A drought is a prolonged period of abnormally low rainfall that leads to a significant shortage of water. This natural phenomenon, a recurring feature in many climates globally, develops slowly over weeks, months, or even years, making its onset subtle and its impacts far-reaching. Droughts cause widespread damage across various sectors, affecting both the environment and human societies in profound ways.
Damage to Water Supplies
Droughts significantly diminish available water resources, leading to reductions in surface and groundwater levels. Reservoir levels often decrease, and rivers and lakes experience reduced flow or even dry up entirely. For instance, low water levels in Lakes Mead and Powell, major reservoirs on the Colorado River, triggered widespread water-use restrictions across the southwestern United States during a severe drought from 2000 to 2021. Groundwater reserves also become depleted as demand for water, especially for irrigation, increases during dry periods, with some regions experiencing significant declines. This depletion can make it harder for communities to access drinking water, sometimes necessitating water rationing.
Reduced water levels can also compromise water quality, as pollutants become more concentrated. Increased water temperatures reduce dissolved oxygen levels, which can harm aquatic life. Salinity can also increase, particularly in coastal aquifers, as saltwater intrudes into freshwater sources due to over-pumping. These changes make water treatment more challenging and costly, straining water supply systems.
Damage to Food Production
The agricultural sector is particularly susceptible to the effects of drought. A lack of sufficient rainfall and soil moisture can lead to widespread crop failure. This results in reduced yields for essential agricultural products, impacting both local and global food supplies. For example, some studies indicate that in the driest seasons, crop losses can range from 5% to 22%.
Drought conditions also severely affect livestock, as pastures dry up and the availability of feed and water diminishes. Ranchers may be forced to reduce their herds or facing higher mortality rates among their livestock. This can lead to decreased production of meat and dairy. The U.S. experienced an 80% year-on-year price increase in costs for vegetables by November 2022 after California and Arizona experienced an extreme drought, highlighting the immediate economic consequences.
The consequences of drought extend throughout the entire food supply chain. For instance, droughts in West Africa led to cocoa shortages and high prices in 2024. Reduced agricultural output, livestock losses, and supply chain disruptions can contribute to food insecurity and economic instability in affected regions and beyond.
Damage to Natural Ecosystems
Droughts profoundly affect natural ecosystems, altering landscapes and threatening biodiversity. Dry vegetation significantly increases the risk and severity of wildfires. These fires can consume vast areas of land and releasing large amounts of carbon into the atmosphere. For example, a study found that wildfires in Los Angeles were worsened by climate-driven drought, making such conditions 35% more likely.
Ecosystems also experience a decline in biodiversity as plants and animals struggle to survive or are forced to migrate. Aquatic ecosystems are particularly vulnerable, with reduced water levels and increased temperatures leading to fish kills. Stagnant water can stress fish, making them more susceptible to disease and predation.
Additionally, dry, exposed land becomes more susceptible to soil erosion, and prolonged drought can contribute to desertification. Forests and other natural habitats face substantial stress, which can make trees more vulnerable to insect attacks and disease. This stress can lead to widespread tree mortality, impacting forest structure and their ability to provide ecosystem services like carbon storage and water regulation.
Damage to Communities and Economies
Droughts impose substantial economic losses across multiple sectors. Industries that rely heavily on water, such as hydropower generation, manufacturing, and mining, face increased production costs or reduced output. Tourism can also suffer, as recreational activities tied to water bodies or natural landscapes become limited.
These economic disruptions can lead to job losses, particularly in agricultural areas and industries directly affected by water scarcity, impacting local economies. Public health concerns also arise during droughts, including respiratory issues from increased dust storms and wildfires. Reduced water availability and compromised water quality can also elevate the risk of water-borne diseases.
Droughts can cause social disruption, including potential migration of populations from severely affected areas and increased competition for dwindling resources. The strain on resources and livelihoods can create societal tensions. Infrastructure can also be affected, as prolonged soil dryness and shrinkage may lead to stress on foundations and other structures. The combined impacts of droughts thus create complex challenges for the stability and well-being of communities.