@tomaspueyo: 18 surprising facts I learned ...

18 surprising facts I learned about climate change:

1. Temperatures are at an all-time high...
... since humans left Africa

Temperatures peaked higher ~120k years ago (humans already lived on Earth)

And the world was generally warmer ~3M ago and before

2. CO2 levels followed the same path:
Humans (who appeared ~200k y ago) have never seen more CO2
But the Earth had more CO2 ~3M y ago and beyond

3. This makes sense: We imagine the Earth as a stable system but it isn't

Eg: The Great Oxidation Event
First: no O2 in the air
Plants* appeared
They started sucking in CO2 and releasing O2—
a pollutant at the time, it oxidized everything
&then started accumulating in the air

4. As a result of such wild CO2 & temp changes, sea levels have gone ⬆️ and ⬇️ wildly (left graph)

Most recently, just ~10k years ago, they were 120m below current levels (right graph)

5. Yes, the recent increase in CO2 levels is due to humans

We know because:
a. Alternative sources are not big enough (eg volcanoes)
b. Scientists looked at carbon isotopes in the air, and they correspond to fossil fuels, not other sources like volcanoes/sea

6. More CO2 means higher temperatures

The correlation between CO2 and temperatures is striking

But it goes both ways:
CO2 increases the greenhouse effect➡️higher Ts
Higher Ts➡️CO2 dissolves less in the sea, and more ends in the air

So which one matters most now?

7. Human-made CO2 does warm the planet.

The scientific consensus that there is global warming and that it's due to human activities (mainly CO2 release) is huge. Ppl think it's just 60-70% of climate scientists, but it's more like 96-100%

8. And every serious climate scientist—measured in ways like citations or papers published—agrees

Why?

a. We know exactly how CO2 is increasing temperatures through the greenhouse effect
b. Climate models can't get to current temps without man-made CO2. When added, they work

9. This is how we get all these horrible graphs showing recent global warming, which has increased current Ts ~1ºC vs pre-industrial levels

10. This global warming has increased sea levels so far by 1-2m vs pre-industrial levels

The current expert consensus is that sea levels will rise by ~0.5-1m by 2100

11. With more CO2, plants grow 20-40% faster now

The majority of new CO2 released is captured by plants* on land and in the ocean

12. Even though average Ts have increased by 1ºC since pre-industrial levels, a small increase in average Ts causes a huge increase in *extreme events*

That's why we see so many dangerous heatwaves

13. But cold waves are also decreasing.
And cold waves kill 9x more than heatwaves

Also note where they kill:
Cold waves kill mostly in hot countries
Hot waves kill in cold countries

Temperature waves kill the unprepared
Africa might benefit (fewer cold waves)

14. As time passes, we manage Ts better. We're more prepared. Between that and fewer cold waves, the net death rate from extreme Ts is *shrinking*

15. Polar bear numbers are likely increasing, not shrinking

That's because we stopped slaughtering them

But as global warming reduces their habitats, their numbers might start shrinking again

Although they might adapt and interbreed with brown bears

Data on all this is scarce

16. Ppl say they care about climate change. But it's not a top priority for them

17. If we want to limit global warming to 2ºC, we must move fast. Every year we wait to take measures, it becomes harder and harder to avoid it

18. We know how to stop climate change

a. Get fuels not from the ground but from the air, using solar panels to turn CO2 into CH4

While we ramp that up:
b. Capture CO2 with olivine weathering

c. Emit SO2 to quickly cool down the atmosphere

Summarizing:
• Humans are causing global warming
• T levels have been higher before—even while humans were on Earth
• The planet, its flora, & fauna have seen massive changes. They will survive now too
• The issue is how fast Ts are rising. Little room for animal adaptation

• Humans will adapt though. The biggest death risks are sea levels rising (not too much) & extreme Ts (which might be beneficial)
• Adaptation might be expensive though
• The wild card? Tipping points. We know little about them today
• We know how to stop global warming today

This is a very polemic topic. It might make both sides angry, so I'm a bit worried about posting this thread. The goal is to understand the pbm better together, with more nuance.

All nuance can't be captured in a thread though, so more details here:
unchartedterritories.tomaspueyo.com/p/how-bad-is-c…

And another deep dive here, with more surprising facts
unchartedterritories.tomaspueyo.com/p/21-suprising…

I write a thread like this every week or so. Follow to get them! Or better, subscribe to the newsletter—it's free!
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Correction: sea levels have gone up by 20cm since pre-industrial levels, not 1-2m! Misread the units