There's a lot of reason to worry, for sure. Nobody is going to come tell you climate change isn't real, and nobody is going to be able to tell you that we know what the unknown unknowns are.

One factor for a bit of hope is that the unknown unknowns may also work in our favour: Life adapts and evolution is amazing.

Life endures because it's a very effective negative feedback mechanism. We've already seen genetic drift as organisms have adapted to human activity on Earth (eg how many city pigeons you think existed 10,000 years ago?), so there's definitely possibility for life to adapt and create a different kind of ecosystem as the world changes both in global temperature and industrial technology. We will likely see plants and animals that can make use of the greater CO2 concentrations thrive (and I believe we can already see this on a global trend to some degree with trees), and consequently help fight the imbalance. Different kinds of food and fruit will replace the kinds that existed before, and if they become a monoculture, they'll soon diversify. Even if phytoplankton die, it's likely another organism would take their place in a similar fashion.

It's not a certainty, and I'm not saying climate change and loss of biodiversity won't be very, very problematic for humans for long time. But it is one factor to think about and perhaps think everything isn't totally doomed - Life is fuckin' cool and will find some way forward, that may include more symbiosis with more humans than you think.

Chances would sure be a lot better if we replaced capitalism though. Let's do that.

Well no, no, you’re right though.

But say an asteroid was headed to earth and we knew it was going to come and kill everyone in 25 years. Would you change your life? I think most people wouldn’t.

But plenty do and already have. If that’s the life you want, go for it. Fuck working.

You gotta be less doomer about the thing that will kill you slowly in the far future (climate change) and more doomer about the thing that will kill you quickly in the near future: global thermonuclear war.

After that's done, it's a simple hop skip and a jump to Posadism, join us comrade

Yes those things will get trend to the worse, but we're not going full Canfield Ocean by Tuesday, Venus on Friday, that will take a very long time. There is a mass extinction event going on by simple human greed and poor resource management, we're not going to wipe it clean 2024, but the world will look more boring with far fewer species to interact with.

Deaths of economic systems take time, its a slow transition, think about how long feudalism was the main economic form before giving way to capital. Can't change it without persisting though.

your unreasonable ,nuclear winter will balance all that heating out..

I feel like that won't happen

However, nobody talks about the known known:
What are the effects of rising CO2 levels on human life?

Not the heating and desertification, but the physical effects of CO2 itself.

There's 50% more CO2 in every breath you take today, than there was in 1960. That's wild bro! And noone talks about it! Prolly cause they ain't got no oxygen in they brains!

How do we even know that the universe will not spontaneously disappear at any moment? The whole issue and solution to unknown unknowns is to recognize they exist and subsequently that it doesn't matter if you do or do not because they are unknowable

As others have said, the plankton thing isn't going to happen but it also doesn't have to in order for climate change to cause industrialized society to collapse. You're right to be worried about climate change, and the best you can do is actual activism to maybe do something to mitigate it. The second best thing you can do is make yourself numb and not think about it.

Life evolved originally in extremely harsh conditions. Multicellular life once endured temperatures both much hotter and much colder than the present day.

I can't predict anything conclusive from this but I do have a reason to believe in the flexibility and resilience of living things, even if we are at the beginning of possibly the biggest-ever extinction event.