Alpine glaciers leave spectacular records of climate change. Lakes, moraines, and other landforms shaped by past glacier advances and retreats domi nate the foreground of nearly all mountain landscapes. These glacial deposits are rich records of past climate that are widespread, obvious, and easily accessible. In many regions without sedimentary or ice-core records, they are the only record of climate before instrumental records began. A report on page 622 of this issue by Schaefer et al. highlights the value of these glacial records in understanding past climate dynamics while also revealing their complexity.