Comment by 4bpp | Hacker News Reader

Comment by 4bpp | Hacker News Reader

It seems to me that most of the recent wave of climate change alarmist articles take it for granted that a mean temperature increase of +4°C or more would result in a collapse of the functioning of Earth's ecosystems/render the planet uninhabitable/cause in a runaway effect where more carbon is released and the planet heats until it turns into Mercury or Arrakis. However, based on our best knowledge [1], it seems that during the Cretaceous period and for a while after, temperatures were well in excess of this (~+10°C or more?), but the global ecosystem was closer to being tropical and extremely fertile than to being barren, and there was no runaway warming. What is the argument that this isn't going to happen in our current iteration of climate change? If there is none, is it safe to dismiss any documents that claim or imply an uninhabitable Earth as a consequence of climate change as primarily ideological rather than scientific?

(I'd be much more willing to entertain arguments that a rapid transition to a Cretaceous-style planet would be a political catastrophe for the "global south"/equatorial countries that are already struggling with drought, but then I'd need to see reasoning why we should expect any threat to human civilisation as a whole rather than "just" a massive humanitarian crisis through which the residents of the currently-temperate northern hemisphere can just sit back on their pile of futuristic weaponry and laugh.)

[1] https://en.wikipedia.org/wiki/Geologic_temperature_record#/m...

I think the claim that Earth is going to turn into Venus or Arrakis is absurd - I haven't heard anyone argue that, but I have heard the claim that it will cause a mass extinction on a geologic scale that could affect humans and our 'pets' as well.

I don't know if it is accurate and based on good science, but I believe that the argument revolves around the timescale that the change is occurring compared to natural climate shifts: that the temperature is increasing so fast there is not enough time for plants and animals to evolve, or even for ecosystems to gradually migrate their locales. For example, one reason you can't simply replace farms with land in, say, the Canadian shield is the lack of good topsoil. According to [1] it takes at least 100 years to form an inch of topsoil in wet, hot climates, and the process is much slower in cold or dry climates. Thus if we render our existing farmland unfit for our existing crops in timescales measured in tens of years, we would have to rely on manually bringing a literal continent's worth of soil north - whatever process was at work during the Cretaceous cannot be relied on to solve this particular problem.

[1] https://www.nrcs.usda.gov/wps/portal/nrcs/detail/wa/soils/?c...

Right, but it's not like nothing would grow on it if you took good Canadian topsoil into the tropics, is it? I assume that even if there is a substantial difference that renders soil that is conducive to plant growth in one climate less suitable for it in another, the correction of this difference should not take the same amount of time as it takes for the "correct topsoil for the climate" to form from nothing, and in fact probably should be much faster.

Glass half-full. I like it.

Also on the positive side, a lot of us will possibly learn the answer to this question.

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