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.