Lok Sabha Question No. 1001 (UNSTARRED), answered on 2020-02-07
Subject: Heat Waves
Ministry: EARTH SCIENCES
Asked by: Gowdar Mallikarjunappa Siddeshwara

## GOVERNMENT OF INDIA

## MINISTRY OF EARTH SCIENCES LOK SABHA

## UNSTARRED QUESTION No. 1001

## TO BE ANSWERED ON FEBRUARY 07, 2020

## HEAT WAVES

## 1001. SHRI G.M. SIDDESHWAR:

Will the Minister of EARTH SCIENCES be pleased to state:

- (a) whether it is a fact that there has been an increase in heat waves in the country during the last three years and if so, the details thereof
- and the reasons therefor;
- (b) the details of mechanism adopted by the Government to track heat waves and also changes in temperature that would be classified as
- heat wave; and
- (c) the effects of heat waves on labour productivity, public health and disaster events?

## ANSWER MINISTER FOR MINISTRY OF SCIENCE AND TECHNOLOGY AND MINISTRY OF EARTH SCIENCES (DR. HARSH VARDHAN)

- (a) Latest  studies  show  an  increase  in  temperatures  as  well  as occurrence  of  Heat  Waves  in  many  parts  of  country  during  the recent years. One of the reasons for the increase in heat waves is global warming associated with the increase in greenhouse gasses like Carbon dioxide, Methane etc. in the atmosphere.

In India, rise in maximum temperatures as well as Heat Waves are found  to  be  more  in  the  months  of  April,  May  &  June.  Core  Heatwave  Zone  (CHZ)  is  the  most  prone  area  for  Heat  Wave  (HW)  & Severe  Heat  Wave  (SHW)  with  highest  frequency  of  occurrence during  the  month  of  May.  The  CHZ  covers  States  of  Punjab, Himachal  Pradesh,  Uttarakhand,  Delhi,  Haryana,  Rajasthan,  Uttar Pradesh, Gujarat,  Madhya Pradesh, Maharashtra, Chhattisgarh, Bihar, Jharkhand, West Bengal, Odisha, Andhra Pradesh and Telangana.

The Heat Wave events happened during last three years, viz. 2017, 2018 & 2019 are given in the table below:

| States         | Heat Wave events   |
|----------------|--------------------|
| Year 2017      | Year 2017          |
| Andhra Pradesh | 1                  |
| Jharkhand      | 2                  |
| Maharashtra    | 6                  |
| Odisha         | 8                  |
| Telangana      | 12                 |
| West Bengal    | 1                  |
| Year 2018      | Year 2018          |
| Uttar Pradesh  | 2                  |
| Maharashtra    | 5                  |
| Jharkhand      | 1                  |
| Kerala         | 3                  |
| Chattisgarh    | 1                  |
| Year 2019      | Year 2019          |
| Maharashtra    | 15                 |
| Kerala         | 6                  |
| Bihar          | 4                  |
| Rajasthan      | 1                  |

- (b) India Meteorological Department (IMD) uses temperature data from surface  observatories  to  track  heat  waves.  IMD  also  uses  various numerical weather prediction models to track and predict occurrence and intensity of Heat Waves.

In India the latest criteria used for defining the HW are based on the climatological  values  for  the  period  of  1971-2000  and  are  given below:

Criteria  for  declaring  heat  wave  based  on  maximum  temperature (Tmax):

Heat wave over a station is declared only when the actual Tmaxof the station is 40°C for plains and 30°C for Hilly regions. However, when the  Tmax  is  40°C  for  coastal  stations  and  45°C  for  other  stations, conditions are declared as heat wave.

The  following  criteria  are  used  for  defining  severity  of  the  heat wave:

When normal Tmax   is less than or equal to 40°C and i.  ActualTmax is greater than  Normal Tmax  by  5°C / 6°C:  heat wave

- ii.  ActualTmax  is greater than  Normal Tmax  by  7°C:  severe heat wave

When normal Tmax is greater than 40°C and i.  ActualTmax is greater than  Normal Tmax  by  4°C / 5°C: heat wave ii.  Actual  Tmax  is  greater  than    Normal  Tmax    by    6°C:  severe  heat

- wave

Note: Normal Tmax - Average maximum temperature of the day.

Actual Tmax - observed  maximum temperature of the day.

## Criteria for Hot day

Whenever,  the  maximum  temperature  remains  40ºC  or  more  and minimum  temperature  is  4.5ºC  or  more  above  normal,  it  may  be defined  as  Hot  Day,  provided  it  is  not  satisfying  the  heat  wave criteria given above.

- (c) A large section of mostly daily wage labourers and others engaged in outdoor work and/ or exposed to indoor heat in Indian cities are more likely to be affected by heat waves. In addition to cities and villages, specific industrial operations (e.g., mining, thermal power, furnace, refineries) emit as well as absorb considerable heat. With the  majority  of  workplace  settings  in  developing  countries  being heavily influenced by outdoor temperatures, it can be expected that both  indoor  and  outdoor  workers  will  experience  increased  heat stress.  Even  relatively  modest  increase  in  ambient  temperatures could be expected to tip large worker populations over the threshold into the realm of heat stress related health risks and thereby impact the productivity.

Four Common  heat health impacts resulting from excessive exposure  to  heat  waves  include  dehydration,  cramps,  exhaustion and heatstroke. It is also learnt that there is a sharp rise in number of cases of acute gastroenteritis and food poisoning due to spoilage of  food  and  reduction  of  its  shelf  life  due  to  high  temperatures. There  is  also  rise  in  number  of  cases  of  anxiety,  palpitations, nervousness and behavioural change linked to extreme temperature rise. The occupational profile of most of the victims was ascertained as  agricultural  labourers,  coastal  community  dwellers,  and  people living below  poverty line (BPL) category with mostly outdoor occupations.

Taking these onto notice, Government has adapted Heat Action Plan in different States to tackle the impact of Heat Waves.

Heat  Action  Plan  is  a  comprehensive  early  warning  system  and preparedness  plan  for  extreme  heat  events.  The  Plan  presents immediate as well as long-term  actions  to  increase  preparedness, information-sharing, and response coordination to reduce the health impacts of extreme heat on vulnerable populations.

IMD  in  collaboration  with  local  health  departments  has  started preparing/implementing  Heat  Action  Plan  in  many  parts  of  the country to forewarn about the heat waves and also advising action to  be  taken  during  such  occasions.  Heat  action  plan  became operational in the year 2013.

*****