Gravity Anomaly Map Using GRACE Data

Scientists have predicted that droughts and floods will become more frequent and severe as our planet warms and climate changes, but detecting this on regional and continental scales has proven difficult. Now a new NASA-led study confirms that major droughts and pluvials – periods of excessive precipitation and water storage on land – have indeed been occurring more often.

In a recent study, scientists found that a previously unmeasured source – water percolating through soil and fractured rock below California’s Sierra Nevada mountains – delivers an average of 4 million acre feet (5 cubic kilometers) of water to the state’s Central Valley each year. This underground source accounts for about 10% of all the water that enters this highly productive farmland each year from every source (including river inflows and precipitation).

Researchers have untangled puzzling patterns of sinking and rising land to pin down the underground locations where water is being pumped for irrigation.

Decades of drought across the U.S. Southwest has led some scientists to classify the intense, prolonged dryness as a “megadrought.” But drought in North America took a different shape in 2021, affecting areas that do not face long-term or intense drought as often. The northern Great Plains has been coping with drought for months.

Focusing on the GRACE and GRACE-FO missions, the award cites the “outstanding leadership of the international consortium in the planning and implementation of the successful Earth gravity missions.”

Scientists have gained new insights into the processes that have driven ocean level variations for over a century, helping us prepare for the rising seas of the future.