The enigma of high-latitude paleoclimate

Abstract

The geological record of paleontology, paleobotany and oxygen-isotope determinations show conclusively that the Mesozoic and early Tertiary paleoclimates of arctic and antarctic latitudes were far warmer than that of the present. Observations indicate that temperate to subtropical conditions existed in these regions in the past. The problem is just as cogent for the paleogeaphic reconstructions of North America and Antarctica that are based on studies of rock magnetism. Temperatures computed by the application of a thermodynamic climate model to paleogeography, which verify well for the present and most of the past, are very discrepant for high-latitude observations. Tentative explanations of the climate problem that involve changes in solar luminosity, earth's axial tilt and ocean currents appear to be untenable. Another tentative and somewhat heretical proposal is offered here that paleogeography as related to former pole positions determined from rock magnetism may have gross errors due to a long-term bias between the rotational and dipole pole locations. As a consequences erroneous high paleolatitude locations would be assigned to regions whose fauna, flora and paleolatitudes all suggest lower-latitude locations.