changes in hydrological conditions have occurred, particularly in the tropics. Wetter conditions in the Sahara from 12 000 to 4,000 years BP enabled cultural groups to survive by hunting and fishing '(p 202). Figure 7.1 is about global temperature. A paper by Jones, Keith Briffa et al. noted that the schematic 7.1 (c) figure on p.202 had no clear source, but can be traced to publications by Hubert Lamb representing the Central England temperature record; those publications have no "explicit calibration against instrumental data, are just Lamb’s qualitative judgement and interpretation of what he refers to as the ‘evidence’".