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Cse In News

Cse In News

Heat wave: शहरीकरण का गर्मी कनेक्शन क्या है... ये खुद पर्यावरण विशेषज्ञ सुगीत ग्रोवर से सुनिए

CSE की रिपोर्ट में क्या कुछ खुलासे हुए हैं.. आपको बताते हैं..पिछले दो दशक बेहद गर्म रहे हैं और तापमान लगातार बढ़ रहा है... महानगरों जैसे दिल्ली मुंबई, चेन्नई में उमस बीते दशक में 5 से 10 फीसदी बढ़ी है.. हैदराबाद में 10 फीसदी...मुंबई में 8 फीसदी... कोलकाता में 7 फीसदी तो वहीं चेन्नई में 5 फीसदी तक उमस बढ़ गई है.. इसकी वजह है बढ़ता शहरीकरण क्योंकि बिल्टअप एरिया लगातार बढ़ा है.. 2003 में 31 दशमलव 3 फीसदी बिल्टअप एरिया बढ़कर 2022 में 38 दशमलव 2 फीसदी पहुंच गया है...

चार दिन में केरल पहुंचेगा मानसून, इन 6 राज्यों में होगी झमाझम बारिश

इन छह शहरों में लू का कहर सेंटर फॉर साइंस एंड एनवायरनमेंट (सीएसई) ने भी भारत के छह प्रमुख शहरों में लू के थपेड़ों और ऊंचे तापमान को खतरनाक बनाने वाले कारणों का विश्लेषण कर बताया कि इस बार पारा के साथ हवा में बढ़ती नमी (ह्यूमिडिटी) का खतरनाक संयोजन परेशान करने वाला है। यह अध्ययन दिल्ली, मुंबई, बेंगलुरु, हैदराबाद, चेन्नई और कोलकाता के आंकड़ों का आकलन किया।

खुल गया राज! रात को भी क्यों कम नहीं हो रही गर्मी

अगर आप उत्तर भारत में कहीं भी रहते हैं तो आप जानते होंगे कि गर्मी से हाल बेहाल है। ऐसी गर्मी सालों से नहीं पड़ी। क्या आपने ये सोचा है कि दिन ब दिन पारा क्यों बढ़ता जा रहा है। एक हैरान करने वाला फैक्ट ये है कि अब रात में शहरों में उतनी तेजी से पारा नहीं गिर रहा जिस तरह 2001 से लेकर 2010 के बीच होता था। और ये बात सिर्फ सुनी सुनाई नहीं बल्कि दिल्ली के थिंकटैंक सेंटर फॉर साइंस एंड इनवायरमेंट यानि CSE की स्टडी से पता चला है।

दिल्ली में पारा पहुंचा 50 के करीब, गर्मी का नया रिकॉर्ड

रात का तापमान भी बढ़ा इस बीच निजी संस्थान सेंटर फॉर साइंस एंड एनवायरनमेंट ने गर्मी पर एक नया अध्ययन किया है. अध्ययन में कहा गया है कि किसी भी शहर में गर्मी की लहर का कारण सिर्फ बढ़ता तापमान नहीं है, बल्कि हवा के तापमान, जमीन की सतह का तापमान और तुलनात्मक ह्यूमिडिटी का मिश्रण है. अगर कहीं पर हवा का तापमान गिर भी जाए तो बाकी दोनों कारण मिल कर ऐसे हालात नहीं बनने देते जिनमें थोड़ी राहत महसूस हो. अध्ययन के मुताबिक देश के लगभग सभी बड़े शहरों में बीते 10 सालों में तुलनात्मक ह्यूमिडिटी बढ़ी है. इसके अलावा एक और चिंताजनक बात यह है कि रात का तापमान भी लगातार बढ़ा हुआ रह रहा है. अध्ययन के मुताबिक 2001 से 2010 तक गर्मियों में जमीन का तापमान रात को 6.2 से 13.2 डिग्री सेल्सियस तक गिर जाता था, लेकिन 2014 से 23 के बीच रात के समय तापमान 6.2 से लेकर सिर्फ 11.5 डिग्री तक ही गिरा. दिल्ली में अब रातें नौ प्रतिशत, हैदराबाद में 13 प्रतिशत, बेंगलुरु में 15, चेन्नई में पांच और मुंबई में 24 प्रतिशत कम ठंडी रहने लगी हैं.

Urban Heat Island Effect: दिन में बहुत गर्मी है लेकिन रात के किसी पहर भी सुकून क्‍यों नहीं मिल रहा?

10 दिन से अधिक दिनों की हीटवेव बढ़ते तापमान और गर्मी के लिहाज से देखें तो ये लगातार तीसरा ऐसा साल है जब हीटवेव (Heatwave) यानी तपिश लगातार 10 दिन से अधिक रही है. जबकि आमतौर पर ये अवधि 4-10 दिन की होती है. तापमान की अवधि के बढ़ने का कारण क्‍लाइमेंट चेंज है और इसी वजह से ह्यूमिडिटी भी बढ़ी है. इस संदर्भ में सेंटर फॉर साइंस एंड एन्‍वायरमेंट (CSE) की एक रिपोर्ट कहती है कि हवा में नमी के कारण पसीना बेहद तेजी से सूख रहा है लिहाजा वास्‍तविकता की तुलना में गर्मी ज्‍यादा महसूस हो रही है. इसके लिए सिर्फ यही कारण जिम्‍मेदार नहीं हैं बल्कि जमीन के इस्‍तेमाल और शहरी बुनावट में बदलाव भी इसके प्रमुख कारणों में शुमार है.

दिल्ली मेंपारा पहुंचा 50 के करीब, गर्मी का नया रिकॉर्ड

राजस्थान के चूरू मेंपारा 50.5 तक और हरियाणा के सिरसा में 50.3 तक पहुंच गया. मौसम विभाग का कहना हैकि तापमान अपेक्षित स्तर सेनौ डिग्री ज्यादा है. विभाग नेबुधवार को भी गर्मी की लहर के बरकरार रहनेका पूर्वानुमान दिया है. मीडिया रिपोर्टों मेंदावा किया जा रहा है कि राजस्थान मेंगर्मी की वजह सेकई लोगों की मौत हो चुकी है. रात का तापमान भी बढ़ा इस बीच निजी संस्थान सेंटर फॉर साइंस एंडएं एनवायरनमेंट नेगर्मी पर एक नया अध्ययन किया है. अध्ययन मेंकहा गया हैकि किसी भी शहर मेंगर्मी की लहर का कारण सिर्फ बढ़ता तापमान नहीं है, बल्कि हवा के तापमान, जमीन की सतह का तापमान और तुलनात्मक ह्यूमिडिटी का मिश्रण है. अगर कहीं पर हवा का तापमान गिर भी जाए तो बाकी दोनों कारण मिल कर ऐसे हालात नहीं बननेदेतेजिनमेंथोड़ी राहत महसूस हो. अध्ययन के मुताबिक देश के लगभग सभी बड़े शहरों मेंबीते 10 सालों मेंतुलनात्मक ह्यूमिडिटी बढ़ी है.

Heatwave Alert: दिल्ली, मुंबई समेत कई शहरों में हीट स्ट्रेस का कहर, दिन के अलावा रात में भी क्यों सता रही गर्मी?

दिन में लू की मार और रात में गर्मी का सितम...मौसम का मिजाज इन दिनों बेहद गर्म है. दिन का गर्म होना लाजिमी है लेकिन क्या आपने सोचा है रात के वक्त भी इत...

Heat stress exposes dangerous trends in India’s biggest cities

Amid ongoing scorching summer, six mega cities across India are facing an unprecedented heat wave that is worsening the urban heat island effect. This has been revealed by a latest study done by New Delhi-based Centre for Science and Environment (CSE). The CSE study highlighted that heat stress is not just about rising temperatures. It is a deadly combination of air temperature, land surface temperature and relative humidity that leads to acute thermal discomfort and heat stress in cities. The CSE has tracked heat in six megacities—Bengaluru, Chennai, Delhi, Hyderabad, Kolkata and Mumbai. The time frame of the study is the summer of January 2001 till April 2024. “An unprecedented heat wave has been enveloping Indian cities, worsening the urban heat island effect, this summer. There are far deeper and longer term evidences on the nature of this changing trend that is impacting India’s biggest cities” the study said. Anumita Roychowdhury, executive director, research and advocacy at CSE, said in a statement that: “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 the urban centres. This is needed to implement emergency measures during heatwaves to protect public health, and also to develop longer term strategies to mitigate heat by increasing green areas and waterbodies, improving thermal comfort in buildings, and reducing waste heat from vehicles, air-conditioners and industries”. According to the study, cities in the warm-humid and moderate climate zones show an increase, while cities in composite and hot-dry climate zones indicate a decline. Ambient air temperature has changed by less than 0.5°C between 2001-10 and 2014-23. Decadal summer-time average ambient temperature has risen by about 0.5°C in Mumbai, Bengaluru and Chennai compared with 2001-10. Kolkata’s decadal average is also up by 0.2°C. Delhi and Hyderabad, two metros which are located in composite climate zones known for the driest and harshest summers, have registered lower decadal average compared with 2001-10, the study adds. Decadal summer-time average for Delhi is down by 0.6°C and for Hyderabad, by 0.9°C, compared with 2001-10. “Addressing the combination of high heat and humidity is particularly important as this 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. As a result, people can suffer heat stress and illness, and the consequences can even be fatal even at much lower ambient temperatures. Interestingly, night time temperature is remaining elevated in cities,” Avikal Somvanshi, senior programme manager, Urban Lab, CSE said in a statement related to the study’s release. Relative humidity has increased in all zones. This increase has made heat stress worse in warm-humid and moderate climate zones, while it has nullified the fall in air temperatures in composite and hot-dry climate zones, especially during monsoons. Average relative humidity (RH) has significantly increased in the last 10 summers compared with the 2001-10 average, the study noted. Barring Bengaluru, decadal summer-time average RH has increased by 5-10% in the other five mega cities, it added. The CSE study said that given the rise of relative humidity during summers, the heat index (HI) has risen among mega cities. Chennai´s summer average heat index stood at 37.4°C (impact of humidity: 6.9°C) making it the hottest among the mega cities. Kolkata with a summer HI average of 36.5°C (impact of humidity: 6.4°C) and Mumbai with 34.3°C (impact of humidity: 5°C) were almost equally hot. Delhi’s summer HI average stood at 32.2°C (impact of humidity: 3.3°C) and Hyderabad’s at 29.3°C (impact of humidity: 1.2°C). Bengaluru was the least hot among the mega cities with a summer HI average of 26.9°C (impact of humidity: 0.8°C). The study noted that monsoons were more thermally uncomfortable in Delhi, Mumbai, Kolkata and Chennai with their heat index being higher than during pre-monsoon period. Besides, cities are not cooling down at night at the rate they used to during 2001-10: This phenomena has been observed across all climatic zones. During the summers of 2001-10, land surface temperatures used to drop by 6.2°C-13.2°C from the day-time peak. Hyderabad used to cool down at night the most, while Kolkata the least. Now, in the last 10 summers (2014-23), night-time cooling has reduced to 6.2°C-11.5°C. The study noted that night-time cooling was getting lesser in the past few years for all megacities compared with the mid-2010s. “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. A study published in the Lancet Planetary Health has noted that the risk of death from excessively hot nights would increase nearly six-fold in future. This prediction is much higher than the mortality risk from daily average warming suggested by climate change models,” said Somvanshi. The study also noted a direct co-relation between increase in built-up area and increase in urban heat stress. All megacities have become more concretised in the last two decades; this has contributed to the rise in heat stress; increase in green cover can moderate day-time heat, but is not that ineffective in arresting night-time heat. 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, it said. Over the past two decades, built-up area in Chennai has doubled. Kolkata has registered an only 10 percentage points increase in its built-up area, making it the slowest as far as concretisation is concerned. Hyderabad has doubled its green cover in the past two decades—fastest among the megacities. However, green cover has declined in Mumbai, Kolkata and Chennai. The maximum decline was noted in Chennai, whose green cover shrank by almost 14 percentage points, the CSE study said. The technical summary of the Intergovernmental Panel on Climate Change (IPCC), Working Group-I, Sixth Assessment Report (AR6 WG-I) notes that the frequency and intensity of heat extremes and duration of heat waves have almost certainly increased since 1950, and will keep rising even if global warming is stabilized at 1.5°C. The CSE study recommended implementation of city-specific heat management plans to go beyond immediate emergency responses to help cope with specific heat events during summer and prevent heat lock-in. Key heat generators, such as concrete built surfaces, barren land and waste heat generators like vehicles, industries, and cooling devices should be brought under the ambit of the plan. Guidelines and action plans to reduce thermal load on buildings and enhance thermal comfort; manage waste heat must be adopted. It also called for ensuring reversal of land-use changes to expand green areas and waterbodies for stronger cooling effect. Among the other recommendations are and increase in shaded areas. “There should be tracking of annual and diurnal trends in temperature, humidity and overall heat index to inform planning and implementation. It is critical to develop emergency healthcare systems for heat-related disease burden, expand the shaded areas in cities, ensure availability of drinking water in public spaces, and reduce heat exposure for vulnerable and occupationally exposed groups in cities,” the study added.

Heat Stress Exposes Dangerous Trends in India’s Biggest Cities

Amid ongoing scorching summer, six mega cities across India are facing an unprecedented heat wave that is worsening the urban heat island effect. This has been revealed by a latest study done by New Delhi-based Centre for Science and Environment (CSE). The CSE study highlighted that heat stress is not just about rising temperatures. It is a deadly combination of air temperature, land surface temperature and relative humidity that leads to acute thermal discomfort and heat stress in cities. The CSE has tracked heat in six megacities – Bengaluru, Chennai, Delhi, Hyderabad, Kolkata and Mumbai. The time frame of the study is the summer of January 2001 till April 2024. “An unprecedented heat wave has been enveloping Indian cities, worsening the urban heat island effect, this summer. There are far deeper and longer term evidences on the nature of this changing trend that is impacting India’s biggest cities” the study said. Anumita Roychowdhury, executive director, research and advocacy at CSE, said in a statement that: “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 the urban centres. This is needed to implement emergency measures during heatwaves to protect public health, and also to develop longer term strategies to mitigate heat by increasing green areas and waterbodies, improving thermal comfort in buildings, and reducing waste heat from vehicles, air-conditioners and industries”. According to the study, cities in the warm-humid and moderate climate zones show an increase, while cities in composite and hot-dry climate zones indicate a decline. Ambient air temperature has changed by less than 0.5°C between 2001-10 and 2014-23. Decadal summer-time average ambient temperature has risen by about 0.5°C in Mumbai, Bengaluru and Chennai compared with 2001-10. Kolkata’s decadal average is also up by 0.2°C. Delhi and Hyderabad, two metros which are located in composite climate zones known for the driest and harshest summers, have registered lower decadal average compared with 2001-10, the study adds. Decadal summer-time average for Delhi is down by 0.6°C and for Hyderabad, by 0.9°C, compared with 2001-10. “Addressing the combination of high heat and humidity is particularly important as this 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. As a result, people can suffer heat stress and illness, and the consequences can even be fatal even at much lower ambient temperatures. Interestingly, night time temperature is remaining elevated in cities,” Avikal Somvanshi, senior programme manager, Urban Lab, CSE said in a statement related to the study’s release. Relative humidity has increased in all zones. This increase has made heat stress worse in warm-humid and moderate climate zones, while it has nullified the fall in air temperatures in composite and hot-dry climate zones, especially during monsoons. Average relative humidity (RH) has significantly increased in the last 10 summers compared with the 2001-10 average, the study noted. Barring Bengaluru, decadal summer-time average RH has increased by 5-10% in the other five mega cities, it added. The CSE study said that given the rise of relative humidity during summers, the heat index (HI) has risen among mega cities. Chennai´s summer average heat index stood at 37.4°C (impact of humidity: 6.9°C) making it the hottest among the mega cities. Kolkata with a summer HI average of 36.5°C (impact of humidity: 6.4°C) and Mumbai with 34.3°C (impact of humidity: 5°C) were almost equally hot. Delhi’s summer HI average stood at 32.2°C (impact of humidity: 3.3°C) and Hyderabad’s at 29.3°C (impact of humidity: 1.2°C). Bengaluru was the least hot among the mega cities with a summer HI average of 26.9°C (impact of humidity: 0.8°C). The study noted that monsoons were more thermally uncomfortable in Delhi, Mumbai, Kolkata and Chennai with their heat index being higher than during pre-monsoon period. Besides, cities are not cooling down at night at the rate they used to during 2001-10: This phenomena has been observed across all climatic zones. During the summers of 2001-10, land surface temperatures used to drop by 6.2°C-13.2°C from the day-time peak. Hyderabad used to cool down at night the most, while Kolkata the least. Now, in the last 10 summers (2014-23), night-time cooling has reduced to 6.2°C-11.5°C. The study noted that night-time cooling was getting lesser in the past few years for all megacities compared with the mid-2010s. “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. A study published in the Lancet Planetary Health has noted that the risk of death from excessively hot nights would increase nearly six-fold in future. This prediction is much higher than the mortality risk from daily average warming suggested by climate change models,” said Somvanshi. The study also noted a direct co-relation between increase in built-up area and increase in urban heat stress. All megacities have become more concretised in the last two decades; this has contributed to the rise in heat stress; increase in green cover can moderate day-time heat, but is not that ineffective in arresting night-time heat. 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, it said. Over the past two decades, built-up area in Chennai has doubled. Kolkata has registered an only 10 percentage points increase in its built-up area, making it the slowest as far as concretisation is concerned. Hyderabad has doubled its green cover in the past two decades -- fastest among the megacities. However, green cover has declined in Mumbai, Kolkata and Chennai. The maximum decline was noted in Chennai, whose green cover shrank by almost 14 percentage points, the CSE study said. The technical summary of the Intergovernmental Panel on Climate Change (IPCC), Working Group-I, Sixth Assessment Report (AR6 WG-I) notes that the frequency and intensity of heat extremes and duration of heat waves have almost certainly increased since 1950, and will keep rising even if global warming is stabilised at 1.5°C. The CSE study recommended implementation of city-specific heat management plans to go beyond immediate emergency responses to help cope with specific heat events during summer and prevent heat lock-in. Key heat generators, such as concrete built surfaces, barren land and waste heat generators like vehicles, industries, and cooling devices should be brought under the ambit of the plan. Guidelines and action plans to reduce thermal load on buildings and enhance thermal comfort; manage waste heat must be adopted. It also called for ensuring reversal of land-use changes to expand green areas and waterbodies for stronger cooling effect. Among the other recommendations are and increase in shaded areas. “There should be tracking of annual and diurnal trends in temperature, humidity and overall heat index to inform planning and implementation. It is critical to develop emergency healthcare systems for heat-related disease burden, expand the shaded areas in cities, ensure availability of drinking water in public spaces, and reduce heat exposure for vulnerable and occupationally exposed groups in cities,” the study added.

India is Scorching, Daytime Temperature up to 50 Degrees Celsius

Major cities in India, such as New Delhi, Mumbai, Chennai, Bengaluru, Kolkata, and Hyderabad, are predicted to experience worsening heatwaves due to increasing humidity in the next two decades. A study by the Center for Science and Environment (CSE) in India revealed that the phenomenon of urban heat islands occurs due to the reduction of green areas, traffic congestion, heat absorption, and the addition of heat from human activities.

Rising Humidity and Urban Heat Islands Worsen Heat Stress in India's Megacities, Study Reveals

India’s megacities, including Delhi, Mumbai, Chennai, Bengaluru, Kolkata, and Hyderabad, are experiencing worsening heat stress due to rising relative humidity over the past two decades, according to a study by the Centre for Science and Environment (CSE). This unprecedented heat wave has exacerbated the urban heat island effect this summer, revealing long-term trends that significantly impact these major cities.

Delhi summers in past 100 years: Were several days of heatwave as common back then?

But were Delhi summers always this bad? If not, what has led to the intense heatwave weather condition in Delhi. A detailed analysis by the Centre for Science and Environment (CSE), conducted between the summers of January 2001 and April 2024, heat stress has increased manifolds in the urban landscape over the years. Similarly, a study by the India Meteorological Department (IMD), and the Institute for Climate Change Studies (ICCS) stated that the number of heat wave days in India in a decade has increased from 413 in between 1981-90 to 575 between 2001-10 and further to 600 between 2010-20. In addition to this, most of the 103 weather stations, that study heat wave occurrences in the country, shown an increase or a significantly increasing trend in heat wave frequency between April and June during the 1961-2020 period.

Why is North India including Punjab & Delhi witnessing record-breaking high temperatures? Explained

India heatwave reason explained As per a report, 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 CSE analysed that 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. A program officer named Sharanjeet Kaur was quoted saying 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." The CSE outlined 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.

June is but to finish and the mercury is touching 49°! Know what the climate division mentioned about ‘warmth hunter’ – extra heatwave alert issued in Delhi, UP, Bihar, IMD warns climate replace

Temperatures are usually not the one factor rising in these cities The Heart for Science and Setting (CSE) has completed a examine on 6 cities of the nation – Delhi, Bangalore, Chennai, Hyderabad, Kolkata and Mumbai. This examine has discovered that not solely the temperature is rising, however the wind, floor floor temperature and humidity collectively are pushing these cities in the direction of insufferable warmth. A warmth index of 41 levels is taken into account deadly for folks. In response to Anumita Raichaudhuri, Government Director of CSE, in view of this variation, there’s a must make a warmth administration plan for day and night time. It is necessary that emergency measures are taken throughout warmth wave. A long run plan needs to be made to scale back this outbreak. For this, there’s a want to extend inexperienced space and water our bodies, enhance the thermal consolation of buildings, scale back the warmth emitted from autos, concentrate on AC and trade. The examine has in contrast between January 2001 and April 2024.

Urban heat island effect hits Indian cities harder by night—make that 60 per cent hotter

ccording to an analysis by the Centre for Science and Environment (CSE), New Delhi Delhi, cities are not cooling down at night like they used to in 2001–10 because they have 'become more concretised in the last two decades', contributing to a rise in heat stress. The analysis said that while increasing green cover can moderate daytime heat, it is ineffective for arresting nighttime heat. According to the World Resources Institute (WRI) India Ross Center, seven out of 10 people around the world are projected to be living in urban areas by 2050. While about 90 per cent of the growth is expected to happen in the Global South, a significant fraction of this will occur in India, it said.

What Is Causing Severe Heatwaves In Delhi, Mumbai, Other Big Cities? New Study Explains Factors Causing Heat Stress

An analysis of six megacities in India - Delhi, Mumbai, Kolkata, Hyderabad, Bengaluru, and Chennai - revealed that nighttime temperatures are not cooling down at the rate they used to during 2001-10. The analysis also highlighted the factors causing increased heat stress in urban cities.\"Increasing relative humidity across all climate zones has worsened the heat index (combination of air temperature and relative humidity) and heat stress in every city,\" said a trend-analysis report released by the Centre for Science and Environment. The study was conducted by the CSE between the summers of January 2001 and April 2024 is heat stress?The CSE explained in its analysis that the heat stress is not just about rising temperatures. \"It is a deadly combination of air temperature, land surface temperature and relative humidity that leads to acute thermal discomfort and heat stress in cities,\" the report said has made heat stress worse?1. Rising Humidity: As per the report, the increase in relative humidity in all zones \"has made heat stress worse in warm-humid and moderate climate zones\". This increase has also \"nullified the fall in air temperatures in composite and hot-dry climate zones, especially during monsoons\".The report highlighted the city-wise trends and added that the increased humidity in Delhi and Hyderabad, which are located in climate zones known for the driest and harshest summers, \"somewhat nullifies their marginal drop in ambient air temperatures\".2. Spike in built-up area: An increase in the built-up area in cities is another factor contributing to the urban heat stress. \"All megacities have become more concretised in the last two decades; this has contributed to the rise in heat stress,\" the report said added that though an increase in green cover can moderate day-time heat, it is not that effective in arresting night-time heat.\"Built-up area has increased from 31.4 per cent in 2003 to 38.2 per cent in 2022. Green cover has increased from 32.6 per cent in 2003 to 44.2 per cent in 2022. An increase in green cover shows the impact on daytime temperatures, but it has had no impact on night-time temperatures and the increasing heat index,\" the CSE said in its analysis in the other four cities, increased humidity intensifies the heat stress temperatures in 6 citiesThe analysis revealed that Mumbai, Kolkata, Bengaluru, and Chennai have seen an increase in air temperature, while Delhi and Hyderabad appear to be defying the trend summer-time average ambient temperature has risen by about 0.5°C in Mumbai, Bengaluru and Chennai compared to 2001-10. Kolkata's decadal average is also up by 0.2°C, the CSE study added, Delhi and Hyderabad registered \"lower decadal average compared to 2001-10\". It added that the decadal summer-time average for Delhi is down by 0.6°C and for Hyderabad, by 0.9°C, compared to 2001-10 does heat stress affect humans?The combination of high heat and humidity may compromise the \"human body's main cooling mechanism\" – that is sweating. Avikal Somvanshi, senior programme manager, Urban Lab, CSE, explained that the evaporation of sweat from the skin cools 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 even at much lower ambient temperatures. Interestingly, nighttime temperature remains elevated in cities,\" said Somvanshi hotter nights ahead?The analysis further showed that the six big cities are not cooling down at night at the rate they used to during 2001-10. Only Kolkata, among other metro cities, cools down at night at the same rate as in 2001-10, the expert from CSE, said hot nights are as dangerous as mid-day peak temperatures. She cited a study published in the Lancet Planetary Health to inform that the \"risk of death from excessively hot nights would increase nearly six-fold in future\".\"This prediction is much higher than the mortality risk from daily average warming suggested by climate change models,\" Somvanshi added CSE study further revealed that the \"urban heat island effect\" is stronger at night. It said that at night, the peri-urban area cools down by 12.2°C, while the city core cools down by only 8.5°C. \"Thus, the city core is cooling down 3.8°C less than its peri-urban areas,\" it added. The study noted that March-April of 2024 was 3°C cooler than the average of 2014-23 is the urban heat island effect?The new analysis by the CSE showed that an unprecedented heat wave has been gripping Indian cities this summer, worsening the urban heat island effect \"urban heat island\" effect happens when built-up areas in urban regions trap heat, reduce green cover, cause congestion, absorb heat, and generate additional heat from human activities said the urban heat island effect can add 2°C to local warming, reducing the adaptive capacity of cities and increasing the risks.\"This is due to reduced ventilation, heat-trapping by closely spaced tall buildings, heat generated directly from human activities, heat-absorbing properties of concrete and urban building materials, and limited vegetation,\" the analysis explained.