FIGURE 3. Observed and modelled evolution of SLP since the nineteenth century.

Five-year running-mean SLP from: a, observations (black from Kaplan²⁹, and blue from Hadley Centre²⁸; the record is extended through to 2005 with NCEP ship-based observations²⁷ (dashed line)); and b, GCM historical integrations (five-member ensemble mean in black, an illustrative ensemble member (number 3) in blue, dashed lines indicate linear trend of ensemble members 1, 2, 4 and 5). In both panels, the linear trends in SLP are shown as thick lines, with shadings corresponding to each time-series.