Heat Waves Meaning, Causes, Effects, and Possible Solutions

The duration of heat waves can vary significantly, from as short as two days to as long as several weeks. The importance of heat waves is especially due to the fact that they are responsible for some intense effects on the environment and the human population [5].

In both developing and developed countries, heat waves have been the cause of significant levels of mortality and illness, with other effects on the ecosystem as well.

Heat waves have also recently become even more important. due to their relationship to climate change. It has been predicted that the global increase in the severity and frequency of heat waves since the mid-twentieth-century, is caused mainly by climate change [22].

As we may assume, heat waves are also associated with other serious climatic problems, like drought, low atmospheric humidity, or high atmospheric humidity. These conditions are known to trigger some heat-related health challenges, such as dehydration, heatstroke and heat exhaustion [3].

According to The World Meteorological Organization (WMO), a heatwave is a consecutive period of at least five days, in which there is a rise by at least 5°C above the average normal temperature [24].

By another, similar definition, a heatwave can be referred to as a period of unusual and unfavorable high temperature on the Earth’s surface, which may span at least two or more days.

Based on all the foregoing definitions, we may describe heat waves as prolonged periods of relatively and excessively hot weather conditions, which is often associated with drought, and high or low humidity.

Heatwave Facts

1). A heat wave usually involves a combination of high temperature and high humidity, which occur over a relatively long period of time

2). In America, heat waves are known to cause more deaths than hurricanes, storms, tornadoes and floods

3). A quantity known as the Heat Index Value can be used to evaluate the severity of high temperature conditions. Heat Index Values comprise of temperature and humidity factors

4). The visible effects of extreme hear include swelling, exhaustion, fainting and cramps

5). Most parts of the United States are vulnerable to very high temperature conditions every year

6). Individuals who face the greatest risk of heat-related problems and illnesses include young children and the elderly

7). Between 1999 and 2009, an average of 600-700 deaths due to heat conditions, have occurred yearly in the U.S

8). More than 700 deaths were recorded as a result of a heatwave which occurred in Chicago in 1995

9). The risk of heat waves and extreme heat conditions is much higher in urban areas. Heat propagation in such areas is described using the ‘Urban Heat Island Effect.’

Causes of higher temperatures in urban areas include close-spacing of buildings and infrastructure, as well as heat-generating economic and industrial processes and facilities

10). In France, the heatwave of 2003 caused the deaths of more than 14,000 individuals. In Wales and England, the number of deaths exceeded 2,000. The affected people were mostly elderly individuals

11). Because they increase the demand on electricity (in order to power air-conditioning systems) heat waves often cause power outages and blackouts

12). Salty, light food, and large amounts of water are essential to stay hydrated during heat waves

13). Heat waves often lead to drought conditions, especially when prolonged.

An example of a drought caused by heat waves is the Sub-Saharan drought of 1991-1992 which affected more than 105 million people, across an area of more than 6. 5 million miles

14). In the United Kingdom, several workers are affected seriously by heatwave conditions on a yearly basis, and this ultimately results in reduction of the output of labor

15). The number of heatwave-related deaths in the U.S varies with the severity of heat conditions per year. Although the average yearly number of deaths does not exceed 700, some years such as 1980, encounter above 1,000 heat-related deaths

16). The frequency and intensity with which heat waves occur, has increased over the years. in the same manner, heat waves have started to occur across a wider geographic area than before

17). Similarly, the average duration of heat waves has increased over the years, from three to four days

18). Heat waves also affect cold regions, with serious impacts such as glacial melting and rise in sea level

19). Mitigation as well as adaptation approaches are required, in order to address the heatwave problem

How are Heat Waves Measured?

The general way to measure heat waves, is by comparing the temperature on the earth surface, when they occur, with the average temperatures under normal conditions.

However, there are a few simple parameters which are used to measure the intensity of heat waves. These include;

1). HWN (yearly number of heat waves)

2). HWD (length of the longest yearly event)

3). HWF (yearly sum of participating heat wave days)

4). HWA (hottest day of hottest yearly event), and

5). HWM (average magnitude of all yearly heat waves)

It is also important for us to note that heatwave conditions may vary greatly in intensity and severity. This implies that what could be considered a heatwave in some cool regions of the world, could be the normal weather condition in other, warmer regions [9].

Causes of Heat Waves

The main cause of heat waves is trapped air which has been subjected to thermal radiation.

While air usually traverses the Earth continuously, provided this air is trapped and immobile over any given region for a period of time, it becomes heated after long exposure to sunlight and other forms of radiation.

The trapping of air itself is usually a result of pressure variations in the atmosphere. If the pressure in the upper atmosphere is high and acting downwards, it forces air to remain confined over the Earth’s surface [20]. This trapped air is also prevented from rising into the upper atmosphere, and this delays rainfall and other forms of precipitation.

When high pressures in the upper atmosphere remain consistent over an area for a prolonged period of time, heat waves may form. This usually occurs in the summer period of the year [4].

The Mechanism of Heatwave Formation

Because of the relative consistency of the weather conditions in summer, high atmospheric pressures are more likely to persist. The high-pressure conditions push the air in the lower atmosphere downward, toward the Earth’s surface. At the same time, it prevents the occurrence of various forms of gaseous dynamics that could evenly distribute the temperature of the air. These dynamics include convection, and cloud formation.

The absence of cloud formation increases the ease with which solar radiation permeates the atmosphere to reach the Earth’s surface [11]. Also, at the surface of the Earth, which has relatively lower gaseous pressure than the upper atmosphere, lower latitudinal; warm air currents rise, contributing further to the warming of the lower atmosphere.

The same air currents at the Earth’s surface may blow horizontally in any direction, causing intense heat waves, as they are called.

In a simpler description, heat waves occur when a high atmospheric pressure system persists for two or more days over a given region. Such a high-pressure system will basically push air from the upper and lower atmosphere toward the Earth’s surface, causing it to become highly compressed and heated.

Because the high-pressure conditions prevent air and heat circulation, heat waves are not easily affected by weather conditions in adjacent regions, and can therefore last for very long periods.

The high pressure basically prevents winds or air currents from being active, and prevents clouds from forming. These conditions all contribute to the intense high temperature that characterizes heat waves.

As we can predict from these explanations, heat waves have a similar mechanism in some ways, to the greenhouse effect and global warming. Global warming basically increases the likelihood of such intense weather conditions as heat waves [5].

Heat Waves and Climate Change: How does Climate Change Cause Heat Waves?

Climate change tends to cause a general increase in global temperatures [28]. This is basically the same conditions by which we can describe heat waves. The process of climate change serves to intensify the occurrence, formation and prevalence of heat waves around the world.

While it is generally expected that cooler and warmer weather conditions should occur yearly in the form of summer and winter, climate change has caused these natural conditions to be changed. As a result, it is now fairly common to experience prolonged period of hot weather in normally cool periods of the year.

In the United States, extreme high temperatures were recorded in the year 2012 [10]. These temperatures dominated the cooler temperatures by at least tenfold (i.e. 10:1). Such observations simply show that greenhouse effect, global warming, and climate change have all taken a significant toll on Earth’s climatic condition.

Climate change is particularly effective in making heat waves more intense, because it involves more high temperatures than low temperature effects. Climate change causes a shift in average temperatures on Earth, from the cooler margin, toward the warmer or hotter margin. It also causes high variability of the weather, which makes it possible for events like heat waves to occur.

What these observations tell us, is that climate change is a very significant problem which needs to be addressed. By intensifying other environmental challenges such as heat waves (and others like flooding and drought), climate change is a potential cause of increased mortality rates on Earth.

Effects of Heat Waves

As you must have understood already, heat waves are a potential source of various forms of weather-related hazards on Earth.

In this section, we will briefly discuss the effects of heat waves on different components of the Earth. These include the environment, ecosystem, and the human population.

Effects of Heat Waves on the Ecosystem

Heat waves may leach the soil of some important nutrients, causing a reduction in fertility and productivity. Given that the soil is a major source of nutrients to plants, microorganisms, soil organisms and indirectly to higher animals, this is likely to deprive the ecosystem of a significant amount of nourishment.

Crops are also directly affected by the heat, which is able to kill some of their important cell components. This usually results in crop failure on a large scale, in impacted regions.

Heat waves may cause aquatic organisms to migrate toward cooler regions, leading to an imbalance in the distribution of living organisms across the aquatic ecosystem. Under such conditions, food may become scarce in overcrowded habitats, and this may reduce the productivity of aquatic biodiversity.

Effects of Heat Waves on the Environment

The environmental effects of heat waves are very similar to ecological effects.

In the absence of sufficient precipitation, heat waves, may result in shortages in water supply [6]. This often places great stress on plants, stunting their growth and productivity. Because plants are the primary source of energy to the food chain, all organisms including humans may be affected.

The landscape under such conditions would tend toward dryness and exposure to leaching and weathering.

Reduction of plant productivity causes an increase in carbon dioxide in the atmosphere, because plants usually serve as carbon sinks. This occurrence, intensifies the Greenhouse Effect, Global Warming, Weather Variability and Climate Change.

The dry and hot weather conditions caused by heat waves, increase the tendency of forest fires to occur. For this reason, it has been observed that forest fires often occur in association with heat waves [21]. Such events are very harmful to the environment, since they cause the loss of forest vegetation, as well as the release of atmospheric pollutants and greenhouse gases [8].

An example of such is the 2010 forest fire in Russia, that led to the destruction of over 15 million hectares of forest land as well as important vegetation [12]. This forest fire incident occurred alongside one of the hottest heat waves in Russia in over a century.

In addition, heat waves contribute to sea level rise and flooding. We can predict that this is very possible, as prolonged hot weather would cause the melting of glaciers in polar regions [30].

It is estimated that up to 10 percent of the glacial mass on Europe was lost in the heatwave event of 2003. Aside flooding, these glacial melting episodes increase the risk or avalanches, rock-falls, debris flows and landslides.

Effects of Heat Waves on the Human Population

For the human population, heat waves present high risks as well. This is mainly because, extremely hot weather conditions can result in various forms of illness, and in death.

Such impacts as these, mostly affect the elderly, and the lower-class members of society. However, the entire human population stands at risk of being seriously impacted by heat waves.

We can find a real-life example of the effect of heat waves on the human population, by looking at the European heat waves of 2003. This singular event is estimated to have led to the deaths of about 70,000 people, and health-related expenses in hundreds of millions of pounds [7].

It is expected that the effects of heat waves on humans would be more intense in urban regions. This is because of the built-in, compact nature of most cities, and the absence of sufficient vegetation to produce oxygen. Coupled with the large and growing urban population, heat waves lead to poor air circulation, and atmospheric pollution in cities [17].

The cities with the highest mortality rates include those with limited access to healthcare, large population, high levels of pollution, less vegetation, and large-scale industrial activity [26].

It is also necessary for us to note, that the impacts of heat waves are not usually distributed evenly, across the human population. The poor, who mostly reside in overcrowded parts of urban areas, are usually the most susceptible.

On the other hand, the wealthier members of the human population, generally have better access to facilities like healthcare and air-conditioning systems [23].

Heat waves can also lead to social problems within the human population. Because they are often accompanied by drought and water shortages, they increase the risk of violence and conflict over the scarce resources [29].

The following are examples of human health problems caused by heat waves;

1). Heat Rash

Also referred to as ‘Prickly Heat,’ this is an acute and itchy, skin inflammation which blocks the sweat ducts and forms visible rashes. Prominent in areas of the body covered mostly by tight clothing, heat rashes can be prevented by wearing loose, light clothing in hot weather.

In severe cases, the heat rash may lead to bacterial infection. Treatment involves the use of antibiotics, chlorhexidine and antihistamines.

2). Heat Cramps

Heat cramps can be described as painful muscle spasms that occur as a result of strenuous exercise. These spasms usually occur in the large muscle groups, and are often the products of the exertion of these muscles.

Heat cramps develop in individuals who sweat excessively during physical activity, with little or no replacement of the lost fluids. The condition can be treated by rehydration with salt-containing fluids [15].

3). Heat Stroke

Also known as Hyperthermia, heat stroke is a condition which occurs mainly during prolonged periods of highly humid, hot weather [19]. It is most likely to affect the elderly and the very young.

Heat stroke can be viewed as the most severe heat-induced ailment [2]. The characteristics of this condition include an inability of the body to regulate its temperature. This usually causes extreme increase in body temperature within a very short period of time.

Symptoms of heat stroke include loss of consciousness, slurred speech, profuse sweating or high body temperature, and seizures. In the absence of immediate treatment, it may become fatal and could lead to death.

4). Heat Syncope

Heat syncope is a condition which is believed to result from intense heat, sweating and dehydration. It typically produces an orthostatic hypotension, which may develop a syncopal episode.

Heat syncope occurs when peripheral vasodilation and decreased flow of venous blood, both occur as a result of dehydration. The measures for managing heat syncope include rehydration and cooling of the patient.

5) Heat Exhaustion

Closely associated with hyperthermia (or heat stroke), heat exhaustion involves dehydration and excessive loss of body electrolytic fluid.

The symptoms of this condition include headache, vomiting, diarrhea, dizziness, myalgia, tachycardia, nausea, and malaise [16]. Like most other heat-induced ailments, it is treated by cooling and rehydration therapy.

6). Heat Edema

Heat Edema typically involves swelling of the feet, ankles, and hands. It is caused by water retention as well as peripheral vasodilation.

It has a duration of a number of days and usually subsides when the body adjusts to the high-temperature conditions of the environment.

Examples of Heatwave Effects on the Human Population

Instances of heat waves include that of 2012 in the United States, as well as the 2003 European heat waves and the 2010 heatwave in Russia which caused the deaths of up to 40,000-70,000 people [1].

Effects on the Economy

Heat waves, like any other natural hazard, can have serious impacts on the economy.

As a result of the effects of heat waves, several aspects of the economy may experience a reduction in terms of productivity. Typically, the unpleasant nature of heat waves makes it difficult to work with a high level of effectiveness in any sector.

Among the economic sectors which are most affected by this problem, are construction and agriculture. Working hours are usually lost under heatwave conditions, as work is either slowed-down or stopped altogether.

It is predicted that in the coming years, heat waves would result in economic losses worth trillions of dollars across the globe. The agricultural sector is likely to be one of the most vulnerable to these effects. Heatwave conditions imply less crop yield, less production, less labor, food insecurity, and higher cost of agricultural produce [14].

It is also predicted that the general standard of living would reduce as a result of heat waves in the near future, provided no active measures are taken. This is especially the case in developing, high-populated countries where the energy demand for cooling might overwhelm the available resources, subjecting businesses and industries to economic recession.

Solutions to the Problem of Heat Waves: Ensuring Sustainable Development

1). Reduction of Greenhouse Gas Emissions

The reduction of greenhouse gas emissions is perhaps the most important and effective method by which heat waves can be managed or prevented.

This is because, the greenhouse effect is very significant as a contributor to climate change and heat waves. By reducing these emissions, the global average temperatures would be kept at a minimum, without further rise [27].

Reducing greenhouse emissions will also help to mitigate air pollution and encourage the circulation of air currents in urban areas [13].

2). Development of Warning and Response Systems

Monitoring systems consisting of instruments that continuously measure and record atmospheric temperature, are needed in the effort to control heat waves.

In addition to such monitoring systems, efficient communication methods are required; in order to generate early warning signals as well as implement response systems. This approach would help reduce the losses caused by heatwave events [18].

3). Policy Development, Implementation and Strategic Decision-Making

It is important for decision-makers to develop and employ policies and strategies to reduce the degree of damage caused by heat waves.

This can be achieved if the policies are designed to address social behavior and ensure that required resources and infrastructure are available. For example, during a heatwave event, policies can be implemented to ensure that offices and schools which lack sufficient air-conditioning are closed down. At the same time, these policies may ensure that healthcare, first aid and water, are all available and accessible to the human population.

Other infrastructure for managing heat waves include public cooling centers. parks and pools. Sustainable urban development and planning are also required in regions that are susceptible to heat waves.

Management of Heat Waves

1). Inter-Agency Coordination and Early Warning Systems should be established, in order to provide early signals and alerts to regional residents, with respect to potential heat waves.

As we may predict, such systems will require a means by which background and atmospheric temperatures can be consistently measured. This will help to predict temperature rise and to identify signs of impending extreme temperatures. Also, such systems can only be managed effectively by a partnership between health and environmental agencies or departments.

2). Community Outreach and Public Awareness are both very important in the efforts to effectively manage heat waves.

These can be achieved by communicating with the public on the potential occurrence, as well as potential effects of heat waves. Tools which can be used for this purpose include posters, advertisements, social media channels, pamphlets and television commercials.

3). Effective Partnership with Civil Society and Non-Governmental Entities, is also very important. This can help to achieve the improvement or provision of needed infrastructure like temporary shelters, water delivery systems, and bus stands, to tackle the conditions associated with heat waves.

4). Training and Capacity-building programs must be organized, especially for local health care professionals.

This would help to improve their competence and capacity to respond to illnesses and other health challenges that may arise as a result of heat waves. Such training programs must be focused on helping these professionals to be able to efficiently manage as well as prevent heat-related illnesses. By this means, associated morbidity and mortality rates would be greatly reduced.

5). Proactive heat management measures must be taken. These may include;

-Installation of green and cool roofs as well as pavements, to mitigate the heat island effect in urban areas

-Development of elaborate plans and strategies for heat preparedness

-Development of energy-efficient systems and methods to reduce the electricity demand during periods of extreme heat

-Planting of trees to provide oxygen, and shade

Heat Stress Risk Assessment

To assess the risk of heat stress, we must consider the following criteria;

1). Working Climate

As we can expect, the risk of heat stress is directly related to climatic conditions. Hotter climates tend to increase the risk of heat-related problems.

The working climate can be assessed through humidity, air temperature and air circulation, as well as the closeness of potential sources of heat in the work place (such as a distillation chamber or a furnace).

Regular monitoring of the working climate especially in hot regions is very important to reduce the risk of heat stroke and other, similar problems. This can be done by measuring the individual climatic factors like temperature and humidity. In extreme conditions, it is recommendable to take precautions like changing to more tolerant clothing and protective equipment, and reducing the rate of work.

2). Rate of Work

The rate of work is also directly proportional to the risk of heat stroke and other heat-related problems. Higher rates of work are equivalent to higher health risks.

When the weather condition is very hot, it is important to regulate the rate of work, while reducing the number of working hours. Short and regular breaks can also be included within the working schedule.

3). Clothing/Protective Equipment

The clothing worn by people at work or in any other circumstance affects the rate of heating-up of the body, as well as the rate of sweating (which serves as a means of temperature regulation).

The table below, shows how we can adjust the clothing used at work, to suit increasing temperature conditions;

Clothing	Recommended Adjustments (with increase in °C)
Work Clothes (long pants, long-sleeved shirt)	0
Cotton Overalls	0
Polypropylene SMS coveralls	+0.5
Polyolefin Coveralls	+1.0
Vapor-barrier Coveralls	>+10.0

In some cases, protective equipment for heatwave events and general high temperature conditions, may include safety goggles or sunglasses. A notable example of such glasses is the Heatwave Sunglasses; which is a brand of protective glasses made from highly durable and resistant polycarbonate. Such glasses are used often in workplaces such as construction sites.

4). Individual Characteristics

Individual characteristics can affect the way a person is affected by hot conditions. These characteristics must therefore be considered. They include medical condition, age, weight and percentage body fat, among others.

Conclusion

In this article, we have seen that heat waves are prolonged periods of high temperature conditions, which are associated with other climate-related challenges like drought, global warming and sea level rise.

The causes of heat waves include high atmospheric pressure, poor air circulation rate, excessive solar radiation and high humidity.

We have also seen that heat waves have been responsible for many hazards and casualties in terms of loss of lives. As has been shown, the death toll as a result of heat waves is higher than that as a result of many other natural hazards. The most vulnerable individuals, as we have discussed, include the old and the very young.

The effects of heat waves include environmental, ecological, economic, social and health problems.

Examples of health problems associated with heat waves include heat stroke or hyperthermia, heat stress, heat exhaustion, heat edema, heat rash, and heat syncope.

Assessing the risk of heat stress and other heat-related health problems, especially at work, can be done by measuring the temperature and humidity of any environment, adjusting work clothing and personal protective equipment, and regulating the rate of work.

There are many recommendable ways by which we may be able to reduce heatwave incidence rates. These ways include reducing greenhouse emission, effective urban planning to reduce overcrowding, industrial regulations, monitoring and warning systems.

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