Lake surface temperatures in a changing climate: a global sensitivity analysis

Abstract

We estimate the effects of climatic changes, as predicted by six climate models, on lake surface temperatures on a global scale, using the lake surface equilibrium temperature as a proxy. We evaluate interactions between different forcing variables, the sensitivity of lake surface temperatures to these variables, as well as differences between climate zones. Lake surface equilibrium temperatures are predicted to increase by ~70-85% of the increase in air temperatures. On average, air temperature is the main driver for changes in lake surface temperatures, and its effect is reduced by ~10% by changes in other meteorological variables. However, the contribution of these other variables to the variance is ~40% of that of air temperature, and their effects can be important at specific locations. The warming increases the importance of longwave radiation and evaporation for the lake surface heat balance compared to shortwave radiation and convective heat fluxes. We discuss the consequences of our findings for the design and evaluation of different types of studies on climate change effects on lakes.

Sensitivity of lake thermal and mixing dynamics to climate change

“…Changes in average surface water temperatures are closely tied to changes in annual air temperature with similar increases for all baseline climates (Figure S-3). The ratio of change in water temperature to change in air temperature is 77 %, consistent with Schmid et al (2014). In contrast, hypolimnetic temperature responds to a variety of complex interactions influenced by lake archetype characteristics ( Fig.…”

“…Reduced light penetration decreases mixing depth and can cause cooling in deeper water (Hocking and Straškraba 1999), while summer surface water temperatures may increase or decline depending on the entrainment of colder hypolimnetic water (Persson and Jones 2008). Schmid et al (2014) evaluated the sensitivity of lake surface temperatures to climate change and predicted anomalies in lake surface equilibrium temperature in the range of 2-5°C by the end of the 21st century. They estimated that surface equilibrium temperatures would increase by 70 to 85 % of air temperature changes, with most of the residual between-lake variance attributed to changes in relative humidity and, to a lesser extent, wind speed.…”

Transparency, Geomorphology and Mixing Regime Explain Variability in Trends in Lake Temperature and Stratification across Northeastern North America (1975–2014)

“…In the most extreme results we reviewed, six large lakes in California and Nevada showed surface warming at twice the rate of regional air temperature changes based on satellite imagery (1991-2008; [34]) relative to 50% faster in this study (Table 2). Air temperature trends alone underestimate LSWT in models of lake surface equilibrium temperature (e.g., [19,47] predict LSWT at 70-80% of air temperature warming rates), suggesting that such models may be missing key integrative factors.…”

“…For example, less transparent lakes could have increased rates of surface absorption and outgoing radiation, especially at night [57], which would lead to decreasing surface warming trends, a rare occurrence in NENA lakes. Additionally, sunlight can only warm a fraction of the mixed layer in less transparent lakes [47], which limits light and heat penetration to sub-surface layers. In NENA in particular, additional regional drivers of increasing transparency (acidification and invasive mussels) or decreasing transparency (browning and land use change) could modify patterns in LSWT (see below).…”

Remotely sensed surface temperature variation of an inland saline lake over the central Qinghai–Tibet Plateau

“…These evidences show that MODIS-derived SWT of lakes can reflect climate change variability over the plateau. The slower rising rate of temperature over the lake than that over land is probably associated with the large heat capacity of water, and may also reflect the sensitivity of alpine saltwater lakes to climate changes with different interactions of forcing variables over the lake from that over land (Schmid et al, 2014).…”