page_title: Drought
section_title: Consequences of drought
hierarchical_section_title: Drought / Consequences of drought
caption_attribution_description: Global Drought Total Economic Loss Risk Deciles
context_page_description: A drought is an event of prolonged shortages in the water supply, whether atmospheric, surface water or ground water. A drought can last for months or years, or may be declared after as few as 15 days. It can have a substantial impact on the ecosystem and agriculture of the affected region and harm to the local economy. Annual dry seasons in the tropics significantly increase the chances of a drought developing and subsequent bush fires. Periods of heat can significantly worsen drought conditions by hastening evaporation of water vapour.
  Drought is a recurring feature of the climate in most parts of the world.
  Many plant species, such as those in the family Cactaceae, have drought tolerance adaptations like reduced leaf area and waxy cuticles to enhance their ability to tolerate drought. Some others survive dry periods as buried seeds. Semi-permanent drought produces arid biomes such as deserts and grasslands. Prolonged droughts have caused mass migrations and humanitarian crisis. Most arid ecosystems have inherently low productivity. The most prolonged drought ever in the world in recorded history occurred in the Atacama Desert in Chile.
context_section_description: One can divide the effects of droughts and water shortages into three groups: environmental, economic and social.
  In the case of environmental effects: lower surface and subterranean water-levels, lower flow-levels (with a decrease below the minimum leading to direct danger for amphibian life), increased pollution of surface water, the drying out of wetlands, more and larger fires, higher deflation intensity, loss of biodiversity, worse health of trees and the appearance of pests and dendroid diseases.
  Economic losses include lower agricultural, forests, game and fishing output, higher food-production costs, lower energy-production levels in hydro plants, losses caused by depleted water tourism and transport revenue, problems with water supply for the energy sector and for technological processes in metallurgy, mining, the chemical, paper, wood, foodstuff industries etc., disruption of water supplies for municipal economies.
  Social costs include the negative effect on the health of people directly exposed to this phenomenon (excessive heat waves), possible limitation of water supplies, increased pollution levels, high food-costs, stress caused by failed harvests, etc. This explains why droughts and fresh water shortages operate as a factor which increases the gap between developed and developing countries.
  Effects vary according to vulnerability. For example, subsistence farmers are more likely to migrate during drought because they do not have alternative food-sources. Areas with populations that depend on water sources as a major food-source are more vulnerable to famine.
  Drought can also reduce water quality, because lower water-flows reduce dilution of pollutants and increase contamination of remaining water-sources. Common consequences of drought include:
  Diminished crop growth or yield productions and carrying capacity for livestock
  Dust bowls, themselves a sign of erosion, which further erode the landscape
  Dust storms, when drought hits an area suffering from desertification and erosion
  Famine
  Habitat damage, affecting both terrestrial and aquatic wildlife
  Hunger – drought provides too little water to support food crops.
  Malnutrition, dehydration and related diseases
  Mass migration, resulting in internal displacement and international refugees
  Reduced electricity production due to reduced water-flow through hydroelectric dams
  Shortages of water for industrial users
  Snake migration, which results in snake-bites
  Social unrest
  War over natural resources, including water and food
  Wildfires, such as Australian bushfires, become more common during times of drought and may cause human deaths.
  Exposure and oxidation of acid sulfate soils due to falling surface- and ground-water levels.
  Cyanotoxin accumulation within food chains and water supply (some of which are among the most potent toxins known to science) can cause cancer with low exposure over the long term. High levels of microcystin appeared in San Francisco Bay Area salt-water shellfish and fresh-water supplies throughout the state of California in 2016.
caption: Global drought total economic loss risk
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