[tfourb]

Europe now has hundreds of excess deaths from heat and hundreds of excess deaths from flooding due to events exacerbated or caused entirely by climate change most years. Africa likely already experiences tens of thousands of climate change related deaths each year, although attribution is tricky. Assuming that climate change and its effects are an exponentially escalating phenomenon, why would it be unthinkable that over the next 10/20/50/100 years the cumulative death toll of climate change will reach into the billions?

[HPsquared]

It's quite a leap of faith to extrapolate from hundreds up to billions, no?

[tfourb]

It all depends ob your assumptions, i.e. the actual effects of climate change on extreme weather events, the capacity of various polities to adapt to these effects and how you would define "climate change related deaths" and the timeframe you are looking at.

Direct fatalities from weather related natural disasters (droughts, floods, storms, etc) between 2005 and 2024 worldwide are estimated somewhere around 200.000 people, so about 10.000 deaths per year [0].

If you assume (just for the sake of the argument) that climate change will increase this death toll by 10% every year for 100 years, direct deaths from natural disasters caused by climate change alone will amount to close to 140.000.000 deaths over that time period.

Add to this indirect deaths, i.e. premature deaths due to insufficient nutrition during childhood caused by drought, disease spread by floods, etc. etc.

And because the effects of climate change are mostly political in nature, you'll have to make some assumptions about that, too. Sea level rise will affect (as in inundate their current homes at least once a year) more than 600 million people by the year 2100 [1]. Many of these peoples will be displaced and depending on the political and economic capacity of their societies to cope with this displacement, this alone could result in millions of deaths.

Climate change is also a contributor to general political instability and the risk of both civil and nation state war. How do you account for those deaths?

In summary, the death toll of climate change can inherently not be known. But if you look at the next hundred years, I doubt you can assume a number of less than in the hundreds of millions, if we assume climate change effects based on current estimates of "status quo" emissions. Which makes emission reductions essential, because there is a literal connection between an additional ton of CO2 in the atmosphere and an increase in the number of deaths.

[0] https://ourworldindata.org/grapher/number-of-deaths-from-nat... [1] https://www.nature.com/articles/s41467-019-12808-z

[HPsquared]

Simply assuming 10% compound growth year-on-year without any basis is, frankly, ridiculous.

[tfourb]

Which is why I wrote "for the sake of the argument". You can of course make your own assumptions, but for my money, 10% is not necessarily unrealistic.

The average global temperature is already rising by several percentage points each year: https://ourworldindata.org/grapher/temperature-anomaly

Temperature = energy and more energy will necessarily lead to an increased number of and more severe weather events which in turn will claim more lives.

Natural disasters also have the nasty tendency to have tipping points. If a disaster (or a string of disasters) overwhelms the ability of a society to mitigate its effects, deaths rise exponentially not linearly with the severity of the event. I.e. the U.S. government can likely mitigate the effects of any one hurricane, but a series of catastrophic hurricanes might lead to a total collapse of the disaster response system, leading to potentially tens of thousands of deaths which otherwise could have been avoided.

And again: direct deaths from natural disasters are only one aspect of climate change and likely a minor one. Indirect effects will likely play an even bigger role, i.e. premature deaths due to worsening life conditions for children and elderly people, mass displacement/migration or political crises up to and including war.

[tinuviel]

> The average global temperature is already rising by several percentage points each year. > Temperature = energy

Plainly incorrect and wrong.

Have you considered mitigating factors to prevent deaths?

Try the calculation with simple growth instead of compounding growth.

[tfourb]

We are talking about a status quo scenario, in which CO2 emissions are continuing unabated along current levels or falling only very slowly. This will result in an increase of average global temperatures of +3°C [0]. It will literally make uninhabitable due to flooding or heat a non-insignificant share of currently settled land area around the world.

If you want to really kill your appetite, google "wet bulb temperature" and think about the (very real) possibility, that a mega-city in pakistan or india could experience a wet bulb temperature of >35°C for several hours sometimes this century, which will probably kill most people who don't have access to air conditioning (which is most of them), while the excessive use of air conditioning will further increase the temperature in this city during the event.

If we are talking about +3°C scenarios, it is really for you to argue why excess deaths shouldn't be assumed to show compounding growth.

> Have you considered mitigating factors to prevent deaths?

I've mentioned the possibility of adaption several times in this thread. But I personally severely doubt that a global society that can't get it's act together to limit CO2 emissions will be able to mobilize adequate economic and political resources to make a dent in the excess deaths resulting from a +3°C scenario. It's the same basic problem: we would need to mobilize considerable public resources, financed mostly by rich people and with significant impact on the lifestyle of the middle class to benefit society at large. Either we manage to achieve this for both emission reduction and adaption, or we will loose at both.

[0] https://www.ngfs.net/ngfs-scenarios-portal/explore

[franktankbank]

> The average global temperature is already rising by several percentage points each year

This marks you as an unserious person in the matter being discussed.

[tfourb]

Why? Because I used the term "percentage points" incorrectly? Or do you have an issue with the facts?

Those are: In 1976, global average temperature was 0.15 degrees C above the 1861-1890 mean. 50 years later, in 2024 it was 1.54 degrees above. On average, that's a 2.79 percent increase in the temperature anomaly per year over the past 50 years. https://ourworldindata.org/explorers/climate-change?Metric=T...

If you look at the graph and the scientific forecasts, it would be dumb not to assume that the rate of temperature increase will increase if we do not drastically cut down emissions quickly. If such a scenario doesn't scare the pants off you, you either have very little investment in the state of the world past 2050 or you are unreasonably confident that it won't impact you or your loved ones.

[vixen99]

https://ourworldindata.org/part-one-how-many-people-die-from...

"Cold deaths vastly outnumber heat-related ones, but mostly due to “moderate” rather than extremely cold conditions."

[defrost]

That's a useful baseline for future comparisons.

Currently (mostly) cities don't see Death Valley or Marble Bar range tempretures or beyond .. this will change.

  Government statistics show there were more than 10,000 heat-related deaths in the UK alone between 2020 and 2024. Close to 3,000 people died amidst the record-breaking 2022 heatwaves, when UK temperatures exceeded 40C for the first time. Despite this, the UK remains unprepared for extreme heat.

~ https://www.climatechangenews.com/2025/07/14/to-help-people-...

Extreme heat could lead to 30,000 deaths a year in England and Wales by 2070s, say scientists

~ https://www.theguardian.com/environment/2025/jul/10/extreme-...

[chopin]

That would be roughly on par with Germany's deaths related to infections contracted in a hospital. That doesn't make it into headlines.

[defrost]

That's just the UK (high latitude), at tempretures lower than current tempretures in Death Valley / Marble Bar.

Give it time for higher tempretures to reach dense urban centres, look to India and equatorial countries that'll experience both high temp and high humidity and you'll see heat exhaustion deaths rise to well past those anglocentric numbers.

The more serious numbers will come from climate related conflict and migration in any case (assuming no change in increasing emmissions, even assuming a flattening to a steady human annual addition).

[tfourb]

Maybe read the second part of this analysis? https://ourworldindata.org/part-two-how-many-people-die-from...

Cold deaths will decrease in high-latitude countries (which tend to be sparsely inhabited) but heat deaths will increase in low latitude countries (i.e. places like India). The exact effects of this will depend on political factors (adaption), but it is unlikely that the decrease in cold deaths will compensate the increase in heat deaths. Also, the people dying from heat will still be dead.