Dr. Ajay Kumar Srivastava is an Agrometeorologist at the College of Agriculture, Jawaharlal Nehru Krishi Vishwavidyalaya (JNKVV), Tikamgarh, Madhya Pradesh

Heat Wave events, magnitude and its timing are changing with every passing year in India. In recent past the month of March is reported as warmest year during past 121 years in India. It is projected that the central parts of the country would be experienced more heat waves events up to mid of this century. A number of publications have been reported that during past two decades heat waves events increased over central parts of India and many deaths had been observed. The present analysis was carried out in eastern part of Madhya Pradesh and observed that the heat wave during the past two decades irrespective of the climatic conditions of a place has lowered.

Eastern Madhya Pradesh

Heat wave is a period of abnormally high (maximum) temperatures, which occurs during the summer season (March to June) in parts of India. It is reported that climate changes leads to changes in the frequency, intensity, spatial extent, duration, and timing of heat waves at global scale (Vimal et al.,2020). India is also witness the impact of climate change and due to which heat waves events, its duration and intensity with time have increased and witness distressing impact on human health (Ray et al., 2021).

It is reported that central parts of India in general and eastern Madhya Pradesh in particular is more vulnerable to climate change and thus due to heat waves (Vimal et al.,2020). In view of these, the present study is focused over the eastern part of Madhya Pradesh. The two districts of eastern Madhya Pradesh in which one is sub- humid climate (Jabalpur), other has semi-arid climate (Tikamgarh) were selected. The Madhya Pradesh state comprises with hills, valley, plateau and plain regions. The whole state is divided into 11 agroclimatic zone namely: Chhattisgarh plains, Northern Hill Region, Kymore Plateau & Satpura Hills of Chhattisgarh, Central Narmada Valley, Vindhya Plateau, Gird Region, Bundelkhand, Satpura Plateau, Malwa Plateau, Nimar Plains and Jhabua Hills (Fig.2).

Among the 11 agroclimatic zones, two districts representing the 2 agro climatic zone were selected and their latitude and normal rainfall and temperatures are given in table 1.

        Table 1 : Climate of the two selected districts

Extreme weather events and heat waves were observed in these two districts in past (Srivastava et al., 2020). The highest maximum temperature values were recorded 48.8°C on 27 May 1998 at Tikamgarh, 48.6°C on 11 May 1984 at Jabalpur during past 40 years. As per India Meteorological Department, March is observed the second warmest month during past 121 years over central India. This year(2022) heat waves over Tikamgarh district of Madhya Pradesh was observed during first fortnight of the April month (Fig.2). The maximum temperature was observed above 43°C from past few days.

Heat waves

Extreme weather events in general and heat wave in particular; are determining factor for human, animal health as well as the agricultural production. To have an idea about heat waves events, its extent in the two districts of eastern Madhya Pradesh long term observed temperature data (1980- 2020) was analyzed and presented below:

Daily maximum temperature data during the period 1980 – 2020 of the two districts were collected and screened for heat waves and the following two criteria were adopted:

Heatwave is considered, when observed maximum temperature of a station ≥ 43°C

Heatwave is considered, when observed maximum temperature of a station ≥ 45°C

The number of days equal to or above 43°C was screened out for both the districts and their decadal number is presented in table 2. It was noticed that the number of heat waves day’s values were decreased over the decades at both the districts. For further details; the annual analysis of the number of days and spells of heat waves were also carried out.

Analysis of observed number of maximum temperature days as well as the spells of heat waves over the eastern Madhya Pradesh on annual scales from 1980 to 2020 was carried out and presented in figures 3 to 6. From the figures 3 and 4 it was observed that the number of days equal to and above 43 and 45°C were decreased both at Tikamgarh and Jabalpur districts of Madhya Pradesh. The decreasing trend of number of days equal to or above 43°C at Tikamgarh was found significant. Similarly the heat waves spells were also showed a decreasing trend at Tikamgarh and Jabalpur, though the trends were found to be non-significant. The above results suggest that though the central India’s climate is warming up but eastern Madhya Pradesh has not showed such trend. An analysis reported by India Meteorological Department on heat wave data (2017-2021) showed that 8-12 day-long heat wave spells were observed over Rajasthan, Madhya Pradesh, Haryana, Chandigarh and Delhi, Punjab and parts of Gujarat from April 2017 to 2019. Das et al., (2020) reported from 39

           years of weather data analysis; that the increasing trends of heat waves were found over Rajasthan, Haryana, Punjab, East Madhya Pradesh, and Orissa. Nandi and Pillai (2022) reported that India recorded its warmest March during past 121 years with maximum temperature across the country was 1.9°C above its  normal value. They further reported that March 2022 was the second warmest in 121 years in terms of maximum temperature over central India. Rajasthan, Madhya Pradesh, and Maharashtra were among some of the worst-affected states from the extreme heat, having experienced the longest spells of dry weather and extreme heat conditions.In West Rajasthan, Churu experienced 50.8°C and Sri Ganganagar recorded  49.6°C on 2nd June, 2019.

Adverse Impact of Heat Waves

The heat wave is natural disaster and spreading over time and affects the human, animal and plant life. Heat waves occur more slowly and over a wider area than typhoons, heavy rain, heavy snow, and strong winds (Kim et al., 2020). It was found that 3014 men died from heat-related causes during 2001–05, which increased to 5157 in the period 2011–15. Deaths caused by heatwaves were found to be higher than those resulting from avalanches, exposure to cold, cyclone, tornado, earthquake, epidemic, flood, landslide, torrential rain and forest fire. The impact of rising temperatures, its  increasing frequency, duration and intensity of hot spells in India poses a challenge to human safety and sustainability for its 1.3 billion populations.  The damage caused by other natural disasters mostly results from external physical forces such as flooding and collapse, but in heat waves, health problems occur mainly due to bodily exposure to high temperatures. Therefore, the damage caused by heat waves is strongly affected not only by heat waves themselves but also by the state of individuals’ health, their residences, and working conditions.

For the last few years, heat waves during the summer season in India are increasingly affecting morbidity and mortality in the country (Figure 7).

The numbers of deaths varies with region and are influenced by the demographics and socioeconomic characteristics of the region(Kumar and Singh,2021). Therefore, there is a need for targeted region-specific interventions for reducing the number of deaths due to heat waves. Heat wave killed thousands of people and has also caused death of cattle and wildlife besides affecting animal’s health in India. The increased occurrences and severity of heat – wave is a wake – up call for all the agencies to take necessary action for prevention, preparedness and community outreach to save the lives of the general public, livestock and wild life.

Heat waves projections

Heat waves are projected to be more intense, have longer durations and occur at a higher frequency and earlier in the coming years in future. In India too, more frequent and intense heat waves are projected, which would negatively impact vulnerable communities and thereby increase mortality. Severe heat waves is projected over India by Mishra et al.(2017) and reported that it would increase by about 15 and 92 times from the current level by the mid and end-21st century respectively.

Way Forward

Extreme heat can lead to serious health consequences, including heat stress and heat stroke. Heat related health impacts are found to be more severe in urban areas, where residents are exposed to higher and nocturnally sustained temperatures compared to surrounding areas due to a phenomenon called the Urban Heat Island (UHI) effect. Thus the heat waves significantly differ from other natural disasters. Therefore, the strategy of establishing countermeasures against heat waves by emulating policies for other natural disasters has limitations. In order to devise appropriate countermeasures against heat wave disasters, scientific research to support the implementation of these counter measures should be carried out at micro level.

References

Srivastava, A. K., Yogranjan and Bal, Lalit M.,(2020), “Variability of extreme weather events and its impact on crop yield in Bundelkhand Agroclimatic zone of Madhya Pradesh” Mausam 71(2):551-560.

Ray, K., Giri, R.K., Ray, S.S., Dimri, A.P.,

Rajeevan, M.,(2021). An Assessment of Long-term Changes in Mortalities due to Extreme Weather Events in India: A Study of 50 Years’ Data, 1970-2019, Weather and Climate Extremes, https://doi.org/10.1016/j. wace.2021.100315.

Kumar Arvind and Singh ,D.P.(2021). Heat stroke-related deaths in India: An analysis of natural causes of deaths, associated with the regional heat wave. Journal of Thermal Biology, 95:       https://doi.org/10.1016/j. jtherbio.2020.102792.

Das, Prabir Kumar, Podder, Ushashi, Das, Rituparna, Kamalakannan, Chandrasekar,Goru,  Srinivasa  Rao

,Soumya, Bandyopadhyay and Raj, Uday. (2020).Quantification of heat wave occurrences over the Indian region   usinglong-term   (1979–

2017) daily gridded (0.5° × 0.5°) temperaturedata—a combined heat wave index approach, Theoretical and Applied Climatology 142:497–511. Nandi Jayashree and Pillai Soumya (2022). Northwest and central India heatwaves during the second half of the March. Hindustan Times 02 April,2022 .

Mishra Vimal, Mukherjee Sourav, Kumar Rohini and Stone Dáithí A (2017).Heat wave exposure in India in current, 1.5 °C, and 2.0 °C worlds. Environmental Research Letters, 12(12) 124012.

Kim, Do-Woo, Kwon, Chaeyoung , Kim, Jineun, and Lee, Jong-Seol (2020). Characteristics of Heat Waves From a Disaster Perspective. J Prev Med Public Health. Jan; 53(1): 26–28.

Vimal Mishra, Udit Bhatia and Amar Deep Tiwari(2020). Bias-correlated climate projections for south Asia from coupled model inter comparison project 6.Scientific data 7:338(1-13).