A review on ice-cores from temperate glaciers: processes, signal preservation, and paleoclimatic significance

Giovanni Baccolo , Anja Eichler, Theo Jenk, Francois Burgay, Margit Schwikowski

Temperate glaciers, characterized by ice at the pressure melting point and the coexistence of solid and liquid water, are generally considered unsuitable as natural archives because meltwater undermines the paleoclimatic signals they hold. Historically, ice-core studies have favoured cold glaciers. However, the ongoing atmospheric warming is driving many formerly cold portions of glaciers toward temperate conditions. As such, the relevance of temperate ice as potential paleoclimate archives is increasing. Assessing its ability to record environmental signals has become a priority for ice core science. This review synthesizes more than seventy years of research on temperate ice-cores, tracing the evolution of scientific approaches from pioneering efforts in the 1950s to recent projects across the globe. The behaviour of ice-core proxies -including soluble and insoluble impurities, water stable isotopes, gases, radionuclides, and organic compounds- is discussed in the context of meltwater-related post-depositional processes. By compiling and comparing evidence from diverse settings, this work highlights both the challenges and the emerging opportunities for retrieving meaningful information from temperate glaciers. Understanding how climatic and chemical signals are modified, preserved, or lost in rapidly transforming glaciers is essential for sustaining the role of ice-core science in a warming world.