If a K-Pg-style extinction event happened today

[Infinity Blade]

Not too long ago I sort of rewatched an old episode of Animal Armageddon, this one being more hypothetical than the rest in depicting a hypothetical K-Pg-style extinction event happening in the present day.

So I've wanted to make this thread for several weeks now. If a K-Pg-style extinction event – that is, same type of impactor (likely a comet), same impactor size, speed, angle->, and impact of a hydrocarbon-rich area-> (these last two have proven to be very important in determining the devastation and accordingly, the amount of extinction) – happened today, what would happen? Who lives? Who dies? How badly are different clades of life hit? And how might life evolve afterwards?

I think, barring perhaps humans, we can obviously rule out any terrestrial animal weighing >25 kg surviving, just as in the original K-Pg extinction event. So my main interest is in which of the small animals would survive and which would suffer.

[Supercommunist]

Rise of hyper intelligent crows, ravens, and magpies!

On a more serious note maybe once the competition is eliminated, the perentie grows up to becomes the new komodo/megalania.

[Infinity Blade]

The original K-Pg destroyed the world's forests, and specialized arboreal species ended up paying the price. So in this case, I think we can also say goodbye to arboreal birds (just like last time), virtually all primates (if they don't already have large body size and/or inability to take adequate shelter going against them), sloths, tree snails, etc., etc.

I'm particularly interested in how well bats would fare. Obviously not all bats are the same, but some can hibernate in caves (which can also provide shelter), some are nocturnal (so lack of light when hunting for food shouldn't be a problem), and are small. However, one thing I'm concerned about for hibernating bats is white-nose syndrome, which is already devastating to hibernating bat populations as is. I think it would be exacerbated by the impact winter, given that these bats will have to be hibernating with each other for an even more prolonged period than normal (and insects will presumably not be available for that same prolonged period).

EDIT: I've since learned that some bats are actually resistant to white-nose syndrome. Still, I can't predict whether or not they'd survive.

[Life]

The impact event might spike C02 ppm levels to significant extent for a while.

Among the animals which are fortunate enough to live through the devastation phase, those will have a better shot at survival whose respiratory systems might allow them to cope with very high C02 ppm levels. Which animals would be these? Some species of birds perhaps?

Pointer: asknature.org/strategy/respiratory-system-facilitates-efficient-gas-exchange/

Alternatively, water conditions would be an issue to deal with.

Post-impact conditions are difficult to predict up to a certain period of time following the impact event unfortunately. This difficulty is apparent in the study of Wang et al (2014) for instance.

[creature386]

I'm pretty sure mammals and birds can pretty much expect a reset button to be pressed as far as their biodiversity is concerned. While they admittedly are now both far more diverse than during the K-Pg event, we can still expect 80-90% of their species to be lost (I think most whales other than maybe orcas would kick the bucket, not sure about bats). I think they'd repopulate (respeciate?) the world though, much like after the first K-Pg event.
This is all assuming humans don't survive, of course. Eight years ago, Vodmeister made a very good case that, with the Svalbard global seed vault, a few thousand humans could survive the impact and then repopulate the planet:
theworldofanimals.proboards.com/thread/258/asteroid-struck-earth-today
Should that be the case, we might use our remaining ecosystem engineering capacities to keep those taxa we find particularly cool alive.

[Infinity Blade]

I think if most marine reptiles were killed off as a result of the K-Pg event, we can expect all marine mammals to perish as well (so we could definitely add orcas to the "will die" list). The only marine reptiles that survived the original K-Pg were sea turtles, and I'm betting that's because they were ectotherms that didn't require as much food.

I think humanity, if only a small minority thereof, would survive as well. As explained before, we have underground and montane bunkers that would provide excellent shelter and we could store emergency food that could be stored for years (and if need be, ration said food). To slightly digress, I think if this were humanity from say, 200 years ago, we would indeed be in serious danger of becoming extinct from such an event. But now I definitely think we could pull through with heavy casualties.

EDIT: also I didn't realize we basically had the same thread made eight years ago.

[creature386]

Feb 21, 2021 22:21:11 GMT 5 Infinity Blade said:

EDIT: also I didn't realize we basically had the same thread made eight years ago.

Neither did I, even though I literally just linked the thread. XD

I assumed it was only about human survival, as that was literally everything we debated back then. However, the title, the OP and the poll suggest that the old thread was about animals as well. Still, it's clear that the discussion here is different from that in the old thread, so we can keep the two separate and focus on the non-human animal side here.

One thing still needs to be discussed concerning mankind. If humans survived the extinction, could they regain their old tech level and then go beyond that to genetically ressurect the animals that went extinct? Most should have their DNA preserved even centuries after the extinction. On the other hand, we are already pretty bad at undoing our own real-life mass extinction and the asteroid-induced habitat changes (which will be beyond our control) would make it impossible for most extinct species to live. Still, the idea of humans undoing a mass extinction they didn't cause (even if it's just in zoos) sounds pretty awesome.

[Infinity Blade]

If humans survived the extinction, could they regain their old tech level and then go beyond that to genetically ressurect the animals that went extinct? Most should have their DNA preserved even centuries after the extinction. On the other hand, we are already pretty bad at undoing our own real-life mass extinction and the asteroid-induced habitat changes (which will be beyond our control) would make it impossible for most extinct species to live. Still, the idea of humans undoing a mass extinction they didn't cause (even if it's just in zoos) sounds pretty awesome.

Welcome...to Holocene Park!

In all seriousness, I think what we could bring back depends on whether we'd even have a suitable surrogate mother species available for the extinct species in question. Given how much life I think would die out, it's going to be hard to find a suitable surrogate for much of them.

[Infinity Blade]

Feb 20, 2021 19:00:48 GMT 5 Infinity Blade said:

The original K-Pg destroyed the world's forests, and specialized arboreal species ended up paying the price. So in this case, I think we can also say goodbye to arboreal birds (just like last time), virtually all primates (if they don't already have large body size and/or inability to take adequate shelter going against them), sloths, tree snails, etc., etc.

I'm particularly interested in how well bats would fare. Obviously not all bats are the same, but some can hibernate in caves (which can also provide shelter), some are nocturnal (so lack of light when hunting for food shouldn't be a problem), and are small. However, one thing I'm concerned about for hibernating bats is white-nose syndrome, which is already devastating to hibernating bat populations as is. I think it would be exacerbated by the impact winter, given that these bats will have to be hibernating with each other for an even more prolonged period than normal (and insects will presumably not be available for that same prolonged period).

EDIT: I've since learned that some bats are actually resistant to white-nose syndrome. Still, I can't predict whether or not they'd survive.

Okay, so I've recently been thinking about this topic again. Inevitably it made me think about how well bats would fare in a K-Pg-style event again. Then it hit me that for bats, white-nose syndrome is far from their worst problem.

Honestly, bats in general have most things going for them when enduring a K-Pg clone. They're small, can shelter in caves, are insectivorous, and their echolocation would be extremely useful when hunting for prey in a darkened world. But while I'm by no means a bat expert, I think a big issue would be how long they can hibernate for. Bats cannot survive freezing temperatures (the main reason why so many of them hibernate during winter in the first place), which will arise from the ensuing impact winter (as it did during the original K-Pg event). If we assume that the impact winter of this event lasts as long as the original K-Pg winter, we'd be looking at below freezing surface air temperatures across the entire globe for 3 years, and even subfreezing temperatures enduring anywhere between 7 and 16 years after the impact (Brugger et al., 2016).

For 2.1 years stratospheric residence time, which is the most conservative assumption for the simulations, global annual mean surface air temperature is reduced by 27∘C when minimum temperature is reached in year 3 after the impact. This temperature difference is not sensitive to the CO2 concentration before the impact: in the case of a preimpact concentration of 1000 ppm, the temperature drops by an almost identical amount from +22∘C to−5.0∘C. Global annual mean surface air temperature remains below freezing for 3 years. For 4.3 years and 10.6 years stratospheric residence time, minimum global annual mean surface air temperature is even lower (cooling by 30∘C and 34∘C) and reached at later times (years 5 and 9 after the impact). In these simulations with longer residence times, global annual mean subfreezing temperatures persist for 7 and 16 years, respectively.

So the question is, how long can bats hibernate for? Well, the answer is it seems to depend greatly on the species, but...

Brack & Twente (1985)

The durations of the periods of hibernation of the big brown bat (Eptesicus fuscus), little brown bat (Myotis lucifugus), and eastern pipistrelle (Pipistrellus subflavus) under natural conditions were determined by following intracave movements through two winter seasons in two Missouri caves. Average durations of periods of hibernation were similar for all three species (10–20 days) over a range of temperatures. Maximum durations of periods of hibernation determined were as follows: E. fuscus, 72 days; P. subflavus, 111 days (?); M. lucifugus, 83 days. Variability in the durations of the period of hibernation was much greater for P. subflavus and may be attributable to a lack of movement after arousal or the inability of the observer to discern movement between periods of hibernation. The frequency of arousal was determined to be statistically temperature dependent for M. lucifugus, but not for E. fuscus or P. subflavus, probably because of insufficient data.

National Park Service->

During hibernation, bats cycle through periods of torpor interrupted by brief periods of arousal when their body temperatures return to normal for a few hours. Some species, such as this little brown bat, may hibernate for more than six months waiting for the return of insects in the spring.

This is only three species, and could very well be not applicable to all but...that doesn't look too good.

While I'm sure most bats of the world would be fine roosting in caves to weather out the most severe natural disasters, I currently doubt that they will be able to weather out the entire impact winter. When the time comes where they need to wake up again and find food, they will most likely either freeze to death while foraging outside or they stay in place and starve. Again, not a bat expert, but I have a bad feeling that this would be their fate. I'm pretty sure that dietary specialists that don't hibernate (particularly vampire bats and fruit bats*) are screwed.

*Fruit bats apparently occasionally eat insects, but I somehow don't think they'd be able to survive without the fruits they typically rely on.