precipitation is the most abundant source of fresh water on earth.
precipitation is the most abundant source of fresh water on earth.
what is the most abundant source of fresh water on earth?
precipitation
saline water in oceans, seas and saline groundwater make up about 97% of all the water on earth. only 2.5–2.75% is fresh water, including 1.75–2% frozen in glaciers, ice and snow, 0.5–0.75% as fresh groundwater and soil moisture, and less than 0.01% of it as surface water in lakes, swamps and rivers. freshwater lakes contain about 87% of this fresh surface water, including 29% in the african great lakes, 22% in lake baikal in russia, 21% in the north american great lakes, and 14% in other lakes. swamps have most of the balance with only a small amount in rivers, most notably the amazon river. the atmosphere contains 0.04% water. in areas with no fresh water on the ground surface, fresh water derived from precipitation may, because of its lower density, overlie saline ground water in lenses or layers. most of the world's fresh water is frozen in ice sheets. many areas suffer from lack of distribution of fresh water, such as deserts.
fresh water
species of fish living in cold or cool water can see a reduction in population of up to 50% in the majority of u.s. fresh water streams, according to most climate change models. the increase in metabolic demands due to higher water temperatures, in combination with decreasing amounts of food will be the main contributors to their decline. additionally, many fish species (such as salmon) utilize seasonal water levels of streams as a means of reproducing, typically breeding when water flow is high and migrating to the ocean after spawning. because snowfall is expected to be reduced due to climate change, water runoff is expected to decrease which leads to lower flowing streams, effecting the spawning of millions of salmon. to add to this, rising seas will begin to flood coastal river systems, converting them from fresh water habitats to saline environments where indigenous species will likely perish. in southeast alaska, the sea rises by 3.96 cm/year, redepositing sediment in various river channels and bringing salt water inland. this rise in sea level not only contaminates streams and rivers with saline water, but also the reservoirs they are connected to, where species such as sockeye salmon live. although this species of salmon can survive in both salt and fresh water, the loss of a body of fresh water stops them from reproducing in the spring, as the spawning process requires fresh water. undoubtedly, the loss of fresh water systems of lakes and rivers in alaska will result in the imminent demise of the state's once-abundant population of salmon.
climate change and ecosystems