In 2.4 – alkalinity, point 4, you say “silicates are weathered by carbonic acid to hydrogen carbonate”, but carbonic acid is hydrogen carbonate.

No. Whereas carbonic acid (H2CO3) exists in low concentration in a solution of distilled water and dissolved CO2, hydrogen-carbonate is the soluble product (anion) of the carbonic acid reaction with rock that contains silicate minerals. Importantly, weathering also introduces alkali metal cations such as sodium, magnesium and calcium making the respective bicarbonates: (NaHCO3, Mg(HCO3)2, Ca(HCO3)2).


In 1.4 what is the magnitude of the chemical cooling effect?

For terrestrial forests we calculate chemical cooling to be about 1% of the evaporative cooling.