Reasons why droughts occur

Causes of droughts There are three main types of drought: Meteorological drought - when the amount of precipitation received in a specific area is less than the average. Hydrological drought - when reduced precipitation impacts on water supply, eg there is decreased streamflow, soil moisture, reservoir and lake levels, and groundwater.

Agricultural drought - when the above two types of drought impact on agricultural activities, eg reduced soil moisture or reservoir levels required for irrigation. Droughts can also be caused by human activities, for example: Agriculture - using large amounts of water to irrigate crops removes water from lakes, rivers and groundwater.

Some crops require more water than others, eg cotton. A drought can carry various implications depending on its geography. Some effects of drought include:. The climate crisis is a major driver of extreme weather conditions including drought.

Excess heat associated with climate change will increase dry climates' susceptibility to drought conditions and the severity of their effects. Droughts threaten the lives of millions of children around with world. Today, almost million children are exposed to severe and prolonged droughts. By , it is estimated that one in four children will be living in areas with extreme water shortages. Access to clean drinking water is essential for all life, and sources of water may dwindle during a drought.

Without the presence of water, people must bring in enough water from elsewhere to survive. Water is also needed for crops to grow. When not enough precipitation falls to naturally water crops, they must be watered by irrigation.

Irrigation is possible only when there is enough water in nearby rivers, lakes, or streams, or from groundwater. During a drought, these water sources are diminished and may even dry up, preventing crops from being irrigated and causing them to die off. She started Blue Legacy to raise awareness that we live on a water planet and must take care of it. Cousteau, the granddaughter of the famed ocean explorer Jacques Cousteau, believes that water will be a crucial issue in this century.

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They will best know the preferred format. Soil moisture can impact cloud formation, and hence precipitation. When water from wet soil evaporates, it contributes to the formation of rain clouds, which return the water back to the earth.

When land is drier than usual, moisture still evaporates into the atmosphere, but not at a volume adequate to form rain clouds. The land effectively bakes, removing additional moisture and further exacerbating dry conditions.

While drought occurs naturally, human activity—from water use to greenhouse gas emissions—is having a growing impact on their likelihood and intensity. Climate change—and global warming , specifically—impacts drought in two basic ways : Rising temperatures generally make wet regions wetter and dry regions drier.

For wetter regions, warm air absorbs more water, leading to larger rain events. But in more arid regions, warmer temperatures mean water evaporates more quickly. In addition, climate change alters large-scale atmospheric circulation patterns, which can shift storm tracks off their typical paths. This, in turn, can magnify weather extremes, which is one reason why climate models predict the already parched U. Southwest and the Mediterranean will continue to get drier. Drought often reflects an imbalance in water supply and demand.

Regional population booms and intensive agricultural water use can put a strain on water resources, even tipping the scale enough to make the threat of drought a reality. One study estimates that from to , the human consumption of water increased the frequency of drought in North America by 25 percent.

Meanwhile, demand for water supplied by upstream lakes and rivers, particularly in the form of irrigation and hydroelectric dams, can lead to the diminishing or drying out of downstream water sources, which may contribute to drought in other regions. When trees and plants release moisture into the atmosphere, clouds form and return the moisture to the ground as rain. When forests and vegetation disappear, less water is available to feed the water cycle, making entire regions more vulnerable to drought.

As a result, soil dries out faster which can induce agricultural drought , and less groundwater is replenished which can contribute to hydrological drought. Indeed, experts believe the s Dust Bowl was caused in large part by poor agricultural practices combined with the cooling of the Pacific and the warming of the Atlantic by as little as a few tenths of a degree. The Intergovernmental Panel on Climate Change IPCC did not see a global trend toward increasing dryness or drought across the world in , when it released its most recent assessment.

But global temperatures have unequivocally become hotter, and hotter conditions precipitate extreme weather —including severe drought. Hotter conditions also reduce snowpack, which provides a key source of water supply and natural water storage in many regions. Regionally, the driest parts of the earth are getting drier, while the wettest parts are getting wetter.

Looking forward, as temperatures continue to rise, the IPCC and other researchers anticipate an intensification of those regional trends. But by limiting our climate change contributions, reducing water waste, and using water more efficiently, we can prepare for —and maybe even curb—future dry spells.