Scientists warn of climate 'time bomb' for world's groundwater

Future generations face an environmental "time bomb" as the world's groundwater systems take decades to respond to the present day impact of climate change, scientists warned on Monday.

Found underground in cracks in soil, sand and rock, groundwater is the largest useable source of freshwater on the planet and more than two billion people rely on it to drink or irrigate crops.

It is slowly replenished through rainfall -- a process known as recharge -- and discharges into lakes, rivers or oceans to maintain an overall balance between water in and water out.

Groundwater reserves are already under pressure as the global population explodes and crop production rises in lockstep.

But the extreme weather events such as drought and record rainfall -- both made worse by our heating planet -- could have another long-lasting impact on how quickly reserves replenish, according to a study published in Nature Climate Change.

An international team of researchers used computer modelling of ...