Fig. 2: Sea surface temperature (SST) and tropical precipitation (Pr) forcing.

Linear trends of annual mean fields in a ERSSTv5 SST and b CMAP precipitation from June 2013 to May 2023; and c, d pattern of Interdecadal Pacific Oscillation (IPO) and associated raw unfiltered (red line) and low-pass filtered (black line) time series since January 1950, and Nino34 SST index (blue line) since January 1979. Dotted in (a, b) indicate observed values significant at the 90% confidence level. The linear trend of raw, unfiltered IPO index and Nino34 SST index during 2013–2022 are shown in (d) (unit: °C decade⁻¹), with ** indicating the statistical significance at the 95% confidence level. Dark green lines demarcate the area of prescribed Pacific or global pacemaker SSTs in the PACTrend and GLTrend experiments in (a) and in the idealized Pacific pacemaker experiment in (c). Note that the contour interval is 0.2 °C decade⁻¹ in (a) and 0.1 °C in (c).