According to usgs.gov, a drought is an extended period of drier-than-normal conditions that negatively impact the availability of water.
While there will always be years with below average water supply, as this is part of the natural climate cycles, droughts are becoming more common.
On top of this, they are also lasting longer and becoming more severe. This leads to harsher consequences and conditions that extend over great periods of time.
In this article, we’ll be discussing what causes droughts and why they are becoming more severe.
What Causes Droughts?
The Global Precipitation Measurement, part of NASA, has been monitoring droughts and average rainfall and collecting valuable data on these events for some years now.
The objective of the GPM mission is to better understand Earth’s water and energy resources/cycle, along with improving our ability to forecast extreme weather events.
Much like usgs.gov, the GPM states that droughts are caused by low precipitation over an extended period of time.
It outlines a number of causes of droughts, these include:
- Atmospheric Conditions (like Climate Change)
- Changes In Ocean Temperature
- Changes The The Jet Stream
- Changes The The Local Landscape
It’s worth noting that, depending on your perspective, some or all of the causes listed above can be influenced by human activities on Earth.
However, there are more direct ways droughts can be caused by human activities, we’ll discuss these in more detail further down this article.
We’ll now discuss the different types of droughts and why they are getting more severe.
What Are The Three Main Types Of Drought?
Droughts are categorized into three main types which are dependent on the overall cause of the drought.
This first type of drought is caused by less than average rainfall in a specific area. There are some areas on Earth where droughts are more common.
It’s important to mention that humans have keep records of the amount of precipitation for many years.
This is important because we can determine the average rainfall for a particular area.
Since these records began and up to the present day, we have amassed an incredible amount of precipitation data.
What does this mean?
Well, an area is experiencing a drought when there is abnormally low rainfall over a period of time.
So, for example a desert would not be classified as in a drought unless it was experiencing less than average rainfall for that desert.
A hydrological drought is a direct result of a meteorological drought.
It is defined as a reduction in rainfall having an impact on a water supply, i.e. decreased soil moisture, stream flow, lake/reservoir levels, and groundwater.
An area slips into an agricultural drought when the above two conditions have a direct impact on farming/agricultural activities.
For example, if soil moisture is compromised, this has a negative effect on water levels needed to irrigate crops in a field.
Agricultural drought is by far the most severe of the three, because it has far-reaching consequences that directly affect human life.
Can Human Activities Cause Droughts?
The short answer is yes, human interaction and alteration of the earth has been proven to cause droughts in certain areas.
We mentioned earlier that there are some direct ways humans can cause droughts, these activities include:
Dams are built across rivers to help us produce electricity and store water in a reservoir.
Damming a river can cause a reduction in water flowing downstream and cause a drought below the dam.
Deforestation has massive consequences for the environment.
Not only does it damage natural habitats for local wildlife, but it negatively affects the soils’ ability to retain water.
The removal of a large area of trees reduced the amount of water stored in the soil, so the rain washes off the land as surface run off.
This reduced amount of water in the soil leaves the area vulnerable to desertification and erosion. These two factors can lead to a drought.
Agriculture can place a huge demand on the amount of water needed to irrigate crops. This process usually calls for water to be taken from lakes and rivers, along with water being siphoned from the ground.
Some crops, like cotton, need a huge amount of water to survive.
Atmospheric changes due to climate change are predicted to have a huge impact on the severity and frequency of droughts.
It is suggested that climate change is causing average temperatures in areas around the world to increase.
This suggests that there will be an increase in evaporation which disrupts the water cycle. This could also lead to less rainfall.
Both of these factors increase the risk of droughts.
Can Droughts Be Caused By Changing Climate Patterns?
We’ve discussed the possibility of man made climate change causing an increase in droughts.
However, a case could be made for natural climate phenomena causing prolonged droughts.
Both El Niño and La Niña have been linked to droughts.
These climate phenomena are described in the following ways:
This climate phenomenon disrupts storm patterns by increasing the surface temperature of the Pacific Ocean along the central South American coast. This is thought to cause droughts in Australia and Indonesia.
La Niña is categorized as the exact opposite of El Niño. It is described as causing a decrease in the surface temperature of the Pacific Ocean along the central South American coast.
This also disrupts storm patterns but makes areas in North and South America prone to droughts.
There are a number of causes of droughts, some of these are as a direct result of human activities.
That being said, it’s important to remember that an area is classified as being in a drought if it is experiencing lower than average rainfall.
This average changes from place to place, as some areas of Earth have naturally lower amounts of rainfall than others.