Here’s what a 5°C global warming, ocean acidification event that lasted for 200,000 years looks like in a sediment core pulled up from the bottom of the ocean. We’ll probably leave something similar behind in the rocks. [📸 J. Zachos] In fact, this dissolution of chalky seafloor sediments from anthropogenic CO2 is already underway in some parts of the ocean ncbi.nlm.nih.gov/pmc/articles/P…

This is probably the most well-known geology “fact” for which there’s no evidence

https://twitter.com/Rainmaker1973/status/1129453166549000192

From biochemist Nick Lane

800 years ago the West was stricken with a mega-drought, like it is today. As a result, huge swathes of the Sand Hills of Nebraska weren't grass-covered hills and wetlands, like today, but were instead mobile, Sahara-style sand dunes--the largest in the Western Hemisphere Around the same time, from Rocky Mountains to California, the record of charcoal in lake sediments indicates widespread forest fires. But "the magnitude of variation in climate & fire" was "still smaller than those projected to occur over the next century" pnas.org/content/109/9/…

One (very important) topic I didn't get to address in this story is: how do we know what the temperature, or the co2 level in the atmosphere was millions of years ago? 1/x

https://twitter.com/PeterBrannen1/status/1357429391312101376

Continuous ice core records from Antarctica & Greenland are great. They contain trapped pockets of air containing ancient CO2, & the ice can be geochemically analyzed to reconstruct temps. But they "only" go back 800,000 years. (efforts are underway to retrieve older ice cores)

Something I think a lot of Silicon Valley-type space enthusiasts really don’t appreciate is that there is nothing we could do, nuclear war-wise or climate change-wise that would make the Earth more uninhabitable than Mars. Like, even after an End-Permian-style climate catastrophe, or all-out nuclear war, there would still be oxygen and a magnetic field

Paleoclimatology, is the study of Earth's ancient climates. Taking the extreme long view it becomes unsettlingly apparent that Earth's climate is "an angry beast," as Columbia climate scientist Wally Broecker used to say, "And we are poking it with sticks" theatlantic.com/magazine/archi… Within recorded history, climate changes have been linked with the faltering of the Hongshan & Yangshao cultures, the Akkadian Empire, the Bronze Age, the Roman Empire, the Ptolemaic Empire, Ancestral Puebloans, the Khmer Empire, Classic Maya... But recorded history is nothing.

Things (I think) humanity can Survive v Not Survive

Not Survive:
Sufficiently large Large Igneous Province
Sufficiently large asteroid
Vacuum decay
Burn-it-ALL (12k GtC)

Survive but not very fun:
RCP 8.5
Nuclear war
Yellowstone-style eruption
Gamma-ray burst
Bad AI
Geomag storm NB: I think "civilization" would collapse in every one of these scenarios with possible exceptions of bad AI and big geomagnetic storm

PART 2 Over huge area of Siberia, enough lava erupted in a few thousand years to cover the lower 48 United States A KILOMETER DEEP. But as mindblowing as eruptions were, they only covered part of Russia--so lava itself couldn't have killed almost everything on the planet. It had to be the volcanic gases that came up out of the earth, especially CARBON DIOXIDE. Most ominously, these volcanoes had the misfortune of burning through one of the largest coal basins in the world, the Tunguska Basin.

It seems like people are into MASS EXTINCTIONS these days and I wrote a book on them so here's a 2-Part ⚡️MEGATHREAD⚡️ on the worst things that have ever happened EXTINCTION 1: The first major mass extinction was 445 million years ago, the End-Ordovician. It happened on a planet that as alien as any in science fiction.