There must be adequate monitoring along with appropriate conservation actions in order to minimise impacts of climate change on the lake’s biodiversity
A map of Lake Victoria and the countries that border it. Map: iStock Heavy rains, wind storms, and floods threaten the survival and water access of the communities living in the Lake Victoria Basin (LVB), East Africa. A new scientific report published in the journal Nature shows significant precipitation changes and increasing extreme climate events in the near future of the already sensitive region, affecting both its large human populations as well as endemic biodiversity.
One of the largest freshwater lakes and fisheries in the world, LVB’s 40 million inhabitants are strongly affected by extreme weather events such as regular flooding. In late 2019 and early 2020, Lake Victoria’s water levels were observed at an unprecedented high.
The resultant massive flooding in lake-adjacent areas displaced over 200,000 people in Kenya, Uganda and Tanzania. These are three of the five countries that the LVB covers, also including Burundi and Rwanda.
Lake Victoria and its surrounding wetlands and forests have faced extreme pressure and degradation due to rapid population growth, agricultural expansion, urbanisation and industrialisation.
This pressure is only heightened due to LVB’s modified equatorial climate: Warm and humid with long rains from March to May and short rains from October to December.
Most of the recharge into Lake Victoria is from regional rainfall as the lake is fed by 23 rivers. Kagera, the largest of these, runs through Rwanda and Burundi before emptying into the lake. Regional rainfall is what regulates the water levels in the lake.
The report, titled Extreme climatic events to intensify over the Lake Victoria Basin under global warming, presented an analysis of future precipitation patterns over the LVB.
The study computed mean annual and seasonal (March-May, June-August and October-December) precipitation values over the study domain. Findings suggest that significant precipitation changes are likely to occur over the LVB at the sub-seasonal scale rather than seasonal and annual.
It shows an overall increase in mean daily precipitation intensity for all seasons, with more changes during the end of the century period (potential increase by 16 per cent) than the middle of the century period (potential increase by six per cent).
In the 2050s, precipitation over the study domain would increase by about five per cent for mean annual and seasonal relative to the 1985-2014 baseline period.
These changes will significantly impact the region, which already sees water and water resource conflicts. The study recommends use of climate services to minimise the risk posed by the projected changes and ultimately, enhance the socio-economic wellbeing of communities in the LVB.
It also shows high impacts on LVB’s fish and other biodiversity. This is in addition to a previous report by the International Union for Conservation of Nature (IUCN) which warns that 76 per cent of the lake’s endemic biodiversity faces the threat of extinction.
There must be adequate monitoring along with appropriate conservation actions in order to minimise impacts of climate change on the lake’s biodiversity. This presents a challenge as currently limited understanding and climate models are unable to adequately explain weather and climate dynamics over the LVB.
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