Equable Paleogene climates: The result of a stable, positive Arctic Oscillation?

The Early Paleogene is recognized as a particularly warm interval in Earth' s history. Paleogene proxy climate indicators suggest warm polar and mid-la titude continental interior temperatures, and a reduced latitudinal tempera ture gradient. Most researchers believe that Early Paleogene climate was dr iven by forcing fields that act globally (e.g. greenhouse gases). However, modeling work based on this hypothesis has failed to reproduce Paleogene cl imate as indicated by proxy data. Quite possibly, an ameliorating influence acting directly at the poles would more effectively warm high latitudes, p rovide an additional heat source to mid-latitude continental interiors, and reduce the latitudinal temperature gradient. Here we present a hypothesis based on the positive phase of the modern Arctic Oscillation; in short, tha t prolonged low pressure over the Arctic Ocean would have warmed mid-latitu de continental interiors and drastically reduced the Arctic Ocean's ice cov er, thus producing conditions consistent with proxy climate indicators for the Paleogene greenhouse interval.