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Strong coupling of Asian Monsoon and Antarctic climates on sub-orbital timescales

View Article: PubMed Central - PubMed

ABSTRACT

There is increasing evidence that millennial-scale climate variability played an active role on orbital-scale climate changes, but the mechanism for this remains unclear. A 230Th-dated stalagmite δ18O record between 88 and 22 thousand years (ka) ago from Yongxing Cave in central China characterizes changes in Asian monsoon (AM) strength. After removing the 65°N insolation signal from our record, the δ18O residue is strongly anti-phased with Antarctic temperature variability on sub-orbital timescales during the Marine Isotope Stage (MIS) 3. Furthermore, once the ice volume signal from Antarctic ice core records were removed and extrapolated back to the last two glacial-interglacial cycles, we observe a linear relationship for both short- and long-duration events between Asian and Antarctic climate changes. This provides the robust evidence of a link between northern and southern hemisphere climates that operates through changes in atmospheric circulation. We find that the weakest monsoon closely associated with the warmest Antarctic event always occurred during the Terminations. This finding, along with similar shifts in the opal flux record, suggests that millennial-scale events play a key role in driving the deglaciation through positive feedbacks associated with enhanced upwelling and increasing CO2.

No MeSH data available.


Coupling of sub-orbital timescale changes in EDC ΔδD, cave Δδ18O and ocean upwelling.(a, b) Cave Δδ18O (cyan), EDC ΔδD (ref. 2; magenta) and opal flux from TN057-13PC in the Southern Ocean9 (black) during Termination (T) I. The double-peak structures are highlighted by yellow bars. (c) Cave Δδ18O (cyan) and EDC ΔδD (magenta) as in Fig. 3b but 99-point average, and opal flux from TT013-PC72 in the equatorial Pacific33 (black) over the last two glacial-interglacial cycles. Terminations are indicated by grey bars. All records are plotted on their individual timescales.
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f4: Coupling of sub-orbital timescale changes in EDC ΔδD, cave Δδ18O and ocean upwelling.(a, b) Cave Δδ18O (cyan), EDC ΔδD (ref. 2; magenta) and opal flux from TN057-13PC in the Southern Ocean9 (black) during Termination (T) I. The double-peak structures are highlighted by yellow bars. (c) Cave Δδ18O (cyan) and EDC ΔδD (magenta) as in Fig. 3b but 99-point average, and opal flux from TT013-PC72 in the equatorial Pacific33 (black) over the last two glacial-interglacial cycles. Terminations are indicated by grey bars. All records are plotted on their individual timescales.

Mentions: Figure 3 shows larger-amplitude millennial-scale events at the glacial Terminations (G1-G3) in contrast to those of other millennial-scale climate changes (A1-A9 and B1-B9). An opal flux record from the Southern Ocean shows two intervals of enhanced upwelling that are concurrent with the two intervals of rising atmospheric CO2 during the last deglaciation9. The dominant features of these upwelling records are similar to the double-peak structure observed in cave Δδ18O and in Antarctic ΔδD (Fig. 4a,b). A similar feature was detected in opal flux record from equatorial Pacific sediments33 for the past 260 ka (Fig. 4c). Equatorial opal accumulation rates sustained relatively low values over much of the record and were punctuated by large increases in opal centered on Terminations I and II, as well as prior to Termination III. Large nutrient supplies in the Equatorial Pacific mainly originate from Subantarctic Mode Water during the Terminations33. These lines of evidence suggest that millennial-scale events could act as a trigger, via atmospheric teleconnections, to push the ITCZ and SH westerly southward, eventually enhancing the wind-driven upwelling and rising atmospheric CO2 levels that contributed to deglaciation89.


Strong coupling of Asian Monsoon and Antarctic climates on sub-orbital timescales
Coupling of sub-orbital timescale changes in EDC ΔδD, cave Δδ18O and ocean upwelling.(a, b) Cave Δδ18O (cyan), EDC ΔδD (ref. 2; magenta) and opal flux from TN057-13PC in the Southern Ocean9 (black) during Termination (T) I. The double-peak structures are highlighted by yellow bars. (c) Cave Δδ18O (cyan) and EDC ΔδD (magenta) as in Fig. 3b but 99-point average, and opal flux from TT013-PC72 in the equatorial Pacific33 (black) over the last two glacial-interglacial cycles. Terminations are indicated by grey bars. All records are plotted on their individual timescales.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5015120&req=5

f4: Coupling of sub-orbital timescale changes in EDC ΔδD, cave Δδ18O and ocean upwelling.(a, b) Cave Δδ18O (cyan), EDC ΔδD (ref. 2; magenta) and opal flux from TN057-13PC in the Southern Ocean9 (black) during Termination (T) I. The double-peak structures are highlighted by yellow bars. (c) Cave Δδ18O (cyan) and EDC ΔδD (magenta) as in Fig. 3b but 99-point average, and opal flux from TT013-PC72 in the equatorial Pacific33 (black) over the last two glacial-interglacial cycles. Terminations are indicated by grey bars. All records are plotted on their individual timescales.
Mentions: Figure 3 shows larger-amplitude millennial-scale events at the glacial Terminations (G1-G3) in contrast to those of other millennial-scale climate changes (A1-A9 and B1-B9). An opal flux record from the Southern Ocean shows two intervals of enhanced upwelling that are concurrent with the two intervals of rising atmospheric CO2 during the last deglaciation9. The dominant features of these upwelling records are similar to the double-peak structure observed in cave Δδ18O and in Antarctic ΔδD (Fig. 4a,b). A similar feature was detected in opal flux record from equatorial Pacific sediments33 for the past 260 ka (Fig. 4c). Equatorial opal accumulation rates sustained relatively low values over much of the record and were punctuated by large increases in opal centered on Terminations I and II, as well as prior to Termination III. Large nutrient supplies in the Equatorial Pacific mainly originate from Subantarctic Mode Water during the Terminations33. These lines of evidence suggest that millennial-scale events could act as a trigger, via atmospheric teleconnections, to push the ITCZ and SH westerly southward, eventually enhancing the wind-driven upwelling and rising atmospheric CO2 levels that contributed to deglaciation89.

View Article: PubMed Central - PubMed

ABSTRACT

There is increasing evidence that millennial-scale climate variability played an active role on orbital-scale climate changes, but the mechanism for this remains unclear. A 230Th-dated stalagmite δ18O record between 88 and 22 thousand years (ka) ago from Yongxing Cave in central China characterizes changes in Asian monsoon (AM) strength. After removing the 65°N insolation signal from our record, the δ18O residue is strongly anti-phased with Antarctic temperature variability on sub-orbital timescales during the Marine Isotope Stage (MIS) 3. Furthermore, once the ice volume signal from Antarctic ice core records were removed and extrapolated back to the last two glacial-interglacial cycles, we observe a linear relationship for both short- and long-duration events between Asian and Antarctic climate changes. This provides the robust evidence of a link between northern and southern hemisphere climates that operates through changes in atmospheric circulation. We find that the weakest monsoon closely associated with the warmest Antarctic event always occurred during the Terminations. This finding, along with similar shifts in the opal flux record, suggests that millennial-scale events play a key role in driving the deglaciation through positive feedbacks associated with enhanced upwelling and increasing CO2.

No MeSH data available.