# Equilibrium climate sensitivity

- kind: problem
- status: partial
- year: 1896
- authors: Svante Arrhenius; 1979 Charney report: 1.5–4.5 °C

**Statement.** How much does global temperature eventually rise if atmospheric CO2 doubles?

The Charney report's range stood for forty years. Combining process understanding, historical warming and paleoclimate narrowed it: the IPCC's 2021 assessment gives a likely range of 2.5 to 4 °C. Cloud feedbacks remain the biggest source of uncertainty, and they are what separates a manageable future from a severe one.

Posed 1896, Svante Arrhenius; 1979 Charney report: 1.5–4.5 °C.

## What would settle it

A narrower observed range

## Sources

- [Wikipedia: Climate sensitivity](https://en.wikipedia.org/wiki/Climate_sensitivity)

[Climate](/wiki/Space:climate.md) · [Earth](/wiki/Continent:earth.md)

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