell the public the truth about the crises we face in simple and direct terms.
The truth is that we are shocked by the ferocity of the extreme weather events in 2023.
We are afraid of the uncharted territory that we have now entered.'
1/2
The truth is that we are shocked by the ferocity of the extreme weather events in 2023.
We are afraid of the uncharted territory that we have now entered.'
1/2
This is such a great visualization of the carbon cycle and of how humanity has completely altered it within a geological instant, by @rarohde.bsky.social:
December 7, 2025 at 11:17 PM
This is such a great visualization of the carbon cycle and of how humanity has completely altered it within a geological instant, by @rarohde.bsky.social:
Reposted by Leon Simons
I had a fascinating and wide-ranging discussion with California Energy Commission Chair David Hochschild today on Climate Chat:
youtube.com/live/PHfMa6o...
@calenergy.bsky.social y @leonsimons.bsky.social @bikingmzstacey.bsky.social @radsci.bsky.social
#EnergyTransition #CleanEnergy
youtube.com/live/PHfMa6o...
@calenergy.bsky.social y @leonsimons.bsky.social @bikingmzstacey.bsky.social @radsci.bsky.social
#EnergyTransition #CleanEnergy
California & Clean Energy with CEC Chair David Hochschild
YouTube video by Climate Chat
youtube.com
December 7, 2025 at 8:12 PM
I had a fascinating and wide-ranging discussion with California Energy Commission Chair David Hochschild today on Climate Chat:
youtube.com/live/PHfMa6o...
@calenergy.bsky.social y @leonsimons.bsky.social @bikingmzstacey.bsky.social @radsci.bsky.social
#EnergyTransition #CleanEnergy
youtube.com/live/PHfMa6o...
@calenergy.bsky.social y @leonsimons.bsky.social @bikingmzstacey.bsky.social @radsci.bsky.social
#EnergyTransition #CleanEnergy
The EPA website showing this insightful 800,000 year methane concentration graph has been taken offline...
Reality doesn't change by pretending it isn't real.
Reality doesn't change by pretending it isn't real.
December 7, 2025 at 2:53 PM
The EPA website showing this insightful 800,000 year methane concentration graph has been taken offline...
Reality doesn't change by pretending it isn't real.
Reality doesn't change by pretending it isn't real.
This provides both a strong indication of a higher aerosol forcing (change) and a higher climate sensitivity (mainly from stronger cloud feedbacks).
If the aerosol forcing isn't stronger than in CMIP6 models, NASA CERES data indicates that ECS could be >6°C‼️
DOI: 10.1126/science.adt0647
If the aerosol forcing isn't stronger than in CMIP6 models, NASA CERES data indicates that ECS could be >6°C‼️
DOI: 10.1126/science.adt0647
December 6, 2025 at 5:54 PM
This provides both a strong indication of a higher aerosol forcing (change) and a higher climate sensitivity (mainly from stronger cloud feedbacks).
If the aerosol forcing isn't stronger than in CMIP6 models, NASA CERES data indicates that ECS could be >6°C‼️
DOI: 10.1126/science.adt0647
If the aerosol forcing isn't stronger than in CMIP6 models, NASA CERES data indicates that ECS could be >6°C‼️
DOI: 10.1126/science.adt0647