A new study has revealed how climate change might affect the ecosystems of the world’s greatest lakes by exposing how their water layers are mixed together at different levels throughout the seasons. Long-term shifts in temperatures and weather patterns are referred to as climate change. These movements might be due to natural causes, such as oscillations in the solar cycle. However, human activities have been the primary cause of climate change since the 1800s, owing to the combustion of fossil fuels such as coal, oil, and gas.
Natural turbulence in deep water bodies causes mixing, which regulates the transfer of heat, oxygen, nutrients, and contaminants across layers and hence shapes how ecosystems react to external influences. Emissions are continuing to climb. As a result, the Earth has warmed by around 1.1°C since the late 1800s.
Many individuals believe that climate change primarily entails higher temperatures. However, the rise in temperature is merely the beginning of the narrative. Changes in one place can impact changes in all others since the Earth is a system in which everything is interrelated. The energy necessary for mixing is given by wind blowing at the surface, which energizes currents inside the water body in lakes and other inland water bodies where tidal currents are weak.
An international research team employed the 100-square-metre LéXPLORE floating research platform in Lake Geneva to continually assess wind speed, lake current velocities, and temperature in the interior of the water body and near the sediment for a full seasonal cycle for this new study.
Inland freshwater bodies like lakes are an important resource for the communities living around them; they can provide drinking water, food, generate energy, and offer recreational opportunities.
Dr. Fernández Castro
Seasonality controls energy channels through variations in wind intensity and distinct layers of density within the water, according to the results, which were published in the journal Nature Communications Earth & Environment.
Mixing is weaker and limited to the core of the water body in the summer due to lesser winds and the stability brought about by heat from the sun, which holds wind energy in the top water layers. Mixing was three times greater during the windier winter season, with the majority of it occurring in the lower boundary layers over the lake sediments.
Dr. Bieito Fernández Castro, a research fellow at the University of Southampton, conducted the study, which began when he was working at the École Polytechnique Fédérale de Lausanne in Switzerland.
Dr. Fernández Castro said: “Inland freshwater bodies like lakes are an important resource for the communities living around them; they can provide drinking water, food, generate energy, and offer recreational opportunities. However, this close interaction also means they face threats from human factors such as climate warming.”
Technical and practical obstacles in monitoring turbulence in the field with appropriate temporal coverage and precision have plagued previous studies on mixing in lakes. As a result, this is the first time such unpredictability has been seen, highlighting the threat that rising global temperatures pose to the natural mixing mechanism.
“This work illustrates the importance of monitoring lake currents and turbulence over long periods of time to understand their response to climate change. Our results show that warmer climates in the winter months could strongly affect the patterns of turbulent mixing, particularly in the lowest layers. This could in turn have a significant effect on a lake’s oxygen levels, resuspension of sediments where particles on the bed are redistributed within the lake’s water layers, and other vital environmental processes,” Dr. Fernández Castro concluded.
Many issues about the variability of this process along the coastlines compared to the open ocean, as well as the reaction of near-surface mixing to severe, episodic wind events, remain unanswered, according to the study.
