claim: temperatures rise and they fall, and they rise and they fall… and for the last 400 years we’ve had a gentle warming as we’ve been coming out of the little ice age.
evidence: A typical value of λ, 0.8 K/(W/m2), gives an increase in global temperature of about 1.6 K above the 1750 reference temperature due to the increase in CO 2 over that time (278 to 405 ppm, for a forcing of 2.0 W/m2), and predicts a further warming of 1.4 K above present temperatures if the CO 2 mixing ratio in the atmosphere were to become double its pre-industrial value; both of these calculations assume no other forcings.