New Scientist: This is surprisingly unclear. Some things that seemed fairly certain in the last report in 2007, no longer appear to be. For instance, the 2007 assessment confidently reported that "more intense and longer droughts have been observed over wide areas since the 1970s." This led to dire warnings of droughts to come, including an IPCC prediction that "between 75 and 250 million people [in Africa] are projected to be exposed to an increase in water stress due to climate change" by the 2020s. But the...