Ecosystem

Geology

Sea surface temperature

Ice core

Computer network

Biology

Atmospheric sciences

Oceanography

Machine learning

Glacial period

Paleontology

Ocean current

Ecology

Proxy (statistics)

Computer science

Climatology

Insolation

Environmental science

Carbon cycle

Nature Communications

The δD temperature proxy in Antarctic ice cores varies in parallel with CO2 through glacial cycles. However, these variables display a puzzling asynchrony. Well-dated records of Southern Ocean temperature will provide crucial information because the Southern Ocean is likely key in regulating CO2 variations. Here, we perform multiple isotopic analyses on an Antarctic ice core and estimate temperature variations at this site and in the oceanic moisture source over the past 720,000 years, which extend the longest records by 300,000 years. Antarctic temperature is affected by large variations in local insolation that are induced by obliquity. At the obliquity periodicity, the Antarctic and ocean temperatures lag annual mean insolation. Further, the magnitude of the phase lag is minimal during low eccentricity periods, suggesting that secular changes in the global carbon cycle and the ocean circulation modulate the phase relationship among temperatures, CO2 and insolation in the obliquity frequency band.

Asynchrony between Antarctic temperature and CO2 associated with obliquity over the past 720,000 years