A temperature snapshot from MIS 5c in southeastern Alaska

Marine Isotope Stage (MIS) 5c, between ~106 000 and ~93 000 years ago, represents an important warm period in which the current anthropogenic warming can be contextualized. Although viewed as a pronounced interstadial, its climate expression is regionally disparate, with different regions on Earth showing evidence of either cooler or warmer conditions than modern-day. It is therefore important to expand temperature reconstructions to different regions on Earth to gain a better picture of climate dynamics during MIS 5c. In Alaska, there are no quantitative temperature reconstructions for MIS 5c, limiting our knowledge of temperature changes in this climatically sensitive high-latitude region. Here, we fill this gap by providing the first quantitative temperature estimates from MIS 5c in Alaska using hydrogen isotopes of fluid inclusions in precisely dated speleothems. We find that regional temperatures during MIS 5c were within error of the modern-day reference period (1929–1989 ce) temperatures, possibly representing the most recent time period that regional temperatures were as high as modern-day.