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Density and sea level changes weaken the Atlantic Overturning: mechanistic insights from ocean bottom pressure

Qianjiang Xing, Shane Elipot, Susan E. Wijffels, Matthew R. England, Alex Sen Gupta, Wenju Cai, Agus Santoso, Jianping Li, Matthew H. England

Featured June 17, 2026

Original Paper

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Simply

A detailed ocean model reveals that the Atlantic Ocean's slowing circulation is driven by a tug-of-war between rising sea levels near coasts and decreasing water density in the open ocean.

In depth
This study uses a high-resolution ocean model to reveal that the observed opposing trends in western and eastern boundary contributions to the Atlantic Meridional Overturning Circulation (AMOC) are driven by a vertically coherent structure in ocean bottom pressure (OBP) trends. This OBP trend structure is shaped by two competing drivers: rising coastal sea level and decreasing density in the ocean interior. This dual-driver mechanism explains the partial compensation between boundaries and the overall basin-wide AMOC decline.

Key Takeaways

  • 1
    The paper identifies a dual-driver mechanism where rising sea level and decreasing ocean density create an opposite-sign vertical structure in ocean bottom pressure (OBP) trends.
  • 2
    This OBP trend structure leads to opposing trends in deep overturning transport at the western (declining) and eastern (strengthening) boundaries of the mid-latitude North Atlantic.
  • 3
    Despite partial compensation, the western boundary's declining trend is generally stronger, resulting in a meridionally consistent decline in the Atlantic Meridional Overturning Circulation (AMOC) across most latitudes.

Conceptual Flow

HIGH LEVEL
1
Modeling Ocean Bottom Pressure to Understand AMOC

Scientists used a detailed computer model to track how pressure at the ocean floor changes, helping them understand why big ocean currents are slowing down.

Ocean Model Data
Calculate Bottom Pressure
Identify Pressure Trends
2
Two Forces Drive Ocean Current Changes

They found that rising sea levels push water one way, while lighter ocean water pulls it another, causing the big ocean current to slow down overall.

Rising Sea Level
Lighter Ocean Water
Create Opposite Pressure Changes
Slowing Ocean Current