Global Warming

Climate Change and Groundwater

Climate change may be creating a groundwater "time bomb" as the world's underground water systems catch up to the impacts of global warming.

Researchers for a study published Monday in the journal Nature Climate Change say more than half of the world’s groundwater systems — the largest source of usable freshwater in the world — could take more than 100 years to completely respond to current environmental changes from global warming.

Groundwater is replenished primarily by rainfall through a process known as recharge. Concurrently, water exits or discharges from groundwater sources into lakes, streams and oceans to maintain an overall balance.

When there is a change in recharge due to a lack of rainfall, for example, levels of groundwater drop until balance is restored.

Groundwater systems take a lot longer to respond to climate change than surface water, with only half of the world’s groundwater flows responding fully within ‘human’ timescales of 100 years. This could be described as an environmental time bomb because any climate change impacts on recharge occurring now, will only fully impact the base flow to rivers and wetlands a long time later.