claim: Elementary radiative-transfer calculations demonstrate that a natural surface global brightening amounting to ~1.9 Wm–2 over the 18-year period of study would be expected – using the IPCC’s own methodology – to have caused a transient warming of 1 K ( 1.8 F° ).
evidence: The Paleocene–Eocene thermal maximum was an approximate 200,000 year long event where the global average temperature rose by some 5 to 8 °C ( 9 to 14 °F ), and mid-latitude and polar areas may have exceeded modern tropical temperatures of 24–29 °C ( 75–84 °F ).