Last glacial maximum cooling of 9 °C in continental Europe from a 40 kyr-long noble gas paleothermometry record.

The Last Glacial Maximum (LGM; ∼26–18 kyr ago) is a time interval of great climatic interest characterized by substantial global cooling driven by radiative forcings and feedbacks associated with orbital changes, lower atmospheric CO2, and large ice sheets. However, reliable proxies of continental paleotemperatures are scarce and often qualitative, which has limited our understanding of the spatial structure of past climate changes. Here, we present a quantitative noble gas temperature (NGT) record of the last ∼40 kyr from the Albian aquifer in Eastern Paris Basin (France, ∼48°N). Our NGT data indicate that the mean annual surface temperature was ∼5 °C during the Marine Isotope Stage 3 (MIS3; ∼40–30 kyr ago), before cooling to ∼2 °C during the LGM, and warming to ∼11 °C in the Holocene, which closely matches modern ground surface temperatures in Eastern France. Combined with water stable isotope analyses, NGT data indicate δD/NGT and δ18O/NGT transfer functions of +1.6 ± 0.4‰/°C and +0.18 ± 0.04‰/°C, respectively. Our noble-gas derived LGM cooling of ∼9 °C (relative to the Holocene) is consistent with previous studies of noble gas paleothermometry in European groundwaters but larger than the low-to-mid latitude estimate of 5.8 ± 0.6 °C derived from a compilation of noble gas records, which supports the notion that continental LGM cooling was more extreme at higher latitudes. While an LGM cooling of ∼9 °C in Eastern France appears compatible with recent data assimilation studies, this value is greater than most estimates from current-generation climate model simulations of the LGM. Comparing our estimate for the temperature in Eastern France during MIS3 (6.4 ± 0.5 °C) with GCM outputs presents a promising avenue to further evaluate climate model simulations and constrain European climate evolution over the last glacial cycle. • A ∼40 kyr-long noble gas temperature (NGT) record in Western Europe (Paris Basin). • Observed NGTs yield a Last Glacial Maximum (LGM) cooling of −9.1 ± 0.9 °C (∼25 kyr ago). • Average cooling during the Marine Isotope Stage 3 was −5.1 ± 0.5 °C. • Most PMIP4 GCM models give smaller LGM cooling (lower climate sensitivity) than NGT. • δD and δ18O correlate with NGT, yielding +1.6 ± 0.4‰ and +0.18 ± 0.04‰/°C, respectively. [ABSTRACT FROM AUTHOR]