2003: Another $45 trillion question from Keith Briffa: "why the extreme divergence in the series pre-1200 and post 1900?"

ClimateGate FOIA grepper!

thanks for this - and it is intriguing , not least because of the degree of coherence in these series between 1200 and 1900 - more than can be accounted for by either replication of data between the series (of which there is still some) or artifact of the standardisation method (with the use of RCS curves which are possibly inappropriate for all the data to which each is applied) . Having then got some not insubstantial confidence in the likelihood of a real temperature signal in this period - the question of why the extreme divergence in the series pre-1200 and post 1900? [Briffa]