Premium
No Evidence for a Large Atmospheric CO 2 Spike Across the Cretaceous‐Paleogene Boundary
Author(s) -
Milligan Joseph N.,
Royer Dana L.,
Franks Peter J.,
Upchurch Garland R.,
McKee Melissa L.
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl081215
Subject(s) - macrofossil , paleogene , extinction event , geology , paleontology , cretaceous , extinction (optical mineralogy) , biological dispersal , population , demography , sociology , holocene
Currently, there is only one paleo‐CO 2 record from plant macrofossils that has sufficient stratigraphic resolution to potentially capture a transient spike related to rapid carbon release at the Cretaceous‐Paleogene (K‐Pg) boundary. Unfortunately, the associated measurements of stomatal index are off‐calibration, leading to a qualitative interpretation of >2,300‐ppm CO 2 . Here we reevaluate this record with a paleo‐CO 2 proxy based on leaf gas exchange principles. We also test the proxy with three living species grown at 500‐ and 1,000‐ppm CO 2 , including the nearest living relative of the K‐Pg fern, and find a mean error rate of ~22%, which is comparable to other leading paleo‐CO 2 proxies. Our fossils record a ~250‐ppm increase in CO 2 across the K‐Pg boundary from ~625 to ~875 ppm. A small CO 2 spike associated with the end‐Cretaceous mass extinction is consistent with many temperature records and with carbon cycle modeling of Deccan volcanism and the meteorite impact.