It will cause mass migration and refugee crises as coastal cities and low lying areas slowly flood. That seems inevitable at this point.
That could maybe lead to wars, and nuclear war is still an existential threat.
If the changes somehow disrupt the ability to support cereal crops in the northern hemisphere (which actually is also the biggest risk from nuclear winter), that could lead to widespread starvation and more wars. Not an existential crises necessarily, but not pretty.
Similarly, there is no reason to be very concerned about crops: we already are able to grow crops in a very wide variety of climates, and we have cultivars specially selected for local climate conditions. While climate change is very fast on geological scale, it’s rather slow on human scale, which gives us plenty of time to adjust our crops and farming patterns.
This is the biggest reason why climate change is not an existential threat: we are not going to sit on our thumbs, and watch the steamroller slowly ride over us, at speed of 1 cm per day. That’s not going to happen: mitigating the problems associated with climate change is rather simple, relative to other problems our societies solve on a regular basis, and we have a lot of time for it.
You can roll up agonizing in fear, or you can prepare yourself for a bit of struggle. We can help lower the impact, but there's no reason to panic.
Most likely the impact on humanity will be minimal, if not the impact on life itself will be medium, and the Earth will spin a few more cycles with or without us.
This doesn't really matter, and we should just take it calmly, and talk to each other. No need for end of the world nuclear war hysteria.
If we saw significant changes to where is wet and where is dry, we’d be scrambling to catch up and the fallout could be pretty large.
This gives plenty of time for people to build and/or move to new cities on higher ground.
people are moving to Miami in droves right now and there's a big push to turn it into the next Silicon Valley. that's an aspirational goal and future facing in a geography that's among the most vulnerable to climate change. they know we can solve slow moving disasters.
And to the parent of this thread we keep seeing constant research showing IPCC is off (sometimes wayy off) in their worst case (e.g. we're there or past it in many respects).
Armagedon is the last battle. To me that's what climate crisis is and how we need to look at it and take immediate action. We battle and win or we lose and it's really really really bad.
Maybe others have better examples of worse than imagined climate problems, but here is one I read from Reddit/HN last week.
New research shows faster slowing Gulf Stream. I can't find the exact thread that summarized - it did a direct comparison to the recent article to IPCC showing IPCC's worst case is not even close to as bad as the new measured slow down.
A few sources below, one decade old one says 10x from IPCC's worst and the recent article showed even faster slowdown; like on the scale of a less than a century we could be past a tipping point. When it tipped in the past it made europe very cold and rose eastern us sea levels a lot.
From my understanding, this would affect staple crops in Europe (google says europe 300 tonnes, us at 440), help melt a LOT more ice & sea level rise etc.
I think that the faster than expected melting ice in greenland we're seeing also increases the slowdown?
"totally unexpected decline in the AMOC of about 30% - far greater than the range of interannual variability found in the climate models used for the IPCC assessments" "10 times as fast as predicted by climatemodels."
https://www.ucl.ac.uk/news/2021/feb/earths-gulf-stream-syste...
https://www.metoffice.gov.uk/binaries/content/assets/metoffi...
https://www.rapid.ac.uk/research/tenyearsofrapid.php
https://www.nature.com/articles/s41558-020-0897-7.epdf?shari...
https://www.reddit.com/r/collapse/comments/j6nl18/siberian_a...
