A fascinating new study from NASA reveals how the amount of freshwater in certain regions changed over the years due to various factors, including human water management and climate change.

A joint mission between NASA and the German Aerospace Center — called the Gravity Recover and Climate Experiment (GRACE) mission — observed from 2002 to 2016 the amount of freshwater available across the globe through the use of satellites, precipitation measures, and other available data. What the mission found was that wetland areas are getting wetter while drylands are getting drier. Some of the changes, both positive and negative, were due to human activity that contributes to climate change.

Areas that saw a large decrease in freshwater were California and Greenland. A severe drought for most of the state began taking its toll on the amount of freshwater available starting in 2011. Due to reduced snow and river flows, there was a heavy reliance on aquifers for watering crops, as well as for human consumption. In Greenland, melting glaciers fall into the ocean, thus reducing the amount of freshwater on the land.

As for areas that saw an increase, the Okavango Delta region in Southern Africa saw the amount of freshwater improve due to increased rainfall. Saudi Arabia’s water storage shrank until the country ended a domestic wheat farming program in 2015, which led to an increase in available water.

So why is this important? Even though the Earth is covered in water, only two to three percent is naturally occurring water, known as freshwater. It comes from water sources such as rivers and lakes but also from snowfields and glaciers. This study showed how significantly the available water can change in a matter of 15 years, and that with action, the situation could be improved.

The original GRACE satellite launched in 2002 and ended its mission in 2017. Its replacement, GRACE Follow-On, will launch on May 22 from Vandenberg Air Force Base in California. It will be carried on a SpaceX Falcon 9 rocket.