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.

Considering that since 1988 world population went from a little over 5bln to 8bln, our output per capita rose by around 10%, which is not great, but also not terrible.

Meanwhile the number of infants globally peaked around 2013-2017 and according to revised estimates overall population will peak late this century reaching 10.4bln - largely in countries with a small carbon footprint anyway.

We're going to blow past that 2°C target and millions will die due to extreme weather, but I firmly believe life on Earth and our species will survive, especially now that the "business as usual" scenario is considered highly unlikely due to how differently e.g. China's coal usage changed compared to projections.

> I firmly believe life on Earth and our species will survive

Few people are doubting that. The issue is that

> millions will die due to extreme weather

and due to climate-related wars, and life in general will become less pleasant. Just breathing air with higher CO2 concentration already isn’t that great.

> Just breathing air with higher CO2 concentration already isn’t that great.

Or less O2. I wonder if there any study that does show any impact already or these are still speculations?

There isn't less O2. Even if all plants on earth disappeared (and animals somehow survived that), it would take millions of years before there's any measurable impact on O2 concentrations.

Moreover, there's no physiological impact whatsoever until you drop several percent.

O2 does decrease and is measurable: https://www.oxygenlevels.org/

I think this is a more marketable concern than CO2 as without O2 most know that you can’t live.