Abstract
Lake Baikal is the oldest, deepest, and most voluminous freshwater lake on Earth. Despite its enormous depth, episodically (almost twice a year) large amounts of surface, cold, and oxygenated water sink until the bottom of the lake due to thermobaric instability, with consequent effects on the ecology of the whole lake. A minimal one-dimensional model is used to investigate how changes in the main external forcing (i.e., wind and lake surface temperature) may affect this deep ventilation mechanism. The effect of climate change is evaluated considering the IPCC RCP8.5 and some idealized scenarios and is quantified by (i) estimating the mean annual downwelling volume and temperature and (ii) analyzing vertical temperature and dissolved oxygen profiles. The results suggest that the strongest impact is produced by alterations of wind forcing, while deep ventilation is resistant to rising lake surface temperature. In fact, the seasons when deep ventilation can occur can be shifted in time by lake warming, but not dramatically modified in their duration. Overall, the results show that Lake Baikal is sensible to climate change, to an extent that the ecosystem and water quality of this unique lacustrine system may undergo profound disturbances.
Highlights
Lake Baikal is the lake of records: it is the oldest (25 million years), deepest, and most voluminous (23′615 km3) freshwater lake on Earth (Fig. 1)
The increase of Tsurf expected in scenario global warming (GW) taken alone or in combination with the wind scenarios (GW-calm wind (CW) and GW-strong wind (SW)) does not have a relevant effect on the vertical water temperature profile, which undergoes only a slight warming compared to the counterparts control scenario, CW and SW
Despite results certainly depend on the choice of the climate change scenario, here we propose a meaningful description of the fundamental response of Lake Baikal to changing external forcing
Summary
Lake Baikal is the lake of records: it is the oldest (25 million years), deepest (max depth 1′ 642 m), and most voluminous (23′615 km3) freshwater lake on Earth (Fig. 1). It contains an outstanding variety of endemic species that adapted to singular conditions (e.g., large depth, several months of ice cover, high water clarity, low nutrient concentrations) during thousands. Owing to its large depth and climatic conditions, it is a fine example of thermobarically stratified lake (e.g., Boehrer and Schultze 2008), whereby thermobaricity is the combined dependence of water density (ρ) on temperature (T) and pressure (P) (e.g., McDougall 1987). In Lake Baikal a weak (10−4–10−5 °C/m) direct stratification, with temperatures warmer than Tρmax and ranging from ~ 3.50 °C to ~ 3.35 °C, is permanently present below ~ 250 m, while the upper layers are either directly stratified (with surface water warmer than Tρmax) or inversely stratified (surface water colder than Tρmax, or ice cover), depending on the season
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
