Impossible maps and how to use them​ - From uncertain global models to a new global understanding of groundwater

Groundwater makes up 99% of all non-frozen freshwater on our planet, sustaining ecosystems by providing water to vegetation, to rivers, lakes and wetlands. Groundwater offers a relatively constant supply of freshwater to 43% of the world’s irrigated agriculture and safe drinking water to 3.7 billion people. While surface water supply is increasingly fragile due to climate change, groundwater is assumed to remain a reliable source of freshwater. Thus, groundwater is critical for ecosystem health, food supply and access to clean drinking water – three of Sustainable Development Goals (SDG) of the United Nations. With a rapidly changing climate, increasing population and economic growth, the importance of groundwater will even increase. However, the recent IPCC 6th assessment report concluded that our knowledge of how groundwater will be affected by climate change is still poor. What are the consequences of this lack of knowledge and how can we improve our understanding of groundwater?