The problem with this story is that the previous ice age lasted around 80,000 years before it ended. It was shortly after that when the asteroid hit. So then, how did these animals survive the ice age, only to become extinct after just a short period of warming?
The data I’ve seen is that the Younger Dryas cold was no worse than the worst of the ice age.
Plausibly, the earlier Ice Age was due to relatively slow cyclical changes in earth’s orbit that permitted adaptation and survival. A more abrupt transition due to a comet or asteroid impact like the Younger Dryas would have been more challenging.
The black mat exists from California to Belgium and down to South America which is evidence of a massive firestorm in North America following the impact. The non burrowing animals in the open probably perish immediately while some small groups in protected valleys may have survived but the food source was gone for a couple of seasons for sure.
What happens after an extensive volcanic eruption?
Lots and lots of ash thrown into the atmosphere.
When Mt St Helens erupted, day light turned to night light in the surrounding areas. The museum near Mt St Helens has great videos showing all the aftermaths from the eruption.
Ditto when Krakatoa erupted in SE Asia, the darkening effect lasted long time. Which then leads what would happen if a giant asteroid big enough to cause crater the size of Gulf of Mexico. Yeah a nuclear winter lasting months. Those large Dinosaurs were cold blooded animals like Crocs are. They become immobile with cold. They had no energy to hunt for food. Thus they may have just starved to death.
The small mammals of that era on the other hand were warm blooded animals and can regulate their body temp better and many survived. Try this experiment. Place a gecko lizard in a jar (those are ubiquitous here in Florida and they eat insects and have no teeth and are cute) and place the jar in your fridge. Then catch a mouse and do the same thing. The cold blooded gecko will lie immobile and asleep. The mouse will be awake and respond to opening the fridge. That is the difference between cold blooded and warm blooded animals.
When the big herbivores died, so did the predators, including many humans.
True.
The glacial maximum - and CO2 minimum - occurred around 20,000 years ago.
Not sure about temps - that may have been earlier
The Earth had been warming for 7,000 years when large animals went extinct.
The impacts were global, and set the whole world on fire. Nearly every animal over a hundred pounds perished from the fire, the smoke, or the subsequent famine.
Only the mega fauna in Africa and the Orient survived it.
The Toba eruption around 73,000 years ago caused a long term sudden drop in the already dropping temperature (see temperature charts for the last several hundred thousand years. Also there were several severe dips in temperatures in the 20 thousands BC. One was probably a huge Vesuvius eruption. Another about 22,000 ya was probably caused by the eruption of the Japanese volcano Sakarajima. It left a caldera over 10 miles in diameter and the modern volcano is on one edge of that crater. This Dryas event was apparently very widely spread and cause a major cooling lasting well over a thousand years.