E-Mail IMAGE: Ancient groundwater flows from a well in the North China plain during a field campaign in 2004 to measure noble gases to reconstruct past temperature. view more Credit: Photo credit: Werner Aeschbach Woods Hole, Mass. (May 12, 2021) -- Low-to-mid latitude land surfaces at low elevation cooled on average by 5.8 ± 0.6 degrees C during the Last Glacial Maximum (LGM), based on an analysis of noble gases dissolved in groundwater, according to a new study published in Nature. Temperature estimates in the study are substantially lower than indicated by some notable marine and low-elevation terrestrial studies that have relied on various proxies to reconstruct past temperatures during the LGM, a period about 20,000 years ago that represents the most recent extended period of globally stable climate that was substantially cooler than present.