Abstract. The last deglaciation, which occurred from 18 000 to 11 000 years ago,
is the most recent large natural climatic variation of global extent. With
accurately dated paleoclimate records, we can investigate the timings of
related variables in the climate system during this major transition. Here,
we use an accurate relative chronology to compare temperature proxy data and
global atmospheric CO2 as recorded in Antarctic ice cores. In addition to
five regional records, we compare a δ18O stack, representing
Antarctic climate variations with the high-resolution robustly dated WAIS
Divide CO2 record (West Antarctic Ice Sheet). We assess the CO2 and Antarctic temperature phase
relationship using a stochastic method to accurately identify the probable
timings of changes in their trends. Four coherent changes are identified for
the two series, and synchrony between CO2 and temperature is within the
95 % uncertainty range for all of the changes except the end of glacial termination 1 (T1). During the onset of the last deglaciation at 18 ka and the deglaciation
end at 11.5 ka, Antarctic temperature most likely led CO2 by several centuries (by 570 years, within a range of 127 to 751 years, 68 %
probability, at the T1 onset; and by 532 years, within a range of 337 to 629
years, 68 % probability, at the deglaciation end). At 14.4 ka, the onset
of the Antarctic Cold Reversal (ACR) period, our results do not show a clear
lead or lag (Antarctic temperature leads by 50 years, within a range of
−137 to 376 years, 68 % probability). The same is true at the end of the ACR
(CO2 leads by 65 years, within a range of 211 to 117 years, 68 %
probability). However, the timings of changes in trends for the individual
proxy records show variations from the stack, indicating regional differences
in the pattern of temperature change, particularly in the WAIS Divide record
at the onset of the deglaciation; the Dome Fuji record at the deglaciation
end; and the EDML record after 16 ka (EPICA Dronning Maud Land, where EPICA is the European Project for Ice Coring in Antarctica). In addition, two changes – one at 16 ka in the CO2 record and one after the ACR onset in three of the
isotopic temperature records – do not have high-probability counterparts in the other record. The likely-variable phasing we identify testify to the
complex nature of the mechanisms driving the carbon cycle and Antarctic
temperature during the deglaciation.
Sequence of events during the last deglaciation in Southern Ocean sediments and Antarctic ice cores