Fig 1.
Lake temperature modeling process.
Schematic of the process used to create models of lake surface temperature and predicted future thermal conditions of southern Rocky Mountain lakes. Input variables are shown in ovals and the model of surface temperature and model output are in rectangles. Thermal metrics include the warmest 30-day running mean of daily mean water temperature (M30AT), the mean annual surface temperature (MAT), the mean summer surface water temperature (MST), and number of ice-free days (IFD). The gray polygon in B indicates upper and lower bounds of the predictions derived from uncertainty analysis (see Materials and Methods).
Fig 2.
Future thermal conditions of southern Rocky Mountain lakes.
Location, relative size, and juxtaposition of each study lake. Maps show portions of the Flat Tops Wilderness (A.) and Rocky Mountain National Park (B.) within the Southern Rocky Mountains. Model predictions of M30AT in the 2080s are shown in color for each of the 27 lakes, and the predicted increase in the number of ice-free days (IFD) over seven decades (circles). The three lakes that are labeled were used to present our uncertainty analysis (see Fig 3).
Table 1.
Trends in thermal conditions for southern Rocky Mountain lakes.
Predicted change in lake surface temperature metrics for 27 southern Rocky Mountain lakes. Metrics were calculated using the lake-specific non-linear models of daily mean lake surface temperature, mean weekly air temperatures form SNOTEL sites, and future mean weekly air temperature predicted from climate models [41]. Rates of change ·decade-1 were calculated by linear regression using annual measures of each metric as a function of year. Upper and lower bounds of these predictions from our uncertainty analysis are shown in parentheses.
Fig 3.
Trends in southern Rocky Mountain lake thermal regimes.
Example plots of thermal change (1988–2085) and the uncertainty analysis for these rates of change in three thermal metrics for three representative lakes. These lakes span the range of relative thermal regimes observed which include cold (Odessa Lake; a-c), cool (Ypsilon Lake; d-f), and warm (Sandbeach Lake; g-i). Thermal metrics presented are the mean annual lake surface temperature (a,d,g), the mean summer lake surface temperature (b,e,h), and number of ice-free days (c,f,i). Green trend lines represent the upper and lower bounds of future thermal trends. These bounds are calculated using the highest and lowest projected mean weekly air temperatures from both climate models combined.