Unless thirsty aliens come and take it, Earth’s water isn’t going anywhere. It’s just becoming increasingly difficult for thirsty humans to access. But there’s reason to hope we can do a better job of that even as the planet warms.

The bulk of Earth’s water, about 97 percent, is in salty oceans and thus useless for drinking or growing food. Of the 3 percent that is fresh, most is locked in ice sheets and glaciers, many of which are melting rapidly into the oceans thanks to climate change. A relative few drops of fresh water are available in ponds, lakes and rivers, which are easily accessible but also vulnerable to pollution, overuse and drought.

Humanity’s biggest source of fresh water — representing just 0.8 percent of Earth’s total water — is in underground aquifers. Decades of drought, pollution and overuse are shrinking even that precious supply, and rising sea levels threaten to spoil even more of it with saltwater incursions.

A recent survey of groundwater levels at hundreds of wells worldwide found that 71 percent have fallen since the start of the 21st century. Groundwater loss worsened at more than half of the studied wells during that time. But........

© The Korea Times