Fig. 2: | Nature Communications

Fig. 2

From: Southern Hemisphere westerlies as a driver of the early deglacial atmospheric CO2 rise

Fig. 2

Sequence of events leading to a pCO2 rise and initiation of the deglaciation. Results of experiment LH1–SO–SHW (as shown in Fig. 1) at 16 ka and compared to 19 ka. (Top centre panel) Sea–air pCO2 anomalies (μatm), with positive values indicating a potential CO2 flux out of the ocean (Southern Ocean) or reduced CO2 uptake (North Atlantic). Overlaid are tropical precipitation anomalies (blue contour lines, ±8 cm yr−1), Southern Ocean SST anomalies (grey dots indicate an area with ΔSST ≥ 2 °C), and the 0.1 m austral summer sea-ice contour (19 ka, solid black and 16 ka, dashed black lines). (Side panels) DIC anomalies zonally averaged over the (left) Indo-Pacific and (right) Atlantic basins. Southern Ocean isopycnals at 16 ka are overlaid (grey contours, 0.05 kg m−3). 1. NADW cessation cools the North Atlantic and warms the South Atlantic, thus 2. shifting the ITCZ southward, 3. which strengthens/shifts the SH westerlies (SHW) poleward, 4. thus enhancing the upwelling of Circumpolar Deep Water (CDW) on a decadal timescale. 5. Polar/intensified SHW enhances deep ocean convection, leading to a centennial-scale Southern Ocean CO2 outgassing and mid/high southern latitude warming