Changing spatio‐temporal trends of heat wave and severe heat wave events over India: An emerging health hazard

Abstract

Heat wave (HW) and severe heat wave (SHW) events are the manifestations of extreme temperature causing an array of impacts on health, ecosystem, and economy. Since the mid-20th century, an increasing trend in the characteristics of heat waves has been observed over India causing an increased rate in human mortality. Our study aimed to analyse monthly, seasonal, and decadal variations along with long-term trends of HW and SHW events for premonsoon (March-May) and early summer monsoon (June-July) season during 1951-2016. HW and SHW events were identified using revised criteria given by the India Meteorological Department (IMD) using daily gridded maximum temperature data at 0.5 × 0.5 resolution from IMD. The study found a Spatio-temporal shift in the occurrence of HW events with a significantly increasing trend in three prominent heat wave prone regions that is northwestern, central, and south-central India, the highest being in West Madhya Pradesh (0.80 events/year), while a significantly decreasing trend was observed over an eastern region that is Gangetic West Bengal (−0.13events/year). SHW events showed a southward expansion and a spatial surge during the decades of 2001-2010 and 2010-2016. Tri-decadal comparative assessment shows a decadal increase of around 12 HW and 5 SHW events post the 1980s. Statewise Pearson's correlation between HW/SHW events and observed mortality reveals that the eastern coastal states that are Odisha and Andhra Pradesh show a significant positive correlation of 0.62 and 0.73, respectively. This significantly increasing trend in HW and SHW events may pose a grave risk to human health, predominantly on the vulnerable sections of the society. Heat waves need to be recognized as a potential health risk and demand further study, robust preparedness, and policy intervention. K E Y W O R D S heat waves, long term trends, mortality, severe heat waves 1 | INTRODUCTION India, the second-most populous and seventh-largest country of the world is also the sixth most vulnerable country to the extreme events (Eckstein et al., 2017; Mall et al., 2019). The dynamics of climate-dependent mechanisms are changing at a great pace due to the rise in global mercury. Both man-made and natural ecosystems are at a risk to climate-related extreme events such as heat waves, extreme precipitation, droughts, wildfires,

Time between Sequential Exposures to Multiple Stress Turns Antagonism into Synergism

“…For example, storm events channel pesticides from fields into aquatic environments in the form of pulses. − Also, ultraviolet-B (UV-B) radiation is an intrinsically pulsed stressor due to its dial nature and dependence on cloud cover. Heat waves may further increase the risk of occurrence and intensity − of those pulsed stressors, which can occur in any arbitrary order or temporal alignment in nature.…”

Exploring heat and cold wave susceptible areas of India using consistency and frequency coupled novel approach

“…So far the research on heat and cold waves is concerned, most of them focused on the identification of HW and CW events of some specific years, and trends (Mahdi and Dhekale, 2016;Chakraborty et al, 2019;Das et al, 2020;Singh et al, 2021;, their mechanisms of formation (Ratnam et al, 2016) and fatalities (Malik et al, 2020). All these works reported that the north western and central parts of India are experienced heat waveprone areas and Jammu & Kashmir as well as north western parts and some portions of Central India are cold waves prone areas in their respective period of study.…”

Mapping Heat Wave Hazard in Urban Areas: A Novel Multi-Criteria Decision Making Approach

“…Liu et al [56] used mean land surface temperature to map heat wave hazard in China. Similarly, Wu et al [47] argue the mean temperature level across 24 h during a heat wave predicts mortality and morbidity rates better than maximum and minimum temperatures; yet, most studies focus on maximum daytime or nighttime temperature as an indicator of heat wave hazard [71][72][73].…”