India is currently experiencing an intense heatwa across North India in Uttar Pradesh, Punjab, Rajas The rising temperatures, combined with high hum people to go about their daily activities. As per a stu Environment (CSE), while the average temperature lesser, the humidity levels were high, which worse Understanding how humidity is measured can he by this weather
Heat Stress Increases In Mega Cities Of India, Warmer Nights Add To Discomfort, Says Study. India's mega cities Delhi, Mumbai, Kolkata, Hyderabad, Bengaluru, Chennai are experiencing heat stress. According to Delhi based think tank Centre for Science and Environment, the cities are experiencing rising relative humidity over past two decades. The cities are also experiencing warmer nights turning the cities into 'urban heat islands'.
A study Decoding the Urban Heat Stress among Indian cities by the Centre for Science and Environment (CSE) analysed data from six major cities - Delhi, Kolkata, Chennai, Mumbai, Bengaluru and Hyderabad -- for about 23 years from January 2001 till Apr...
Summer time relative humidity has increased by 5-10 per cent this decade leading to excessive heat stress in Hyderabad and other metros. This increase is nullifying the drop in night temperatures in Hydeabad and Delhi too, a study by the Centre for Science and Environment says. Increased humidity is worsening the heat stress in Hyderabad and other metro cities like Delhi, Mumbai, Kolkata, Bengaluru and Chennai. This particular phenomenon is even nullifying the marginal drop in air temperatures in Hyderabad and Delhi, says a report by the Centre for Science and Environment (CSE). The report says increasing concretization and humidity levels are exacerbating heat stress in India’s megacities, which are not cooling down at night at the same rate as a decade ago The Centre analysed summer air temperature, land surface temperature, and relative humidity data for six megacities — Delhi, Mumbai, Kolkata, Hyderabad, Bengaluru and Chennai — from January 2001 to April 2024. The think tank found that increased humidity is worsening heat stress across all climate zones, even nullifying the marginal drop in air temperatures in Delhi and Hyderabad. Barring Bengaluru, summertime average relative humidity has increased by 5-10 per cent in the other five megacities from 2014-2023 compared to the 2001-2010 average. The CSE report comes at a time when blistering heatwaves are affecting health and livelihoods in large parts of India. “Assessing the changing trend in heat, relative humidity, and land surface temperature along with day and night-time temperatures is necessary to develop a comprehensive heat management plan for urban centres,” said Anumita Roychowdhury, executive director of research and advocacy at CSE. Avikal Somvanshi, senior programme manager at CSE’s Urban Lab, said addressing the combination of high heat and humidity is particularly important as it can compromise the human body’s main cooling mechanism, sweating. “The evaporation of sweat from the skin cools our bodies, but higher humidity levels limit this natural cooling. As a result, people can suffer heat stress and illness, and the consequences can even be fatal at much lower ambient temperatures,” he explained. The study showed that megacities are not cooling down at night. The land surface temperature during the summers of 2001-2010 would drop by 6.20-13.20 degrees Celsius from the daytime peak to the nighttime low. In the last 10 summers (2014-2023), night-time cooling has reduced to 6.20-11.50 degrees Celsius, the CSE said. “Hot nights are as dangerous as midday peak temperatures. People get little chance to recover from daytime heat if temperatures remain high overnight,” Somvanshi said. “A study published in ‘The Lancet Planetary Health’ noted that the risk of death from excessively hot nights could increase nearly six-fold in the future. This prediction is much higher than the mortality risk from daily average warming suggested by climate change models,” he said. The study said that rising humidity levels have also made monsoons in Delhi, Mumbai, Kolkata, and Chennai hotter than pre-monsoon periods. It noted that all megacities have become more concretized in the last two decades, increasing heat stress. The CSE highlighted that an increase in green cover is not effective in mitigating nighttime heat. The study showed that Kolkata has the highest percentage of land under concrete and the lowest green cover among the megacities, while Delhi has the least area under concrete and the maximum green cover. Green cover has declined in Mumbai, Kolkata, and Chennai. The built-up area in Chennai has doubled in the last two decades, while its green cover shrank by almost 14 percentage points.
Bengaluru, along with other major Indian cities, is witnessing a troubling rise in nighttime temperatures, as revealed by a recent study by the Centre for Science and Environment. Factors such as urban expansion and reduced green cover are contributing to this concerning trend, posing significant risks to public health A recent study conducted by the Delhibased think tank Centre for Science and Environment (CSE) sheds light on the alarming phenomenon of rising nighttime temperatures in major Indian cities, including Bengaluru. The study reveals that a combination of factors, including urban expansion and changing climate patterns, is contributing to this concerning trend.
Heatwave Alert: सेंटर फॉर साइंस एंड एनवायरनमेंट (CSE) की एक स्टडी में बताया गया है कि कैसे तेजी से बढ़ते बिल्टअप एरिया, कम होती ग्रीनरी की वजह से तापमान लगातार बढ़ रहा है. इससे हीटवेव बढ़ रहा है. Heatwave Latest News: एक तरफ दिल्ली-एनसीआर के लोग भीषण गर्मी और हीटवेव से परेशान हैं तो दूसरी तरफ साउथ इंडिया में खासकर बेंगलुरु में हो रही बारिश से वहां मौसम ठंडा बना हुआ है. इन सबके बीच सेंटर फॉर साइंस एंड एनवायरनमेंट (CSE) के एक अध्ययन में काफी दिलचस्प खुलासा हुआ है. इस स्टडी में कहा गया है कि पिछले दो दशकों में ह्यूमिडिटी में लगातार हो रही बढ़ोतरी के कारण दिल्ली, मुंबई, चेन्नै, कोलकाता और हैदराबाद में गर्मी लगातार बढ़ रही है. स्टडी इसके लिए "अर्बन हीट आइजलैंड" प्रभाव को जिम्मेदार ठहराती है, जहां बिल्टअप एरिया ग्रीन कवर को कम करते हैं, भीड़भाड़ पैदा करते हैं, गर्मी को एब्जॉर्ब्ड करते हैं और मानवीय गतिविधियों से अतिरिक्त गर्मी पैदा करते हैं. इन सब वजहों से शहर के केंद्र अधिक गर्म हो जाते हैं, विशेषकर रात में. अधिक गर्मी और ह्यूमिडिटी शरीर को ठंडा रखने वाले मैकनिज्म को प्रभावित करती है, जिससे लोग बीमार हो जाते हैं. बढ़ता तापमान और ह्यूमिडिटी मिलकर हीट इंडेक्स को बढ़ा रहा है, जो असुविधा की एक वजह है. अधिकतर महानगरों में बढ़ी गर्मी इस गर्मी में लंबे समय तक चलने वाली हीटवेव ने समस्या और बढ़ा दी है. अप्रैल में ओडिशा में 18 और पश्चिम बंगाल में 16 हीटवेव केस एक दिन में दर्ज किए गए हैं. भारत मौसम विज्ञान विभाग के अनुसार, राजस्थान, हरियाणा और दिल्ली इस समय सबसे ज्यादा गर्मी का सामना कर रहे हैं और अभी यहां कम से कम तीन दिनों तक राहत की उम्मीद नहीं है. अध्ययन में पिछले दशक में अधिकांश महानगरों में औसत गर्मी की ह्यूमिडिटी में 5-10% की वृद्धि देखी गई, जिसमें हैदराबाद में 10% की उच्चतम वृद्धि देखी गई. मुंबई, कोलकाता और चेन्नई में क्रमशः 8%, 7% और 5% की वृद्धि देखी गई. हालांकि इसमें बेंगलुरु अपवाद था. दिल्ली में क्यों बरस रही आग स्टडी और अन्य विश्लेषण से पता चलता है कि दिल्ली की अत्यधिक गर्मी सीधे तौर पर बिल्टअप एरिया (निर्मित क्षेत्रों) में वृद्धि से जुड़ी हुई है. जैसे-जैसे शहर का विस्तार हुआ है, बिल्टअप एरिया 2003 में 31.4% से बढ़कर 2022 में 38.2% हो गए हैं, शहरी गर्मी का तनाव बढ़ गया है. जबकि अधिक ग्रान कवर दिन के तापमान को कम करने में मदद करता है, यह रात के तापमान या बढ़ते ताप सूचकांक को प्रभावित नहीं करता है। इसकी वजह से ही शहर अधिक गर्म हो जाता है, विशेषकर रात में.
बेंगलुरु: सेंटर फॉर साइंस एंड एनवायरनमेंट (सीएसई) ने सोमवार को जारी अपनी रिपोर्ट में कहा कि हाल ही में कर्नाटक में गर्मी की लहर की स्थिति का अनुभव अधिकांश भारतीय शहरों द्वारा किया जा रहा है, और बढ़ते हीट आइलैंड प्रभाव के कारण स्थिति केवल खराब हो रही है। सीएसई ने अपने अध्ययन के लिए भारत के छह मेट्रो शहरों - बेंगलुरु, चेन्नई, कोलकाता, मुंबई, दिल्ली और हैदराबाद की हीटवेव स्थितियों पर नज़र रखी और विश्लेषण किया कि भारत के शहरों को प्रभावित करने वाली इस बदलती प्रवृत्ति की प्रकृति कहीं अधिक गहरी और लंबे समय तक है।
Scorching daytime temperatures due to the intense heat wave sweeping large parts of India and Pakistan are not the only problem facing tens of millions of people in cities. A new study warns that hotter nights and rising humidity levels are worsening heat stress on tens of millions of people, posing a growing health hazard. The study by the New Delhi-based Center for Science and Environment (CSE) points out that cities are not cooling down at night as much as they used to. It looked at six of India’s megacities, Delhi, Mumbai, Kolkata, Hyderabad, Chennai and Bengaluru over 23 years. “The temperature difference from morning to night used to be about 12 degrees Celsius or more two decades ago. That is not happening anymore in cities,” according to Avikal Somvanshi at the Center for Science and Environment. “If you see Delhi for example, the city does not cool down more than six to seven degrees Celsius in the peak summer season.” Somvanshi says hot nights are as dangerous as midday peak temperatures because people get little chance to recover from day-time heat. “This is a public health crisis, especially for the elderly and those who work outdoors.” In the Indian capital, rising nighttime temperatures are a double whammy for thousands of street vendors who brave the sizzling sun to ply their trade. Atma Prakash Singh, who sells rice and a lentil curry on a city pavement, takes care to park his cart under the shade of a tree. Still he says he gets frequent headaches and his feet ache at night. “Even standing here on this road is a problem. What to do? I have to survive the heat to earn a living,” he says. A study by Lancet Planetary Health has warned that the mortality risk on days with hot nights could be 50% higher than on days when nights are not so hot. Sunday, more than 30 cities recorded temperatures of over 45 degrees Celsius, mostly in northern, central and western India. That included parts of the capital New Delhi. Ice cream vendor, Jai Singh, does not need studies to tell him it has been a sizzling summer. He works from about noon to midnight on the roadside. “I get skin rashes. I keep eating cucumber and drinking water to stay cool,” he says. The nights provide little respite, he says.
New Delhi: Increasing concretization and humidity levels are exacerbating heat stress in India's megacities, which are not cooling down at night at the same rate as a decade ago, according to a new report by the Centre for Science and Environment (CSE)
NEW DELHI: In scorching Rajasthan, Phalodi reached a blistering 50 degrees Celsius, turning Sunday into a real test of endurance for people across India, especially those heading out to cast their votes in the ongoing elections. The India Meteorological Department noted that this is the highest temperature recorded since June 1, 2019, when Churu, also in Rajasthan, felt the heat at 50.8 degrees Celsius. Let's not forget Phalodi's record-setting moment back in 2016, when it hit a blazing 51 degrees Celsius. (IMD) predicted on Monday that the country can expect 'above normal' monsoon rainfall overall, especially in the monsoon core zone crucial for rain-fed agriculture, during the June to September rainy season. This is a positive signal for the economy, with a 61% probability of 'above normal' rainfall predicted. However, relief from the sweltering heat won't come soon for most parts of northwest India. The region will continue to endure scorching temperatures in June, with only brief relief expected after three days due to western disturbances. The IMD forecasts at least four to six days of heatwave conditions next month. Other regions of the country will also experience normal to above normal maximum and minimum temperatures in June. While climate change is a significant factor in rising temperatures, there are multiple underlying reasons contributing to the extreme heat in India. Let's dig into deeper into the causes behind these scorching temperatures. Historic temperatures Official data revealed that on Wednesday, temperatures soared to 45°C or higher in at least 24 locations across Delhi, Punjab, Haryana, Rajasthan, Uttar Pradesh, Gujarat and Madhya Pradesh. Rajasthan, Phalodi reached a blistering 50 degrees Celsius. The El Niño effect Scientists had already predicted the incoming heatwave in India, largely due to the El Niño effect. El Niño alters global weather patterns by shifting warm water to the eastern Pacific, heating the air and causing hotter weather worldwide. It began in 2023 and a NOAA report shows that 2023 was hotter than previous years. El Niño's impact is expected to last until June 2024, potentially making this summer extremely hot. How heatwave is form in India? A series of atmospheric and oceanic events triggers heatwaves over north-central and eastern India. Persistent hot and dry conditions in the wheat-growing north-central region, like the 2015 event that claimed over 2,500 lives, are linked to stationary high-pressure systems. These systems disrupt normal weather patterns by blocking usual flows and allowing slow-moving Rossby waves to transfer heat. El Niño, which raises ocean temperatures, along with a high-pressure system blocking moist sea breezes from the Bay of Bengal and Arabian Sea, led to record-high April temperatures in many parts of India this year. Even Kerala, a coastal state in the southwest where heatwaves are rare, was affected. However it's raining heavily today. The urban effect A study by the Centre for Science and Environment identifies the "urban heat island" effect as a key factor in rising temperatures. This phenomenon occurs when densely built areas trap heat, reduce green spaces, create congestion, and absorb and generate additional heat through human activities. Effect on human body Intense heat and humidity disrupt the body's ability to cool itself, leading to illness and potentially fatal outcomes even at lower temperatures. This dangerous combination is driving up the heat index, a metric that gauges how uncomfortable the weather feels Deaths According to Tirthankar Banerjee from the Institute of Environment and Sustainable Development at Banaras Hindu University, Varanasi, severe heatwaves cause immediate fatalities, but milder ones result in more deaths over time due to their frequency, according to Nature. World bank report A World Bank report predicts that by 2030, heat stress could lead to a global loss of 80 million jobs due to decreased productivity, with India potentially bearing 34 million of these job losses.
Northwest experienced severe weather conditions in over 17 locations, with temperatures breaching the 48 degrees Celsius mark, testing human endurance. Notably, Delhi's Mungeshpur reported a temperature of 48.8 degrees Celsius yesterday, while Haryana's Sirsa recorded 48.4 degrees Celsius. Meanwhile, the strength of heatstroke patients in Rajasthan increased from 2809 to 3622 yesterday. The Centre for Science and Environment (CSE) tracked heat waves in six major cities in India and the dangerous trends contributing to high temperatures. The science department assessed data from Delhi, Mumbai, Bengaluru, Hyderabad, Chennai, and Kolkata. The heat waves in India have worsened the Urban Heat Island Effect, i.e. when the temperature in urban areas is higher than in rural areas, resulting in a difference, CSE showed. Sharanjeet Kaur, program officer at the Centre for Science and Environment, told NDTV that high temperature and humidity are crucial to understanding cities' heat stress. "Usually, heatwaves occur between March and July, but nowadays, we are witnessing more humidity than heat, resulting in heat stress. The temperature is relatively high at night. Pavements and concrete structures absorb the heat during the day, which gets trapped, resulting in warmer nights," she said. The CSE analysis showed that heat stress results from a deadly combination of air temperature, land surface temperature and relative humidity. This leads to acute thermal discomfort and heat stress in cities. The analysis has pointed to a worrying trend in cities that are increasing in concretisation and decreasing in green cover and water reservoirs. All cities have registered a significant increase in their built-up areas and concretisation, this contributes to the urban heat island effect. During the day, heat is absorbed by concrete, which cannot emit it and hence causing the heat to be trapped. In rural areas, where more green cover is present, the process of transpiration - absorption of water by plants and evaporation through leaves and stems, allows water to be released into the atmosphere.
The temperature in 17 locations across the northwest breached the 48 degrees Celsius mark amid a severe heatwave which is testing human endurance. Delhi's Mungeshpur reported 48.8 degrees yesterday. Meanwhile, Haryana's Sirsa recorded 48.4 degrees. Meanwhile, the number of heatstroke patients in Rajasthan increased from 2809 to 3622 yesterday. The Centre for Science and Environment (CSE) tracked heat waves in six major cities in India and the dangerous trends contributing to high temperatures. The think tank assessed data from Delhi, Mumbai, Bengaluru, Hyderabad, Chennai, and Kolkata. Heat Wave Analysis Severe heat waves in India have worsened the Urban Heat Island Effect, i.e. when the temperature in urban areas is higher than in rural areas, resulting in a difference. Sharanjeet Kaur, a program officer at the Centre for Science and Environment, told NDTV that high temperature and humidity are crucial to understanding cities' heat stress. "Usually, heatwaves occur between March and July, but nowadays, we are witnessing more humidity than heat, resulting in heat stress. The temperature is relatively high at night. Pavements and concrete structures absorb the heat during the day, which gets trapped, resulting in warmer nights," she said. The CSE analysis shows that heat stress results from a deadly combination of air temperature, land surface temperature and relative humidity, which leads to acute thermal discomfort and heat stress in cities. The analysis points to a worrying trend in cities - The increasing concretisation and decreases in green cover and water reservoirs. All cities have registered a significant increase in their built-up areas and concretisation, this contributes to the urban heat island effect. Concrete absorbs heat during the day but cannot emit infrared heat, causing the heat to be trapped. In rural areas, where relatively more green cover is present, the process of transpiration - Absorption of water by plants and evaporation through leaves and stems, allows water to be released into the atmosphere. In 2023, Kolkata had the highest percentage of its land under concrete and the lowest green cover among the megacities. Delhi has comparatively the least area under concrete and the maximum green cover. Over the last two decades, built-up area in Chennai has doubled. Meanwhile, Kolkata registered only a 10% increase in its built-up area, making it the slowest as far as concretization is concerned. Increase In Relative Humidity Relative humidity has increased in all zones, the analysis said. This increase has worsened heat stress in warm-humid and moderate climate zones while it nullified the fall in air temperatures in composite and hot-dry climate zones, especially during monsoons. The average relative humidity (RH) has significantly increased in the last 10 summers compared to the 2001-10 average. Barring Bengaluru, the average relative humidity has increased by five to 10% in other megacities. In dry zones like Hyderabad, the relative humidity increased by 10% compared to 2001-2010. Meanwhile, in Delhi, it increased by 8%. Mumbai, Kolkata and Chennai are still over 25% more humid than Delhi and Hyderabad. When the relative humidity is combined with high heat, it adversely impacts human thermal comfort and health, Ms Kaur told NDTV. The report said high humidity is responsible for adding to heat stress. An average of 3.3 degrees Celsius of heat stress is being added, the report said. Delhi is not cooling down at night, the cooling down of land surface temperature between day and night-time is down by 9%. At night, the peri-urban area cools down by 12.2 degrees, while Delhi's core cools down by only 8.5 degrees - thus the city core is cooling down by 3.8 degrees less than its peri-urban areas. Heat Action Management Plan Summer temperatures often peak during May, but India Meteorological Department scientist Soma Sen Roy, earlier told Reuters that they are predicting 7-10 heatwave days in northwestern regions this month, compared to the usual 2-3 days. It was primarily due to fewer non-monsoon thundershowers and an active but weakening El Nino, she said, referring to a climate pattern that typically leads to hot and dry weather in Asia and heavier rains in parts of the Americas. The report said if climate change projections and urban growth scenarios are combined, future urbanization will amplify the projected increase in local air temperature. Listen to the latest songs, only on JioSaavn.com "We have analysed satellite imagery and assessed the change in land covers. We have to reverse the land use by ensuring an increase in green cover and water reservoirs in cities. We have to strengthen scientific monitoring of land use, activate emergency action plans and increase shaded areas and access to drinking water," Ms Kaur said.
Heat Wave Update: बीते दस साल में लगातार ह्यूमिडिटी (Humidity) बढ़ रही है. CSE की गर्मी पर एक रिपोर्ट सामने आई है. जिसमें बताया गया है कि 2001 से 2010 से मुक़ाबले बीते दस साल में ह्यूमिडिटी का स्तर तेज़ी से बढ़ा है. और ये हुआ है देश के बड़े महानगरों में, 10 सालों में सबसे ज़्यादा ह्यूमिडिटी हैदराबाद में बढ़ी है. जबकि दिल्ली (Delhi), मुंबई (Mumbai), कोलकाता (Kolkata), चेन्नई (Chennai) में भी 5 फ़ीसदी या उससे ज़्यादा ह्यूमिडिटी बढ़ी है.आपको बता दें कि गर्मी बढ़ने की एक बड़ी वजह ह्यूमिडिटी है.
According to a study by Delhi-based Centre for Science and Environment, India’s megacities of Delhi, Mumbai, Chennai, Bengaluru, Kolkata and Hyderabad are experiencing worsening heat stress. This is due to a trend of rising relative humidity over the past two decades. The study also pointed out that these cities are also experiencing warmer nights due to urban heat island effect. What is Heat Stress? About Heat stress occurs when the body cannot get rid of excess heat. When this happens, the body's core temperature rises and the heart rate increases. Basically, it refers to the physiological stress experienced by the body when exposed to excessive heat, particularly in high-temperature environments. Causes High ambient temperatures High humidity levels, which reduce the body's ability to cool through sweating Physical exertion, especially in hot conditions Inadequate hydration Poor ventilation in workspaces or living environments Symptoms As the body continues to store heat, the person begins to lose concentration and has difficulty focusing on a task, may become irritable or sick, and often loses the desire to drink. The next stage is most often fainting and even death if the person is not cooled down. What is Urban heat island (UHI) effect? About UHI effect refers to the phenomenon where urban areas experience significantly higher temperatures than their rural surroundings. This temperature difference is primarily due to human activities and the specific characteristics of urban environments. Causes Surface Characteristics Urban areas have more asphalt, concrete, and buildings that absorb and retain heat, unlike rural areas with vegetation that provide cooling through evapotranspiration. Heat Generated by Human Activities Industrial processes, vehicles, air conditioning units, and other machinery generate heat. Reduced Vegetation Less green space and fewer trees mean less shading and cooling from plants. Building Density Tall buildings and narrow streets can trap heat and reduce airflow, limiting cooling. Waste Heat Energy consumption for lighting, heating, and cooling buildings releases additional heat. Mitigation Strategies Increased Vegetation: Planting trees and creating green spaces can help cool urban areas through shading and evapotranspiration. Cool Roofs and Pavements: Using materials that reflect more sunlight and absorb less heat can reduce temperatures. Green Roofs: Installing vegetation on rooftops can provide insulation and reduce heat absorption. Urban Planning: Designing cities to include more parks, green belts, and open spaces can improve airflow and reduce temperatures. Energy Efficiency: Improving the energy efficiency of buildings can reduce the heat generated by human activities. Key highlights of the study Megacities are experiencing worsening heat stress India’s megacities of Delhi, Mumbai, Chennai, Bengaluru, Kolkata and Hyderabad are experiencing worsening heat stress. This is due to a trend of rising relative humidity over the past two decades. With the exception of Bengaluru, all the other metros have seen a 5-10 per cent rise in average relative humidity during summer. Impact of high heat and humidity on human body The combination of high heat and humidity can compromise the human body’s main cooling mechanism: sweating. The evaporation of sweat from skin cools our bodies, but higher humidity levels limit this natural cooling. The combination of these two factors makes people sick and, in some cases, can also prove fatal, even at lower ambient temperatures. Urban heat island effect impacting the night temperature These cities are also experiencing warmer nights as land surface temperatures are not falling at the same rate as a decade ago. The study has blamed this on the urban heat island effect. Hot nights are as dangerous as mid-day peak temperatures. People get little chance to recover from day-time heat if temperatures remain high overnight. Factors leading to increase in the heat index and heat stress The combination of rising air and land surface temperatures and high relative humidity is increasing the heat index and heat stress in these cities. Heat index is a measure of discomfort felt due to high heat and humidity. Monsoon period has become hotter The monsoon period has become hotter in Delhi, Mumbai and Kolkata, while in Chennai, the marginal cooling during monsoon has disappeared. In Bengaluru and Hyderabad, the monsoon was still a bit cooler than pre-monsoon.
New Delhi: Increasing concretisation and humidity levels are exacerbating heat stress in India’s megacities, which are not cooling down at night at the same rate as a decade ago, according to a new report by the Centre for Science and Environment (CSE). The CSE analysed summer air temperature, land surface temperature, and relative humidity data for six megacities – Delhi, Mumbai, Kolkata, Hyderabad, Bengaluru and Chennai – from January 2001 to April 2024. The think tank found that increased humidity is worsening heat stress across all climate zones, even nullifying the marginal drop in air temperatures in Delhi and Hyderabad. Barring Bengaluru, summertime average relative humidity has increased by 5-10% in the other five megacities from 2014-2023 compared to the 2001-2010 average. The CSE report comes at a time when blistering heatwaves are affecting health and livelihoods in large parts of India. “Assessing the changing trend in heat, relative humidity, and land surface temperature along with day and nighttime temperatures is necessary to develop a comprehensive heat management plan for urban centres,” said Anumita Roychowdhury, executive director of research and advocacy at the CSE. Avikal Somvanshi, senior programme manager at CSE’s Urban Lab, said addressing the combination of high heat and humidity is particularly important as it can compromise the human body’s main cooling mechanism, sweating. “The evaporation of sweat from the skin cools our bodies, but higher humidity levels limit this natural cooling. As a result, people can suffer heat stress and illness, and the consequences can even be fatal at much lower ambient temperatures,” he explained. The study showed that megacities are not cooling down at night. The land surface temperature during the summers of 2001-2010 would drop by 6.20-13.20 °C from the daytime peak to the nighttime low. In the last 10 summers (2014-2023), nighttime cooling has reduced to 6.20-11.50 °C, the CSE said. “Hot nights are as dangerous as midday peak temperatures. People get little chance to recover from daytime heat if temperatures remain high overnight,” Somvanshi said. “A study published in ‘The Lancet Planetary Health’ noted that the risk of death from excessively hot nights could increase nearly six-fold in the future. This prediction is much higher than the mortality risk from daily average warming suggested by climate change models,” he said. The study said that rising humidity levels have also made monsoons in Delhi, Mumbai, Kolkata, and Chennai hotter than pre-monsoon periods. It noted that all megacities have become more concretised in the last two decades, increasing heat stress. The CSE highlighted that an increase in green cover is not effective in mitigating nighttime heat. The study showed that Kolkata has the highest percentage of land under concrete and the lowest green cover among the megacities, while Delhi has the least area under concrete and the maximum green cover. Green cover has declined in Mumbai, Kolkata, and Chennai. The built-up area in Chennai has doubled in the last two decades, while its green cover shrank by almost 14 percentage points.
जून का महीना शुरू होने से पहले ही देश के राज्यों में भयानक गर्मी पड़ रही है। खासकर उत्तर-पश्चिम भारत में, दिल्ली का तो हाल बेहाल है। उत्पीड़न करने वाली हीटवेव है। लोग परेशान हैं लेकिन गर्मी कम नहीं हो रही है। अधिकतम तापमान सामान्य से करीब 8 डिग्री सेल्सियस ऊपर चल रहा है यानि 50 डिग्री पारा छू रहा है। मंगलवार को भी दिल्ली के कई इलाकों में मौसम विभाग के जारी आंकड़ों के अनुसार यह पारा छूता नज़र आया। मौसम विभाग ने दिल्ली को लेकर रेड अलर्ट जारी किया है। भारत मौसम विज्ञान विभाग (आईएमडी) के चीफ डॉ. मृत्युंजय महापात्रा की माने तो जून में इस तापमान में और ज्यादा इजाफा हो सकता है। हालांकि 30 मई के बाद कुछ दिन जरूर राहत मिल सकती हैं। फिलहाल अभी गर्मी से राहत मिलने के कोई आसार नहीं हैं। इसलिए भभक रही दिल्ली मौसम विभाग के अनुसार दिल्ली चारों तरफ से लैंडलॉक्ड है। यानी इसके चारों तरफ किसी भी दिशा में सिर्फ जमीन ही जमीन है। भौगोलिक स्थित देखें तो यह पाकिस्तान की गर्मी, राजस्थान के रेगिस्तान और हिमालय के बीच की जमीन है। इन जगहों पर होने वाले मौसमी या जलवायु संबंधी बदलाव का असर सीधे तौर पर दिल्ली तक आता है। दिल्ली के पश्चिम में मौजूद राजस्थानी रेगिस्तान में वायुमंडलीय बदलाव होने पर सीधा असर राष्ट्रीय राजधानी पर पड़ता है। मई में सूरज की गर्मी की वजह से रेगिस्तान गर्म हो जाता है। तापमान 50 डिग्री सेल्सियस तक चला जाता है। वायुमंडलीय स्थितियां सूखी रहती हैं। ह्यूमिडिटी खत्म हो जाती है या बेहद कम रहती है। सूखा और उसके साथ हवा की दिशा दिल्ली, राजस्थान, हरियाणा और पंजाब में गर्मी बढ़ा देती है। फिलहाल जो गर्मी है, उसके पीछे एक वजह पश्चिम से आ रही गर्म हवा है। इससे रेगिस्तानी गर्मी बहकर उत्तर-पश्चिम के मैदानी इलाकों में आती है। इसकी वजह से दिल्ली और उसके आसपास का तापमान तेजी से बढ़ जाता है। पारा 40 डिग्री सेल्सियस या उससे ऊपर ही रहता है। इसलिए 50 छू रहा पारा मई को एतिहासिक तौर पर देश का सबसे गर्म महीना माना जाता है। लेकिन इस साल दिल्ली में तापमान ने सारे रिकॉर्ड तोड़ दिए। जो संभावनाएं, आशंकाएं और उम्मीदें थी, सब टूट गईं। लगातार 15 दिन से दिल्ली और आसपास के इलाकों में भीषण गर्मी पड़ रही है। मौसम का नया पैमाना सेट हो रहा है। दिन का तापमान तो जला ही रहा है। रात का बढ़ता पारा भी शरीर को झुलसाने लायक हो चुका है। लोग रात में ढंग से सो नहीं पा रहे हैं। इससे उनका पूरा दिन खराब हो रहा है। शारीरिक दिक्कतें हो रही हैं। मानसिक समस्याएं भी हो रही हैं। दिल्ली अर्बन हीट आइलैंड में तब्दील हो चुकी है, इस वजह से ही पारा 50 डिग्री छू रहा है। क्या होता है अर्बन हीट आइलैंड अर्बन हीट आइलैंड्स वो जगह होती है जहां पर शहर के अंदर ही ज्यादा गर्मी महसूस होती है। तापमान ऊपर रहता है क्योंकि वहां पर काफी ज्यादा घनत्व में इमारतें होती हैं, हरियाली कम होती है या न के बराबर होती है। ये इलाके ज्यादा गर्मी सोखते हैं और ज्यादा समय तक गर्म रहते हैं। इसलिए ही दिल्ली और आस-पास के काफी इलाके रात में भी गर्म रहते हैं, क्योंकि वहां की इमारतों के मैटेरियल गर्मी निकालते रहते हैं। ये भी एक वजह इसके अलावा दूसरी सबसे बड़ी वजह है एयर कंडिशनर (एसी) का बेतहाशा इस्तेमाल, इसकी वजह से पारा और ऊपर जाता है। एसी अपने आप में हीट पंप होते हैं। ये गर्मी पैदा करते हैं। घर के अंदर तो ये ठंडा कर देते हैं लेकिन वायुमंडल को गर्म बना देते हैं। इनकी वजह से भी गर्मी में इजाफा होता है। जून में तापमान अधिक रहने की संभावना मौसम विभाग का कहना है कि उत्तर पश्चिम भारत के हिस्सों में भीषण लू चल रही है। 30 मई से इसकी तीव्रता कम होगी। वेस्टर्न डिस्टरबेंस के सक्रिय होने और अरब सागर से नमी के कारण देश के उत्तर पश्चिम और मध्य भागों में गरज के साथ बारिश होने की संभावना है। बारिश ज्यादा नहीं होगी और राहत मिले इसकी गुंजाइश कम है। जून में दिल्ली, पश्चिमी उत्तर प्रदेश, हरियाणा, पंजाब, राजस्थान समेत देश के ज्यादातर हिस्सों में तापमान सामान्य से अधिक रहने की आशंका है। यहां सामान्य से ज्यादा दिनों तक तेज लू चल सकती है। दिल्ली में इस बार गर्मी पहले से अधिक दिल्ली में लगातार दूसरे दिन अधिकतम तापमान 45 डिग्री के पार रहा। कई जगह तो 50 डिग्री को भी छू गया। नजफगढ़ में 49.7 डिग्री तापमान दर्ज किया गया। मौसम विभाग ने 29 मई को भी लू व भीषण गर्मी का रेड अलर्ट जारी किया है। 28 मई को हीट इंडेक्स 48 डिग्री रहा। यानी 45 डिग्री में लोगों को 48 डिग्री वाली गर्मी का अहसास हुआ। 41 डिग्री हीट इंडेक्स घातक सेंटर फॉर साइंस एंड एनवायरमेंट (सीएसई) ने देश के 6 शहरों- दिल्ली, बेंगलुरु, चेन्नै, हैदराबाद, कोलकाता और मुंबई को लेकर एक स्टडी की है। 24 सालों की इस स्टडी में पाया है कि सिर्फ तापमान नहीं बढ़ रहा है। बल्कि हवा, जमीनी सतह का तापमान और नमी मिलकर इन शहरों को असहनीय गर्मी की तरफ धकेल रहे हैं। 41 डिग्री का हीट इंडेक्स लोगों के लिए घातक माना जाता है। सीएसई की एग्जीक्यूटिव डायरेक्टर अनुमिता राय चौधरी के मुताबिक इस बदलाव को देखते हुए दिन और रात के लिए हीट मैनेजमेंट प्लान बनाने की जरूरत है। जरूरी है कि लू के समय इमरजेंसी उपाय किए जाएं। इस प्रकोप को कम करने के लिए लॉन्ग टर्म प्लान बने। इसके लिए ग्रीन एरिया और वॉटरबॉडी बढ़ाने, बिल्डिंग का थर्मल कंफर्ट सुधारने, गाड़ियों से निकलने वाली गर्मी को कम करने, एसी और इंडस्ट्री पर फोकस करने की जरूरत है।