Lake George (NY) water temperature increased significantly between 1980 and 2009, leading to a longer aquatic growing season and increased degree-days. Surface water (0-10 m) temperatures increased by 0.063 and 0.051 C/yr, and degree-days increased by 229 and 195 degree-days in the North and South basins, respectively. The aquatic growing season increased by similar to 2 weeks, with extensions in both the spring and fall. The rate of warming, degree-days, and the duration of the growing season were consistently greater in the North Basin, due in part to a greater input of groundwater in the South Basin. Weather variables over the same time period changed significantly with wind speed and cloud cover decreasing, humidity and precipitation increasing, and no significant change identified for air temperature. Wind and cloud cover were correlated to the onset of the growing season and degree-days in both the North and South basins, suggesting they are influencing the lake thermal regime through reduced evaporative cooling in the fall, diminished spring mixing and increased solar radiation absorption. Warmer water temperatures have a myriad of consequences for aquatic ecosystems from increased primary production and shifting species composition to uncoupling of trophic dynamics and increased mineralization of organic carbon. While management practices are available for some of these issues, others have no management protocols, creating a foreseeable problem for lake managers in the future.
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