[agere_contra]

Virtually all (circa 98%) global CO2 comes from natural sources

With respect - and I'm on your side with this - doesn't most atmospheric CO2 come from oceanic outgassing? The oceans contains colossal amounts of CO2 some of which is released in an average ~ 800 yr lag after a period of high insolation. The famous Vostok Ice core data shows this lag:

[drlevy88]

Hmm. The warm Coke effect. Makes sense. Cooling imposed from outside would also cause the ocean to soak up more CO₂ by the same token.