Experts are investigating how sensitive global groundwater systems are to climate change.

As the climate changes, the storage, replenishment and discharge of groundwater varies substantially.

Groundwater, the largest available store of global freshwater, is relied upon by more than two billion people. It is therefore important to quantify the interactions between groundwater and climate.

However, current understanding of the global-scale sensitivity of groundwater systems to climate change - as well as the resulting variation in feedbacks from groundwater to the climate system - is limited.

Using groundwater model results in combination with hydrologic data sets, an international team has examined the dynamic timescales of groundwater system responses to climate change.

Accounting for changes driven by climate change, they found that naturally water-scarce parts of the world are likely to be more resilient to climate fluctuations than humid areas, but take the longest time to regain equilibrium.

Because of the long time it takes to replenish the water table, they say long timescale planning for water resources should be an essential part of any climate adaptation strategy.

“Adaptation strategies must therefore account for the hydraulic memory of groundwater systems, which can buffer climate change impacts on water resources in many regions, but may also lead to a long, but initially hidden, legacy of anthropogenic and climatic impacts on river flows and groundwater dependent ecosystems,” the study by experts from the University of New South Wales says.