This is the #1 climatologist in the world: James Hansen.
He’s spent 50 years studying what humans are doing to the climate.
He's gone out on a limb time and time again - and been proven right.
His message? It’s far worse than they’re telling you. 🧵
He’s spent 50 years studying what humans are doing to the climate.
He's gone out on a limb time and time again - and been proven right.
His message? It’s far worse than they’re telling you. 🧵
Hansen grew up poor on a small farm in Iowa.
He saved up enough to attend university, studied physics and - by chance - came under the wing of space scientist James Van Allen.
That’s how he ended up in astrophysics.
He saved up enough to attend university, studied physics and - by chance - came under the wing of space scientist James Van Allen.
That’s how he ended up in astrophysics.
Hansen earned a NASA scholarship.
At first, he studied the atmosphere of Venus. What he found was a warning to us Earthlings: Venus is a hellscape because of a runaway greenhouse effect.
Our atmosphere matters more than we realise.
At first, he studied the atmosphere of Venus. What he found was a warning to us Earthlings: Venus is a hellscape because of a runaway greenhouse effect.
Our atmosphere matters more than we realise.
So Hansen turned his focus homeward.
At NASA he helped build one of the first climate models, giving humanity a new way to see its own future.
By 1981, he was leading NASA’s Goddard Institute for Space Studies.
At NASA he helped build one of the first climate models, giving humanity a new way to see its own future.
By 1981, he was leading NASA’s Goddard Institute for Space Studies.
He was one of the first scientists to publicly warn what humanity is doing to our climate.
In 1988, he testified to the US Senate that climate change was real, human-driven, dangerous and already heating the Earth.
It was a turning point in global awareness - and he was right.
In 1988, he testified to the US Senate that climate change was real, human-driven, dangerous and already heating the Earth.
It was a turning point in global awareness - and he was right.
But speaking the truth has a price.
The George W Bush administration banned him from speaking to the press - Hansen spoke out about that too.
When Obama pushed the Keystone XL pipeline, Hansen got arrested protesting outside the White House.
The George W Bush administration banned him from speaking to the press - Hansen spoke out about that too.
When Obama pushed the Keystone XL pipeline, Hansen got arrested protesting outside the White House.
Through it all, he kept publishing groundbreaking science.
He’s in his 80s now, but his recent work may be his most alarming yet.
And he’s taken the all-too-unusual step of writing a plain-language newsletter to explain it.
columbia.edu/~jeh1/
He’s in his 80s now, but his recent work may be his most alarming yet.
And he’s taken the all-too-unusual step of writing a plain-language newsletter to explain it.
columbia.edu/~jeh1/
What does Hansen now believe?
CO₂ has a bigger impact than many scientists thought.
Heating will be on the high end of expectations, threatening organised global society.
CO₂ has a bigger impact than many scientists thought.
Heating will be on the high end of expectations, threatening organised global society.
His conclusion rests on 3 lines of evidence:
1⃣ “Paleoclimate data”, which is evidence from Earth’s past: ice cores, sediments, fossils.
They show that relatively small changes in greenhouse gases once caused huge swings in climate.
1⃣ “Paleoclimate data”, which is evidence from Earth’s past: ice cores, sediments, fossils.
They show that relatively small changes in greenhouse gases once caused huge swings in climate.
2⃣ Recent observations.
Satellite data from CERES reveal the Earth is absorbing much more energy than models predicted. That means the planet is heating faster than we realised.
Satellite data from CERES reveal the Earth is absorbing much more energy than models predicted. That means the planet is heating faster than we realised.
3⃣ Climate models.
Updated runs confirm what paleoclimate and satellites are saying. Hansen says past estimates of climate sensitivity were too low. More CO₂ means much more heating to come.
Updated runs confirm what paleoclimate and satellites are saying. Hansen says past estimates of climate sensitivity were too low. More CO₂ means much more heating to come.
Why? In part because of aerosols.
Air pollution has been shielding the planet from the sun more than we thought. As we clean our air (a good thing for health), this hidden cooling vanishes.
Hansen calls it a “Faustian pact”.
Air pollution has been shielding the planet from the sun more than we thought. As we clean our air (a good thing for health), this hidden cooling vanishes.
Hansen calls it a “Faustian pact”.
So what does Hansen say we must do now?
Rapidly phase out fossil fuels. 2050 is too late.
Deploy clean energy at scale, now.
Remove CO₂ already in the atmosphere.
These are huge challenges that require huge resources and focus. Humanity’s future depends on it.
Rapidly phase out fossil fuels. 2050 is too late.
Deploy clean energy at scale, now.
Remove CO₂ already in the atmosphere.
These are huge challenges that require huge resources and focus. Humanity’s future depends on it.
And we must act globally - because physics doesn’t care about borders.
"We are damned fools" for our failure to act so far.
"We are damned fools" for our failure to act so far.
Hansen has dedicated his life to warning us.
From building the first climate models, to testifying in Congress, to being arrested in protest, to publishing in his 80s...
His message:
The crisis is worse than we thought. But it’s not too late to avert the very worst outcomes.
From building the first climate models, to testifying in Congress, to being arrested in protest, to publishing in his 80s...
His message:
The crisis is worse than we thought. But it’s not too late to avert the very worst outcomes.
• • •
Missing some Tweet in this thread? You can try to
force a refresh
