Heat Wave
Overview
A heat wave (폭염, heat wave) refers to a weather condition in which abnormally high temperatures significantly exceeding the annual average persist for several days or more in a specific region. Due to climate change, the frequency, intensity, and duration of heat waves are increasing globally, causing various social and economic problems such as heatstroke, increased mortality, agricultural damage, and power supply crises. Heat waves are classified as a type of natural disaster, and their impact is particularly severe in urban areas due to the heat island effect.
Main Content
Definition and Criteria
The definition of a heat wave varies by country and institution, but generally, it is considered a heat wave when the daily maximum temperature is 33°C or higher for two or more consecutive days. The World Meteorological Organization (WMO) defines a heat wave as a period of at least five consecutive days where the daily maximum temperature is 5°C or more above the long-term average. The Korea Meteorological Administration classifies days with a daily maximum temperature of 33°C or higher as heat wave days, and days with 35°C or higher as tropical night days.
Causes
The main causes of heat waves are as follows:
- Climate Change: Global warming increases the concentration of greenhouse gases in the atmosphere, raising surface temperatures.
- Atmospheric Circulation Patterns: Stagnant high-pressure systems trap hot air, creating a heat dome phenomenon.
- Urbanization: Asphalt and concrete absorb and release heat, intensifying the urban heat island effect.
- Land Use Changes: Deforestation and conversion of farmland reduce evapotranspiration, raising local temperatures.
Health Impacts
Heat waves pose direct threats to the human body:
- Heatstroke: The body's temperature regulation center fails, causing body temperature to rise above 40°C, with a high mortality rate.
- Heat Exhaustion: Excessive sweating leads to loss of water and electrolytes, causing dizziness and fainting.
- Heat Cramps: Muscle cramps occur in high-temperature environments.
- Worsening of Chronic Diseases: Exposure to heat waves sharply increases the risk of death for individuals with cardiovascular or respiratory diseases.
- Mental Health: Sleep deprivation and stress lead to increased depression and anxiety disorders.
Social and Economic Impacts
- Power Supply Crisis: Soaring demand for cooling overloads the power grid, increasing the risk of blackouts.
- Agricultural Damage: Crops wither, livestock die, and production decreases.
- Infrastructure Damage: Roads expand and crack, railway rails buckle, and power lines sag and break.
- Ecosystem Disruption: Rising water temperatures cause fish die-offs and increase the risk of wildfires.
- Economic Losses: Reduced labor productivity, increased medical costs, and a surge in insurance claims result in enormous economic losses.
Response and Adaptation Strategies
- Early Warning Systems: The meteorological agency provides heat wave advisories and action guidelines for each risk level.
- Expansion of Cooling Facilities: Operate cooling shelters and cooling centers, and provide air conditioners to vulnerable groups.
- Urban Design Improvements: Mitigate the heat island effect through rooftop greening, reflective paint, shade structures, and wind corridor creation.
- Individual Action Guidelines: Recommend adequate hydration, avoiding outdoor activities, wearing light clothing, and using cooling devices.
- Policy Efforts: Set greenhouse gas reduction targets, transition to renewable energy, and strengthen building insulation standards.
Latest Trends
The years 2024 and 2025 are assessed as record-breaking heat wave periods globally. In the summer of 2024, the global average temperature exceeded 1.5°C above pre-industrial levels for several months, and heat waves exceeding 50°C persisted for weeks in India and Pakistan, resulting in thousands of deaths. In Europe, the highest temperature ever recorded, 48.8°C, was observed in Sicily in July 2024, causing severe wildfires and agricultural damage. In South Korea, the number of tropical night days in August 2024 set a record, with Seoul experiencing 39 consecutive tropical nights, posing a major threat to public health. In 2025, despite the weakening of El Niño, early heat waves occurred across the Northern Hemisphere, with temperatures exceeding 40°C appearing as early as May. Scientists warn that this phenomenon represents a new phase of climate change and emphasize that adaptation efforts alone are insufficient, making greenhouse gas reduction urgent. Additionally, AI-based heat wave prediction models have been developed, enabling more accurate early warnings, and technological responses such as smart shade structures and automatic irrigation systems are expanding in cities.
Related Topics
- [[Climate Change]]
- [[Urban Heat Island Effect]]
- [[Heatstroke]]
- [[Greenhouse Gases]]
- [[Natural Disaster]]
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