Scientists have studied data from 16 years of sounding in the largest freshwater lakes on Earth to understand how the climate has affected them.
NASA has funded a study of 11 of the largest freshwater lakes in the world. The analysis was carried out using field and satellite imagery to understand how large bodies of water capture carbon, as well as how they are affected by climate change.
Scientists at the Michigan Technological Research Institute (MTRI) studied five Great Laurentian Lakes bordering the United States and Canada, three African Great Lakes – Tanganyika, Victoria and Malawi, Lake Baikal in Russia and Great Medvezhe and Great Slave Lake in Canada. These 11 lakes contain more than 50% of surface fresh water, which is consumed by millions of people and animals.
Two Canadian lakes and Lake Tanganyika experienced the greatest changes in primary productivity, with algae grown there.
The basis of the food chain in these lakes is algal productivity. We measured the rate of carbon fixation, that is, the rate of photosynthesis of algae in these lakes. As this speed changes, increases or decreases, the entire lake changes.
Gary Fanenstil, MTRI Fellow and Senior Fellow at NOAA’s Great Lakes Environmental Research Laboratory.
These lakes are influenced by many factors. Climate change, increased nutrient levels (eutrophication) and invasive species combine to cause system-wide changes. This makes it difficult to determine the specific causes of changes in large bodies of water.
One of the most notable aspects of the results is how quickly these freshwater lakes have changed — almost 20 years later.
The three largest lakes are showing major transformations due to climate change: they have swamped by 20-25% in just the last 16 years. During this time, the greatest increase in the number of algae was observed in Canadian lakes, as well as on Lake Tanganyika in southeast Africa. These trends are associated with rising water temperatures, solar radiation, and lower wind speeds.