Known as the marine isotope stage 11 (MIS 11), the interglacial period centered around 400,000 years ago was the longest and possibly the warmest interglacial in the past 0.5 million years. Because the orbital configurations, atmospheric greenhouse gas concentrations, climate, and faunal characteristics during MIS 11 closely resemble those of the past 5,000 years, paleoclimatologists use MIS 11 as a geological analogue of the present and the near future....