Humans have caused 1.5 °C of long-term global warming according to new estimates

The last IPCC report estimates that to limit warming to 2C, humans can only emit at most 1150 GtCO2 (at 67% likelihood) [1].

There are 8.2 billion humans, so about 140tCO2/person left on average. If we assume that we get to net zero by 2050, that means the average person can emit about 5.4tCO2/person/year from today to 2050 (hitting 0tCO2/person/year in 2050). This is what emissions look like currently [2]

    Top 5 countries > 10m population
    Saudi Arabia  22.1t 
    United Arab Emirates 21.6t  
    Australia            14.5t 
    United States  14.3t
    Canada          14.0t
    Some others
    China           8.4t
    Europe 6.7t
    World average 4.7t
    Lower-middle-income countries of 1.6t
    Low-income countries 0.3t

Guess what's going to happen and who is going to suffer, despite not doing anything.

[1] Page 82 https://www.ipcc.ch/report/ar6/syr/downloads/report/IPCC_AR6...

[2] https://ourworldindata.org/co2-emissions-metrics

> that means the average person can emit about 5.4tCO2/person/year from here on out. This is what emissions look like currently

Using a world average target number and then presenting a list that leads with world outliers is misleading. This is the kind of statistical sleight of hand that climate skeptics seize upon to dismiss arguments.

The world average is currently under the target number:

> World average 4.7t

I think you meant to imply that the CO2 emissions of poor countries were going to catch up to other countries, but I don’t think it’s that simple. The global rollout of solar power, battery storage, and cheap EVs is exceeding expectations, for example.

I don’t want to downplay the severity of the situation, but I don’t think this type of fatalistic doomerism is helping. In my experience with people from different walks of life, it’s this type of doomerism that turns them off of the topic entirely.

I believe the causation runs the other way. The IPCC was founded in 1988, when CO2 emissions were 22 gigatons per year. Nearly four decades later it's 40 gt/y, and continuing to rise.

Doomerism is the reaction to our utter failure to even pretend to try. It did not cause that failure. Nor are people looking at the data and going, "yeah, I ought to do something, but people on Hacker News were gloomy so I'm going to buy a bigger SUV instead." EVs and solar and suchlike are much, much, much too little and much, much, much too late.

Doomerism doesn't help, except in the extremely limited sense of helping someone express their frustration. But it also isn't hurting because we'd be doing exactly the same nothing if they were cheerful.

Global warming will cause suffering, but extreme poverty was worse for billions than any projections from 2.0C above baseline. The global population grow by 3 billion people since 1988 yet extreme poverty is way down.

What nobody talks about is there’s not enough oil and natural gas left to miss 2C by much. At current consumption rates we run out of both in ~50-60 years. Coal isn’t competitive with renewables and as soon as we stop pumping hydrocarbons the associated influx of Methane also stops. So we’re almost guaranteed to miss 2.5C of global warming, and stopping at 2C is likely.

So congratulations humanity, all that money spent on R&D instead of directly cutting emissions without any solid alternatives actually worked!

> At current consumption rates we run out of both in ~50-60 years

At current prices. As prices go up new sources of fuel become economical and the cycle continues. Not to mention that methane emissions from agriculture are a significant contributor as well (30% from cows) so just removing hydrocarbons doesn’t solve that problem.

It seems like an unrealistic bet that hydrocarbon-based emissions drop to 0 just because you think we’ll run out of fuel in 50 years. Does that mean airplanes stop flying in 50 years? No one is making these bets in the marketplace alongside you for good reason. And remember, consumption grows quite a bit year over year so you’re looking at a much shorter time frame if your prediction were to be true.

Consumption is also heavily tied to prices. Who is going to pay the equivalent of 50$/gallon when they can use an EV?

We use oil because it’s cheap not because it’s the only possible solution. It’s not that we’re going to run out 100% year X, it’s that as economies of scale end priced inherently spike. Gas stations can scale down to 1940’s levels by having most of them close, but giant fuel refineries, pipelines, etc need scale to be worth the maintenance.

You're basically arguing for the latest estimates for peak oil. Maybe they're right this time but I still think that improving technology & prices make new sources available.

> Who is going to pay the equivalent of 50$/gallon when they can use an EV?

If we're going to be arguing for peak oil, let's argue for peak lithium then too. EVs are going to get more and more expensive too as we have to extract from more expensive lithium stores.

> We use oil because it’s cheap not because it’s the only possible solution

For some things sure. Aviation fuel and ship fuel notably don't have any real replacements on the horizon.

From your sibling comment:

> The cost premium of biofuels for air travel aren’t that high and the scale can meet demand for long distance flights. Fertilizer from nitrogen in the atmosphere is again cost competitive relative to that kind of increase. Batteries are fine for ocean shipping on a ~50 year timescale, and that basically covers burning fossil fuels. Using it as a feedstock for plastics etc is a non issue for climate change.

I think you're mistaken here. Biofuels for air travel are much more complex than just pricing. You've got regulatory approvals, cost of retrofitting existing engines / figuring out how to make them drop-in without needing petroleum, etc. If you're thinking that batteries are fine for ocean shipping, I'd like a sample of what you're taking because the energy demands of massive ship containers dwarf the capabilities of batteries. That's why they're talking hydrogen fuel cells and nuclear.

> It’s not that we’re going to run out 100% year X, it’s that as economies of scale end priced inherently spike. Gas stations can scale down to 1940’s levels by having most of them close, but giant fuel refineries, pipelines, etc need scale to be worth the maintenance.

Conversely, there's a huge incentive to have oil be competitively priced and avoid a total collapse of that segment. That's why you see huge resistance politically - there's no real plan put forward for how we transition to a clean energy economy for the people currently participating in the oil economy.

> Peak lithium

Oil is consumed, lithium isn’t. There’s plenty of lithium to electrify the world multiple times, but it’s just an element so you can literally recycle it for billions of years.

> You've got regulatory approvals, cost of retrofitting existing engines / figuring out how to make them drop-in without needing petroleum, etc

0.2% of global aviation fuel is already biofuels, the regulatory processes is already involved and we’re talking a 50+ year timeframe here there’s plenty of options without retrofitting existing aircraft.

As to boats, weight and volume are a non issue so they scale just fine into the 24,000 TEU behemoths. Upfront costs are prohibitively expensive though operating costs are presumably. That said, there’s many options, ships are one of the few cases where hydrogen is a realistic possibility.

> There’s plenty of lithium to electrify the world multiple times, but it’s just an element so you can literally recycle it for billions of years.

Recycling lithium is typically more expensive than extracting it through mining. Recycling companies claim a recovery rate of 95-98% so certainly lithium is lost and that's ignoring that smaller batteries often don't even end up in the recycling stream. But the important bit is the cost - if it's more expensive than mining then the recovery isn't economical then either there's a government subsidy or the lithium ends up diluted in the trash stream. You'd have a point about nickle or cobalt because they're particularly valuable but lithium is not so it is effectively being consumed.

> 0.2% of global aviation fuel is already biofuels

But it's not even clear that biofuels reduce CO2 due to production, processing & transport as well as land clearing for scaling it up. [1] suggests that biofuels can actually end up emitting more CO2 than the fossil fuels they replace (for example here's an earlier study [2]). And that's ignoring the substantial scaling challenges that SAF faces on the production side. I hope it works out but the lesson with huge risky bets is that many don't pan out and all we have now is large risky bets left which makes me pessimistic we'll succeed just because we run out of oil (assuming we even do which again seems highly unlikely to me because that's not how economics works).

[1] https://climate.mit.edu/ask-mit/how-should-we-measure-co2-em...

[2] https://theconversation.com/biofuels-turn-out-to-be-a-climat...

Calculating Biofuels today is irrelevant when we haven’t removed fossil fuels from the rest of our economy. They are currently a farming subsidy not an environmental panacea. Long term they can’t be a net carbon producer because that carbon would need to be endlessly produced from nothing.

As to lithium being consumed, we’re talking hundreds to thousands of years from now before mining becomes an issue, current economic issues are largely meaningless. Unlike oil, these are the early days of the lithium economy. Making a big battery pile somewhere is perfectly reasonable form of recycling.

The incentives for a government subsidies for lithium recycling are strategic. Reducing dependence on foreign imports is inherently useful, but a stockpile and battery pile serves the same basic need.

> Long term they can’t be a net carbon producer because that carbon would need to be endlessly produced from nothing

As noted in the MIT article:

> Since most natural ecosystems absorb and store carbon, while farmland in active use tends to produce it, this land use change can create more climate-warming pollution

Basically the land is changed from a carbon store to a carbon producer for biomass meaning you're no longer sequestering the carbon which is where you get extra carbon in the ecosystem even if you're not having any carbon in the transportation & production.