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Mortality from climate change

Two studies have estimated how many climate related deaths will happen as a result of CO2 emitted. Both estimates were around one climate death for each 4,000 tonnes CO2 emitted.

• A paper published in Nature [1] estimated one death per 4,434 tonnes CO2. The paper pointed out that this is equivalent to the lifetime emissions of 3.5 average Americans. This was reported in The Guardian [2].
• A second paper [3] gave an estimate of one death per 1,000 tonnes carbon burnt - which releases 3,700 tonnes CO2.

Loss of habitable land due to heat

Information comes from a study of unprecedented heat (mean annual temperature at least 29°C) [4]. Some key conclusions are that

• global warming has already exposed about 9% of the world's population (over 600 million) to unprecedented heat
• current policies, leading to global warming of around 2.7°C, would leave about one third of the world's population exposed to unprecedented heat
• one person will be exposed to unprecedented heat for every c.1700 tonnes CO2 emitted
• c. 2.7 average EUcitizens or c. 1.2 average US citizens emit enough CO2 in their lifetimes to expose one future person to unprecedented heat, and the average citizen of Qatar emits enough CO2 in their lifetime to expose c. 2.8 future people to unprecedented heat.

Biodiversity loss

As global warming worsens, the effects get more severe.

For example, the SR15 report explains that

• the majority (70-90%) of warm water (tropical) coral reefs that exist today will disappear if global warming reaches 1.5°C (reference [5], p179)
• 99% of corals will be lost with warming of 2°C above the pre-industrial period (reference [5], p230).

See appendix.

References

[1]	The mortality cost of carbon (2021) https://www.nature.com/articles/s41467-021-24487-w

[2]	Three Americans create enough carbon emissions to kill one person, study finds (2021) https://www.theguardian.com/environment/2021/jul/29/carbon-emissions-americans-social-cost

[3]	The Human Cost of Anthropogenic Global Warming: Semi-Quantitative Prediction and the 1,000-Tonne Rule (2019) https://www.frontiersin.org/articles/10.3389/fpsyg.2019.02323/full

[4]	Lenton et al (2023) Quantifying the human cost of global warming Nature Sustainability https://www.nature.com/articles/s41893-023-01132-6

[5]	IPCC SR15 report: Chapter 3: Impacts of 1.5°C of Global Warming on Natural and Human Systems (2019) https://www.ipcc.ch/site/assets/uploads/sites/2/2019/02/SR15_Chapter3_Low_Res.pdf

Appendix: Loss of coral reefs

It works out that 1 tonne CO2 will destroy 0.4 sq m of coral reefs.


First published: 15 Apr 2023
Last updated: 12 Jan 2024