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Comment by Geee | Hacker News Reader

None of these tipping points are exponential. Global warming is most likely an S-curve with a few degree maximum. Mispresenting the issue as an exponential is scaremongering.

In the worst case, we would likely end up with something like the Eocene, where the whole planet is covered with forests: https://en.wikipedia.org/wiki/Eocene#Flora

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I think the worst case is not how much of the world is forest. The worst case is failure of the world agriculture system, widespread famine, poverty, disease, war, death, and eventual failure of the human race.

If you're worried about whether stuff will continue to live on earth it's not a big deal. If you're worried about whether humans in particular will continue to live on earth and the parameters of what 'live' means you should be very, very concerned.

Covered with forests except for the parts that are new shallow oceans. This includes parts of the world like the American Midwest. Some countries will simply cease to exist.

In even the worst case the Earth will be fine. People, not so much.

I don't understand this comment. It comes up a lot, but nobody is seriously concerned about the Earth. Clearly global warming is a threat to humans and our way of live. Pretending that people worry about the Earth is a strawman.

Even if it is not, how is it of any consolation that a round rock revolving around a burning ball of hydrogen and helium will be fine? Even stating that "humanity will survive (but millions or billions will suffer and die)" isn't any consolation at all.

A common argument from climate change deniers is that the planet was warmer before and things were fine then. So I guess the comment plays into that, as the changes we are facing might not be new for Earth, but they are new for a Earth with humans.

Having a more accurate image of what is happening is important. I think many people imagine the planet becoming an inhabitable desert, all life dying and oceans boiling off. This is a wrong image and causes unnecessary pain and anxiety. I know a young person who killed themselves because of climate anxiety.

I'm optimistic that humans and most animals could adapt into a warmer planet.

That is the point of the comment. No matter how bad it gets, biological creatures will adapt as they always have while lots of existing species will become extinct; none of this is new. The question is can people adapt and remain what we think of as people in what we think of as our civilization. Given the current horrific weather (droughts/floods/heat/cold/storms/fires etc) how will humanity adapt without seriously changing what we think of as life. Perhaps we can live underground, or all move to the poles, or try a new planet somewhere. But if weather continues to get worse and worse eventually fewer and fewer people will survive, and we might become like the majority of species that no longer exist.

Global heating caused by carbon in atmosphere => melting permafrost => releasing more carbon stored in permafrost => even more heating of globe.

Even if it is S-curve I do not sure lots of people can survive Venus' climate.

Are you sure it's going to be like Venus? Didn't all the carbon used to be in the atmosphere in earlier points in history?

Even the worst case predictions don't result in Venus-like temperatures, do they?

No, but what if we got half way to Venus-like temperatures and only made it to 200C?

In reality, the planet will stall out around 100C due to all of the water that needs to boil off and the huge steam clouds that would then increase the planet's albedo (but also trap heat). That's probably the top of the S-curve for the lifetime of mankind. Having the solar rays split that water and let the hydrogen escape to make an actual Venus like atmosphere is a more geological timescale process.

When I google for "worst case global warming", I'm not finding anything like 100C. More like +5C.

Here's one link I followed: https://www.science.org/content/article/after-40-years-resea...

While I was exaggerating somewhat in my original post, I should point out that most climate change papers stop around +7C or so because after that it's assumed most everyone is dead and the models won't be valid anymore. Plus, there won't be anybody around to care.

This argument is hysterical and counterproductive.

Even the conversion of all known organic carbon [0] on Earth into CO2 isn't going to be close to Venus.

Sun expanding over the next billion years might just about do that, unless the water vapour dissociates and the hydrogen escapes, but that's about the only way we get even close to Venusian conditions, IIRC.

[0] as in, the biomass and all of the fossil fuel reserves; I'm not including carbonate rocks, though it looks like including inorganic minerals still wouldn't be Venusian even though it would be far enough from today that it might as well be as far as "life" was concerned.

How do you explain the presence of carbon in permafrost? For the concentration of carbon in permafrost to exceed the present concentration of carbon in the atmosphere, wouldn't the concentration of carbon in the atmosphere at the time the permafrost was initialy frozen have had to exceed the current concentration of carbon in the atmosphere? Which would imply that the current level of carbon in the atmosphere is not the cause of the increased temperature?

>For the concentration of carbon in permafrost to exceed the present concentration of carbon in the atmosphere, wouldn't the concentration of carbon in the atmosphere at the time the permafrost was initialy frozen have had to exceed the current concentration of carbon in the atmosphere?

Do you think permafrost is giant bubbles of air that got trapped in frost or something? Your comment baffles me somewhat.

What do you think of the concentration of carbon in our current atmosphere when you see a rotting log?

CO2 levels were higher in the past, but the sun was dimmer.

Edit: hey dang. I now delete the last sentence of most of my posts. Thanks for the advice!

? Umm. An S curve IS exponential. It's exponential growth, followed by exponential decay.

No, it's not. An S-curve is logarithmic.

It may mimic a quadratic curve in smaller values, but for pragmatic purposes it becomes asymptotic to some arbitrarily chosen value, in most cases.

There is no decay either, because the value of y is still always increasing.

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