Freshwater ecosystems are vulnerable to the effects of global environmental change1. Lakes are sentinels of climate change2 and are an effective indicator of a limnological response to global climate change, as they integrate climatic and landscape factors3. Lake surface temperatures can directly or indirectly influence physical, chemical, and biological processes in a lake, including the temperature of the photosynthetic zone4, water-column stability, lake primary productivity5, fish species range shifts3, and species interactions6.
Climatic factors, including air temperature, cloud cover, and solar radiation, in addition to geomorphometric factors, such as lake surface area and depth, influence surface water temperatures in lakes7,8. Here, we present a database of 25-year (1985–2009) lake surface water temperatures from 291 lakes around the world, collected by either in situ, satellites, or both, and some of the main corresponding climatic and geomorphometric factors that are relevant to lake surface water temperatures.
Between 1986 and 2005, global air temperatures have increased by 0.61 °C (ref. 9). Water temperatures have increased over recent decades coinciding with changing air temperatures, with a few exceptions. Generally, water temperatures tend to coincide with regional air temperatures, warming or cooling at similar rates to that of air temperatures10,11. However, there are some regions, such as around the Great Lakes region of North America and northern Europe, in which bodies of water are warming more rapidly than ambient air11,12.
Solar radiation is a key component of lake heat budgets13. Increases in the amount of incoming solar radiation increase average lake temperatures14. Cloud cover can reduce incident solar radiation, but also result in greater longwave (atmospheric) radiation15. Thus, the influence of cloud cover on lake temperatures can be bidirectional and complex.
Lake-specific properties, including depth, surface area, and volume can mediate the effects of these climate drivers and influence lake temperatures13. For example, surface water temperatures have been found to be inversely correlated with mean depth8,16. In general, shallower lakes tend to warm more rapidly with higher surface water temperatures compared to deep lakes that have greater heat storage capacities8. However, at broad spatial scales, climatic factors have a larger influence on surface water temperatures than lake morphology17.
The motivation to assemble a global database of lake surface water temperatures, climatic forcing variables, and geomorphometric characteristics was to address two key scientific issues by the Global Lake Temperature Collaboration (www.laketemperature.org): i) What are the global and regional patterns of water temperature changes over the past 25 years and are they coherent over spatial and temporal scales?; and ii) Which climatic forcing variables and geomorphometric factors are most important in driving changes in water temperature, i.e., do similar lake types exhibit similar rates of warming or cooling globally? This novel dataset can be used to address additional research questions including those pertaining to understanding the mechanistic drivers of surface water temperature warming and ecological consequences of changes in lake temperatures.
