Global lake response to the recent warming hiatus

Understanding temporal variability in lake warming rates over decadal scales is important for understanding observed change in aquatic systems. We analyzed a global dataset of lake surface water temperature observations (1985-2009) to examine how lake temperatures responded to a recent global air temperature warming hiatus (1998-2012). Prior to the hiatus (1985-1998), surface water temperatures significantly increased at an average rate of 0.532 degrees C decade(-1) (+/- 0.214). In contrast, water temperatures did not change significantly during the hiatus (average rate -0.087 degrees C decade-1 +/- 0.223). Overall, 83% of lakes in our dataset (129 of 155) had faster warming rates during the pre-hiatus period than during the hiatus period. These results demonstrate that lakes have exhibited decadal-scale variability in warming rates coherent with global air temperatures and represent an independent line of evidence for the recent warming hiatus. Our analyses provide evidence that lakes are sentinels of broader climatological processes and indicate that warming rates based on datasets where a large proportion of observations were collected during the hiatus period may underestimate longer-term trends.