The polar regions are among the most sensitive and vulnerable regions on Earth. The long-term interactions between climate, ecosystems, and humans in polar regions are still poorly understood. The research section "Polar Terrestrial Environmental Systems" investigates the past climate, the biodiversity, and vegetation dynamics in the polar regions as well as ice and snow dynamics and the atmospheric coupling. We use isotopes in ice, permafrost and snow and inland ice and paleothermometry, and genetic data from flora and fauna, and pollen from lake sediment and marine sediment cores. The working groups "Earth System Diagnostics" and "Earth System Complexity" conduct research at the global level, focusing on analyzing the entire complex Earth system. Understanding climate and environmental indicators, biodiversity and vegetation dynamics in the high latitudes, from expedition data, data synthesis, as well as data analysis of global interactions, are central research interests of the group. The goal is to achieve a better understanding of continental polar regions and their interactions with the global Earth system.