High-latitude lakes act as integrators of climate change, recording shifts in hydrology, permafrost thaw, and ecosystem dynamics across the Arctic landscape. As part of the Toolik Lake Long-Term Ecological Research (LTER) program on Alaska’s North Slope, I contributed to studies of lake limnology and paleolimnology, tracing how nutrient cycling and microbial processes respond to a rapidly warming climate. These lakes not only provide early warning signs of global change on Earth but also serve as analogs for understanding how surface and subsurface waters could archive biosignatures on cold planetary bodies.