Steady decline in mean annual air temperatures in the first 30 k.y. after the Cretaceous-Paleogene boundary

Lauren K. O’Connor, Emily Dearing Crampton-Flood, Rhodri M. Jerrett, Gregory D. Price, B. David A. Naafs, Richard D. Pancost, Paul McCormack, Aris Lempotesis-Davies, Bart E. van Dongen, Sabine K. Lengger

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Abstract

The Cretaceous-Paleogene (K-Pg) boundary marks one of the five major mass extinctions of the Phanerozoic. The ways in which the climate system responded to a bolide impact and extensive volcanism at this time over different time scales are highly debated. We used the distribution of branched tetraether lipids (brGDGT) from fossil peats at two sites in Saskatchewan, Canada (paleolatitude ~55°N), to generate a high-resolution (millennial) record of mean annual air temperature (MAAT) spanning the last ~4 k.y. of the Cretaceous and the first ~30 k.y. of the Paleogene. Our study shows that MAATs ranged from 16 to 29 °C, with the highest value in the first millennia of the Paleogene. The earliest Paleogene averaged ~25 °C—maintaining or enhancing warmth from the latest Cretaceous—followed by a general cooling to ~20 °C over the following ~30 k.y. No abrupt postboundary cooling (e.g., an “impact winter”) or abrupt warming is evident in our data, implying that if such phenomena occurred, their duration was relatively short-lived (i.e., sub-millennial-scale). Further, no long-term impact or volcanism-driven warming is evident. The range of temperature change observed is considerably greater than that derived from marine proxy records over the same time interval. Our findings therefore more properly place bounds on the magnitude and duration of temperature change on land during this critical interval—the main setting for the demise of nonavian dinosaurs and the rise of mammals.

Original languageEnglish
Pages (from-to)486-490
Number of pages5
JournalGeology
Volume51
Issue number5
Early online date22 Mar 2023
DOIs
Publication statusPublished - 1 May 2023

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