How do you imagine human extinction being an outcome? It seems to me that the worst case scenario is large loss of population which would decrease greenhouse gas output. There would still be some increase in temperature even once we stop emitting, but wouldn't people in colder climates still survive?
It's of course a very urgent issue, but I think exaggerating it until it becomes a threat to "all life on earth" levels is a) dishonest b) does nothing to convince sceptics that it's a real issue, quite the opposite c) is not really all that actionable (at least not in a good way).
Well, hundreds of millios displaced and/or dead would be enough. Doesn't have to "turn earth into a barren rock".
And as for "suddenly", many systems tend to have a breaking point, especially systems, like the environment, which have feedback loops that can easily feed into each other and make things worse fast. Collapse is seldom linear or a nice gradual curve.
Actually, yes it does. The OP specified "human extinction". We're arguing that single point. The fact that thousands/millions/billions might displaced isn't being contended.
What is the greatest tragedy is how much worry and anxiety climate change causes. The earth is not a thinking thing - “Mother Nature” is not a being. The planet will exist and doesn’t care about humans. A century after the last human lives nature will swallow up almost everything we built. Earth exists for humans because we live here and make it so. We will adapt to whatever climate exists.
It doesn't matter what Earth was like at some point in the distant past. There weren't 8 billion humans living on it. It's not easy or cheap to move cities with populations in the millions because sea level rise puts them below water.
Humans can adapt to climate change but it's very likely to be very painful and very expensive.
Do you expect that several hundred million people who's previous land of habitation is now unable to support human life will just lie down and die peacefully?
> We will adapt to whatever climate exists.
also, air conditioning and the netherlands are ways to deal with existing nature, global warming on the other hand is entirely man-made and compunding
[0] https://www.nytimes.com/2022/04/28/world/asia/india-extreme-...
If that's not a "threat to all life on earth," I don't know what is. And that's just what I could find with 5 seconds of googling.
https://www.theguardian.com/environment/2019/feb/10/plummeti...
To 'wipe out' life on earth, you have to crash the moon into it or do something similarly ridiculous - remember that a giant asteroid wasn't enough.
Wiping out all human life is possible, but again I don't think that anyone is comforted by the idea that 0.1% of the population might survive in an arctic cave.
Where we seem to fail is in communicating to folks that don't want to spend money to fix the problem today how their life will become miserable tomorrow.
https://www.scientificamerican.com/article/insects-are-dying...
The loss of insects isn’t caused by climate change, it’s too much pesticide use and people trying to have lawns instead of native plants.
The "barren rock" is a bit of a strawman. Very few if any people believe that the elimination of all life on Earth is in the cards. Human life, on the other hand, is certainly possible.
For the vast majority of major extinction events in history it looks like rapid climate change was the major trigger, and at some point small changes lead to a "self-reinforcing climate resonance cascade of unforeseen consequences", and we currently don't know exactly what the limits are.
This is the focus of a huge amount of the work of Peter Ward and he has written plenty both for scientific and a popular audiences.
Now he may, of course, be wrong. But his work is credible enough that you have to at least take into account that the real risk of extinction is possible.
And how many climate scientists actually believe extinction is on the table? I've seen some say collapse of global civilization and mass death is a possibility under the worst case scenarios, but not really anyone claiming all humans would die. Anyway, the latest IPCC report puts the upper range of warming at 3.7°C. Which is bad, but not the apocalyptic hot house Earth scenario. But even with that, some environments will still be livable. People live on mountains, near likes, far inland, way up north and all over the place. Earth isn't going to turn into Venus, and it was a lot hotter when the dinosaurs evolved. Plants and animals still survived after the Permian die off.
Human life today is mostly maintain with infrastructure (water, food, security, health, etc). A cascade of failure due to climate change can destroy all but very local and small infrastructures. With society eventually returning to a pre-industrial conditions. It is not the end of humanity but the pre-industrial world economy can't support food, water safety and health care for 9 billion people. In pre-industrial era world population were less than 1 billion, we might return to these numbers. That means death of the large majority of human. Not extinction but the biggest threat in human history.
Think of the world population's size and global distribution as hedges against disaster: the fewer people who live, in fewer habitable places, the more likely it is that some disaster will affect everyone remaining and leave no one unaffected. We have fewer rolls of the dice, and there may come a day where they're all snake eyes.
This why many are excited about the idea of "making humanity an interplanetary species", as I once was until I realized how hard it would be to make a working biosphere anywhere else, given how bad we are at maintaining one that already works. If we don't figure out how to save this biosphere, we won't have enough time to make more.
("Without"? Well, nobody today knows how to build a cast-iron plough.)
I don't believe this scenario is likely. For one thing we're not headed for 8C of heating; for another, technological change seems to be coming just in time to head off the very worst outcomes, assuming we struggle hard enough.
We aren't struggling at all, though. We just eased off the accelerator a little. (Assuming that our accounting is correct, and that methane leakage isn't worse than we think. [1])
[1] It's worse than we think.
I need to retain some optimism, or I get too depressed to keep on. In this case, my optimism is that solar/wind and batteries will drop enough in price that fossil fuels become economically unfeasible.
It seems possible! I just hope it isn't too little, too late.
One of my "favorites" is the "world without clouds" scenario, which for the record, I consider unlikely, but is horrifying to imagine: https://www.quantamagazine.org/cloud-loss-could-add-8-degree...
What we're dealing with are "unknown unknowns": what tipping points might exist that we don't know about, that might result in more warming faster than expected based on today's science? We shouldn't take those kind of existential risks.
Society as it stands is much more fragile, but I’m sure we’re more likely to destroy ourselves from within before climate is a really major factor.
Of course I would've thought "aren't you worried your grandchildren will live miserable, dangerous lives struggling to survive" would be a decent argument but I've encountered no Boomer who seems to worry about it as they excitedly tell me about the coming collapse of something or imminent major war in wherever.
[1] https://www.businessinsider.com/genetic-bottleneck-almost-ki...