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Comment by amelius | Hacker News Reader

Perhaps a stupid question, but why wouldn't coral reefs naturally move to colder areas (closer to the poles)?

EDIT: turns out they do: https://e360.yale.edu/features/as-oceans-warm-tropical-coral...

The problem isn’t necessarily that they won’t move to colder areas (well that is a problem for coastal regions susceptible to hurricanes, etc, but I digress). The problem is that the waters around those reefs are warming up faster than the reefs could ever possibly hope to move. Reefs are built by corals excreting calcium carbonate onto their attached surface. This process is an incredibly slow one with mature reefs taking many hundreds of thousands of years to form. The reefs can’t keep ahead of water temperatures that are projected to change within the next 50 years.

My understanding is that temperature is only part of the problem. Acidification is ongoing, due to increased CO2 in the atmosphere. That's a global problem: the ocean is literally starving for oxygen, everywhere.

If the thermohaline cycle in the Atlantic continues slowing down, there will be significantly less water circulating. There's a risk that bigger & bigger parts of the ocean just sit, don't flow, and thus never get exposed to the air: that they truly deeply & forever run out of oxygen.

The dynamical processes of earth are being disrupted. We talk about extreme weather being the risk, but a lack of weather, a lack of variety, a forever hot, non-humidity bearing (higher temperatures carry less humidity) sit-and-stew earth, just sitting here, baking, is the hell we are headed to. The dynamical processes risk becoming static, stagnant situations. The flow of life & change & systems is being baked off the planet.

Nope. Chaos theory says very much the opposite, and our experience is tending to back chaos theory here. I mean yes what you describe would also be bad, but it's not that we're going to see. I can't speak to the thermohaline cycle: perhaps you're describing something that'll happen specifically in the depths of the ocean? Sounds bad.

Up here where WE live, the possible extremes of weather are factors of chaotic energy, and small increases in global temperature will produce wider potential swings in weather behavior. So we are not at all going to see 'a lack of variety' and we're not seeing it now. We're seeing 'wait, WHAT' weather and it's only going to get worse.

The challenge is surviving those energies. Never mind colonizing Mars or Venus, the challenge we'll face is clinging on to THIS planet, and a hell of a lot of people will end up not able to survive what's coming. And it's subcultures like Hacker News we'll depend on, for people who'll come up with the 300-mph storm windows etc.

I own a house: I'm not thrilled at what's going on. I'm trying to work out what I've got to do in order to not be taken out by some kind of weather extreme beyond what we used to have when I was growing up.

Venus is also high energy. There are ferocious winds. But there are no dynamic processes there. Everything is static, perpetual endless howling 200 mph winds, crushing dryness, forever, always.

Mistaking energy for dynamic is a bad mistake. Yes, we are headed towards higher energy. But whether there are any dynamics that will survive, as the extreme conditions rise, is very much the existential question.

Coral reef and corals are different things. A coral is just an animal. Will settle in any suitable place reached by sea currents. If the currents in their place go from poles to equator will never survive to settle there. A coral reef needs 1000 years and several submarine mounts to appear. It hosts tens of thousands of species interacting together, is more complex than the more complex software that we could imagine and not all of those species can just move with the coral and survive in the new area. Algae for example, that are of crucial importance in the survival of the reef, both as symbionts but also as competitors.

Wipe the 10% of the species, just the rare ones, and you will have still a stunning "virgin" coral reef but is neither healthy nor sustainable long term. Wipe all the uncommon species of coral and Acropora will refill all empty space so technically there is plenty of coral still. Wipe all sharks and there will be a chain of unexpected consequences down on the food chain. The reef works as a whole entity.

Is about quantity but also about quality of the remaining corals.

Acidity increases everywhere and does not depend on temperature.

Also, coral reefs grow extremely slowly.

At the end-Permian extinction, nearly everything that made carbonate skeletons was wiped out, probably because of the enormous amounts of CO2, SO2, and HCl that were produced. Coral had to re-evolve from non-carbonate producing species.

You already have several answers, but I want to add a different one.

A bird that was very common when I was a boy is dying now. Why doesn't it just move a few km northwards, to where the temperature is right for it? It doesn't because it needs craggy islands in a shallow sea and the right temperature range.

A lot of species can move, but that doesn't mean that there are many suitable new locations. What we have now has been optimised for the current geography and climate over a long, long time. Shifting all the locations 100km isn't likely to produce as many geography/climate matches.

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