New research by Dr. Scott Jasechko (University of Calgary) and GroFutures Team member, Richard Taylor, published in Environmental Research Letters shows that the intensification of rainfall associated with global warming favours the replenishment of tropical groundwaters.
Global warming amplifies extreme rainfall giving rise to fewer but heavier rainfalls. This impact of climate change is particularly strong in the tropics where, by 2050, most of the people on this planet will live. Richard and Scott
examined chemical signatures in precipitation and groundwater from 15 stations across the tropics in an effort to trace the relationship between rainfall intensity and groundwater replenishment. The chemical signatures comprising ratios of the stable isotopes of oxygen and hydrogen in water molecules, reveal that groundwater recharge derives preferentially from months of intensive rainfall – typically the top 30% – at 14 of the 15 tropical stations.
The pan-tropical bias in groundwater recharge to intensive rainfall identified by this research under an UPGro Catalyst Grant (Groundwater recharge in Africa – identifying critical thresholds) led by GroFutures team member, Alan MacDonald, suggests that groundwater is a climate-resilient source of freshwater in the tropics, enabling groundwater-sourced strategies to adapt to the more variable rainfall and river discharge brought about by climate change.
It is important to note that the results simply indicate a propensity towards increased groundwater recharge associated with the intensification of precipitation in a warming world. Other influences on groundwater storage including excessive pumpage, substantial changes in total precipitation, and land-use change can undermine and overwhelm this resilience of groundwater resources in the tropics to climate change.