See more from this Division: Topical Sessions
See more from this Session: Ancient Polar Ecosystems and Environments: Proxies for Understanding Climate Change and Global Warming
Abstract:
Focusing on oxygen isotope data, oxygen isotope gradients inferred from enamel are shallower than at present. Intra-tooth/seasonal variations in oxygen isotope ratios in polar regions during both time periods is greater than at lower latitudes for each time slice, but is much less than at present in both cases. Both observations are consistent with fossil evidence for amplified warming in polar regions compared to the tropics, and thus shallower temperature gradients for both the late Cretaceous and Eocene time periods.
Diagenetic patterns in isotopic data provide insight into mechanisms of amplified polar warming during hothouse time periods. Carbon isotope ratios of dentine, which is more susceptible to alteration than enamel, are much higher than associated enamel at polar localities, with values reaching +5 per mil. These high values suggest methane production/stratospheric cloud formation at high latitudes during both times.
See more from this Division: Topical Sessions
See more from this Session: Ancient Polar Ecosystems and Environments: Proxies for Understanding Climate Change and Global Warming