Southern Hemisphere climate variability forced by Northern Hemisphere ice-sheet topography

Area of Science:

• Paleoclimatology
• Climate dynamics
• Glacial geology

Background:

• Large Northern Hemisphere ice sheets and low greenhouse gases during the Last Glacial Maximum (LGM) significantly altered global climate.
• The El Niño-Southern Oscillation (ENSO), a key driver of short-term climate variability, was influenced by glacial conditions.
• Understanding high-latitude climate variability during glacial periods remains a challenge.

Purpose of the Study:

• To reconstruct and quantify high-latitude climate variability during the LGM.
• To investigate the teleconnections between tropical climate and West Antarctica during glacial periods.
• To understand the impact of deglaciation on climate variability.

Main Methods:

• Analysis of a high-resolution water isotope record from West Antarctica.
• Climate model simulations to interpret the paleoclimate data.
• Comparison of LGM variability with Holocene variability.

Main Results:

• Interannual to decadal climate variability in West Antarctica was nearly double during the LGM compared to the Holocene.
• Increased variability was linked to stronger teleconnections between the tropical Pacific and West Antarctica.
• A shift in tropical convection, influenced by North American ice sheets, drove this enhanced teleconnection.
• The teleconnection strength decreased most rapidly between 16,000 and 15,000 years ago during deglaciation.

Conclusions:

• High-latitude climate variability was significantly amplified during the LGM.
• North American ice sheet dynamics played a crucial role in modulating tropical-high latitude climate connections.
• Deglaciation led to a substantial reduction in this amplified climate variability.