Skip to main content
U.S. flag

An official website of the United States government

October 19, 2015

While prolonged drought with widespread impacts on food and water supplies for people is among the oldest stories in human history, ecological drought has only been recently recognized as an important climate stressor for fish and wildlife species.

Image: Colorado River Runs Dry
The Colorado River runs dry on the U.S./Mexico border 2 miles below the Morelos Dam. Photo Credit: Pete McBride, USGS

While prolonged drought with widespread impacts on food and water supplies for people is among the oldest stories in human history, ecological drought has only been recently recognized as an important climate stressor for fish and wildlife species. Ecological drought is defined by the Science for Nature and People (SNAP) Ecological Drought Working Group as “a prolonged and widespread deficit in naturally available water supplies — including changes in natural and managed hydrology — that create multiple stresses across ecosystems.”

Many communities, ecological and human, are experiencing the negative effects of ecological drought across the United States. From reduced water supplies and decreased streamflow to dry riverbeds and disastrous forest fires, the extent of extremity at which drought can be experienced is broad, and without sufficient research and planning, the effects over time can be alarmingly unpredictable. Every region is susceptible to drought, and widespread, prolonged drought can challenge even the most desert-adapted or drought-resilient plants and animals.

Although drought occurs naturally, the compounding effects of rapid and recent global climate and land use change and fire-promoting, drought-tolerant invasive plant species can exacerbate its harmful impacts on ecosystems and human communities. Consequently, we may no longer be able to depend on historical patterns of temperature and precipitation for planning and decision making as climate change drives the nation into hotter, drier conditions. It is critical to identify areas most at risk. Land managers urgently require new scientific insight that takes into account the compounding effects of drought and climate change on ecosystems and wildlife.

Image: Mule Deer Doe
A female mule deer forages near the Caverns of Sonora in Texas. Climate change and drought are affecting the diet of many wildlife species throughout the United States. Photo Credit: Alex Demas, USGS

The Department of the Interior Climate Science Centers (CSCs) and the U.S. Geological Survey National Climate Change and Wildlife Science Center are studying the effects of drought nationwide to help decision-makers understand this issue. Learn more about some of their projects below.

Wildlife in the Waterless West

Climate and ecological landscapes vary greatly throughout the west, but nearly the entire region has or is currently (in 2015) experiencing severe or extreme drought. Some of the biggest concerns include decreased snowpack, wildland fire and changes in watershed hydrology.

The fourth year of severe drought continues in California. California's 2015 and 2014 “water years” (October through September) were the warmest years on record. 2014 was the third driest year on record. On April 1, 2015, the California Department of Water Resources measured the statewide water content of Sierra snowpack at five percent of average for April 1st. These levels are lower than any year in records going back to 1950. Snowpack, through runoff, provides about one-third of the water used by California's cities and farms.

To address some of these issues across the west, CSC researchers are conducting studies, including those discussed below, to help provide resource managers with the answers they need to make decisions, facilitate adaptation for wildlife and fisheries, and protect the area’s natural and cultural heritage.

Across the Southwest, researchers are undertaking projects that are locally relevant but also valuable to decision-makers everywhere, such as looking at whether or not tree thinning practices are effective at improving forest health and fire resistance. In another study, scientists will use remote sensing data to learn more about wetland habitat location. This information will be used by managers to make important decisions on matters regarding the allocation of limited water resources during drought conditions, which could affect waterbirds that depend on wetland habitats.

This large sinkhole is normally full of water. During the lengthy drought it has been reduced to a small mud hole. Photo Credit:
This large sinkhole is normally full of water. During the lengthy drought it has been reduced to a small mud hole. Photo Credit: Alan Cressler, USGS

In the Northwest, where severe drought can exacerbate dangerous fire conditions, researchers are examining the effects of changing fire frequency on watersheds and the ecosystem services they provide. They are discovering how “unburned islands” can serve as refuges for plants and animals during and after wildfire, and are filling critical knowledge gaps about the effects of projected temperature and precipitation changes on particularly vulnerable areas such as the Great Basin and Columbia Plateau. Scientists are even looking into the possibility of using beavers to help manage and restore wet meadows in eastern Oregon.

Over-Baking America’s Bread Basket

In the central part of the United States, areas such as the Rio Grande River Basin and Missouri River Basin are of particular concern because of the cascading effects of drought. Damage to such important river systems can cause major socio-economic dilemmas, especially in areas where human demand for water could potentially be greater than available supplies. This is the case in the Rio Grande Basin, where studies are being conducted to collect data and review the effectiveness of different water resource models.

In addition, CSC scientists in both the South Central and North Central U.S. are working to gather information on the perceptions of both resource managers and the public to help identify the information needed to support decisions and put science into action. This knowledge will be used to understand ways in which the coordination and management of current water use practices throughout the central U.S. can be improved.

Image: Prescribed Fire at Sunset in the Jemez Mountains, New Mexico
Sunset as seen through the smoke of a prescribed burn in the Jemez Mountains, New Mexico. Photo Credit: Craig Allen, USGS

Ecodrought on the Sly

In some areas of the country, drought can be less obvious and may receive less attention, but nevertheless its impacts are often tremendous. Alaska, the Pacific Islands and the northeastern U.S. all fall into this category, but scientists have identified substantial risks for these relatively under-studied areas. Parts of interior Alaska, for instance, have annual precipitation levels similar to the deserts of the southwestern U.S., yet they also support extensive forests and wetlands. In the recent and distant past, permafrost and snowpack helped maintain these ecosystems by buffering them from shorter-term variations in climate, but warming threatens to alter this buffering capacity. Due to the combination of drought and warming temperatures, for example, Hawai’i’s fire-promoting invasive grasses now make up almost a quarter of its land cover and contribute to the United States’ most severe fire regime in proportion to size. In the Pacific atolls, severe water shortages impact human communities and natural areas on a daily basis. Finally, the northeastern U.S. has adapted to such reliable water regimes (rainfall, snowfall, etc.) that even small changes in water supply could be detrimental to short-rooted trees and sensitive estuary systems, among other ecosystems and species.

To effectively manage the impacts of drought across the country, science, research and the development of practical adaptive management strategies are essential. The CSCs are poised to conduct this research and fulfill the needs of managers, policy makers, tribal leaders and other stakeholders as the nation continues to work to adapt to the challenges of climate change, such as drought.

These projects reflect only a small portion of the work the CSCs are conducting to fulfill their mission to provide useful guidance and scientific information for decision makers and to help human and natural communities adapt to climate change. The CSCs are managed and coordinated by the USGS National Climate Change and Wildlife Science Center (NCCWSC). Please visit our project pages to learn more about our work.

Learn more

California Drought, visualized

Landsat Helps Feed the Birds (NASA feature story, USGS data)

USGS WaterWatch

Get Our News

These items are in the RSS feed format (Really Simple Syndication) based on categories such as topics, locations, and more. You can install and RSS reader browser extension, software, or use a third-party service to receive immediate news updates depending on the feed that you have added. If you click the feed links below, they may look strange because they are simply XML code. An RSS reader can easily read this code and push out a notification to you when something new is posted to our site.