Rising snowline altitudes across Southern Hemisphere glaciers from 2000 to 2023

Understanding of Southern Hemisphere glacier response to climatic changes is limited by a paucity of direct observations. However, glacier Equilibrium Line Altitudes (ELAs), which are determined by air temperature and precipitation and represent glacier mass balance, can be approximated using remote sensing of end of summer snowline altitudes (SLA_EOS). This study shows that SLA_EOS increased on the majority of 6364 glaciers and by up to 7.18 m yr^-1 between 2000 and 2023 across five Southern Hemisphere mountain regions. Over this period anomalies from the multi-decadal mean SLA_EOS became predominantly positive for all regions. In the most extreme cases, the rate of SLA_EOS rise accelerated by up to x 4.0 in the western Southern Alps of New Zealand when comparing pre- and post-2010 rates of change. Contrastingly, the western Antarctic Peninsula and the western Southern Andes experienced declining SLA_EOS and slowing rates of change at -1.0 and - 8.1 m yr^-1, respectively. These spatio-temporal patterns reveal the interplay of temperature and precipitation, and the effects of them on a wide variety of mountain glaciers and ice cap outlet glaciers, with implications for understanding glacier response times, committed ice losses and overall meltwater production in the coming decades.