Recent studies have revealed relationship between rainfall, soil moisture, and the onset of humid heat waves in tropical and subtropical regions. These findings are particularly relevant for highly populated areas like India and equatorial Africa. Researchers have identified that as climate change progresses, the frequency and intensity of these humid heat events are expected to increase. This poses serious health risks, as humid heat can impair the human body’s ability to cool itself.
About Humid Heat Waves
Humid heat waves are periods of high temperature combined with elevated humidity levels. These conditions can overwhelm the body’s natural cooling mechanisms. The combination of temperature and humidity is measured using the wet-bulb temperature (Twb). At a Twb of 35°C, humans may struggle to regulate body temperature effectively. Vulnerable populations, such as the elderly and very young, are at an even greater risk at lower Twb levels.
Climate Change and Humid Heat
The study marks that extreme humid heat events have become more frequent since 1979. Climate change is a driving factor behind this increase. For instance, South and Southeast Asia experienced severe humid heat events in April 2023, illustrating the immediate impacts of climate change on weather patterns.
Role of Soil Moisture and Rainfall
The research indicates that soil moisture and recent rainfall patterns influence the occurrence of humid heat waves. In arid regions, humid heat waves often follow rainfall, as moisture from the ground evaporates and increases humidity. Conversely, in wetter areas, humid heat waves typically occur after a period of suppressed rainfall, allowing sunlight to warm the surface more effectively.
Regional Variations in Humid Heat Events
Different regions exhibit varying responses to rainfall concerning humid heat waves. For example, northwestern India has an arid climate where rainfall can trigger humid heat events. In contrast, humid regions experience high soil moisture levels during the monsoon season, which can limit evaporation due to cloud cover. However, after rainfall subsides and skies clear, surface temperatures can rise sharply, leading to humid heat waves.
Implications for Early Warning Systems
The strong connection between soil moisture, precipitation, and humid heat suggests that satellite technology can enhance monitoring capabilities. Near real-time observations of soil moisture and precipitation can be integrated with climate models to improve forecasts. This could lead to more effective early warning systems for humid heat waves, potentially saving lives in vulnerable populations.
Questions for UPSC:
- Critically analyse the impact of climate change on human health in tropical regions.
- Estimate the role of soil moisture in the formation of humid heat waves and its implications for agriculture.
- What is the significance of wet-bulb temperature in assessing heat-related health risks? Explain.
- Point out the differences in humid heat wave occurrences between arid and humid regions. How do these differences affect local climates?
Answer Hints:
1. Critically analyse the impact of climate change on human health in tropical regions.
- Climate change exacerbates heat extremes, leading to increased humidity and higher wet-bulb temperatures.
- Vulnerable populations, including the elderly and children, face heightened health risks due to impaired thermoregulation.
- Rising temperatures can lead to heat-related illnesses, such as heat exhaustion and heat stroke.
- Increased frequency of extreme weather events disrupts healthcare systems and food security.
- Long-term impacts include increased morbidity and mortality rates in densely populated tropical areas.
2. Estimate the role of soil moisture in the formation of humid heat waves and its implications for agriculture.
- Soil moisture influences humidity levels; low moisture can lead to rapid evaporation, intensifying humid heat waves.
- In arid regions, recent rainfall contributes to increased humidity, triggering humid heat events.
- In humid regions, high soil moisture limits evaporation during the monsoon, but post-rainfall warming can lead to heat waves.
- Impacts on agriculture include crop stress and reduced yields due to extreme heat and humidity conditions.
- About soil moisture dynamics can aid in better crop management and irrigation strategies.
3. What is the significance of wet-bulb temperature in assessing heat-related health risks? Explain.
- Wet-bulb temperature (Twb) combines temperature and humidity, providing a comprehensive measure of heat stress.
- At Twb of 35°C, humans struggle to cool down, risking heat-related illnesses.
- Vulnerable groups may experience health impacts at lower Twb values, denoting the need for targeted interventions.
- Twb is crucial for developing early warning systems for heat waves and public health advisories.
- Monitoring Twb can help in assessing the effectiveness of climate adaptation strategies in affected regions.
4. Point out the differences in humid heat wave occurrences between arid and humid regions. How do these differences affect local climates?
- Arid regions see humid heat waves following rainfall, where moisture from the ground evaporates, increasing humidity.
- Humid regions experience heat waves after periods of suppressed rainfall, with clearer skies allowing for rapid surface warming.
- Arid climates may have more intense but less frequent humid heat waves, while humid climates may experience prolonged events.
- These differences can lead to varying agricultural practices, water management, and health responses in local populations.
- About these patterns is vital for regional climate adaptation strategies and disaster preparedness.
