Limits...
Response of the North Atlantic surface and intermediate ocean structure to climate warming of MIS 11

View Article: PubMed Central - PubMed

ABSTRACT

Investigating past interglacial climates not only help to understand how the climate system operates in general, it also forms a vital basis for climate predictions. We reconstructed vertical stratification changes in temperature and salinity in the North Atlantic for a period some 400 ka ago (MIS11), an interglacial time analogue of a future climate. As inferred from a unique set of biogeochemical, geochemical, and faunal data, the internal upper ocean stratification across MIS 11 shows distinct depth-dependent dynamical changes related to vertical as well as lateral shifts in the upper Atlantic meridional circulation system. Importantly, transient cold events are recognized near the end of the long phase of postglacial warming at surface, subsurface, mid, and deeper water layers. These data demonstrate that MIS 11 coolings over the North Atlantic were initially triggered by freshwater input at the surface and expansion of cold polar waters into the Subpolar Gyre. The cooling signal was then transmitted downwards into mid-water depths. Since the cold events occurred after the main deglacial phase we suggest that their cause might be related to continuous melting of the Greenland ice sheet, a mechanism that might also be relevant for the present and upcoming climate.

No MeSH data available.


Related in: MedlinePlus

temperature reconstructions for 0–200 m water layer along with planktic and benthic δ18O from core M23414 compared with 21 June insolation53 (65°N) and climate related records from ODP Site 983: IRD49, relative abundance of N. pachyderma(s)49, and benthic δ13C and δ18O 50.Mcd means meter composite depth. Blue bar indicates the cold event. Dashed lines indicate a tentative correlation of the cold events between the two sites. MIS 11, MIS 11ss and Termination V (TV) are indicated on the top panel.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5385537&req=5

f3: temperature reconstructions for 0–200 m water layer along with planktic and benthic δ18O from core M23414 compared with 21 June insolation53 (65°N) and climate related records from ODP Site 983: IRD49, relative abundance of N. pachyderma(s)49, and benthic δ13C and δ18O 50.Mcd means meter composite depth. Blue bar indicates the cold event. Dashed lines indicate a tentative correlation of the cold events between the two sites. MIS 11, MIS 11ss and Termination V (TV) are indicated on the top panel.

Mentions: Further northwestward of site M23414, at ODP Site 983 (Fig. 1), two brief but significant cold events are clearly recognizable after the main period of deglacial IRD input had ceased49 (Fig. 3). The earlier cold event at Site 983 was associated with an IRD input, but the younger cold event, which occurred at the end of global ice volume decrease, was substantially more pronounced as seen in the increase of N. pachyderma (s) relative abundance. Therefore, the timing and expression of these cooling events suggest that they likely represent the cold events identified in M23414. Although at site M23414 the benthic δ13C record does not resolve the cold events (Fig. 2), at Site 983 the younger cold event is reflected by δ13C of C. wuellerstorfi50 indicating an association with the slowing down of AMOC (Fig. 3). This apparent inconsistency can be solved by considering the different deep water sources at these sites. The supra-regional character of at least the youngest of these two events is supported by -based SST reconstructions from farther south and southeast of the SPG33343551, which all register a short climate deterioration at the end of postglacial warming, i.e. at the end of the global sea lever rise.


Response of the North Atlantic surface and intermediate ocean structure to climate warming of MIS 11
temperature reconstructions for 0–200 m water layer along with planktic and benthic δ18O from core M23414 compared with 21 June insolation53 (65°N) and climate related records from ODP Site 983: IRD49, relative abundance of N. pachyderma(s)49, and benthic δ13C and δ18O 50.Mcd means meter composite depth. Blue bar indicates the cold event. Dashed lines indicate a tentative correlation of the cold events between the two sites. MIS 11, MIS 11ss and Termination V (TV) are indicated on the top panel.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5385537&req=5

f3: temperature reconstructions for 0–200 m water layer along with planktic and benthic δ18O from core M23414 compared with 21 June insolation53 (65°N) and climate related records from ODP Site 983: IRD49, relative abundance of N. pachyderma(s)49, and benthic δ13C and δ18O 50.Mcd means meter composite depth. Blue bar indicates the cold event. Dashed lines indicate a tentative correlation of the cold events between the two sites. MIS 11, MIS 11ss and Termination V (TV) are indicated on the top panel.
Mentions: Further northwestward of site M23414, at ODP Site 983 (Fig. 1), two brief but significant cold events are clearly recognizable after the main period of deglacial IRD input had ceased49 (Fig. 3). The earlier cold event at Site 983 was associated with an IRD input, but the younger cold event, which occurred at the end of global ice volume decrease, was substantially more pronounced as seen in the increase of N. pachyderma (s) relative abundance. Therefore, the timing and expression of these cooling events suggest that they likely represent the cold events identified in M23414. Although at site M23414 the benthic δ13C record does not resolve the cold events (Fig. 2), at Site 983 the younger cold event is reflected by δ13C of C. wuellerstorfi50 indicating an association with the slowing down of AMOC (Fig. 3). This apparent inconsistency can be solved by considering the different deep water sources at these sites. The supra-regional character of at least the youngest of these two events is supported by -based SST reconstructions from farther south and southeast of the SPG33343551, which all register a short climate deterioration at the end of postglacial warming, i.e. at the end of the global sea lever rise.

View Article: PubMed Central - PubMed

ABSTRACT

Investigating past interglacial climates not only help to understand how the climate system operates in general, it also forms a vital basis for climate predictions. We reconstructed vertical stratification changes in temperature and salinity in the North Atlantic for a period some 400 ka ago (MIS11), an interglacial time analogue of a future climate. As inferred from a unique set of biogeochemical, geochemical, and faunal data, the internal upper ocean stratification across MIS 11 shows distinct depth-dependent dynamical changes related to vertical as well as lateral shifts in the upper Atlantic meridional circulation system. Importantly, transient cold events are recognized near the end of the long phase of postglacial warming at surface, subsurface, mid, and deeper water layers. These data demonstrate that MIS 11 coolings over the North Atlantic were initially triggered by freshwater input at the surface and expansion of cold polar waters into the Subpolar Gyre. The cooling signal was then transmitted downwards into mid-water depths. Since the cold events occurred after the main deglacial phase we suggest that their cause might be related to continuous melting of the Greenland ice sheet, a mechanism that might also be relevant for the present and upcoming climate.

No MeSH data available.


Related in: MedlinePlus