Since the 1940s, farming on the southern Great Plains of the USA—Colorado, Kansas, Oklahoma and Texas—has relied on irrigation.
On the high plains of Texas, tens of thousands of wells pumping from the 10-million-year-old Ogallala Aquifer have reduced the water content by 50 percent.
Most of the remaining underground water source will probably be useless within about 30 years.
Katharine Hayhoe, professor and director of the Climate Science Center at Texas Tech University in Lubbock, says big changes are on the way for agriculture on the Great Plains.
"We're seeing major shifts in places and times we can plant, the types of crops we can grow and the pests and diseases we're dealing with.
"If you talk to seed companies, the U.S. Department of Agriculture (USDA) and even farmers, they tell you we can modify our way out of this, that we can overcome all these problems with technology.
"There's no question we can adapt to some of the change, but whether we can adapt to all of it is a very open question."