Abstract

Although the current paradigm is that CO2 is the primary driver of large-scale Earth System change over the last 150 million years, the relative importance of changing palaeogeography on climate dynamics through this greenhouse period is yet to be fully explored. In particular, the opening and closing of key ocean gateways, orogenesis, and continentality, could have a key role in determining not only the timing of key transitions (e.g. Eocene-Oligocene glaciation), but could also contribute directly to the large-scale trends.

Here, we present a new series of climate model simulations, built upon state-of-the-art palaeogeographic maps (_{20 in total covering a} 100 million year period). The suite of simulations allows us to consider key questions related to climate dynamics through this time period:

(1) What is the role of changing palaeogeography (including gateways) in mediating ocean circulation, through changing gateways and continental configuration?

(2) What is the contribution of changing palaeogeography to climate, and climate sensitivity?

Through considering the relationship between the local and regional scale, we explore the dangers of drawing global conclusions from local data, and highlight key areas where new palaeodata could be targeted to inform the above questions and better evaluate the models.