Droughts are mainly caused by long periods of below‑normal rainfall, made worse by heat, dry soils, and human activities like overuse of water, deforestation, and climate change.

What is a drought?

A drought is a prolonged period when an area does not get enough water to meet environmental, agricultural, and human needs. It usually starts with a lack of rainfall, then spreads through rivers, reservoirs, soils, and ecosystems as everything dries out over time.

Main natural causes of droughts

  • Lack of rainfall (meteorological drought) : When a region receives much less rain than its long‑term average over months or years, the first stage of drought begins. Areas that already have low normal rainfall are especially vulnerable because even small deficits matter.
  • High‑pressure systems and “stuck” weather patterns : Persistent high‑pressure systems suppress cloud formation and rainfall, keeping skies clear and dry. This can block storm systems and make one region dry while others get normal or heavy rain.
  • Air circulation, El Niño and La Niña : Large‑scale ocean–atmosphere patterns shift where rain falls; some regions get wetter, others much drier during these events. Changes in North Pacific and North Atlantic sea surface temperatures have been linked to more persistent droughts in places like North America and the Mediterranean.
  • Dry season in the tropics : In tropical areas, the movement of the Intertropical Convergence Zone creates distinct wet and dry seasons; the dry season naturally raises drought risk as rivers and waterholes shrink.

Hydrological and soil‑related causes

Even after rain stops, deeper water systems control how severe drought becomes.

  • Falling river, lake, and reservoir levels (hydrological drought) : When less rain and snowmelt feed rivers and reservoirs, and evaporation is high, surface water stores drop, leading to water shortages downstream.
  • Depleted groundwater and aquifers : Aquifers refill slowly; years of low recharge plus heavy pumping for cities and farms can produce long‑lasting drought conditions below ground.
  • Low soil moisture (agricultural drought) : Dry soils mean crops and natural vegetation cannot get enough water, even if some rain falls. When soil moisture is low, feedback loops kick in: the land heats up more, the near‑surface air becomes hotter and drier, clouds form less often, and the drought can intensify rapidly.

Human causes and amplifiers

Human actions increasingly determine how bad and how frequent droughts become.

  • Climate change (global warming) : Rising temperatures increase evaporation from land and water, drying soils and stressing plants even where rainfall totals do not change much. Scientific assessments conclude that droughts are now more frequent and more intense in many regions because the atmosphere’s “thirst” has increased as the climate warms.
  • Deforestation and land‑use change : Trees recycle water to the atmosphere; removing forests reduces local humidity and can weaken cloud formation and rainfall, contributing to regional drying. Bare or degraded land also erodes more easily and absorbs less water, so rain runs off instead of soaking in.
  • Intensive agriculture and irrigation : Large‑scale farming can compact soil, reduce its ability to hold water, and increase evaporation. Excessive irrigation and groundwater pumping can drain rivers and aquifers, turning a dry spell into a serious drought because supply can no longer keep up with demand.
  • High water demand from people and industry : Rapid population growth, expanding cities, hydropower dams, and big irrigation schemes can leave too little water for downstream users when rainfall is low. In these cases, drought is partly a supply‑and‑demand problem, not just a weather problem.

How climate change is shaping today’s droughts

Recent research and assessments show that modern droughts are increasingly linked to heat waves and a warming climate.

  • Higher land temperatures increase atmospheric evaporative demand , so soils and plants lose water faster.
  • Heat waves now more often trigger sudden, severe “flash droughts,” where conditions move from normal to extreme dryness within weeks.
  • Without strong climate‑change mitigation, projections suggest that around one‑third of global land areas could face moderate or more severe drought by the end of the century.

Quick HTML table of key causes

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Cause category Specific cause How it leads to drought
Natural climate Prolonged low rainfall, high-pressure systems, El Niño / La Niña Reduces storm formation and shifts where rain falls, creating long dry periods.
Hydrological Low river flow, low reservoir levels, depleted aquifers Cuts available surface and groundwater supplies, especially after multiple dry seasons.
Soil and land Low soil moisture, land degradation, erosion Prevents crops and ecosystems from accessing water and reduces water storage in the landscape.
Human pressures Overuse of water, intensive irrigation, dams Increases demand beyond what nature can supply in dry years, worsening shortages.
Climate change Rising temperatures, more heat waves Boosts evaporation and plant stress, making droughts more frequent and intense.
Deforestation Loss of trees and vegetation Reduces moisture recycling and local rainfall, and speeds runoff instead of infiltration.
Information gathered from public forums or data available on the internet and portrayed here.