Climate change is accelerating the rate at which droughts occur. Said to be the second-most costly weather event on the planet just after hurricanes, droughts have changed the trajectory of human life for millennia.
Droughts are usually described by scientists as a prolonged period when a region experiences a below-average level of precipitation in the form of rain, snow, or sleet. They occur naturally and are known for reducing the amount of water and moisture in the environment. Crop damage and chronic water shortages are two of the most common effects of drought.
In this article, we look at the 10 facts about droughts that everyone needs to know.
Key takeaways:
Droughts are very costly natural disasters. In the U.S., they can cause nearly $9 billion in losses per year to businesses and local governments.
Scientists have found evidence suggesting that the Ancient Egyptian and Mayan empires collapsed because of drought-induced social disorder.
Drought can be managed using natural land management tools such as “Zai” pots. They can also be prevented if we recycled more of our wastewater and repaired aging pipelines.
1. It’s difficult to know when a drought has started or ended
Droughts gradually build up over a long time that it’s difficult to determine when a drought starts. It can take weeks, months, or even years for people to collect and analyze enough rainfall data to start noticing the abnormally low levels of moisture.
By the time everyone agrees that a drought is occurring, the amount of moisture in the soils has already probably decreased to the point that crops have begun to die. For those living in non-agricultural areas, it could take even longer to notice the effects of drought. Water levels in wells and reservoirs may take up to two years to reflect the shortage of rainfall.
Studies done by the Environmental Protection Agency suggest that at least one region of North America is experiencing drought conditions at any given time. And because it’s difficult to determine when enough rainfall will return to bring moisture levels back to normal, the end of a drought is also difficult to predict.
2. There are 4 different types of drought
The word ‘drought’ may sound like a blanket term used to describe any region with an abnormal absence of water. But there are four distinct types of drought that climatologists use to explain the impact of this phenomenon on different sectors of the economy.
The first and most commonly known type of drought is meteorological drought which occurs when a region does not receive its expected amount of rainfall for too long. When this continues to the point that crops and livestock start to die, it becomes considered an agricultural drought.
Hydrological drought occurs when a sustained period of meteorological drought causes the depletion of surface water in streams, reservoirs, and rivers. The combined effects of all drought on human society are then referred to as socioeconomic drought, which is characterized by a sharp drop in the supply of an economic good such as tap water.
3. Droughts are very costly natural disasters
Droughts may not produce the visually shocking destruction of other natural disasters, but that doesn’t mean that it doesn’t do a lot of economic damage.
Economists estimate that drought causes nearly $9 billion in losses per year for the United States in the form of crop failures, water-related interventions to save livestock, and disruptions to everyday commerce.
For example, the 1988 US drought caused more than $40 billion in losses, more than the combined losses of the 1993 Mississippi River floods, the 1989 San Francisco earthquake, and Hurricane Andrew in 1992.
4. Early modern humans may have left Africa because of megadroughts
The destructive nature of droughts can be traced as far back as the great human migration out of Africa. Scientists working on sediments from Lake Malawi, an ancient lake in East Africa, have found evidence of a drought that occurred between 135,000 and 75,000 years ago in the region.
The drought is believed to have caused a massive famine that forced our ancestors to migrate to Europe and Asia. It’s the latest piece of scientific evidence that has been used to support the hypothesis that homo sapiens originated from Africa.
5. Droughts caused the collapse of the Ancient Egyptian and Mayan Empires
It wasn’t just migrations that were caused by droughts; they also led to the collapse of powerful ancient civilizations in South America and North Africa.
Using sophisticated radiocarbon dating techniques and pollen-sampling methods, archaeologists investigating the royal tombs of Egypt’s ancient pharaohs have found evidence of a series of severe droughts that occurred over 150 years some 4,000 years ago. The lack of food caused the fall of Egypt’s Old Kingdom, whose territory later became a part of the Roman Empire in 30 BCE.
The Mayans suffered a similar fate around 700 CE when they were hit by drought just as they were experiencing rapid population growth. Annual rainfall suddenly dropped by half, which led to crop failures and wars with neighboring empires for scarce water resources. Unable to recover from the devastating impacts of the drought, the Mayan empire collapsed soon after.
6. El Niño and La Niña increase the frequency and intensity of droughts
Thanks to better scientific research methods and tools today, we’re able to determine that the El Niño and La Niña climate patterns influence the location, frequency, and intensity of droughts.
During El Niño events, intense droughts become more likely to occur in Australia, India, Brazil, parts of east and south Africa, and the southwestern United States. The droughts may begin in any season with varying degrees of intensity.
Droughts tend to happen during El Niño events because warm air and dry winds from the Pacific Ocean sweep into almost all the continents except Europe and Antarctica. The hot air creates dry weather conditions that cause surface water and soil moisture to evaporate, leaving the earth increasingly parched.
7. Today’s droughts have serious socioeconomic consequences
Although droughts may seem like a rural occurrence, they can have far-reaching impacts on all communities.
A long drought can disrupt a nation’s food supply chain. Without enough water and rainfall, farmers lose their harvests and livelihoods. This has a knock-on effect further up the supply chain, where a drop in produce and meat supplies can lead to high food prices, leaving the most vulnerable at risk of food insecurity.
But it’s not just the agricultural sector that can get affected. Energy companies, especially those relying on hydropower, may be unable to meet consumer demand. As a result, people may have to rely more on coal and other fossil fuels as a temporary measure.
Drought may also cause dried-up lakes, reservoirs, and rivers. Without enough water to bathe and clean, people may get sick. They may also inhale dust and other particulate matter that can give them respiratory problems.
8. Thankfully, droughts can be managed with careful land management techniques
Humans have experienced droughts for so long that we’ve developed strategies to manage them.
In West Africa, an ancient agricultural technique using “Zai”, which are dug-out pits filled with water and nutrients, has protected crops against droughts. The “Zai” pits capture rainfall and runoff underneath the surface of the soil and replenish moisture in the soil, giving it back its fertility.
And in Japan and India, desertified farmlands have been restored through the use of intercropping, permanent ground cover, and organic fertilizers. Additional trees are also planted to increase the storage of moisture in the soil and the amount of transpiration on the farmland to promote the water cycle.
9. Trees can help fight drought
Trees are a key weapon in the fight against drought. As they extend their roots underneath the soil, they help break up the dry and compacted soil, creating tiny pockets of air between soil particles. Any rain that falls on this soil seeps deep into the ground and gets retained in the air pockets, helping to make the soil moist again.
Trees also help collect mist on their leaves, which accumulate into droplets that drip to the ground. Known as cloud-water interception, these droplets help add to groundwater and reduce the risk of drought-induced wildfires.
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10. Improving water conservation and efficiency in our cities can also help us fight drought
Drought can also be fought by making changes to the way we use water in our cities and towns. It’s estimated that the United States loses 2.1 trillion gallons of drinkable water each year as a result of aging infrastructure, such as crumbling pipes and leaky storage containers.
Upgrading this water infrastructure can help us conserve water and become less dependent on the environment. Installing water recycling systems can also help us put wastewater back into local circulation instead of emptying it into our oceans and rivers.