Comment by photochemsyn | Hacker News Reader

Comment by photochemsyn | Hacker News Reader

Yes, we're heading back to Pliocene conditions at full tilt, no doubt about it, and the trigger has been pulled, the tipping point is in the past, so better start adapting to these new conditions. Don't buy property in flood zones, or in wildfire zones, or in low-lying coastal hurricane zones, and if you do, expect to evacuate regularly at the very least. However, life was abundant in the Pliocene, so hysteria about 'existential threat' is overblown - at least, it is if we stop using fossil fuels over the next half-century or so. Given the boom in solar led by China, this is entirely feasible.

Climate change and tropical Andean glaciers: Past, present and future Vuille et al., Earth-Science Reviews 89 (2008) 79–96

> "Temperature in the Andes has increased by approximately 0.1 °C/ decade, with only two of the last 20 years being below the 1961–90 average. Precipitation has slightly increased in the second half of the 20th century in the inner tropics and decreased in the outer tropics. The general pattern of moistening in the inner tropics and drying in the subtropical Andes is dynamically consistent with observed changes in the large-scale circulation, suggesting a strengthening of the tropical atmospheric circulation. Model projections of future climate change in the tropical Andes indicate a continued warming of the tropical troposphere throughout the 21st century, with a temperature increase that is enhanced at higher elevations. By the end of the 21st century, following the SRES A2 emission scenario, the tropical Andes may experience a massive warming on the order of 4.5–5 °C. Predicted changes in precipitation include an increase in precipitation during the wet season and a decrease during the dry season, which would effectively enhance the seasonal hydrological cycle in the tropical Andes."

Well, the degree of "existential threat" depends on whether you're a rich industrialized country at mid-to-high latitudes or not. And even that is conditional on the question of how many hundreds of millions of climate refugees there will be in the next 50 years, and what exactly can be done about them.

A nontrivial fraction of Earth's land area, currently populated by a billion+ humans, will almost certainly become incompatible with such density. No matter how sedentary a part of humanity has become, people will not just sit down and die when conditions become unbearable; they will start walking. I'm reminded of Sagan's poignant words, even if spoken in a much more optimistic context:

Even after 400 generations in villages and cities, we haven't forgotten. [...] has been meticulously crafted by natural selection as an essential element in our survival. Long summers, mild winters, rich harvests, plentiful game—none of them lasts forever. It is beyond our powers to predict the future. Catastrophic events have a way of sneaking up on us, of catching us unaware.

The refugee issue is something that many people have either not thought about at all, or try their best not to think about to avoid cognitive dissonance, or think that it can be solved by building high enough walls and shooting anyone who tries to get through. Even without regard to the practicality of the latter solution, it is morally abhorrent enough to make it incompatible with any reasonable definition of a civilized society. Particularly because it's the rich industrialized societies that are directly responsible for the crisis in the first place!

China is currently directly involved in helping Africa leapfrog the fossil fuel technology that the industrialized West relied on for economic growth. You won't find much about this in the Western corporate media for fairly obvious reasons, but clearly the world can completely eliminate fossil fuel use within 50 years.

My point is this trajectory still absolutely guarantees steady warming at around current rates 0.1 - 0.2 C per decade IIRC for the next several hundred years. All the tech fixes, aerosol injection etc., only mask the issue for a decade or two and are best classified as worthless scams. The only option is adaptation to new conditions, with replacement of fossil fuels with renewables and storage as priority #1.

Of course fossil fuel producers and exporters like the United States, Russia, Venezuela, Saudi Arabia etc. don't want to hear this, but that cash cow is going the way of whale oil and the kerosene lamp, and fast. There will be much howling and gnashing of teeth.

As far as climate refugees, well maybe - but don't underestimate the capability of humans to adapt to new (degraded) conditions. I'd expect a steep decline in birthrate across much of the world as the pressure rises, however.

The tremendous, astronomical injustice of the climate catastrophe is that specifically the societies that are the least responsible for it, and the least able to mitigate and adapt to it, are going to be the worst affected by its consequences.

This is really not as definitive as you claim, although it is a popular talking point. Polar amplification of warming is well-understood, that's where the greatest temperature swings will take place, and that's going to impact Europe, North America, Japan, Russia, etc. heavily. Nobody is going to escape the consequences, it's planet-wide.

Aug 2022 "The Arctic has warmed nearly four times faster than the globe since 1979"

https://www.nature.com/articles/s43247-022-00498-3

Well I initially thought the same thing (as some rando who put negligible thought or research into it). Then it was pointed out by a science youtuber that mass migration of people is a problem, which I promptly ignored.

However upon reflection, suppose the population of Mexico did try to go north due to drought. Mexico outnumbers the US army by 126:1, so it's definitely not something to dismiss out-of-hand. Also a lot of manufacturing is done there.

So it may not be a "die of heat" type existential threat for people in North America, but it seems plausible that a collapse of the system type existential threat is possible.

Unfortunately it’s not hard to imagine that these pressures are going to cause a huge amount of political instability and dramatically increase the odds of catastrophic conflict though.

It's easy to say to "start adapting [ not the least by ] not buy property in [ negatively impacted ] areas".

If only there weren't gazillions worth of property, and billions of people, in such areas. The Pliocene had a distinct advantage there, I believe.

While there might well be (personal) value in "prepping", as a solution that doesn't "scale" to all of humanity, unfortunately.

it's an existential threat to our way of life, as we know there we be plenty of plants and animals after we're gone just like there were plenty before us

that's not to say that we haven't left a bit of a scar, but even meteor craters fill with time

Also critical, which you failed to notice, is the fact that this anthropogenic-forced climate change is happening 10,000+ times faster than prior unforced climate changes. Changes that took a million years now happen in a mere century.

Systems require time to adapt and this is essentially demanding ecosystems adapt to an explosive shock wave.

When speed increases by orders of magnitude, the phenomena become not only quantitatively different, they are fundamentally different. For example, consider sipping your coffee only 1000x as fast as normal; instead of ~one seconds from table to lip, it's a millisecond. You'll need to accelerate your cup to 2000 fps, almost Mach3, then decelerate it. In is not even close to the same sort of event, considering the required explosive-level forces involved.

Some ecosystems, such as certain bird nesting patterns can move that fast. But others, such as trees with a reproduction cycle of centuries — and the habitats dependent upon them, may be wiped out before their younger generation can establish itself closer to the poles...

With climate change, it really is true that speed kills.

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