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Comment by lisper | Hacker News Reader

Depends on what you consider catastrophic. 5-8C means you lose both the Greenland and Antarctic ice caps, so you get 60m (200 ft) sea-level rise, so you totally lose all the coastal cities, and the current round of civilization is almost certainly done for. But homo sapiens will probably survive, and so civilization will probably eventually be rebuilt. It won't be the end of life on earth under any circumstances.

Actually, the biggest danger is that political instability brought on by climate change will lead to nuclear war. That would be much worse than losing civilization to climate change because it would happen much faster, essentially instantaneously. That is not at all unlikely even under much more modest warming scenarios.

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  But homo sapiens will probably survive, and so civilization will probably eventually be rebuilt

This is a very arrogant assumption. Our species is one component of a little-understood web of interconnected dependencies. Just because humans are slightly more clever than past dominant species doesn't make us any less extinction-proof.

I'm guess you meant that cleverness doesn't make us any more extinction-proof. But actually it does. Cleverness is a huge advantage in the survival game.

Thanks for the correction re: more versus less. But I'll still posit that this is an arrogant line of thinking:

  Cleverness is a huge advantage in the survival game.

Cleverness won't be much help when underlying dependencies disappear.

Edit: one way humans will extinctionize our species:

https://phys.org/news/2017-02-scientists-categorize-earth-to...

We're basically driving this car full speed towards the cliff. No amount of cleverness will stop this.

The relation might not be linear though.

  Just because humans are slightly more clever than past dominant species doesn't make us any less extinction-proof.

Homo sapiens: the Dunning-Kruger hominid.

I've suggested: the anti-ant.

Ants, individually, are stupid. Collectively, they're intelligent, and solve complex problems.

Humans, individually, are brilliant (by animal standards). Collectively, not so much.

Right, you get 5-8 C (9-14 F) increase in global mean temperature. That mostly translates, I think, to temperature increases during winter, and at higher latitudes. Biomes will both be shifted poleward and warped, and that will happen faster than some component species can adapt.

The good news is that runaway greenhouse warming won't evaporate oceans and bake out CO2 from surface rocks :)

Why would civilization be over? The sea rise wouldn't happen over night and people would move or build walls.

We already have tremendous political instability in the US and Europe right now caused in part by a not-so-great-but-not-devastating economy and the Syrian refugee crisis. Imagine a worldwide crisis with tens or hundreds of millions of people losing their homes and livelihood, how is that going to play out?

40% of global population lives in coastal areas of lesser elevation than 50m.[1] That is more like 3 billion people. Syrian refugee crisis seems quite insignificant in comparison. Of course, only one of those is currently underway, and we don't really know how fast sea levels will rise.

[1] http://www.un.org/esa/sustdev/natlinfo/indicators/methodolog...

>We already have tremendous political instability in the US and Europe right now

This is definitely not true for the US. At least not by any global notion of political instability. The US government isn't near collapse, there is a very limited likelihood of any kind of coup, the economy is doing very well, and riots have been very rare.

There is a lot of political bickering, but it doesn't seem to be any more-so than during the last party-in-the-office changes (Clinton to Bush, Bush to Obama).

Florida is porous. You can build walls but they don't do much. The water will rise to cover the entire peninsula. Long before that tides and storm surge will destroy all of the surface roads to coastal cities. I wouldn't lend money there for longer than 30years.

http://geology.com/sea-level-rise/florida.shtml

Because a 60 meter high seawall around pretty much all of the country would be a bit problematic material wise alone (you'd have to chop down a couple of major mountains, assuming you have those), coupled with the slight problem of then having to get rid of all the water landing in your nice new bathtub by precipitation.

A seawall isn't just a wall, it's more like a dike if it is to survive and that means it has a width many times larger than it's height.

And then there is seepage to contend with. This is anything but a trivial problem and we have never done engineering on that scale before.

The easiest solution would be to move to higher ground.

That's a lot of people to move and things to rebuild. Op did say "the current round of civilization". I also agree that lots of things changing at once are likely to create instability, with negative economic and social impacts (unless governments massively intervene, which I suspect many in the US would not appreciate).

I'm sure walls are an option, but they will be expensive to maintain and it doesn't take much to have big consequences. https://en.wikipedia.org/wiki/Drainage_in_New_Orleans

And that was just on a city scale. Doing this country or continent wide is engineering on an entirely different level. NL has something like this but it's only 30 feet high and extrapolating from that experience to something able to withstand 60 meters of ocean (which is dynamic, an an average of 60 meters does not include storm surges and tides) is making me think this is infeasible.

>That's a lot of people to move and things to rebuild. Op did say "the current round of civilization".

If that's the bar for civilization ending, then civilization ended when people came to the US, ended again when they expanded out to the West, etc.

Just because people on the US coasts move means little to the 60 percent of citizens that don't live near the ocean.

And again, it's not going to happen overnight. A wall of water isn't coming in that will force everyone to put their things in a car and go. It will be slow build-up that slowly forces people out as they decide it's to expensive to mitigate.

"If that's the bar for civilization ending, then civilization ended when people came to the US, ended again when they expanded out to the West, etc."

Interesting that your example is literally true both times for the people who where there earlier.

> Actually, the biggest danger is that political instability brought on by climate change will lead to nuclear war

Can you please elaborate on this point?

Elaborate how?

The dipshits in Russia, China and US will push buttons in their briefcases and we are all going to burn (or die of starvation soon after).

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