Climatic Hazards

Causes of climate hazards

Changes in atmospheric or oceanic circulation cause climate hazards. They are also caused by significant alterations to ecosystems and also human activities. Nowadays, climate change also plays a significant role in creating climate hazards.

Types of climate hazards

There are four types of climate hazards about which you will learn. They are:

1. Tornadoes
2. Droughts
3. Tropical storms
4. Flooding

Let's examine each of these extreme weather events in more detail.

Tornadoes

Tornadoes are probably the most violent type of storm. They are vertical funnels of rapidly spinning air which extend from a thunderstorm in the sky to the ground. Tornadoes are formed by powerful updraughts and are often associated with hurricanes. They follow a relatively narrow path up to 50 miles/80 km in length. With winds of up to 250 mph/402 km/h, they destroy everything in their way.

Fig. 1 - Tornado in the US

Droughts

Drought hazards are prolonged periods of abnormally low or no rainfall compared to the average rainfall levels in an area. Droughts can last anywhere between a few weeks to years. The figure below shows how severe droughts can be.

Fig. 2 - The severity of the drought in California, US, from 2000-2020

There are three types of droughts:

1. Meteorological drought: The amount of the deficit in rainfall and the length of time over which this deficit occurs.
2. Hydrological drought: The effect of lower rainfall levels on the surface and sub-surface water supplies, such as reservoir and groundwater levels.
3. Agricultural drought: When meteorological and hydrological drought affects agricultural activities due to lower soil moisture levels.

Tropical storms

Tropical storms, also known as typhoons, hurricanes, and cyclones, are areas of significantly low pressure that develop over warm oceanic areas. They form when the air over the warm ocean becomes warm and rises, creating a zone with extremely low pressure. When the rising air reaches very high altitudes, it begins to spin around the low-pressure central area, creating a storm. The central low-pressure area is known as the eye of the storm. To find out more information, read our tropical storms explanation.

Fig. 3 - The eyes of a tropical storm

Flooding

A flood is when excess water covers normally dry land. There are two types of flooding about which you should know:

1. River flooding: occurs when rivers overflow their banks, and the excess water flows onto the land surrounding the river channel. It is caused by increased precipitation in the river's drainage basin.
2. Coastal flooding: occurs when areas of typically dry land along the coast are inundated with seawater. This is a result of tsunamis or higher than average tides. During tropical storms, coastal flooding is caused by storm surges.

Fig. 4 - River flooding in Little Rock, Arkansas, US, in May 2019

Climatic hazards geography

Let's look at the areas in which these climate-related hazards occur.

Tornadoes

Tornadoes are extreme weather events that occur in many parts of the world, including Australia, Europe, Africa, Asia, South America and New Zealand. The United States, Argentina and Bangladesh have the highest annual incidents of tornadoes.

Droughts

While droughts can occur anywhere on earth, the countries with the highest drought risk are Moldova and Ukraine. Other areas with medium to high risk of droughts are the Middle East, North Africa, Asia and other parts of Europe.

Tropical storms

Generally, tropical storms occur between 5-20^o north and south of the equator, where the sea temperatures are above 27^oC. The highest number of tropical storms occur in the North Pacific Ocean.

Fig. 6 - Distribution of tropical storm tracks across the globe

Flooding

Flooding can occur everywhere in the world where there are rivers that could potentially overflow their banks. Flooding can also be prevalent in coastal areas and areas vulnerable to tropical storms.

Climatic hazards problems

Climate hazards can have many adverse effects and problems on the areas they impact. Some effects are highlighted below:

1. Tornadoes: Because tornadoes are so violent, they destroy everything in their path, including buildings and agricultural crops. Tornadoes can lead to loss of life.
2. Droughts: When droughts occur, especially over long periods, they can dry up water supplies. This will eventually lead to reduced agricultural production, which in turn can cause famine and malnutrition in populations. Many people also face both internal and external displacement.
3. Tropical Storms: Much like flooding, tropical storms result in the damage or destruction of property. Tropical storms can also result in the loss of life and, depending on the damage's extent, can lead to a lack of potable water, destruction of crops and food security issues.
4. Flooding: Flooding results in damage or destruction to property. It can also reduce access to potable water and destroy crops. People also die in floods. If floodwaters take an extended time to recede, the standing water can increase the spread of diseases.

Examples of climatic hazards

Let's look at some examples of each of the climatic hazards about which you just learnt.

Tornadoes

The US's largest and most expensive tornado outbreak occurred from 25-28 April 2011. During this period, almost 350 tornadoes developed across various states in the US, from Texas in the south to New York in the north. This outbreak caused an estimated USD $12 billion in damages.

Fig. 7 - Damage in Coaling, Alabama, US, as a result of the April 2011 tornado outbreak

Droughts

Somalia has experienced three major drought crises between 2011 - 2022.

• 2011/2012 - 3.7 million persons experienced crisis-level food insecurity, and 260,000 people died as a result. Many were also displaced and moved to neighbouring countries.
• 2016/2017 - 2.9 million people experienced crisis to emergency-level food insecurity.
• 2021/2022 - 4.6 million people are experiencing crisis- to emergency-level food insecurity. This is Somalia's worst drought in 40 years

Fig. 8 - People displaced by the 2011/2012 drought in Somalia are waiting to be registered at a refugee camp in Ethiopia

Tropical Storms

Hurricane Katrina is the costliest storm in US history. It caused extensive damage across Mississippi and Louisiana in the southern United States. The worst damage occurred in New Orleans, where 80% of the city was left underwater in its wake. Katrina caused over 1800 deaths and USD $160 billion in damages. Read our Hurricane Katrina Case Study explanation to learn more about this storm.

Flooding

In 2007, the UK experienced the Hull floods, where over 9,000 homes and businesses were destroyed. The flood affected 35,000 persons and caused £41 million/ USD $49.5 million in damages. One person also lost his life due to the flood.

Fig. 9 -Flooding in Kingston upon Hull, UK, June 2007