TCR and Attribution

Over at Climate Etc:

Even with a low sensitivity value, increased CO2 would still have caused most of the recent global warming. You would need a very low climate sensitivity estimate [below the range supported by the evidence], in order for humans not to have caused most of the recent global warming.”

The globally averaged combined land and ocean surface temperature data as calculated by a linear trend show a warming of 0.85 [0.65 to 1.06] °C over the period 1880 to 2012” – AR5 (90% for the range of 0.41)

CO2 increase 45%

TCR – (1.0 to 2.5) X 45%

0.45 C to 1.13 C

Rise: About 0.85 C

0.40 natural variability on the low end.

The transient climate response is likely in the range of 1.0°C to 2.5°C (high confidence) and extremely unlikely greater than 3°C. {Box 12.2}” – AR5

The immediate above: Likely is 66% and high confidence is 80%. See if you can figure out which number they mean? The AR4 table appears first in your search.

So at the top, replace would with could once the uncertainties are taken into account.

The TCR and the GMST since 1880 are poorly constrained.

The total increase between the average of the 1850–1900 period and the 2003–2012 period is 0.78 [0.72 to 0.85] °C, based on the single longest dataset available.” – AR5

The two, How much did it warm, statements are banner statements with Epaulettes from AR5.

The IPCC’s statements on TCR are inconsistent with their attribution statements. Of the two kinds of statements, one has more qualities of being made up.

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