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Comment by goatlover | Hacker News Reader

No, the Earth has been a lot warmer and colder in the past. We've had massive volcanoes going off for thousands of years, we've had iceball earth, we've had crocodiles and palm trees in the arctic.

The Earth's systems always balance out over the long run. We don't stay trapped in ice ages or hot phases.

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The difference is that civilization is a comparatively new development, and nobody really knows how that's going to fare in the face of all this. The human cost is likely to be staggering.

If nobody knows than why do you assume the cost _likely_ staggering?

We're uncertain about the rarity of global collapse due to climate change. The more uncertain we are about our uncertainty of the rarity of a global catastrophe, the more rational it is for us to assume we are likely presently under-estimating its rarity, rather than over-estimating it, because examples of global catastrophe are pretty hard to come by. If nobody knows if it's gonna happen, but the consequence of catastrophe is so bad that it disrupts life as we know it, that means that our uncertainty about our uncertainty of its probability should increase our willingness to defend against its potential ~ -inf payoff, rather than decrease our willingness to.

The thing is, not only is there reasonable evidence that climate change is occurring - which reduces the hesitation to actually spend money protecting against it - but also that it's a problem that concerns pretty much every country.

> The more uncertain we are about our uncertainty of the rarity of a global catastrophe, the more rational it is for us to assume we are likely presently under-estimating its rarity

So the opposite of Occam's razor?

Think of it as Pascal's wager. We are talking about catastrophy here, the cost function is quite out of balance when looking at the alternative of "Reducing our standard of living a bit even though the catastrophy would not have happend anyway".

It took me a long while to come up with a response to this I liked, but think about it this way: there is, maybe, a 10^-a prior climate change destroys life as we know it, right? But my prior for God, heaven, etc existing is, alas, 10^-b, where b >>>>>>>>>>>>> a. (never a 0 or 1 prior kinda guy, even if I know that is dumb in some scenarios, like tautologies and impossibilities, yadada). Too many more factors would have to be revealed to me in terms of the existence of God that I would then believe that a is of similar value to b, if that makes sense? ie that they have similar probabilities (or rather, utilities, which matters since heaven is probably +inf and catastrophe of all life is MAX(badness) which we might as well call -inf, right?

So, not only is -Cost * P(calamity | investment) >> -Cost * P(calamity | not investment), Cost(investment) < [Cost(calamity | no investment) - Cost(calamity | w investment)], so its a rational purchase...

sorry if this is at all unclear, i can clarify anything

Because complexity is the enemy of robustness.

A village that lives entirely off its own subsistence farming, or a band that lives off hunting and gathering, can keep chugging along in merry ignorance of any catastrophe that does not destroy the local food supply (and if one does, they can pick up and move).

A society that depends for daily survival upon massive global flows of food, goods, and information is vulnerable to anything that disrupts those flows.

Even relatively minor changes throw our civilization and economy into panic and disarray. Drought in the Middle East is considered one of the factors that led to the rise of ISIS [0]. But it's not the first time. Drought led to poor harvest which led to the French Revolution when grain prices got too high [1].

If you're wondering why the Netherlands has to reclaim land from the sea, if you wonder where it all went, it was a result of the Little Ice Age and a storm that devastated Northern Europe and washed much the of area out to sea [2].

Of course all of this happened outside of our modern worries about climate change... but it shows even "natural" changes in weather patterns can cause serious economic and cultural upheaval. What we're being warned of right now is far more serious and massive than we've ever seen before, including during all the time periods where drought and famine and storms have famously killed hundreds/thousands before [3].

All you can do is assume the worst. We've seen the impacts throughout history, we're dealing with some of them now. Northern Europe is still paying off the mitigation of the storm that destroyed their land... that storm happened 800 years ago. They'll be paying it off forever.

If we have the ability to stop things like the Little Ice Age or the drought that caused the French Revolution, we should. Right now we're being warned of something like that, but many many times more dramatic. And we have a chance to slow it down. We need to take that chance.

[0]: http://www.politifact.com/truth-o-meter/statements/2015/sep/...

[1]: http://www.academia.edu/4794332/Drought_and_the_French_Revol...

[2]: https://en.wikipedia.org/wiki/Saint_Marcellus%27_flood

[3]: https://xkcd.com/1732/

There's a really good George Carlin bit in one of his stand-ups about how the earth will be fine. Something along the lines of what you're saying; earthquakes, volcanoes, solar flares, etc. She's been around for a looong time folks. It's humanity that might be in for a bad day.

"Save the earth? The nerve, the arrogance. Now the people? The people are f"

There's also this classic page: https://qntm.org/destroy

The difference with the past is that the sun is slowly getting hotter. Increasing the incoming solar power by a mere 10% would be enough to tip the climate into a runaway process that will boil the oceans and scour the surface. Our Earth only has a billion more years to go

https://www.sciencedaily.com/releases/2013/12/131216142310.h...

In a billion years we will find out how to countermeasure this. Is really a long time.

agree, but in the long long run it will lean towards hotter as the sun changes phases. eventually earth will be a scorched rock without anyone's help.

you have to consider, the earth is about 4.5 billion years old, and we only have 1 billion left, but life will be wiped out much 'sooner' then that.

Why does the Earth have one billion years left?

In about a billion years the sun will exhaust enough nuclear fuel to cool and expand, boiling the oceans, blowing off our atmosphere, and turning Earth back into a sterile rock.

It's predicted by astronomers and physicists who study stellar evolution.

No, that doesn't happen until 5 billion years into the future.

The Sun will gradually keep getting hotter and slightly more luminous up to that point.

Earth will be a desert long before the Sun exhausts nuclear fuel to start expanding and becoming a red giant.

All stars become gradually hotter the older they get. G-type stars like our sun are no exception to this. On a certain point in time (currently estimated at 1Gy from now), the energy output of our sun is so big, that the Carbonate–silicate cycle[0] cannot continue uninterrupted. Thus CO2 and CO cannot be absorbed by the geosphere. The breaking of this process will gradually enrich the atmosphere with CO2, leading to a runaway greenhouse effect (a bit like on Venus).

But I would not worry about that. It took 500My for life to evolve from trilobites to humans. This timespan is twice as long...

[0]: https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cyc...

> we only have 1 billion left

Not disputing, but have a source for that theory?

Yes, absolutely. But the species that inhabit the earth come and go, and climate seems to be one driver.

That's less comforting when you realise that cyanobacteria likely caused an iceball phase, nearly wiping itself out in the process.

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