This is part 12 of a series on world-building Climate Change scenarios for fiction.
“One of the penalties of an ecological education is that one lives alone in a world of wounds. Much of the damage inflicted on land is quite invisible to laymen. An ecologist must either harden his shell and make believe that the consequences of science are none of his business, or he must be the doctor who sees the marks of death in a community that believes itself well and does not want to be told otherwise.”
― Aldo Leopold, A Sand County Almanac
Human activities (including climate change) are pushing extinction rates very high. This probably counts as a mass extinction event (or will do if we don’t stop), which is alarming to say the least. Stories featuring climate issues often focus on this mass extinction.
Therefore we need to know what mass extinction actually means. Spoiler: it does NOT mean everything dies.
It is more complicated, and stranger, than that.
Biodiversity
A mass extinction is a dramatic drop in biodiversity. So, what is biodiversity?
Here’s a quick primer.
Depending on how you define things, we have multiple types of biodiversity. We focus a lot on Species diversity, but this is only one measure, and often not the most important.
We have:
- Genetic diversity e.g. a loss of heirloom tomato varieties is a loss of genetics. Tomatoes as a species live on.
- Species diversity e.g. the last dodo gets eaten. No more dodo.
- Phylogenetic diversity e.g. if ginkgo trees went extinct this would mean an entire branch of the tree of life had died. Ginkgoes are the only surviving member of an entire order, the Ginkgoales.
- Functional diversity e.g. if wolves go extinct the entire ecosystem is thrown out of balance because the function of apex predator has been removed. (“Keystone species” is a related concept – this is where a single species holds a critical functional role e.g. seed dispersal or pollination)
- Ecosystem diversity e.g. a forest, a lake, and a grassland is more diverse than three types of grassland.
A second complication is distribution.
Biodiversity is very unevenly distributed. Globally, most diversity exists in the tropics. Locally, most diversity is embodied in uncharismatic species that no one ever notices.
It’s worth keeping all this in mind. First, it means not every extinction is equivalent. Second, it means extinctions are frequently invisible.
If functional diversity is retained then a landscape can still be healthy, in some basic sense. The ecosystem “machinery” of nutrient cycling, soil formation, food webs etc remains intact. Conversely, broken functional diversity will result in a disaster zone even if the raw species count is high. A coral reef without any coral has collapsed, yet a forest with only a single remaining species of tree is still a forest.
This leads to a paradox of sorts.
A single extinction can cause a cascade of chaos, and a mass extinction can leave an ecosystem fundamentally intact. The answer to every question in ecology is this: it depends.
Now, put this all together: a significant portion of biodiversity exists in unremarkable species that live someplace else far away, and killing them off frequently doesn’t cause any dramatic visible effects. Therefore, horrendous levels of destruction can occur without anyone much noticing. A mass extinction can be a non-event, in human terms.
Another paradox of mass extinction, at least in our times, is that a worldwide die-off can be associated with a local level increase in diversity. Indeed, the latter can cause the former.
For example, New Zealand has roughly 2500 native plants. Humans have introduced roughly 30,000 new plant species into the country, with about 2500 of these going wild. Local biodiversity has skyrocketed to the Moon. However, New Zealand has also had many extinctions (mostly of animals).
Here’s the problem. The introductions are the same stuff that gets introduced everywhere. The extinctions were unique. Global biodiversity undergoes a crash while local biodiversity goes up.
So, when we say things like “Climate change will drive 30% of species extinct”, most of these are unnoticed species that no one has ever heard about. These are small things that shrink out of sight, then one day, in a world that barely notices, they are gone. This invisibility of extinction is important for world building a scenario. It throws us back to Part 6 – if I can’t see it, does it exist?
Bad Tropes: Degradation = Desert
Mad Max set the standard that disaster equals desert. But there’s nothing wrong with deserts.
Deserts are often full of life because life is tough and will live pretty much anywhere. Deserts are themselves the product of a living world. If we truly annihilated all life, the effect would be far stranger than creating deserts (the entire chemistry of the planet would go out of whack).
Climate change cannot turn the whole world into a desert. The only places that risk becoming deserts are already near deserts. If you want to know what a degraded ecosystem actually looks like, then look out the window.
Degradation does things like:
- lower the total biomass (e.g. a rainforest is reduced down to a blackberry patch)
- reduce the various forms of biodiversity (e.g. domination by a single invasive plant)
- become unstable (e.g. prone to population booms and busts, disease outbreaks, landslides or fires)
This degradation can be entirely invisible to an untrained eye. I’m fairly familiar with New Zealand botany, so when I look around me I can see just how messed up “Clean Green NZ” really is. But when I look overseas I lack that knowledge. Everything looks fine to me.
The same will probably be true of a climate changed future: it will look fine. Again, this throws us back to Part 6 – if you can’t see it, does it exist?
Bad Tropes: The extinction of all life
One step up from deserts is total annihilation. So let’s consider what it actually takes to kill everything.
Just to get that clear.
Annihilating all life on Earth, total sterilization, would require boiling the oceans and melting the entire crust of the planet to a considerable depth. Prolonged asteroid bombardment or a collision with another planet would be necessary. Being engulfed by the Sun would also work.
Humans are not going to end all life on Earth.
Bad Tropes: The extinction of most life
This is more likely, but still very unlikely.
Again, it is actually very difficult to reduce the entire world to a genuine wasteland.
For all the damage we have done so far, diversity often remains in the cracks. A damp forested valley on a farm, an inaccessible mountain top, an urban creek saved from development. We call these “Refugia”. Many species cling on here without going fully extinct. The world is full of tiny Noah’s Arks.
This is how life survives disasters.
To truly wipe out most life on Earth, we would have to annihilate even these refugia. And it’s not like the gaps between these refugia are currently barren – they are full of an abundance of domesticated and invasive species, all of which are doing just fine.
Climate change will not turn the world into barren wastes. Extinctions will happen, but other species will rush to fill those gaps. Ecosystems of some kind will exist. Some species are going to love climate change.
The likely result will be more “novel ecosystems” (like that mass of vines above) rather than vast fields of bones and death. Only a handful of headline worthy catastrophes – like the collapse of coral reefs - are likely to fit crude notions of what a mass extinction ought to look like. Again, we’re back to part 6.
Bad Tropes: The extinction of all humans
The idea of being the Last Man Standing is very romantic. Cries of human extinction (rebellions even) sound very compelling. However, the current world population is unimaginably huge. Almost 8 billion people.
Human beings are the least endangered mammal in existence.
Barcelona has a larger population than the entire world had during the Neolithic. Istanbul has the same population that the entire world had at the start of the Bronze Age. Even the most catastrophic die-off imaginable would leave a lot of people alive.
For example, let’s take two of the worst mega-deaths in human history.
The Black Death killed maybe up to 60% of Europe? Applied to the world today, a 60% crash would only take us back to the population of the 1960s.
The colonial era population crash of indigenous Americans (due to multiple epidemics, conquest etc) might have been as high as 90%? A global catastrophe on this scale would still leave us with the same world population as in the 18th Century, a time of world spanning empires.
Eight billion is a very, very, very big number. Extinction means zero. Nothing. All gone. Everywhere.
Even some hyper-catastrophe with a 99.9% death rate would leave 8 million people alive – in the grand sweep of human prehistory that is a large population. To get legitimately down to extinction risk level would require a 99.9999% death rate.
If your future scenario actually involves the total annihilation of all humans, then it’s going to have to involve something pretty freaking horrific.
Humanity in its Proper Evolutionary Context
If we were any other animal, all future animal life would consist of our descendants. That’s how evolution works.
Success is hardly a sign of impending doom.
Human level intelligence is an evolutionary innovation of epochal significance that gives us a profound survival advantage over every other comparable animal. We live anywhere. We eat anything. Our cultures adapt a million times faster than evolution. We can reconfigure reality to meet our needs.
Traits of such phenomenal power don’t just go away in the evolutionary process. They take over.
This is why we breath oxygen, can move, and have teeth. Those were the successful traits of their day. All else gets pushed to the margins. Major evolutionary innovations can make a complete mess of the world the into which they emerge (for an example see this video on How Worm Holes Ended Wormworld). This is unfortunate, but also normal.
Humanity’s dominance is hardly a signal of impending extinction. Rather we are too successful, feeling guilty about it, and responding from a two thousand year long habit of apocalyptic thinking. Stories about the annihilation of humanity are extraordinarily pessimistic.
If humans were any other animal we would now undergo an “adaptive radiation”, splitting off into numerous species and filling every niche on the planet.
But humans are not any other animal.
We are planet Earth reaching an entirely new era of development in which symbolic thought and conscious choice has become a force in the story. The evolution of the human species is such a profound event in Earth’s history that we have no point of reference across the billions of years with which to compare ourselves.
We don’t know where this goes.
X-Risk and Climate Change
While human extinction might be unlikely it’s also not impossible. The entire field of “Existential Risk” is dedicated to figuring out what phenomena from the array of Godlike AI, biotech hyper-plagues, or supernovae explosion might do us in – anything that puts a permanent end to the human experiment.
Extinction is a philosophically different kind of event from a mere catastrophe. A catastrophe can be recovered from, extinction cannot. Extinction risk justifies extreme actions in a way that catastrophic risk does not. Best not to confuse these two categories.
Climate change, at the levels we are facing, just isn’t in this x-risk category.
However, to use the military jargon, climate could act as a “Threat Multiplier” for other risks. A chaotic world is a more dangerous place in general. If we do go under it will be from secondary effects, like global war and mismanaged technology, not climate per se.
And again, something can still be extremely bad without literally killing everything on Earth.
Conclusion
Short of global nuclear war or nanobot grey goo consuming the universe, mass extinction is mostly just sad and boring. It makes the world less interesting, makes everywhere look the same, and makes things more degraded but not so much that the average person notices.
At which point I refer you, once again, to Part 6.
Next time... the collapse of civilization.
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