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SCIENCE & CLIMATE DEFINITIONS

Drought

Drought is generally defined as a prolonged period of dry weather caused by the lack of precipitation, resulting in a serious water shortage for some activity, population or ecological system. Drought is also thought of as an extended imbalance between precipitation and evaporation.
As average temperatures rise due to climate change, the Earth’s water cycle accelerates through an increased evaporation rate. As an increased evaporation rate makes more water available in the air for precipitation, it also contributes to drier land areas, leaving less moisture in the soil. Thus, as climate change continues, many areas are likely to experience increased precipitation and increased flood risk, while areas located far from storm tracks are likely to experience less precipitation and increased risk of drought. As a result, since the 1950s, global drought has intensified and lasted longer in some regions, particularly in southern Europe and West Africa, while other regions have seen droughts become less frequent, less intense, or shorter (for example, in central North America).

Impacts of Drought

  • Drought conditions negatively impact agriculture, water supplies, energy production and many other aspects of society. The impacts vary depending on the type, location, intensity, and duration of the drought. For example, drought impacts on agriculture can range from slowed plant growth to severe crop losses, while water supply impacts can range from lowered reservoir levels and evaporated streams to major water shortages.
  • Prolonged drought poses a particular threat to indigenous populations whose economic and cultural dependence relies upon land and water supplies. Warming and drought threatens medicinal and culturally important plants and animals and reduces water quality and water availability, making tribal populations particularly vulnerable to waterborne illnesses. Lower streamflow and groundwater levels can also harm plants and animals, and dehydrated vegetation increases the risk of wildfires.

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