CLIMATE WATCH - CO2 and climate sensitivity

The effect of increasing CO2 is often described using a concept called "climate sensitivity". 

(Sometimes "equilibrium climate sensitivity" ..... ECS)


Climate sensitivity basically =  "how much does the temperature rise if we double the CO2?"

For example - from this paper......

"Emergent constraint on equilibrium climate sensitivity from global temperature variability" - Cox et al, 2018

"2.2-3.4C, 2.8C with 66% confidence limits"

So doubling CO2 from around 270 ppm (the pre-industrial value) to around 540 ppm would raise average global temperatures by around 2.8 C deg +/-0.6 C deg


We are at about 420 ppm now.



At the current increase in CO2, getting to around 540 ppm by the end of century is not impossible.


The IPCC have looked at all the research on climate sensitivity, and their best estimate is that doubling CO2 produces a rise in average global temperature of 3 C degrees.  This is shown in this figure from IPCC AR6 WG1:


    
From https://www.ipcc.ch/report/ar6/wg1/figures/technical-summary/figure-ts-16

UK Met  Office:  

https://www.metoffice.gov.uk/research/climate/understanding-climate/climate-sensitivity-explained


What effect do these potential temperature rises have?  Carbon Brief has an interactive post that explores that question. 






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