Modelled ocean changes at the Plio-Pleistocene transition driven by Antarctic ice advance

Abstract

The Earth underwent a major transition from the warm climates of the Pliocene to the Pleistocene ice ages between 3.2 and 2.6 million years ago. The intensification of Northern Hemisphere Glaciation is the most obvious result of the Plio-Pleistocene transition. However, recent data show that the ocean also underwent a significant change, with the convergence of deep water mass properties in the North Pacific and North Atlantic Ocean. Here we show that the lack of coastal ice in the Pacific sector of Antarctica leads to major reductions in Pacific Ocean overturning and the loss of the modern North Pacific Deep Water (NPDW) mass in climate models of the warmest periods of the Pliocene. These results potentially explain the convergence of global deep water mass properties at the Plio-Pleistocene transition, as Circumpolar Deep Water (CDW) became the common source.

Global Cooling Contributed to the Establishment of a Modern‐Like East Asian Monsoon Climate by the Early Miocene

“…Associated with these changes in SAT and SLP (Figures and S4), the atmospheric meridional circulations between northwestern Australia and East Asia are intensified (Figure S5b), including the strengthened ascending motion around northwestern Australia, strengthened air transport from the Southern to Northern Hemispheres in mid‐high tropospheric level, the strengthened descending motions at East Asia, and strengthened air transport from the Northern to Southern Hemispheres in low tropospheric level. In comparison, the growth of the Antarctic ice sheet not only increases the SAT around northwestern Australia but also significantly decreases SAT in the East Asian continent through both atmospheric and oceanic changes (e.g., Ao et al, ; Hill et al, ; Knorr & Lohmann, ). Particularly, the growth of the Antarctic ice sheet strongly lows the SAT in southern high latitudes (Figure S4b), increasing the corresponding meridional temperature gradient.…”

A Southwest Pacific Perspective on Long‐Term Global Trends in Pliocene‐Pleistocene Stable Isotope Records

“…Other prominent features during this warm interval include a perennially ice-free Arctic Ocean (Ballantyne et al, 2010(Ballantyne et al, , 2013Dowsett et al, 2012), Arctic summer temperatures approximately 8-19°C warmer than modern (Brigham-Grette et al, 2013;Salzmann et al, 2011), reduced meridional and zonal sea surface temperature (SST) gradients (Fedorov et al, 2013), and enhanced production and derived for stable isotope studies (Woodard et al, 2014). However, a recent climate model suggests that such changes in ice sheet extent may have direct implications for the rate of the Pacific overturning circulation (Hill et al, 2017).…”

Expanding Greenland Ice Sheet Enhances Sensitivity of Plio‐Pleistocene Climate to Obliquity Forcing in the Kiel Climate Model

“…The SST cooling following the buildup of the GrIS is rather weak compared to the SST change estimated from North Atlantic Sites ODP 982 (Figure S1a) and Deep Sea Drilling Project (DSDP) 607 of about 3 K (Lawrence et al, ). This suggests the importance of additional drivers during the Plio‐Pleistocene transition such as the closure and opening of Bering and Canadian Archipelago Straits, and the emergence of the modern West and East Antarctic Ice Sheet (Brierley & Fedorov, ; Hill et al, ; Otto‐Bliesner et al, ). The opening of both Bering and the Canadian Archipelago Straits is linked to a 1.3 K SST cooling in the North Atlantic (Otto‐Bliesner et al, ), while the glaciation over West and East Antarctic supports a deep ocean cooling of 2.0 K reconstructed at Site DSDP 607 (Hill et al, ).…”

“…This suggests the importance of additional drivers during the Plio‐Pleistocene transition such as the closure and opening of Bering and Canadian Archipelago Straits, and the emergence of the modern West and East Antarctic Ice Sheet (Brierley & Fedorov, ; Hill et al, ; Otto‐Bliesner et al, ). The opening of both Bering and the Canadian Archipelago Straits is linked to a 1.3 K SST cooling in the North Atlantic (Otto‐Bliesner et al, ), while the glaciation over West and East Antarctic supports a deep ocean cooling of 2.0 K reconstructed at Site DSDP 607 (Hill et al, ). The model‐data discrepancy in this study would likely be smaller if these changes in land surface and land sea distribution were included in the simulations.…”

“…The influence of the ice sheets over North America and Europe (Bintanja & Van de Wal, 2008) is not accounted for in our experiments with the KCM. Additionally, the opening of Arctic oceanic gateways and ice sheets over West and East Antarctic is not considered and may further weaken the interhemispheric temperature gradient (Brierley & Fedorov, 2016;Hill et al, 2017;Otto-Bliesner et al, 2017). Knies et al (2014) suggested the gradual emergence of modern Arctic sea ice, which may also provide a freshwater forcing on the AMOC.…”