Variance of rainfall trends. Estimated percent of ‘variance’ of 20th century observed precipitation, taken from University of East Anglia’s Climate Research Unit version 2p1 (UEA-CRU2p1: (Mitchell & Jones 2005)), annual mean, ascribed to non-linear trend. Data and maps available at IRI Time Scales map room available at: http://iridl.ldeo.columbia.edu/maproom/Global/Time_Scales/. The non-linear trend for each grid box is estimated by regressing the rainfall timeseries on a ‘climate change index’ that is estimated as the decadally-smoothed multi-model average of global mean temperature from the IPCC models used in the 4th Assessment Report (i.e. CMIP-3 models). Note that the observational dataset used on the Time Scales map room, may be updated over time.