26 - Changes in rainfall patterns

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4
Causes

Changes in rainfall patterns

With increasing air and water temperature, evaporation increases. At higher temperatures, the air can hold more water before precipitating (rain). The rainfall pattern is therefore affected by global warming. There is an increase in extreme rain events.


Changes in rainfall patterns

For water vapor to condense, it needs a “core”. Aerosols can constitute this core, promoting the condensation of water vapor and the formation of raindrops.


Changes in rainfall patterns

“A change in land use through deforestation impacts the regulatory role of trees on humidity. Which impacts the rain regime locally. Even globally for tropical and boreal forests. A large oak tree transpires up to 1600 liters of water per day. European forests sweat about 400 mm per year, about half of the continent's precipitation."


Changes in rainfall patterns

The Amazon contributes to the rain regime via the phenomenon of evapotranspiration from trees. Due to the large surface area of ​​the Amazon, its savannahization could lead to a change in the rain regime locally, or even globally.


3
Consequences

Changes in rainfall patterns

In response to global warming, precipitation is expected to decrease in the Amazon and the dry season to lengthen. This drying contributes to the savannahization of the Amazon (in addition to deforestation).


Changes in rainfall patterns

Fresh water resources depend partly on rainfall. Less rain can therefore lead to less fresh water resources in certain regions.


Changes in rainfall patterns

Disruption of the rain pattern (less rain or more intense rain) can have an impact on agricultural yields.