Is water vapor belching from volcanoes gradually increasing the percentage of fresh water to salt water on the Earth?
The total amount of water on the Earth is gradually increasing due to the addition of water vapor from volcanic eruptions. But compared to the amount of water already here, the increase is inconsequential on a human time scale.
Of the Earth’s water, salt water in the oceans comprises the overwhelming majority: 97.21 percent. Fresh-water glaciers and icecaps account for 2.15 percent and ground water adds 0.62 percent. Rivers and fresh-water lakes (like the Great Lakes) contribute only 0.009 percent of the total. Saline lakes and inland seas account for 0.008 percent more. Atmospheric water adds another 0.0001 percent.