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

Area of Science:

• Paleoceanography
• Climate Science
• Geology

Background:

• The Plio-Pleistocene transition (3.2–2.6 million years ago) marked a shift from warm Pliocene climates to Pleistocene ice ages.
• Northern Hemisphere glaciation intensified, but significant changes also occurred in ocean deep water masses.
• Deep water mass properties converged in the North Pacific and North Atlantic during this period.

Purpose of the Study:

• To investigate the impact of Antarctic coastal ice on Pacific Ocean overturning.
• To explain the observed convergence of global deep water mass properties during the Plio-Pleistocene transition.

Main Methods:

• Utilized climate models simulating Pliocene conditions.
• Focused on the role of coastal ice in the Pacific sector of Antarctica.
• Analyzed changes in Pacific Ocean overturning and deep water mass formation.

Main Results:

• Absence of coastal ice in the Antarctic Pacific sector led to significant reductions in Pacific Ocean overturning.
• The modern North Pacific Deep Water (NPDW) mass was lost in Pliocene climate models.
• Circumpolar Deep Water (CDW) emerged as a common source for deep water.

Conclusions:

• The lack of Antarctic coastal ice is a key factor in reduced Pacific overturning during warm Pliocene periods.
• This mechanism helps explain the convergence of global deep water mass properties observed at the Plio-Pleistocene transition.
• Circumpolar Deep Water played a crucial role as a unified deep water source during this climate transition.