Heatwaves: Causes, Impacts, and How to Stay Safe

Heatwaves are characterised by prolonged periods of unusually high temperatures that surpass the seasonal average for the area, usually two or more days in a row. A heatwave may begin at 30°C (86°F) in a temperate region like the UK, but it may need to reach temperatures exceeding 40°C (104°F) in a tropical area.

The precise threshold varies depending on the location. Heatwaves are frequently made worse by high humidity because it prevents the body from cooling itself through perspiration. Heatwaves have become more frequent, intense, and prolonged worldwide due to climate change, therefore it’s important to recognise their warning signs and take appropriate precautions.

Heatwaves can cause stress on crops and cattle, overload electricity infrastructure from increasing air conditioning use, and strain public health systems. The elderly, young children, and people with long-term medical conditions are among the vulnerable groups that are more susceptible to heat exhaustion or heatstroke. Early detection of the symptoms enables preventative actions to save resources and lives.

Top Causes of Heatwaves

Around the world, heatwaves—prolonged episodes of extremely high temperatures—are growing increasingly common, severe, and prolonged. These sweltering occurrences are extremely dangerous for ecosystems, infrastructure, agriculture, and public health. Understanding the causes of heatwaves and the human and environmental elements that contribute to their occurrence is essential to reducing their effects.

• High-Pressure Systems (Atmospheric Blocking)
• Climate Change and Global Warming
• Urban Heat Island Effect
• Deforestation and Land Use Changes
• Jet Stream Disruptions
• Ocean-Atmosphere Interactions (e.g., El Niño)
• Reduced Soil Moisture
• Wildfires and Air Pollution

1. High-Pressure Systems (Atmospheric Blocking)

A continuous high-pressure system is one of the primary meteorological factors that contribute to heatwaves. By trapping warm air beneath them, these structures function as a lid on the atmosphere, preventing rain and cloud formation.

• How it operates: Sinking air in high-pressure areas compresses and warms.
• Impact: Surface temperatures rise as a result of extended clear skies and little breeze.

2. Climate Change and Global Warming

Heatwaves are becoming more common and powerful as a result of greenhouse gas emissions raising global temperatures. Fossil fuel-derived carbon emissions raise the planet’s average temperature, while feedback loops like melting ice and less snow cover intensify the warming.

Fact: Many recent heatwaves are now at least five times more likely to occur due to human-caused climate change, according to the IPCC.

3. Urban Heat Island Effect

The urban heat island (UHI) effect causes temperatures in cities to frequently be higher than in rural areas.

• The reason it occurs: More heat is absorbed and retained by concrete, asphalt, and buildings than by open space or plants.
• Why Cities cool more slowly at night due to a lack of greenery and ventilation.

Advice: Reflective building materials and more urban vegetation can help reduce heatwaves caused by UHI.

4. Deforestation and Land Use Changes

The natural cooling impact of trees and plants is diminished when forests are cleared for development or agriculture. Without trees, the earth warms more quickly and retains heat for longer. Trees also help to reduce temperatures by providing shade and moisture through transpiration.

5. Jet Stream Disruptions

A swift air movement in the upper atmosphere that affects weather patterns is called the jet stream. The jet stream is becoming weaker due to warming in the Arctic, which can cause it to stop or meander. This can lead to air blocking, which can cause extended heatwaves in the impacted areas.

6. Ocean-Atmosphere Interactions (e.g., El Niño)

Global weather patterns can be impacted by variations in ocean temperatures, especially in the Pacific Ocean. In many regions of the world, El Niño episodes are known to raise the risk of heatwaves. Regional warming is exacerbated by warmer ocean temperatures that transfer heat to the atmosphere.

7. Reduced Soil Moisture

Surface temperatures are rising as a result of dry soils heating up more quickly than damp soils. The reduction of evaporative cooling during droughts results in a feedback loop: dry soil → higher temperature → additional evaporation → drier soil.

8. Wildfires and Air Pollution

Smog and wildfires can worsen hot conditions, although they are not the main reason. During heatwaves, respiratory conditions might deteriorate, and vulnerable populations may experience more heat stress due to smoke particles’ ability to trap heat and lower air quality.

Health Impacts of Heatwaves

Heatwaves are hazardous extreme weather conditions that can have a serious negative influence on human health; they are more than just a few scorching days. It is more important than ever to comprehend the health implications of heatwaves as they become more common and harsher due to climate change. The hazards are numerous and increasing, ranging from heatstroke and dehydration to mental health problems and higher mortality.

• Heat-Related Illnesses
• Dehydration and Electrolyte Imbalance
• Respiratory Distress
• Cardiovascular Strain
• Mental Health Effects
• Increased Mortality Rates
• Vulnerable Populations
• Indirect Health Effects

1. Heat-Related Illnesses

• Heat Exhaustion
• Heatstroke

Heat Exhaustion

Occurs when your body loses excessive amounts of salt and water through perspiration. Dizziness or fainting, muscle cramps, a weak and rapid pulse, nausea or vomiting, and cold, pale, and clammy skin are some of the symptoms. It can typically be reversed with prompt rest and hydration, but heatstroke can develop if treatment is not received.

Heatstroke

When the body temperature surpasses 40°C (104°F) and the cooling mechanism fails, a potentially fatal situation occurs.

Among the symptoms are:

• Confusion, disorientation
• Hot, dry skin (no sweating)
• Rapid, strong pulse
• Seizures
• Loss of consciousness

You need to get medical help right away. Without it, heatstroke can harm the kidneys, heart, or brain permanently.

2. Dehydration and Electrolyte Imbalance

Severe heat causes more fluid loss through perspiration. The body becomes dehydrated when it doesn’t get enough water.

Signs of dehydration include:

• Dry mouth and lips
• Fatigue
• Headache
• Decreased urination

Low blood pressure, heat cramps, and kidney damage can result from severe dehydration.

3. Respiratory Distress

Particularly in cities, ozone and pollution during heat waves frequently cause the quality of the air to decline.

• This makes ailments like:
•  Asthma worse
• COPD, or chronic obstructive pulmonary disease
• Bronchitis

In addition to causing air pollution and an increase in respiratory emergency visits, high temperatures can also start wildfires.

4. Cardiovascular Strain

To keep the body, cool during hot weather, the heart has to work harder. This raises the possibility of:

• Heart attacks
• Strokes
• Irregular heartbeat

Individuals who already have high blood pressure or cardiac problems are more vulnerable.

5. Mental Health Effects

Emotional and psychological health can also be impacted by heatwaves. Research has connected excessive heat to:

• Increased aggression and irritability
• Sleep disturbances
• Cognitive impairment
• Higher suicide rates

Mental health issues can be made worse by stress, loneliness, and discomfort during hot weather, particularly for older adults.

6. Increased Mortality Rates

One of the deadliest natural disasters is heatwaves. More than 70,000 extra people died as a result of the 2003 heatwave in Europe.

Typical high-risk categories are:

• Elderly people living alone
• People without air conditioning
• Patients with chronic illnesses
• Infants and children
• Outdoor workers

7. Vulnerable Populations

Heatwaves disproportionately affect the following groups:

• Elderly: Reduced capacity to control body temperature.
• Children: Higher metabolic rates and immature thermoregulation.
• Expectant mothers: Heat can exacerbate pregnancy-related issues.
• Employees working outdoors: prolonged exposure to direct sunlight.
• Low-income areas: Access to healthcare and cooling is restricted.

8. Indirect Health Effects

Critical infrastructure can be affected by heatwaves in the following ways:

• Power outages that stop cooling systems and medical equipment from operating;
• Transportation delays that impact emergency services;
• Crop failures and food insecurity;
• Contaminated water supplies because of algae infestations in reservoir.

Health emergencies may worsen as a result of these secondary effects, particularly in underdeveloped nations.

Environmental & Economic Impacts of Heatwaves

Heatwaves are more than just hot spells that are uncomfortable. These severe temperature events are increasing in intensity and frequency due to climate change, and they leave behind terrible environmental and economic repercussions. Heatwaves have an impact on enterprises, agriculture, infrastructure, and national economies in addition to ecosystems, resulting in wildfires, water shortages, and billions of dollars in losses.

• Environmental Impacts of Heatwaves
• Economic Impacts of Heatwaves
• Long-Term Economic Risks

1. Environmental Impacts of Heatwaves

• Wildfires and Forest Loss
• Drought and Water Scarcity
• Soil Degradation
• Biodiversity Loss

a. Wildfires and Forest Loss

Wildfires are caused by dry, combustible conditions brought on by extreme heat.

• Destroys biodiversity, forests, and wildlife habitats.
• Increases climate change by releasing large amounts of carbon emissions.
• Lowers air quality because of particulate matter and smoke.

For instance, the 2021 heat wave in the Pacific Northwest and Canada set off hundreds of wildfires that burned more than 8.7 million acres.

b. Drought and Water Scarcity

Heatwaves evaporate surface water and dry up rivers, lakes, and reservoirs.

• It becomes challenging to irrigate agriculture.
• Endangers both urban and rural drinking water supplies.
• Affects aquatic life because of rising water temperatures and low oxygen levels.

c. Soil Degradation

The soil is baked by high temperatures, which lowers fertility and destroys vital microbes.

• Leads to desertification in vulnerable regions.
• Makes land less productive for cultivation.
• Raises the possibility of dust storms and erosion.

d. Biodiversity Loss

Many species are unable to adjust to sudden increases in temperature, particularly those found in colder or higher elevation regions.

• Severe heatwaves have been linked to mass fatalities of fish, birds, and mammals;
• They also alter migration patterns and ecosystems.
• Has the potential to wipe out threatened species.

2. Economic Impacts of Heatwaves

• Agricultural Losses
• Energy System Strain
• Infrastructure Damage
• Health-Related Costs
• Reduced Labor Productivity
• Insurance and Economic Disruption

a. Agricultural Losses

Crop productivity and livestock health are impacted by extreme heat.

• Lowers rice, maize, wheat, and other mainstays’ production.
• Reduces the production of milk and meat by causing heat stress in animals.
• Has an effect on food security by raising food prices.

The 2022 heatwave severely decreased wheat exports and resulted in crop failures in Pakistan and India.

b. Energy System Strain

Because of air conditioning and cooling, heatwaves increase the demand for power.

• May result in rolling blackouts and power disruptions.
• Raises the price of energy production and grid upkeep.
• The production of electricity via fossil fuels adds to global warming.

c. Infrastructure Damage

Roads, buildings, and transportation networks are all impacted by prolonged heat.

• Train delays are caused by warping rail lines.
• The melting of road surfaces raises maintenance expenses.
• Makes living conditions in cities worse by increasing urban heat islands.

d. Health-Related Costs

Dehydration, cardiovascular issues, and heatstroke are all exacerbated by heatwaves.

• Higher public health expenditures and hospital admissions;
• Reduced worker productivity as a result of illness and exhaustion.

The 2003 heatwave in Europe caused more than 70,000 unnecessary deaths, placing a burden on healthcare systems and labour productivity.

e. Reduced Labor Productivity

Industrial and outdoor workers are particularly at risk.

• Heat stress impairs focus and productivity.
• A rise in accidents at work.
• Has an impact on the manufacturing, mining, construction, and agricultural industries.

f. Insurance and Economic Disruption

Following agricultural failures and wildfires, insurance claims increase.

• There is a disruption in business continuity.
• Unbearable circumstances or environmental harm cause a drop in tourism.

3. Long-Term Economic Risks

If global temperatures keep rising, interruptions from the heat might cost nations up to 10% of their GDP.

• Low-income countries suffer disproportionate harm, particularly those in South Asia and Africa.
• Shocks brought on by climate change will have an impact on global supply systems.

Heatwaves: Causes, Impacts, and How to Stay Safe – FAQs

Q1: Who is most at risk during a heatwave?

The most susceptible groups are the elderly, young children, those who work outside, those with long-term illnesses, and those with poor incomes.

Q2: How is heatstroke different from heat exhaustion?

With rest and drinks, heat exhaustion can be reversed and is less severe. Heatstroke is a serious illness that needs immediate medical attention.

Q3: Can mental health be impacted by heat waves?

Indeed. Severe heat is associated with anger, anxiety, depression, and even a higher risk of suicide.

Q4: What are some ways to get ready for a heat wave?

Wear light clothing, stay hydrated, stay out of direct sunlight, and make sure your cooling gadgets are working.

Conclusion

Heatwaves are a major health and climate issue, not merely unpleasant weather. We can keep safe and contribute to community protection by being aware of their sources, effects, and appropriate responses. Let’s all do our share to reduce climate change, adopt sustainable lifestyles, and raise awareness during periods of excessive heat.

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