By Sunil Kumar
India has grappled with one of its most intense heat wave seasons on record this year. Heat waves occur when air temperatures soar to levels that pose a significant health risk to humans. These extreme weather events are defined by region-specific temperature thresholds. The India Meteorological Department classifies a heat wave as occurring when maximum temperatures reach at least 40°C in plains and 30°C in hilly regions. Alarmingly, climate change is fuelling a rise in both the frequency and intensity of heat waves. Rising global temperatures act as a catalyst, amplifying extreme weather patterns.
Climate change is expected to markedly increase global heatwave frequency and intensity, including in India. According to the Intergovernmental Panel on Climate Change, global temperatures are rising due to greenhouse gas emissions, resulting in more frequent and severe heatwaves. Human activities such as burning fossil fuels for energy and transportation, release greenhouse gases like carbon dioxide and methane, trapping heat in the atmosphere and driving global warming. Deforestation for agriculture, urban development and logging reduces carbon-absorbing trees, exacerbating the problem. Agricultural practices such as livestock farming and intensive irrigation emit methane and raise local humidity, contributing to heat retention. Industrial activities also produce waste heat and greenhouse gases, disrupting natural climate patterns and intensifying heatwaves.
Urban areas are particularly affected due to the urban heat island effect, where concrete and asphalt retain heat, exacerbating the impact of heatwaves. The increased intensity of these heatwaves poses severe health risks, including higher mortality rates from heat-related illnesses and contributes to environmental issues such as droughts and wildfires, which are becoming more frequent with rising temperatures. Scientific predictions indicate that if global warming continues at the current rate, heatwaves that are currently considered extreme will become commonplace by the end of the 21st century and regions that have not historically experienced such events may start to do so. This underscores the urgent need for global and local climate action to prevent catastrophic outcomes.
However, it’s not just the temperature alone that makes heatwaves unbearable; humidity plays a crucial role in in how our bodies feel and function and exacerbating the discomfort and health hazards associated with these events. Sweat, our natural cooling mechanism, evaporates less efficiently in humid environments, hindering our ability to regulate body temperature. This creates a dangerous situation, increasing the risk of heatstroke and other heat-related illnesses.
During heatwaves and high humidity, people resort to air conditioners to maintain a comfortable indoor environment, as these conditions make it difficult for the body to cool itself naturally, increasing the risk of heat-related illnesses. Air conditioners effectively reduce indoor temperatures and humidity levels, providing relief from the oppressive heat and preventing health issues such as heatstroke. This reliance on air conditioning ensures safety, comfort and well-being during extreme weather conditions.
While air conditioners offer relief from hot and humid conditions, their increasing use in urban areas poses a climate paradox. During heatwaves, electricity demand spikes as residential and commercial sectors ramp up air conditioning to maintain indoor comfort and prevent heat-related health issues. This surge strains the power grid, causing frequent blackouts in areas with inadequate infrastructure. Inefficient buildings worsen the situation by requiring more energy to cool poorly insulated spaces. Coal-fired power plants, used to meet high demand, increase greenhouse gas emissions, exacerbating global warming – the very issue air conditioners aim to mitigate. Additionally, air conditioners use refrigerants with a high Global Warming Potential (GWP). Leaks during installation or servicing, often by under-equipped technicians during peak season, release these harmful refrigerants, further contributing to global warming. Extended operating hours during peak summer strain the power grid and necessitate more frequent refrigerant refills, creating a harmful cycle.
To mitigate the dual threat of heatwaves and humidity and address the climate impact of air conditioners, a comprehensive strategy is crucial. This includes enhancing air conditioning unit efficiency through stricter standards and promoting energy-efficient models to reduce electricity consumption. Transitioning to renewable energy sources such as solar and wind can decrease reliance on coal-fired plants and cut greenhouse gas emissions. Proper technician training and certification are essential to minimize refrigerant leaks during installation and servicing, preventing the release of high-GWP refrigerants. Regular maintenance of air conditioning units further prevents leaks and enhances efficiency. Governments should incentivize low-GWP refrigerant use and invest in alternative cooling technologies like evaporative and passive cooling designs. In densely populated urban areas like the NCR region, where heat accumulation is worsened by direct sun exposure and high population density, residents should adopt precautions such as regular AC maintenance, proper kitchen ventilation and ensuring adequate airflow around refrigerators to manage heat risks effectively during humid summers.
Urban planning should prioritize green spaces, reflective materials and urban forests to combat urban heat islands and create cooler environments. Improving energy efficiency in buildings and adopting sustainable agricultural practices can cut greenhouse gas emissions and mitigate heatwave effects. Public health measures like early warning systems, cooling centers and education campaigns promote heat safety. Transportation policies supporting public transit and green corridors reduce emissions and urban heat. Strong government policies and international cooperation are crucial for climate action and environmental regulation compliance, fostering resilience and sustainability.
Residents can benefit from natural ventilation, particularly during cooler times like early morning and late evening. Opening windows and doors allows fresh air to circulate through living spaces, replacing stagnant, warm air accumulated throughout the day. This natural airflow effectively lowers indoor temperatures without relying heavily on energy-intensive cooling systems, enhancing indoor air quality and overall well-being.
Public awareness campaigns are essential to educate consumers about the environmental impact of air conditioning and encourage responsible usage. Additionally, urban planning and architectural design should focus on enhancing natural ventilation and insulation to reduce reliance on mechanical cooling.
By combining energy efficiency, renewable energy adoption, proper technician training, passive cooling solutions and public awareness, we can not only mitigate the adverse effects of heat and humidity but also ensure long-term climate sustainability without compromising our environment.
(Dr Sunil Kumar is an Associate Fellow, Earth Science and Climate Change Division, The Energy and Resources Institute (TERI))
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