Anticipated and Observed Effects of
Climate Change on Freshwater Ecosystems
Human activities within the last century have led to a dramatic rise in atmospheric concentrations
of carbon dioxide and other gases that contribute to the greenhouse effect.
Within the next century, carbon dioxide concentrations are expected to at rise to levels at
least twice as high as those present in pre-industrial times, and global climate is expected
to change in a number of ways as a result. This climate change will primarily affect
freshwater ecosystems through changes in water temperature, quantity, and quality
(Shuter and Meisner, 1992), as well as through changes in the timing and duration of
flows. Some of the expected physical and biological effects of climate change will affect
all freshwater ecosystems, while others are specific to rivers, lake or wetlands.