Figure 5. Implication on the timing of abrupt climate change as obtained in various ice core records from Greenland and Antarctica.

Our results suggest that anomalies in Tahiti Δ¹⁴C and true atmospheric CO₂ are caused by the same process. This information is used here as an independent age constraint. The onset of the abrupt rise in atmospheric CO₂ (black bold, this study) is thus tied to 14.6 kyr BP. From previous ice core analysis22, it is known that the rise in CO₂ and CH₄ (red circles, Greenland composite69) occur synchronously here. A new study21 on the NEEM ice core tied the CH₄ rise to be near synchronous to Greenland temperature rise. This synchronicity of the start of the abrupt changes in atmospheric CO₂, CH₄ and Greenland temperature tied to 14.6 kyr BP led to the age alignments in CH₄ and NGRIP δ¹⁸O (high24 (black thin line) and low70 (red line) resolution). We furthermore show some Antarctic climate records on their own independent chronologies to illustrate the temporal north–south offsets. WD54 δ¹⁸O, original (blue) and 100 years running mean (yellow) and stack3 of temperature change from five ice cores in East Antarctica, ΔT_ANT, original (black) and 100 years running mean (orange).