The Earth's Freshwater Reserves Are Disappearing

                      you may have heard people call Earth "the water planet." The nickname is well-deserved.

As this mosaic of images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite conveys so well, the majority of Earth's surface is covered by either liquid or frozen water.

The atmosphere is awash with water as well. One satellite-based data set estimates that about 60 percent of Earth's surface is covered by clouds (composed of water and ice droplets) at any given time.


Earth is home to yet another type of water — groundwater — which includes all the fresh water stored underground in soil and porous rock aquifers. Though groundwater is often forgotten because it's not visible, more than two billion people rely on it as their primary water source.

With drought afflicting several parts of the world, and with aggressive use of groundwater in many agricultural regions, this precious water resource is under serious strain, warns NASA Jet Propulsion Laboratory hydrologist James Famiglietti.

In a commentary published by Nature Climate Change in October 2014, Famiglietti wrote:

In many parts of the world, in particular in the dry, mid-latitudes, far more water is used than is available on an annual, renewable basis. Precipitation, snowmelt, and streamflow are no longer enough to supply the multiple, competing demands for society's water needs. Because the gap between supply and demand is routinely bridged with non-renewable groundwater, even more so during drought, groundwater supplies in some major aquifers will be depleted in a matter of decades. The myth of limitless water and the free-for-all mentality that has pervaded groundwater use must now come to an end.