The Short Answer
In 2014, nearly the entire state of California was experiencing extreme drought or worse, exceptional drought. It was very dry. Exactly how bad was the California drought? Scientists found that it was the worst drought in 1,200 years.
The Tuolumne River flows 149 miles westward through the Sierra Nevada foothills before converging with the San Joaquin River in the Central Valley. You can see where the normal water level is by the markings on the bridge pylons. Image credit: U.S. Geological Survey.
A drought in California affects much of the western United States. From 2011 to 2015, there was little rain and snow in much of the region, but that was just part of the problem. These areas also experienced record-high heat, which baked away what little moisture remained in the soil. It was a drought double-whammy.
How Bad Was It?
It was not good. In 2014, nearly the entire state of California was experiencing “extreme drought” or “exceptional drought,” which is a step above extreme. It was dry, dry, dry.
One study from the University of Minnesota and the Woods Hole Oceanographic Institution found it’s the worst drought in 1,200 years. What?!
Credit: The National Drought Mitigation Center
The darker the color, the drier it is. That dark, dark red—that’s really, really bad. Credit: The National Drought Mitigation Center
Wait, How Do You Know About Droughts From So Long Ago?
To get historical data about past dry years, we can use data from the National Oceanic and Atmospheric Administration and a computer climate model called the North American Drought Atlas. We can also look at tree rings from old blue oak trees that are hundreds of years old.
History in the Trees
You may have heard of using tree rings to learn about the past, but what are scientists looking for? There is information in the thickness of each ring. Thick rings indicate a wetter year, allowing the tree to grow faster with abundant water available.
Scientists don’t have to cut down the whole tree to see the rings, either. They can just insert a hollow drill into the trunk and pull out a sliver of the tree to see the rings.
So What Now?
Droughts are really bad, and it’s not like we can control the weather to make it cool down and rain. It all comes down to planning and conservation. California, in particular, has a lot of water needs, as much of the nation’s fruits and vegetables are grown there.
Saving Water Wherever Possible
In a drought, people still want strawberries, tomatoes, and grapes, so the water savings have to come from other areas. People can replace water-wasting grass lawns with drought-tolerant plants, take shorter showers, and fix leaky faucets. Drought affects everyone in these areas and beyond, and getting through droughts will need to involve everyone, too.
How Do We Monitor Droughts?
One way to monitor the drought from space is to measure evapotranspiration. That’s the total amount of water that moves to the atmosphere from Earth’s land and ocean surfaces (evaporation) and plants (transpiration). Yes, plants constantly release water as they undergo their daily cycles.
NOAA’s Geostationary Operational Environmental Satellites carry an instrument called the Advanced Baseline Imager (ABI) that can see Earth in many different colors of light – not just the colors we can see with our eyes, but several in the infrared spectrum as well.
The ABI can track changes in the colors of plants, which is related to how much water those plants are breathing out. The ABI can also measure the amount of heat emitted by Earth using infrared. This way, scientists can link changes in heat to water loss in plants and calculate how much evapotranspiration is happening.
Scientists use data from GOES-R series satellites, along with data from NASA's Landsat Data Continuity Mission, to study land surface temperature and vegetation health and fraction. NOAA also hosts the National Integrated Drought Information System (NIDIS) on Drought.gov, a multi-agency effort that coordinates drought monitoring, forecasting, planning, and information sharing. NOAA has expanded these efforts worldwide with the Global Drought Information System (GDIS) and its Global Drought Monitor.
With this information, scientists hope to identify drought-affected regions more quickly and accurately. However, it will still be up to us to responsibly use water to cope with drought when it occurs.