Prediction of Ice‐Free Conditions for a Perennially Ice‐Covered Antarctic Lake

Abstract

Although perennially ice‐covered Antarctic lakes have experienced variable ice thicknesses over the past several decades, future ice thickness trends and associated aquatic biological responses under projected global warming remain unknown. Heat stored in the water column in chemically stratified Antarctic lakes that have middepth temperature maxima can significantly influence the ice thickness trends via upward heat flux to the ice/water interface. We modeled the ice thickness of the west lobe of Lake Bonney, Antarctica, based on possible future climate scenarios utilizing a 1D thermodynamic model that accounts for surface radiative fluxes as well as the heat flux associated with the temperature evolution of the water column. Model results predict that the ice cover of Lake Bonney will shift from perennial to seasonal within one to four decades, a change that will drastically influence ecosystem processes within the lake.

The littoral zone of polar lakes: inshore–offshore contrasts in an ice-covered High Arctic lake

“…Ice has a low thermal conductivity, limits heat loss in the atmosphere and allows solar heating of the water column to temperatures well above those of the overlying air: Ward Hunt Lake had under-ice water temperatures up to 7°C, yet air temperatures averaged around 1.7°C in July (Bégin et al 2020). This greenhouse effect has been modelled in other ice-covered lakes of the Arctic (Vincent et al 2008) and Antarctica (Obryk et al 2019).…”

Characteristics, Main Impacts, and Stewardship of Natural and Artificial Freshwater Environments: Consequences for Biodiversity Conservation

“…The north-south gradient is accompanied by reducing precipitation, resulting in an increasing dependence on melting of glacial ice to provide meltwater, and a declining temperature, which reduces duration of free-flowing water, from several months in the northern parts to only a few days per year at 80 • S. Increasing aridity at higher latitude also results in a high proportion of endorheic lakes and ponds, within which salinization becomes prevalent. Lakes ( Figure 1X) and ponds in the colder inland parts of the continent can be covered with many meters of perennial ice [446], while those at lower latitudes may receive sufficient summer heat to often become seasonally ice-free [447].…”

“…Threats to the unique biodiversity of Antarctica come primarily through changing climate. Warming is anticipated to fundamentally change some freshwater systems, for example, through the loss of ice cover [446], or enhanced connectivity through increased water flow [460]. Evidence of warming is already found in the Antarctic Peninsula lakes [447], and in continental Antarctica, increased meltwater generation is resulting in dramatic rises in the levels of endorheic lakes with clear examples where unique microbial communities have been lost [461].…”

Modeling present and future ice covers in two Antarctic lakes

“…Recently, Obryk and others (2019) studied the ice thickness evolution of WLB using climate scenarios based on historical extremes of locally observed solar radiation, surface air temperature, relative humidity and wind speed froma 16-year meteorological record (1996–2012). Whereas we relied on General Circulation Model (GCM) projections for our future climate scenarios, Obryk and others (2019) selected the years that exhibited the maximum and minimum values of each meteorological variable (based on the annual mean), and then built future scenarios with different combinations of those years. Obryk and others (2019) found that the ice cover of WLB vanished between ~2025 and ~2055 when scenarios with maximum values of solar radiation, i.e.…”

“…Whereas we relied on General Circulation Model (GCM) projections for our future climate scenarios, Obryk and others (2019) selected the years that exhibited the maximum and minimum values of each meteorological variable (based on the annual mean), and then built future scenarios with different combinations of those years. Obryk and others (2019) found that the ice cover of WLB vanished between ~2025 and ~2055 when scenarios with maximum values of solar radiation, i.e. those observed during the ‘flood year’, were simulated.…”