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Comment by pizzaman1 | Hacker News Reader

> In a similar vein, it looks like we may eventually (at least at some point) turn the tide on CO2 emissions, but not because anyone (at large) really sacrificed anything, or did something that was mildly painful now in the hopes for a better future, but instead because renewable and battery tech is just getting to be the economic best option.

One should not forget the reason that these technologies have become so cheap is policy interventions. Especially renewables got kick-started by programs like the German Renewable Energy Sources Act (EEG) which then created demand for Chinese mass manufacturing to eventually lower prices.

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Correct. Policy can do a whole lot for building (or suppressing) early development of a technology.

Once it has already spread far and wide with clear economic pathways though? Perhaps less so.

Kind of terrifying that "we may" turn the tide on CO2 is an acceptable level of optimism.

If we don't, we all die. it isn't something to leave up to mindless market mechanics.

> If we don't, we all die.

No, we don't. Even in the worse case scenarios, a runaway greenhouse effect a la Venus was never remotely part of the scientific consensus. Heck, the IPCC just retired the worst case RCP 8.5 scenario saying it is now scientifically implausible. Now a big reason it was deemed implausible is the transition to renewable energy is happening. But even if RCP 8.5 did happen, it was not a humanity ending scenario.

Arguing over whether we all die or we all don't cheapens the risk of the death of millions if/when wet-bulb temperature limits (> 35C,95F at 100% humidity) become routine in populated geographies.

I would not take solace in IPCC retiring a scenario. Their predictions are based on conservative aggregates of existing science, and have always been considered by many in the climate science community to be underestimating climate change.

> have always been considered by many in the climate science community to be underestimating climate change.

This is exactly wrong as it relates to RCP 8.5. A number of research papers came out basically showing how 8.5 was completely implausible, and it was only after these papers were widely cited and reached consensus did the IPCC retire 8.5.

This article by some of the original authors of one of those papers explains the situation well: https://www.theclimatebrink.com/p/on-the-death-of-rcp85 . If you actually read their linked research paper, I don't think any unbiased observer could think 8.5 is plausible anymore (and, in fairness, 8.5 was always proposed as a worst case scenario, not a "business as usual scenario", as that climatebrink article explains very well).

Sure, some fraction of humanity will survive. Terrific.

> But even if RCP 8.5 did happen, it was not a humanity ending scenario.

Can you do it like the IPCC report and assign a confidence to that claim?

Mine would be: RCP 8.5 ending humanity (very low likelihood, low confidence), based on absolutely nothing.

In what scenario does humanity not achieve net neutral emissions and survive?

This idea that climate change would lead to "ending humanity" just shows to me how a lot of the popular messaging outran the actual science on the issue.

Again, a "runaway Venus" was never really in the cards. As far as I am aware, basically all the carbon that is now locked in the ground in fossil fuels was once in the environment, and Earth still supported copious life at that time. E.g. at one point when dinosaurs roamed the Earth, there were no polar ice caps (Antarctica, even when it was near its current position over the South Pole, had lush green forests and lots of dinosaurs, even with many months of darkness), sea level was many meters higher, but life still flourished.

I'm not downplaying climate change. A significant, geologically fast rise in global temperatures would kill millions/billions of people, inundate coastal areas, result in major migrations and resource wars, etc. But "ending humanity" by making the entire planet unlivable was never supported by the science.

As far as I'm aware, until we get carbon emissions to zero (or net zero), temperatures will continue to rise.

For another 50 years after we do stabilize them, yes.

The contrarian throwaway said: "A significant, geologically fast rise in global temperatures would kill millions/billions of people, inundate coastal areas, result in major migrations and resource wars, etc."

-- this sounds close enough to what I said, simply "We all die." I didn't say the oceans would evaporate. But with that amount of damage, global civilization and culture would probably not survive. Going carbon-neutral is not a "meh, let's do it later, or not" type of thing.

> this sounds close enough to what I said, simply "We all die."

This is not just arguing over semantics. There is a huge difference between what I wrote and "we all die". The global population is 8.3 billion. Climate change would be most catastrophic to poor populations in heat prone areas like Southeast Asia, parts of Africa, parts of Mexico, etc. where the wet bulb temp would exceed human survivability. Also, coastal cities would have to build defenses or move.

But we could lose one or two billion people and there is nothing that makes me believe that "global civilization and culture would probably not survive". I just done see how you make that leap. There would be huge change but plenty of places would be perfect for human habitation, some moreso than today.

Yes, all this is my understanding also. I would add to that that think it's good to keep as a goal that we want to have the political ability to make prudent changes to avoid disasters even if those disasters are not totally world ending but merely catastrophic levels of suffering for a hundred years or so.

That is bad enough to prioritize avoiding at all costs (mainly costs to the upper crust of the economy, the part most resistant to meaningful change).

I, for one, don't believe civilization could handle perpetual catastrophe, the loss of billions of people while retaining a grow-or-die economic model, our largest cities needing to "move" inland/uphill, and migrating populations escaping ininhabitable areas, etc. etc., without altogether collapsing.

Look how fragile it is - blocking the Strait of Hormuz alone caused economic near-calamity in some markets. It's like we are all on a fast-moving treadmill, and once tripped, there's no getting back up. This isn't the world of 1933.

But there is not unlimited carbon to burn. All that carbon in the ground was in the air/water at one point in Earth's past, when Earth was teeming with life.

There is scope for cautious optimism. Certainly the changes in train around the world (and being wound back in the US) are well and truly heading in the right direction, and at pace. It's a matter of perspective.

c.f. https://ember-energy.org/latest-insights/reframing-energy-fo...

We're now, in 2026, currently at 1.5 degrees above baseline. This used to be the threshold at which we decided it would be too late and everything would be fucked and human civilization would inevitably collapse.

That won't happen, of course, since we kept increasing the threshold every time we approached the previous threshold. Luckily for us now, human society won't collapse until we hit 2 degrees!

> This used to be the threshold at which we decided it would be too late and everything would be fucked and human civilization would inevitably collapse.

Man, reading these comments is making me realize how crazy the messaging on climate alarmism actually got. No, 1.5 C was literally never the threshold where "everything would be fucked and human civilization would inevitably collapse." Where are people getting this misinformation? It wasn't from the IPCC, nor from the broader scientific consensus, nor was it part of the Kyoto or Paris Protocol statements. Yes, there would be colossally bad impacts, but "everything would be fucked and human civilization would inevitably collapse" is just total bullshit.

its science journalism tbh, the realities of climate change's impact is so spread out and complicated that it's difficult to communicate to a largely scientifically-illiterate audience. see the perennial confusion over cold heavy snow winters being an artifact of global warming due to increased energy in the weather systems causing more volatility instead of just a simple "everything is warmer now."

so journalists focus on Number, because Number is simple and understandable. even when Number is mostly or completely bogus.

Who is this "we" you reference? There have always been fear sellers (as well as their cult followers) and their predictions have always been pure fantasy but most of society rightly ignores them.

Check out Charles C. Man's "The Wizard and the Prophet". In this book, a wizard is someone who approaches a problem with technological innovation. A prophet is someone who approaches it with societal transformation, usually involving sacrifice by the masses.

e.g. Malthus (and others) observed that human populations were growing exponentially, but crop-land is a finite resource. Humanity seemed doomed to starvation in just a few short generations. As a prophet, Malthus tried to get people to stop having so many children. Other prophets repeated this effort multiple times, always warning of an apocalypse that was just a few decades away. Meanwhile, wizards tried spreading bat guano on fields and started breeding new varieties of wheat, rice, etc.. The result has been a continual stream of innovation that has led to the world's food supply growing faster than its population. Yet, the warning of the prophets remains sound. There's an ultimate limit.

Humans seem hardwired to both be and love prophets while totally failing to follow their advice. Prophets have been warning us to reduce our energy use, eat local, bicycle everywhere, etc.. Some of us do some of these things some of the time, but not nearly enough to make a real difference. Wizards have gotten solar and wind to the point where they're economically viable enough to supplant coal and internal combustion engines, and that is making a huge difference.

Prophets are valuable for identifying problems, such as AI, but their demands for abstinence and self-sacrifice usually don't gain much traction. It's when the wizards show up that things usually start cooking.

Prophets have identified AI as a problem and are calling for limits, but history has shown that not nearly enough people are likely to listen. How might a wizard approach the problem in a way that lets people keep doing their thing without the world ending? The pace of AI development is so quick that we also have to ask, is there enough time for the wizards to do their thing?

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EDIT: On the bright side, while the rapidity of the AI revolution seems utterly unprecedented, so too is the concentration of power in those who control it. The prophets really only need to convince or coerce a handful of billionaires in order to buy the world's wizards years or decades.

That is a great book. I like how the book describes the Wizards tackling world famine through GMO's.

AI accelerates our rate of energy consumption as we vie for efficiencies and alternative sources of energy. That is concerning.

Maybe the next book will be:

The AI and The Prophet.

prophets are no match for profits

At the same time, it was a cartel of industries that felt threatened by the emerging green technology and became one of its greatest opponents. Government policy only meant the official loss of one side to the other.

We will never reverse CO2 emissions until humanity entertains itself less, spends less time in tourism, and does fewer unproductive recreational activities like drinking and drugs. Only then will waste go down significantly and utility go up. And only then will we reverse co2 emissions.

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