Fig. 4: Timing of persistent transgression of the region-specific upper end of pre-industrial variability.
a–d, For streamflow (at HydroBASINS level 2, a, and at level 3, b) and soil moisture (at HydroBASINS level 2, c, and at level 3, d), local deviations are first aggregated regionally to get pre-industrial percentage of land area with local deviations (Fig. 1c), then the upper end of pre-industrial variability is set to the 95th percentile of the percentage of land area with local deviations (Fig. 1d), and finally the percentage of land area with local deviations is calculated for the industrial period and compared against pre-industrial variability (Fig. 1f). The persistent transgression year is defined as the first year, during which the 10-year moving (trailing) mean of percentage of land area with local deviations has exceeded the region-specific upper end of pre-industrial variability for ten consecutive years, without returning below this limit after this year. The regions shown here depict basins delineated by the HydroBASINS data set97 level 2 (a and c; n = 60, mean area 2,247,000 km2, median area 2,045,000 km2) and level 3 (b and d; n = 265, mean area 509,000 km2, median area 312,000 km2).
