In this first worldwide synthesis of in situ and satellite-derived lake data, we find that lakesummer surface water temperatures rose rapidly (global mean = 0.34°C decade1) between 1985 and2009. Our analyses show that surface water warming rates are dependent on combinations of climate andlocal characteristics, rather than just lake location, leading to the counterintuitive result that regionalconsistency in lake warming is the exception, rather than the rule. The most rapidly warming lakes are widelygeographically distributed, and their warming is associated with interactions among different climatic factors—from seasonally ice-covered lakes in areas where temperature and solar radiation are increasing whilecloud cover is diminishing (0.72°C decade1) to ice-free lakes experiencing increases in air temperatureand solar radiation (0.53°C decade1). The pervasive and rapid warming observed here signals the urgentneed to incorporate climate impacts into vulnerability assessments and adaptation efforts for lakes.
