# Existential Threats **URL:** \ **Category:** Great Debates\ **Created:** [February 5, 2021, 1:51am UTC](https://boards.straightdope.com/t/existential-threats/932232 "2021-02-05T01:51:39Z")\ **Posts on this page:** 20\ **Page:** 8
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [March 18, 2021, 7:29pm UTC](https://boards.straightdope.com/t/existential-threats/932232/141 "2021-03-18T19:29:38Z")
> [@Kimstu](#): > > but what evidence is there to think this decline rate is indefinitely extendable, or even extendable over the next few decades? A quote from the article: “Some of them, called PFAS, are known as “forever chemicals”, because they don’t breakdown in the environment or the human body. They just accumulate and accumulate – doing more and more damage, minute by minute, hour by hour, day by day.” Municipal waste-water treatment plants don’t even try to reduce these chemicals. How much time do you think we have? ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [March 18, 2021, 7:48pm UTC](https://boards.straightdope.com/t/existential-threats/932232/142 "2021-03-18T19:48:32Z")
> [@EastUmpqua](#): > > A quote from the article: > “Some of them, called PFAS, are known as “forever chemicals”, because they don’t breakdown in the environment or the human body. They just accumulate and accumulate – doing more and more damage, minute by minute, hour by hour, day by day.” Yeah, nobody’s denying that PFAS chemicals have negative impacts on human health, including on male fertility. But the question in terms of “existential threat” is whether there’s any reason to believe that the decline trend will simply continue at the same rate. And AFAICT, that’s not so. The fact that accumulating chemicals continue to build up in the body of an individual doesn’t necessarily imply that successive generations of individuals are going to be more and more drastically affected by such chemicals. Especially if regulations are introduced to restrict the use of the chemicals, which given the concerns about their impact on male reproductive health looks like a pretty likely scenario. > [@EastUmpqua](#): > > How much time do you think we have? Until environmental pollution literally wipes out human male sperm counts? Forever, IMO. Absent some very drastic short-term contamination that has an immediate and universal sterilizing effect, I just don’t see the human species literally going extinct due to lack of fertility. I could be wrong, but so far I see no reason to think so. ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [March 18, 2021, 8:07pm UTC](https://boards.straightdope.com/t/existential-threats/932232/143 "2021-03-18T20:07:56Z")
> [@Kimstu](#): > > I just don’t see the human species literally going extinct due to lack of fertility. I could be wrong, but so far I see no reason to think so. I’m not saying we can’t fix this…yet. > **[Overview of Endocrine Disruption | US EPA](https://www.epa.gov/endocrine-disruption/overview-endocrine-disruption)** > > Background information on concerns regarding endocrine disruptors. What worries me is that there’s not much awareness of this problem. It’s interesting that the EPA understands the problem, but it hasn’t implemented any restrictions on municipal treatment plants discharging endocrine disruptors into the receiving environment. Even in the current Clean Water Act section 303(d), there’s no mention of restrictions on discharging these chemicals. > **[Clean Water Act Section 303(d): Impaired Waters and Total Maximum Daily Loads...](https://www.epa.gov/tmdl)** > > The 303(d) program provides guidance and technical resources to assist States in submitting lists of impaired waterbodies and the development of Total Maximum Daily Loads of the pollutant causing the impairment. ---
**Author:** ![JohnnyWest](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnnywest/32/7223_2.png) [@JohnnyWest](https://boards.straightdope.com/u/JohnnyWest)\ **Post date:** [March 19, 2021, 2:15pm UTC](https://boards.straightdope.com/t/existential-threats/932232/144 "2021-03-19T14:15:19Z")
800,000 humans _could_ repopulate, but they’d have to all be in the same area and that’s pretty unlikely. As well, they’d have to all be of an age to procreate, have viable sperm/eggs, have the ability to keep fetuses alive, etc. As well, if an asteroid were large enough to create a “nuclear winter”, the systems to grow crops as you describe would already have to be in place - which they are not - and this is assuming that seeds of a variety of types would be readily available. It’s a lot trickier to get humanity up and running than one might assume. We really hang by a thread on this planet. ---
**Author:** ![JohnnyWest](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnnywest/32/7223_2.png) [@JohnnyWest](https://boards.straightdope.com/u/JohnnyWest)\ **Post date:** [March 19, 2021, 2:18pm UTC](https://boards.straightdope.com/t/existential-threats/932232/145 "2021-03-19T14:18:31Z")
> [@Blue\_Max](#): > > t has been 65 MILLION years since this last happened. So, you’re saying we’re due, right? 🙂 ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [March 19, 2021, 2:40pm UTC](https://boards.straightdope.com/t/existential-threats/932232/146 "2021-03-19T14:40:23Z")
> [@JohnnyWest](#): > > It’s a lot trickier to get humanity up and running than one might assume. We really hang by a thread on this planet. That’s a weird conclusion to draw. Firstly, 800,000 comes from the deliberately extreme scenario of 99.99% of humans dying. That’s not a plausible number even for a dino-killer, you’d probably need something an order of magnitude bigger, to so thoroughly decimate all humanity. Then, yeah, we would expect those remaining humans to be fairly localized because the world has many different environments and it is likely that some of those environments will have a better survival chance than others. It would be very weird for the remaining humans to be homogenously spread worldwide. In terms of sperm and eggs, yeah I’d expect that young adults are the most likely to survive extreme scenarios, but even if they were only half the population, so what? Finally for a population so incredibly small they could probably live for decades at least on tinned food. There’d be 8 billion humans’ worth of resources lying around. ---
**Author:** ![JohnnyWest](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnnywest/32/7223_2.png) [@JohnnyWest](https://boards.straightdope.com/u/JohnnyWest)\ **Post date:** [March 19, 2021, 3:39pm UTC](https://boards.straightdope.com/t/existential-threats/932232/147 "2021-03-19T15:39:48Z")
My conclusion comes from seeing what happened during the first wave of the pandemic. Grocery stores wiped out. Same thing happens during an on-coming blizzard. Sure, the canned goods (those that are reachable and not cooked/exploded, most would not be) would last for a while, but feeding 800,000? Not long. With zero supply chain, most of the canned goods would not be reachable. And that’s surmising that the population you speak of would be located in an area that was modern. What if the only untouched/livable part of the planet was in the Pacific Islands or some other far-flung area? The chances of a fetus being viable and surviving in such a scenario are pretty slim, considering that you’d have very limited medical resources or doctors. It’s quite possible that a given area would have none. All of what is described is contingent on the asteroid hitting just the right place and leaving a nice big land mass on the other side of the planet in good enough shape for the supposed 800K to live in the nuclear winter that would result. The posted scenario sets up a lovely situation that is mostly implausible, i.e. LED lights underground, seeds and canned goods available, all medical conditions nice and comfy, healthy population of brood stock ready to go. It’s all a tad bit convenient to the posted argument, don’t you think? 🙂 ETA: [https://www.scientificamerican.com/article/what-would-be-the-environ/](https://www.scientificamerican.com/article/what-would-be-the-environ/) ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [March 19, 2021, 4:08pm UTC](https://boards.straightdope.com/t/existential-threats/932232/148 "2021-03-19T16:08:57Z")
I’m going to drop in briefly and argue both sides again. First, I can’t imagine that we’d need a population including 800,000 fertile people. That’s considerably larger than estimates of our breeding population during much of our early existence. And they wouldn’t all need to be in the same place, as long as there could be some mixing within a few generations. But second, no, there wouldn’t be “8 billion humans’ worth of resources lying around.” In the areas in which all or most humans were killed, most of such resources would also have been destroyed. Anywhere that there were a lot of resources left that were easy to get to there would also be humans left, at least in the short run, to use those resources. And we have a world distribution system set up that relies on just about everywhere in the world getting essential items from other areas in the world; that’s going to break down entirely. And then back in the other direction: the chances of a fetus being viable and surviving with very limited medical resources or doctors must actually be pretty decent, even if we include the chances of the mother surviving childbirth; otherwise the species would never have lasted long enough to produce doctors and medical resources in the first place. – presuming that the destruction is limited enough to allow some survivors and some resources to still exist in some places: I think a lot of it’s going to come down to pure luck, after that. And some of it, of course, to human behavior; which is known to be a pretty mixed bag, so that brings us partly back to luck again – will the survivors, in enough places, include enough of those whose behavior will lead to long-term survival to outweigh the others? ---
**Author:** ![JohnnyWest](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnnywest/32/7223_2.png) [@JohnnyWest](https://boards.straightdope.com/u/JohnnyWest)\ **Post date:** [March 19, 2021, 5:30pm UTC](https://boards.straightdope.com/t/existential-threats/932232/149 "2021-03-19T17:30:26Z")
> [@thorny\_locust](#): > > the chances of a fetus being viable and surviving with very limited medical resources or doctors must actually be pretty decent Perhaps, but the air quality isn’t going to be real good, what with the particulates and CO2, sulphur, etc. Anywho, the scenario described is totally dependent on the size/location/angle of impact of any meteor we might encounter. Conditions would vary greatly if it were small and hit an ocean vs. large and hit a populated land mass. ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [March 19, 2021, 7:32pm UTC](https://boards.straightdope.com/t/existential-threats/932232/150 "2021-03-19T19:32:08Z")
> [@JohnnyWest](#): > > Anywho, the scenario described is totally dependent on the size/location/angle of impact of any meteor we might encounter. Yes indeed. Could be anything from less damage than Krakatoa to nothing surviving except maybe chemosynthesizers in the deep sea vents. ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [March 19, 2021, 7:33pm UTC](https://boards.straightdope.com/t/existential-threats/932232/151 "2021-03-19T19:33:27Z")
Super volcanoes also might give us a good wallop. If human population is reduced to thousands, or 10’s of thousands, how we react would probably determine our chances of survival. If we work together, we survive. If we fight over limited resources, we cause our own extinction. > **[Would a supervolcano eruption wipe us out?](https://www.bbc.com/future/article/20170724-would-a-supervolcano-eruption-wipe-us-out)** > > Throughout our planet’s history, massive volcanic eruptions have devastated life. Could one bring an end to human civilisation? ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [March 19, 2021, 7:35pm UTC](https://boards.straightdope.com/t/existential-threats/932232/152 "2021-03-19T19:35:55Z")
> [@thorny\_locust](#): > > Yes indeed. Could be anything from less damage than Krakatoa to nothing surviving except maybe chemosynthesizers in the deep sea vents. And Tardigrades… > **[Tardigrade](https://en.wikipedia.org/wiki/Tardigrade)** > > Tardigrades (/ˈtɑːrdɪɡreɪdz/), known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär ("little water bear"). In 1777, the Italian biologist Lazzaro Spallanzani named them Tardigrada (/tɑːrˈdɪɡrədə/), which means "slow steppers". > They have been found in diverse regions of Earth's biosphere – mountaintops, the deep sea, tropica... ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [March 19, 2021, 7:52pm UTC](https://boards.straightdope.com/t/existential-threats/932232/153 "2021-03-19T19:52:14Z")
> [@Mijin](#): > > Finally for a population so incredibly small they could probably live for decades at least on tinned food. There’d be 8 billion humans’ worth of resources lying around. You think an asteroid impact that wipes out 99.99% of humanity is going to leave _decades_ worth of tinned food lying around? Anyway, we just did this (or still kind of are) over [in a GQ thread](https://boards.straightdope.com/t/how-well-would-modern-society-handle-the-dinosaur-killing-meteor-if-it-happened-today/933856) ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [March 19, 2021, 8:01pm UTC](https://boards.straightdope.com/t/existential-threats/932232/154 "2021-03-19T20:01:16Z")
> [@JohnnyWest](#): > > All of what is described is contingent on the asteroid hitting just the right place and leaving a nice big land mass on the other side of the planet The _other_ side is no good. That’s where a) a lot of the high-energy ejecta lands. b) the antipodal hotspot forms. ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [March 19, 2021, 8:16pm UTC](https://boards.straightdope.com/t/existential-threats/932232/155 "2021-03-19T20:16:53Z")
> [@EastUmpqua](#): > > And Tardigrades… Oh, yes. I’m not sure some of the tardigrades might not make it if the impact were big enough to crack the planet into multiple pieces. ---
**Author:** ![JohnnyWest](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnnywest/32/7223_2.png) [@JohnnyWest](https://boards.straightdope.com/u/JohnnyWest)\ **Post date:** [March 19, 2021, 9:07pm UTC](https://boards.straightdope.com/t/existential-threats/932232/156 "2021-03-19T21:07:23Z")
Well I guess the chances are even lower in that case. To quote a Bill Paxton character in Aliens: “We’re toast, man”. ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [March 19, 2021, 9:34pm UTC](https://boards.straightdope.com/t/existential-threats/932232/157 "2021-03-19T21:34:49Z")
[![](https://img.youtube.com/vi/dsx2vdn7gpY/hqdefault.jpg "Game Over Man, GAME OVER!") ](https://www.youtube.com/watch?v=dsx2vdn7gpY) ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [March 20, 2021, 12:18am UTC](https://boards.straightdope.com/t/existential-threats/932232/158 "2021-03-20T00:18:33Z")
> [@MrDibble](#): > > You think an asteroid impact that wipes out 99.99% of humanity is going to leave _decades_ worth of tinned food lying around? Yes. What do you think would happen to it? Bear in mind that the main thing I was objecting to was a characterization of this as “humans be so fragile”. Because, while it’s true that there are many disasters that could wipe out a big chunk of humanity, the kind of scenarios we need to imagine to get anywhere close to 99.99%, let alone full extinction are absurdly extreme, and certainly enough to wipe out the rest of the macrofauna with us. If the requirement now is conditions destructive enough to even destroy the majority of tinned food, I rest my case. ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [March 20, 2021, 12:41am UTC](https://boards.straightdope.com/t/existential-threats/932232/159 "2021-03-20T00:41:42Z")
Tinned food is very far from indestructible. Sufficient heat will burst the cans. Sufficient weight will break the cans. Even falling from a shelf can dent cans enough to break their integrity. Freezing temperatures can also burst the cans, from within as the contents expand. High humidity or exposure to water can cause corrosion. Large temperature swings, even within ranges humans can tolerate, can cause seams to break. And, while canned food iff stored properly is generally safe to eat long past its best-by dates, nutrient values go down over time even if the cans have remained intact. ---
**Author:** ![Blue\_Max](https://avatars.discourse-cdn.com/v4/letter/b/9de053/32.png) [@Blue\_Max](https://boards.straightdope.com/u/Blue_Max)\ **Post date:** [March 20, 2021, 4:16am UTC](https://boards.straightdope.com/t/existential-threats/932232/160 "2021-03-20T04:16:35Z")
Well, if we look at the data, [here](https://en.wikipedia.org/wiki/List_of_impact_craters_on_Earth#Largest_craters_(10_Ma_or_more)): Dinokiller is the second largest impact in Earth’s history, although several impacts of one third its size seem to have happened every few tens of millions of years. These smaller impacts, while probably far beyond any nuclear weapon conceivable, do not wipe out all life on Earth single-handedly. Earth may go another billion years without another Dinokiller, there is little history of such an impact. [Previous page](https://boards.straightdope.com/t/existential-threats/932232.md?page=7) [Next page](https://boards.straightdope.com/t/existential-threats/932232.md?page=9)