Fig. 4: Data-model comparison with driving factors.
From: Greening of India and revival of the South Asian summer monsoon in a warmer world
From bottom to top: Total tropical forest and wet evergreen forest percentages from pollen data (dotted curves) and LOWESS curves (bold curves) (this study); Simulated summer precipitation using LOVECLIM1.3 and HadCM3 (red curves: orbital forcing only = Orb; black curves: orbital and GHG forcing = OrbGHG; blue curves: orbital, GHG and ice volume forcing = OrbGHGIce) and tree fraction simulated with LOVECLIM1.3; Sea-level reconstructions from Rohling et al.109 (blue curve) and Waelbroeck et al.110 (blue dashed curve); Total radiative forcing (ΔR GHG, black curve) calculated from greenhouse gases (CO2, CH4 and N2O) and CO2 radiative forcing (ΔR CO2, solid brown curve) calculated from atmospheric CO2 concentrations77; since the contribution of CH4 and N2O to ΔR GHG is small compared with that of CO2 at orbital scales, the radiative forcing of GHG on the monsoon is mainly exerted by CO2; Atmospheric CO2 concentrations from Antarctic ice-core EPICA Dome C108 (dotted brown curve); Orbital forcing expressed by mean June-July-August insolation at 20°N (red curve), precession (green curve) and obliquity (dotted gray curve)111.
