Earth’s climate has alternated between greenhouse (warm) and icehouse (cool) modes throughout the Phanerozoic (Figure 1A). At present, Earth is in the midst of an icehouse climate. Nevertheless, the rise of industrialization in the last two centuries has led to a dramatic increase in atmospheric CO2 from the burning of fossil fuels, which, in turn, has led to significant global warming (e.g., Ruddiman, 2000). Global warming could profoundly impact human life as a result of consequent global sea-level rise, more numerous and increasingly powerful hurricanes, and enhanced amounts of precipitation. Understanding the ocean-climate system during past greenhouse climate modes is essential for more accurately predicting future climate and environmental changes in a warming Earth.