Middle Miocene climate instability associated with high-amplitude CO2variability

Simulation of the Middle Miocene Climate Optimum

[1] Proxy data constraining land and ocean surface paleotemperatures indicate that the Middle Miocene Climate Optimum (MMCO), a global warming event at 15 Ma, had a global annual mean surface temperature of 18.4 C, about 3 C higher than present and equivalent to the warming predicted for the next century. We apply the latest National Center for Atmospheric Research (NCAR) Community Atmosphere M...

Simulation of the Middle Miocene climate optimum: implications for future climate

Middle Miocene hominoid origins.

Ward et al. (1) ably show that samples of thickly enameled Middle Miocene hominoids that they attribute to a new genus, Equatorius, are distinct from Kenyapithecus. They fail to show, however, how Equatorius differs from Griphopithecus. In so doing, they may have missed the hominoid connection between Eurasia and Africa by 2 to 3 million years. The authors note the presence of a welldeveloped b...

Orbitally-paced climate evolution during the middle Miocene “Monterey” carbon-isotope excursion

One of the most enigmatic features of Cenozoic long-term climate evolution is the long-lasting positive carbon-isotope excursion or “Monterey Excursion”, which started during a period of global warmth after 16.9 Ma and ended at ∼13.5 Ma, approximately 400 kyr after major expansion of the Antarctic ice-sheet. We present high-resolution (1–9 kyr) astronomically-tuned climate proxy records in two ...

Major middle Miocene climate change and the extinction of tundra communities: Evidence from the Transantarctic Mountains

We present a glacial record from the western Olympus Range, East Antarctica, that documents a permanent shift in the thermal regime of local glaciers, from wet to cold based, between 14.11 and 13.94 million years ago (Ma). The record includes classic wet-based tills interbedded with fossil-rich glaciolacustrine deposits overlain by a series of cold-based drifts. Chronologic control comes from A...