Drought in America: Slow moving, far reaching
Droughts differ from most other natural hazards because of their gradual onset and accumulation of impacts over months, seasons, and even years.
Drought is a deficiency in precipitation over an extended period, usually a season or more, resulting in a water shortage causing adverse impacts on vegetation, animals, and/or people. Drought is different from aridity, which is a permanent feature of climate in regions where low precipitation is the norm, as in a desert.
A lack of essential rains can devastate crops, pastures, and ecosystems while severe heat waves that often accompany summer droughts can increase demands for energy and water resources, heighten wildfire risks, and contribute to a wide range of human health impacts. Drought ranks as the second most common type of billion-dollar weather disaster over the past three decades, surpassed only by tropical storms/hurricanes.
In addition to the toll it places on the economy, drought also affects the environment and society. Plants, animals and fish depend on water, just as people do. Drought can shrink their food supplies and damage their habitats. Sometimes this damage is only temporary, and other times it is irreversible.
Drought can also affect people’s health and safety. Examples of drought impacts on society include crop or farmed animal loss, anxiety or depression about economic losses, conflicts among individuals, communities or even countries when there is not enough water, reduced incomes, fewer recreational activities, higher incidence of heat stroke, and even loss of human life.
Scientists study droughts in an effort to identify trends and patterns, as well as natural drivers and human influences.
Unlike hurricanes, which have a clear beginning and end, drought is a complex phenomenon which is difficult to monitor and define. It is a creeping phenomenon that slowly sneaks up and impacts many sectors of the economy, and operates on many different time scales. As a result, the science community has defined four types of drought: meteorological, hydrological, agricultural, and socioeconomic.
Meteorological drought happens when subnormal precipitation dominates an area. Hydrological drought occurs when low water supply becomes evident, especially in streams, reservoirs, and groundwater levels, usually after many months of meteorological drought. Agricultural drought happens when crops and farm animals become affected. And socioeconomic drought occurs when drought affects the supply and demand of various commodities.
Drought frequency varies considerably from year-to-year, over decades and longer. While there is little evidence for any systematic trend toward either more or fewer droughts in the U.S. over the past century, climatologists are actively researching the role of rising heat-trapping greenhouse gas emissions from human activities. Scientists do know, however, that humans can make drought worse through urbanization, food and energy production, and inefficient water usage.
El Niños and La Niñas, naturally-occurring climate cycles that occur every two to seven years, also play a role. When sea surface temperatures in the equatorial Pacific become abnormally warmer (El Niño) or cooler (La Niña), they can bring increased or decreased rains and snows in wintertime to many parts of the U.S. Too much water, however, can be problematic; dry conditions can harden soil, making it difficult for rainwater and snowmelt to be absorbed, which can result in destructive flash floods and mudslides.
A drought’s impacts on the nation's water supply can be extreme and widespread, and include reduced snowpacks, low river flows, and decreased reservoir levels.
During times of drought, limited water supplies pose challenges for water managers tasked with balancing the needs of ranchers and farmers with bustling urban centers. It also requires fish and wildlife managers, including NOAA's Fisheries Service, to refocus protections for vulnerable fish species and their habitats.
Providing businesses and communities with the information they need to deal with drought requires federal, state, and local partners to work together in a coordinated manner. NOAA’s expertise in weather forecasting, climate monitoring, and coastal and marine ecology, allow state and federal managers to make well-informed decisions using the latest observations of river levels and mountain snowpack gathered by satellites, radar, on-land, and offshore systems.
It seems intuitive that fish need water to survive, but during drought years where water is harder and harder to come by, providing sufficient and cool water flows can be exceptionally difficult. Working through such laws as the Endangered Species Act, our fisheries managers work with partners to ensure water actions and policies avoid harming listed species and safeguard their habitats.
Drought can substantially increase a community's risk for dangerous and intense wildfires, which affect the economy, the environment, and society in many ways by destroying neighborhoods, crops, and habitats.
As plants and trees deteriorate and gradually die from a lack of adequate precipitation, insect infestations and diseases increase — both of which are associated with drought — providing additional fuel for wildfires. Since 1914, NOAA meteorologists have supported fire managers, firefighters, and state and local organizations in their efforts to suppress fires. When a major situation occurs, a specially-trained NOAA meteorologist is dispatched to a fire location to provide tailored forecasts and data for a specific fire.
Communities in drought must also be prepared for flash flooding, which seems counterintuitive but is a necessary precaution. Hard, packed soil combined with vegetation loss and burn scars on the earth can cause extensive runoff because rainwater and snowmelt cannot be absorbed into the ground. The runoff can turn into destructive flash floods and mud slides, making it vitally important that people in drought are prepared for any and all types of weather.
The Federal Emergency Management Agency (FEMA) urges people to consider getting flood insurance to protect you and your family from one of the most common and costly disasters not covered by standard homeowner insurance policies. You cannot get flood insurance at the last minute; it usually takes about 30 days to take effect. Visit FEMA’s FloodSmart.gov to learn more about flood risk and explore coverage options.
Communities and individuals that are informed, ready, and willing to make smart decisions before, during, and after a drought will rebound more quickly and recover more fully.
As a result of a drought, government agencies at all levels as well as private sector companies can be forced to make unprecedented and sometimes controversial decisions concerning releases of water, distribution of disaster funding, and rules for household water usage. This is why state and local officials, industry leaders, and federal and academic researchers turn to NOAA for the timely, accurate information they need in times of drought. Our diverse teams of meteorologists, climatologists, hydrologists, coastal habitat planners, fisheries managers, and others provide the data and tools they need to plan for and respond to any and all categories of drought.
The U.S. Drought Monitor is the nation’s leading resource for helping communities understand if they are in drought, and if so, at what level of severity. Every Thursday morning, an updated U.S. Drought Monitor map with narrative shows which parts of the Nation are in drought. The map uses five classifications: abnormally dry (D0), showing areas that are going into or coming out of drought, and four levels of drought: moderate (D1), severe (D2), extreme (D3), and exceptional (D4).
Drought response efforts, planning, and water law vary from state to state. No single federal agency is in charge of water or drought policy; response and mitigation fall to an assortment of federal authorities. For instance, NOAA leads weather monitoring; the U.S. Department of Agriculture mounts response efforts; agencies like the U.S. Geological Survey and NASA contribute data; and the Environmental Protection Agency regulates water quality. The National Drought Resilience Partnership, launched in the aftermath of widespread national drought in 2012, is an effort to unify federal drought response and policy.
To learn more about drought, its impacts, and if your area is affected, visit the U.S. Drought Portal: www.drought.gov.