Read more: 鈥�Climate report 2013: Your guide to the big questions鈥�
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 鈥渕ore intense and longer droughts have been observed over wide areas since the 1970s.鈥� This led to dire warnings of droughts to come, including an IPCC prediction that 鈥渂etween 75 and 250 million people [in Africa] are projected to be exposed to an increase in water stress due to climate change鈥� by the 2020s.
But the new report says confidence is low on whether there has been any increase in droughts so far. And it makes no assessment of whether droughts might become more frequent or intense in the next few decades.
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In 2007, there was also a claim that hurricanes had increased since the 1970s. Now this is again accorded 鈥渓ow confidence鈥�, as is any suggestion of an imminent increase.
The new report is also more wary about predicting what climate change could mean in the future for particular parts of the world. The 2007 report on the impact of climate change was peppered with forecasts of impending droughts, changing river flows and increasing storminess in particular parts of the world.
But this week鈥檚 report warns that: 鈥淥ver the next few decades changes at the regional scale will be strongly influenced by natural internal variability.鈥� In other words, local detail is unknowable because of natural variation in the climate.
