30 - 干旱
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A drought is a period of abnormal water shortage. A meteorological drought is when there is a drop in rainfall, and an agricultural drought is when soil moisture drops abnormally, affecting crop production. A mega-drought is a persistent and widespread drought that lasts much longer than normal (usually a decade or more). Lack of rainfall and evaporation from the ground are the causes of droughts, as well as soil erosion.
1Cause
3Consequences
See card n26: "If the soil is dried by drought it's worse because the water runs off."
2Other possible causes
Heatwaves can cause droughts. They often go together.
Deforestation can be the direct cause of droughts because trees stock a lot of water. If they are cut down, they no longer play their part as humidity regulators.
1Other possible consequence
If a lack of rain occurs while plants are growing, there is less photosynthesis and therefore a reduction in capacity of the carbon sink. In Europe, in 2018, carbon sinks declined by 18%.