Effective Earth stewardship, and preserving and enhancing Earth’s life-support systems requires an understanding of how environmental change, and climate change in particular is influencing both aquatic and terrestrial ecosystems. As the lowest point in the surrounding landscape from which they receive energy and materials, lakes have been touted as effective sentinels of climate change. Lakes exhibit distinct sentinel responses to changes in temperature and precipitation that include physical and chemical changes as well as important biotic consequences. The small size and short generation times of the plankton lead to rapid responses that are ideal tools to assess the biotic consequences of climate change. While numerous examples of the effectiveness of lakes as sentinels of change have been documented, no coherent theoretical framework exists for interpreting these signals or their biotic consequences. In particular, it is not clear which sentinel responses are most effective for separating the effects of the two major components of climate change: temperature and precipitation. This special session will open a discussion on developing a theoretical framework for using lakes as sentinels of climate change and deciphering which sentinel responses are the best (highest signal: noise ratio), as well as assessing the potential biotic consequences of climate change. An opening statement with some ideas and examples of lakes as sentinels of climate change will be followed by a discussion where other investigators are invited to bring their own data, ideas, and join the discussion.