Flaring up rapidly and with little warning, the drought that gripped much of the United States in the summer of 2012 was one of the most extensive the country had seen since the yearslong Dust Bowl of the 1930s. The “flash drought,” stoked by extreme heat that baked the moisture from soil and plants, led to widespread crop failure and economic losses costing more than $30 billion.
While archetypal droughts may develop over seasons, flash droughts are marked by rapid drying. They can take hold within weeks and are tough to predict. In a recent study, a team led by scientists from NASA’s Jet Propulsion Laboratory in Southern California was able to detect signs of flash droughts up to three months before onset. In the future, such advance notice could aid mitigation efforts.
How did they do it? By following the glow.
A Signal Seen From Space
During photosynthesis, when a plant absorbs sunlight to convert carbon dioxide and water into food, its chlorophyll will “leak” some unused photons. This faint glow is called solar-induced fluorescence, or SIF. The stronger the fluorescence, the more carbon dioxide a plant is taking from the atmosphere to power its growth.