Climate change

Climate change directly impacts the natural recharge of groundwater, which is replenished by precipitation directly, and via leakage from surface waters.
Antarctic ice melt
Last update:20 April 2023

Global warming triggers the release of freshwater from long-term storage in continental ice sheets and thermal expansion of the oceans; both of which contribute substantially to sea-level rise and enhance the intrusion of saline water into coastal aquifers.

The threat posed by sea level rise to groundwater is considerable for coastal aquifers in large deltas and islands; seawater intrusion is observed to be associated mostly with heavily exploited coastal aquifers, characterized by high population densities (e.g. Jakarta, Indonesia; Gaza, State of Palestine).

Climate change also modifies the distribution of permafrost, altering soil moisture, streamflow seasonality, and the amount of water stored above and below ground.

Groundwater storage ranks among the most effective water management interventions in terms of water storage and climate change adaptation
Heavy rain

One observed and widespread impact influencing the replenishment process is the intensification of precipitation. Fewer but heavier rainfalls is expected to disproportionately enhance groundwater recharge in many environments. Yet, as the planet warms, considerable uncertainty persists in where, when, and how much rain or snow will fall, such that global projections about the effects of climate change on groundwater recharge also remain somewhat uncertain.

Figure: Key interactions between groundwater and climate change showing how direct and indirect impacts of climate change affect groundwater systems

Climate change also presents direct risks to the quality of groundwater. Heavy rainfalls have the potential to amplify recharge and mobilize contaminants from the surface. Recharge from heavy rainfall events in such environments has been associated with outbreaks of diarrhoeal diseases, including cholera.

Reductions in groundwater recharge in the Mediterranean region for example have led to the concentration of contaminants such as chloride, nitrate, and arsenic in shallow aquifers due to enhanced evaporation and less dilution.

The impacts of climate change on groundwater may be greatest through its indirect effects on irrigation water demand, potentially leading to depletion or contamination of groundwater resources, impacting environmental flows.

Adaptations to climate-driven shortages in water supplies driven by climate change involve supply-side strategies that consider groundwater as a climate-resilient source of freshwater, which can be used conjunctively with surface water resources.

Since aquifers are less exposed to evaporative losses, groundwater storage ranks among the most effective water management interventions in terms of water storage and climate change adaptation, whilst avoiding many of the negative environmental and social impacts of water supply infrastructure such as dams.

Including groundwater storage and abstraction as part of urban water supply planning would add security and flexibility in case of seasonal droughts.

Aquifers transmitting and storing groundwater can also contribute to climate change mitigation through the use of geothermal energy and by capturing and by storing CO2