Because the climate of the Great Plains is arid, water in the aquifer is being used faster than it can be recharged.
That's why some scientists refer to using fossil water aquifers as water mining. Images from the Mars Global Surveyor spacecraft show what looked like gullies carved out by rivers of water on the surface of the planet.
There are different parts of the hydrologic cycle that have an impact the climate.
Some of these parts contribute certain effects of climate change like droughts, melting glaciers, decreasing river flows, and much more (textbook).
Lying below about 175,000 square miles (450,000 square kilometers) of eight states in the Great Plains, the Ogallala Aquifer stores about 2,900 million acre-feet (3,600 million kilometers cubed) of water [source: High Plains/Ogallala Aquifer].
The Ogallala Aquifer was formed between 2 and 6 million years ago, when the Rocky Mountain chain was forming.
Some of this precipitation is captured by tree canopies and evaporates again into the atmosphere.
The precipitation that hits the ground becomes runoff, which can accumulate and freeze into snow caps or glaciers.
It can also infiltrate the ground and accumulate, eventually storing in aquifers.
An aquifer is a large deposit of groundwater that can be extracted and used.