Rising sea levels pose an imminent threat to coastal groundwater resources worldwide

Under the most severe sea level rise predictions, more than 60 million people could lose over five percent of their fresh groundwater resources by 2100. That is what new research from Utrecht University predicts.

Salinisation of groundwater will only be exacerbated with the changing climate.

Dependent on groundwater

Currently, over 1.2 billion people live in coastal regions worldwide. These people often depend on groundwater as their primary source of fresh water. This reliance comes with a price when groundwater salinises because of sea-level rise. “We see this already happening in coastal areas worldwide,” says Daniel Zamrsky, researcher at Utrecht University and lead author of the new study. “Salinisation of groundwater will only be exacerbated with the changing climate.”

Business as usual or best case scenario

The researchers used models to predict salinisation of coastal groundwater in the different climate scenarios proposed by the IPCC. “In the ‘business as usual’ scenario, over 120 million will be affected by 2300. In the best case scenario, eight million people will be affected by 2100 and 16 million by 2300,” Zamrsky says.

Collaborations between fields will be essential.

Strategies for the future

“In order to protect coastal communities against this threat, water management strategies need to be devised.” Those include changes in agricultural production and limiting water demand. “Collaborations between fields will be essential, and groundwater models will play a crucial role in evaluating potential threats to and solutions for groundwater resilience,” Zamrsky concludes.

Publication

Zamrsky, D., Oude Essink, G. H. P., & Bierkens, M. F. P. (2024). Global impact of sea level rise on coastal fresh groundwater resources. Earth's Future, 12, e2023EF003581. https://doi.org/10.1029/2023EF003581