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.
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.
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.
Levees don't work in south Florida. Well, they work to stop water that comes in horizontally above ground level, but in south Florida floods usually come in by bubbling up through the porous ground.
Worldwide, cities on river deltas face problems. Mostly in Asia. New Orleans is the only US city built on sand flatland at the mouth of a huge river. Asia has several of those.
New York is building a seawall around lower Manhattan. The West Coast isn't that vulnerable because the coast is mountainous. Even in areas of LA that look flat, go a few blocks inland and you're up 10m or so above sea level. The parts of SF built on fill may have problems.
This isn't the end of the world. But some cities will need rebuilding.
[1] https://www.thestoryoftexas.com/discover/texas-story-project...
[2] https://en.wikipedia.org/wiki/Raising_of_Chicago
[3] https://mdc.maps.arcgis.com/apps/webappviewer/index.html?id=...
There are some problems with the assumption of a flooding crisis. The historical record from tide gauges have been retroactively altered over time, to make apparent level rises in modern times worse and level rises in older times less so (this seems to be a common theme with data from climatologists - they rewrite historical datasets to make the magnitude of changes seem larger).
Additionally at some point they switched to satellites and stopped using tide gauges but it's not clear that's more accurate and may actually be less accurate (but it did make the rises seem larger, so there's a conflict of interest there). In particular, NOAA and NASA disagree by a large amount on what the actual level of rise is. NOAA say it's about half what NASA say it is.
But you are right that it will keep rising for a thousand years or more. But now at that timeframe we're talking 6-12 meters or more.
This is all in the fairly conservative public estimates that so far have underrepresented the pace and scale of change.
https://apnews.com/article/bd45c372caf118ec99964ea547880cd0
UNITED NATIONS (AP) _ A senior U.N. environmental official says entire nations could be wiped off the face of the Earth by rising sea levels if the global warming trend is not reversed by the year 2000.
Coastal flooding and crop failures would create an exodus of ″eco- refugees,′ ′ threatening political chaos, said Noel Brown, director of the New York office of the U.N. Environment Program, or UNEP.
He said governments have a 10-year window of opportunity to solve the greenhouse effect before it goes beyond human control.
As the warming melts polar icecaps, ocean levels will rise by up to three feet, enough to cover the Maldives and other flat island nations, Brown told The Associated Press in an interview on Wednesday.
The most conservative scientific estimate that the Earth’s temperature will rise 1 to 7 degrees in the next 30 years, said Brown.
It's thirty years later now and the temperature rise since then has been at the very lowest end of the most conservative estimate (which was itself so wide that it was basically useless and hardly an estimate at all).
In the USA, is that even possible anymore? I've been to both Galveston and Chicago, and you can see oddities here and there in some neighborhoods. In many cases, homes were not actually raised - the main floor became a basement and above it new doors were made into the existing walls!
In a lot of locations, you cannot have a basement and get flood insurance. So what poorer people did in Galveston and Chicago is no longer an option.
Levees are expensive, and not always viable. It depends on the geography, the wealth of the city / county, the porosity of the ground, etc.
Some places will be sure to use levees, some won't.
With regards to crops, we don't know the outcome. If the Gulf stream stops or some regions dry out it could greatly affect crop yield, especially over the short-term. And that's all that matters for starvation to occur. The term year average yield isn't as important as this year's harvest.
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.
This gives plenty of time for people to build and/or move to new cities on higher ground.
What do you do in Florida?
Floridians have a continent of 49 other states to move to.
The Bangladeshis are in a tougher spot, since they're approaching 200 million and might need to cross a political border.
If the rest of the world closes its borders, maybe they'll have to look into landfills, flood walls etc. Or maybe they can settle the newly habitable Siberian lands.
The "if" is funny. There's already many hundreds of millions of poor people around the world that have the borders closed to them. I don't see why 200M extra poor Bangladeshis wouldn't suffer the same fate.
And there is no reason to believe Siberia will be habitable, at least not in exactly the timeframe it needs to be to offset other habitable areas that are lost.
Climate change will be a slow moving, albeit accelerating, series of crisis that will grind those who are poorer and don't have the power to move to suffer losses.
Because of Russia's famous open borders policy, and China happy to open their borders to let refugees pass through? What planet do you live on?
That's like saying the US would open its southern border to let migrants pass thorough up to Canada.
With respect to the "If" statement around countries closing their borders - seriously, where have you been? The sudden and significant rise in popularity of the far-right in Europe almost coincides to the Syrian refugee crisis, and that was roughly one million people. In my country (Australia) we give our Pacific islands neighbours platitudes while still pushing coal on the rest of the world, and then indefinitely detain those seeking asylum for years (including years after they've been assessed as legitimate refugees). Countries are now proposing the Australian approach to "protect" their own borders. To think that this issue (of climate-change forced population movements) will not cause existential threats for those people is plainly wrong.
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.
That's just being blind about the problems. Nuclear war is all one of the biggest existential threats to civilization. It didn't end with the cold war.
Think of all the close calls we've had. Now look forward 100 years, what's the odds it happens? 1000 years? 10000?
We're our own worst enemy and our civilization is the biggest threat to civilization.
It'll cost a few tens of trillions to mitigate climate change and many non-human species will be in serious trouble if we don't do anything about it.
Either way, humans will be fine. But I still advocate strongly for option number 1.
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...
Of course, that's expected. Even if you assume that IPCC is 100% on point, then with p-value threshold of 0.05, you'd expect 1 in every 20 studies to show that IPCC is off.
The real question is whether the scientific consensus changes by the time the next IPCC report comes out. Maybe it will, we shall see. At the same time, consider what kind of message you are sending here: you are asking everyone to not listen to scientific consensus, and instead promote alarmism, because there are a few studies that challenge the consensus.
There is nothing wrong with challenging the consensus, that's how we get progress, but how do you want to win trust of the society, which is required to deal with this planet-wide situation, when, right after the (mostly won) fight for people to stop with denialism and believe the science, you turn around and say "yeah, that consensus we asked you to believe, instead of a handful of contrarian papers, is not what we actually want you to believe, instead you should believe this other handful of contrarian papers"? That's only going to sow distrust and alienate people.
i agree with you on the nitty gritty for a general audience. mostly i dont think bogging down the public with research helps and it's way too often used in bad faith to do the opposite by industry and certain political groups acting in their own interest
on the other hand
on the other hand if like half the country experiencing some weather catastrophe in the last 5 years doesnt do it im not sure ;( so i do think we need more fear and for sure a lot more alarm, but yeah probably not alarmism in the sense i think you are probably referring to
i do love HN though for a higher level discussion
It's one of the reasons why Vancouver and London have similar climates, and both never get as cold as either of New York or Vladivostok, both of which are to the south of them.
It's actually more complicated than that - the Gulf Stream contributes not to warming Europe but to cooling the eastern seaboard of the US:
https://www.livescience.com/13573-east-coast-colder-europe-w...