Email 2409, June 1999, Phil Jones actually suggests that he knows the average 11th or 12th century temperature of the entire Earth with an accuracy of one or two tenths of a degree Centigrade

Email 2409

All conclude that 20th century is the warmest of the millennium and the warming during it unprecedented since 1400. All centuries this millennium are cooler than the 1961-90 base period - the 20th by about -0.05 and the 17th (coldest) 0.5 below 1961-90. Warmest century in the first half of the millennium was about 0.1-0.2 below 1961-90. Range of values of decades over the last 1000 years is quite small - 1990s about 0.35 and 1601-1610 -0.7. Even the coldest year of 1601 was only about 1 C below 1961-90. This level of variability of hemipsheric average temperature is in accord with the long model control runs and the few runs with solar forcing since ~ 1650.

Email 4582, Feb 2009, Phil Jones on global average surface temperature: "The work that estimated the 14 number (it was 14.02 for the globe) made lots of assumptions over the sea ice areas and the Antarctic. I always thought this was accurate to about +/- 0.5 deg C"