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Comment by jeremyt | Hacker News Reader

Could you lay out the play-by-play on how global warming is a threat to civilization? It seems to me, at worst, a slow-motion problem that will take almost a century to unfold and perhaps force large chunks of people to relocate to other places.

I would appreciate it very much if you wouldn't read any kind of tone into my question. Straight up honest question.

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Yes, It would take a very long time for global warming to cause the sea levels to rise such that cities are underwater.

But the primary way that global warming manifests itself is by causing severe weather events to be more frequent and more severe. (This happens mainly because warmer air holds more water vapor.) So the next Katrina will happen sooner, and it will be worse - because of global warming.

Another problem is that warming will cause lots of problems for agriculture. Those of us growing corn in the Midwest will be okay - but places with marginally fertile land will have famines.

Another problem is that insect-borne illnesses (which already kill millions) are helped in a huge way by warming, even just a few degrees' worth.

These are all bad. But the civilization-threatening part is what happens politically with the people displaced by floods, famine, and plagues of malaria/etc. This kind of stuff causes refugee migrations, political upheaval, revolutions, dictators, etc. The U.S. government is legitimately worried about this stuff [1].

[1] https://www.whitehouse.gov/sites/default/files/docs/National...

Already climate change is causing disease and death on an alarming (and growing) scale. Rich people, as always, have a buffer. We in the developed world will be the last to be hit by it and the least impacted.

But, Africans are already feeling it. The Zika virus, which was identified in the 40s, was never been considered a serious health crisis, until climate change enabled it to spread farther and faster. Anything that enables mosquitoes to live longer and breed faster is a death sentence for people in many parts of the world.

Drought-prone regions are also feeling it already. It isn't a matter of "just move to another place" when your wages are measured in single-digit dollars per week or month. So, as climate change progresses, more people go hungry.

And, I think what's most alarming about it is that it is progressing faster than even the most extreme (mainstream) projections predicted. Where small changes were expected over a long period of time, we seem to be seeing a domino effect, where slight rises in temperature trigger other events that cause faster change. So, we probably don't have a century to adjust, particularly in areas that already have challenging weather events; Florida and Louisiana because of hurricanes and flooding, Texas and California because of drought. Many of our food producing states will be forced to evolve rapidly...I doubt it will be a smooth transition. There's already constant political battles over water in some parts of California.

Like the guy you replied to, I don't want any tone inferred into my question.

Those points you made, while worrisome, are not "civilization-ending" or catastrophic. Is there worse, or is that what you expect to continue?

That's what I expect this decade. My concern is that it is all happening faster than even many of the most pessimistic scientists in the field expected, and it seems to be accelerating.

What I see when I try to extrapolate from what is happening today: Less food and clean water for more people, sometimes dramatically so in places that are already stressed for food and clean water (again, this will strike the poor far sooner than it will hit the developed world...but, that doesn't make it less horrifying, to me, and it is merely a leading indicator of what we will all experience). More forced migration, more refugee crises, more war over resources (including resources we don't yet generally currently consider worth going to war over, like water and arable land), more disease epidemics (and with no effective antibiotics to treat them), more mosquitoes, etc.

All of these things are already happening. We can see and measure them. And, they are trending in the wrong direction, and accelerating.

I just don't see how to interpret what we see happening as anything other than a slow moving disaster. There's only so much "relocation" can solve, when speaking of a world with billions of people. If you consider literally millions (or even billions) of people dying off to be a non-catastrophic event, I guess it's not catastrophic. But, it looks like a catastrophe, to me. And, when that many people are put at risk of starvation and disease, the likelihood of war, even world war, seems likely to increase remarkably.

Edit: A useful current article on the subject, with references: https://www.theguardian.com/commentisfree/2016/aug/03/climat...

That seems like the current conclusion. But as people start dying, the population should decrease and that will limit global warming. Life as humans knew it has already ended, and civilization as we know it might end, but shouldn't mankind and civilization still survive pretty well? (Legitimate question)

I'm not sure what to make of that question. I think part of what makes civilization "civil" is that we don't accept huge swaths of the human population dying horrible deaths so that a lucky and rich portion of the human population can survive.

You seem to assume that the temperature will slowly increase, giving us time to adapt, without descending into another global war due to all the shufling of agricultural areas and mass migrations.

But there's a scarier scenario, where temperatures change much more rapidly due to a positive feedback loop: https://en.wikipedia.org/wiki/Runaway_climate_change

The even more scary thing is our models are so bad that we have no idea of how likely a positive feedback loop is. We are basically driving down the freeway at 100 miles per hour with our eyes shut with the hope the road stays straight.

The regugee crisis of today, one could argue, is a result of supply issues caused by climate change... and things haven't even really started to get bad yet. As things get worse, the people who are impacted will resort to more extreme measures.

Even if we turn this planet into Mars, we can figure out how to live on it... humans are amazing adaptable. The issue is can we scale that up to 10 billion people? I imagine resource wars are the biggest threat from climate change.

One big impact is the change to food supply. Plants and animals thrive in certain climates (the midwest of the United States for example). Those zones are moving due to climate change. Does that mean they are getting larger or shrinking? Will it require more energy (water, fertilizer, mechanical harvesting) to get the same amount of food? It's my understanding that both land-based and water based sources of food will shrink with a warming planet.

(Not sourced as I am currently at work - presumably someone is composing a detailed response to you as well)

One of the big news stories right now is how people are unhappy with the idea that other people want to relocate to other places.

I'm guessing that even more people wanting to relocate in the future would be slightly unpopular.

The rising temperature and acidification of the oceans threatens their oxygene production. Climate change on land threatens oxygen production there. With falling oxygene production, oxygen in the atmosphere will not be replenished, and aerobic organisms will die.

Is this no longer a problem because it wont affect YOU during your lifetime?

As climate change leads to more frequent and intense natural hazards, it is expected that climate displacement will only increase in Bangladesh. The best estimates suggest that up to 18 million people may be displaced by sea level rise alone.

I don't think people can comprehend re-housing 18 million souls.

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