In 2005, I argued that ice sheets may be more vulnerable than the Intergovernmental Panel on Climate Change (IPCC) estimated, mainly because of effects of a warming ocean in speeding ice melt. In 2007, I wrote “Scientific Reticence and Sea Level Rise,” describing and documenting a phenomenon that pressures scientists to minimize the danger of imminent sea level rise.

About then I became acquainted with remarkable studies of geologist Paul Hearty. Hearty found strong evidence for sea level rise late in the Eemian to +6-9 m (20-30 feet) relative to today. The Eemian is the prior interglacial period (~120,000 years ago), which was slightly warmer than the present interglacial period (the Holocene) in which civilization developed. Hearty also found evidence for powerful storms in the North Atlantic near the end of the Eemian period.

It seemed that an understanding of the late Eemian climate events might be helpful in assessing the climate effects of human-made global warming, as Earth is now approaching the warmth that existed then. Thus several colleagues and I initiated global climate simulations aimed at trying to understand what happened at the end of the Eemian and its relevance to climate change today.