Global patterns in lake surface temperature trends

Abstract:

Temperature profoundly affects dynamics in the water bodies

on which human societies depend worldwide. Even relatively small water temperature changes

can alter lake thermal structure with implications for water level, nutrient cycling, ecosystem

productivity, and food web dynamics. As air temperature increases with climate change and

human land use transforms watersheds, rising water temperatures have been reported for

individual lakes or regions, but a global synthesis is lacking; such a synthesis is foundational

for understanding the state of freshwater resources. We investigated global patterns in lake

surface water temperatures between 1985 and 2009 using in-situ and satellite data from 236

lakes. We demonstrate that lakes are warming significantly around the globe, at an average rate

of 0.34 °C per decade. The breadth of lakes in this study allowed examination of the diversity

of drivers across global lakes, and highlighted the importance of ice cover in determining the

suite of morphological and climate drivers for lake temperature dynamics. These empirical

results are consistent with modeled predictions of climate change, taking into account the

extent to which water warming can be modulated by local environmental conditions and thus

defy simple correlations with air temperature. The water temperature changes we report have

fundamental importance for thermal structure and ecosystem functioning in global water

resources; recognition of the extent to which lakes are currently in transition should have broad

implications for regional and global models as well as for management.