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Comment by torben-friis | Hacker News Reader

>“Every additional fraction of a degree and additional year of warming above 1.5°C raises the risk of irreversible changes including in ice sheets, permafrost carbon, ocean circulation and coral systems, along with devastating human impacts,” the report states.

The mention to coral systems, from an ignorant perspective, seems weirdly specific to me. Kinda like "civilization will collapse and the price of sweaters will go up".

Does their disappearance have indirect consequences I'm not aware of?

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  Sometimes called rainforests of the sea, shallow coral reefs form some of Earth's most diverse ecosystems. They occupy less than 0.1% of the world's ocean area, about half the area of France. Yet, they provide a home for at least 25% of all marine species ...

~ https://en.wikipedia.org/wiki/Coral_reef

Aside from being home to a lot of seafood they also play a not fully understood part in the breeding of a good number of other seafood in ways not yet fully understood.

ie. Lose the reefs .. and then we find out how our supply of seafood is impacted.

That's what I was missing yeah. I always took the bleaching of corals in media as a visible 'canary in the mine' situation, never knew they were so central to marine life.

Coral is the first to go. It's the metaphorical canary in the coal mine. We will probably survive without coral (we might lose a lot of fish but humanity will persist).

Coral bleaching is also accelerated by ocean acidification. Acidification due to CO2 being absorbed into the ocean affects all marine life, but importantly, also plankton. Phytoplankton produces most of the oxygen on earth, and we kind of need that to live. It's not exactly "coral reefs are dead = oxygen depleted", but you don't get many visual representations of oceanic climate change that could threaten all mammals on earth.

Not sure what consequences you are aware of but the key point with corals is loss of biodiversity. It's (I believe) the tipping point that goes at the lowest temperature rise.

> Coral reefs are some of the most diverse and valuable ecosystems on Earth. Home to over 4,000 species of fish, corals, and other marine life, coral reefs cover only 1% of the world’s oceans, but provide habitat for at least 25% of the world’s marine life, with many reef species still to be discovered.

https://oceanservice.noaa.gov/education/tutorial_corals/cora...

> Coral reefs have an estimated global value of £6 trillion each year, due in part to their contribution to fishing and tourism industries and the coastal protection they provide.

https://www.nhm.ac.uk/discover/quick-questions/why-are-coral...

It’s the marine equivalent of “forests die worldwide.” You might not know why you need them, but you’ll probably miss them when they’re gone

Coral systems are a major part of aquatic life, so you'd lose a ton fish, a major food source.

You'd also lose erosion protection on coasts, plant systems like Mangroves (e.g. CO2 sinks).

Additionally, the biodiversity in coral systems has been a rich source of biochemicals, think Alzheimer treatments, cancer and arthritis research.

replace "corals" with "temperate forests" to realize the scale of affected animal populations/species

corals are along the coasts all around the tropics and they are food chain, from plants to herbivores to predators

People really like coral reefs. "Civilization will collapse and this baby kitty will die."

Baby kitty and 1bn people competing for your dinner.

A quick Google suggests 25% of marine life and 1bn people.

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