How does the worsening of the global warming crisis affect the lakes? A team of researchers from the University of Montreal and the University of Basel examined how this global problem on climate change affects the behavior and overall condition of lakes. The team found out why the bottom part of the lake remains cold even when the top part of the water has warmed up. In the process, the team has also discovered the consequences that came with the production and emission of greenhouse gases on the lake and the living organisms that thrive in it.
Lakes play a huge role in the cycle of carbon in the atmosphere. They act as a large bioreactors when the temperature of the lake is a key indicator of how much methane and carbon dioxide it emits in the atmosphere. A team of international researchers has examined the interactions between the carbon storage, its sediments left behind in lakes, as well as the greenhouse gases released in the air and they discovered some of its unexpected effects on the water form.
The project did not only focus on the direct effects of global warming, but also the indirect ones. The main focus was to look into how the warming temperature on the surface and the cold temperature in the deepers parts of the lake are affected by the overall conditions in the atmosphere.
"There is no question as to how the fundamentals of thermodynamics came to be and are put in place. There is also no doubt that the respiratory metabolic processes are generally higher in warmer waters," as explained by Professor Moritz Lehmann, professor from the University of Basel in the Department of Environmental Sciences. "However, it is important to note that climate change will not cause all the lakes in the world to warm up."
Lakes all over the world have become warmer on the surface, but their transparency is greatly affected by the presence and growth of algae. "The warming of the surface water as well as the growth of the algae keeping the warming to the surface is causing the water below to be colder than the usual. They have become thermally isolated because the heat from the sun can't compete with the blanket covering of the algae on the surface," said Dr. Maciej Bartosiewicz from the University of Basel in the Department of Environmental Sciences.
"Under particular circumstances, this deprivation of heat could result to the cooling of water masses near the bottom part of the lake." The subtle cooling, however, slows down the respiratory decaying process, which in turn means less carbon dioxide is produced. The model simulations suggest that the effects that were observed were most pertinent in smaller, more shallow lakes.
"All in all, global warming increases the likelihood of lakes to be a potential producer of greenhouse gases. However, this process has less to do with the actual warming of the lake and is more likely because of the increased rate of depletion of oxygen at the bottom of these lakes," as Bartosiewicz concludes.
