Researchers have linked a 1 degree Celsius rise in the yearly average temperature with a 4.5 per cent increase in intimate partner violence (IPV) in a study of almost 1,95,000 ever-partnered women across three South Asian countries including India.

They have predicted a 21 per cent increase in family violence in the region by the end of the 21st century, with India estimated to experience the highest increase of 23.5 per cent among the three countries, the other two being Nepal and Pakistan.

Ever-partnered women are defined as those who have had sex, been married or been in a romantic relationship.

The study -- 'Association of Ambient Temperature With the Prevalence of Intimate Partner Violence Among Partnered Women in Low and Middle-Income South Asian Countries' -- has been published in medical journal JAMA Psychiatry.

"Given the higher prevalence of IPV in South Asia compared to the global level, and the region's recent history of more frequent and intense heatwaves, we conducted this study to evaluate the association of ambient temperature with IPV prevalence, including its types -- physical, sexual, and emotional -- among partnered women," corresponding author of the study Renjie Chen, Fudan University, China told PTI in an email.

The cross-sectional study included ever-partnered women in the 15-49 age group from India, Nepal and Pakistan and used self-reported data from the Demographic and Health Survey (DHS) Programme, collected from October 1, 2010 to April 30, 2018.

Active in more than 90 countries, the DHS Programme is responsible for collecting and disseminating accurate, nationally representative data on health and population in low and middle-income countries, routinely conducting surveys at intervals of 3-5 years.

Among the women surveyed, the study found, physical violence to be the most prevalent at 23 per cent, followed by emotional at 12.5 per cent and sexual at 9.5 per cent.

Further, the study projects increases in physical and sexual violence stemming from hotter temperatures to 28.3 per cent and 26.1 per cent, respectively, far greater than the projected rise in emotional violence at 8.9 per cent, by modelling changes in IPV prevalence under various future climate change scenarios through the 2090s.

In the 2090s, India is estimated to experience the highest IPV prevalence increase at 23.5 per cent, followed by 14.8 per cent in Nepal and 5.9 per cent in Pakistan under an unlimited carbon emissions scenario.

Previous studies have shown higher ambient temperature to be linked to multiple forms of manifestations of violence such as intentional homicide, collective violence, and even regional conflicts.

Chen said the heat-aggression hypothesis is likely to be behind such violence stemming from hot temperatures.

According to the hypothesis, hot temperatures can increase aggressive motives and behaviours by directly increasing feelings of hostility and indirectly increasing aggressive thoughts.

So, what are the factors arising from a warming climate that contribute to domestic violence? "In a warming climate, characterised by more intense and frequent heatwaves, extreme heat could also directly activate the brain areas associated with thermoregulation and emotion regulation and activate high aggression under certain conditions such as provocation.

"Acute heat exposure is linked to increased adrenaline production, which could heighten physiological arousal. In addition, heat-related events may contribute to a range of adverse mental health outcomes, which potentially increase IPV risk.

"Further, economically strained circumstances from decreased agricultural production and labour efficiency to a deteriorating living environment due to damage caused by extreme weather events could also exacerbate the issue of intimate partner violence," Chen said.

Historical evidence has been unearthed by researchers suggesting that violence happened in the south central Andes during climatic change between AD 470 and 1500. They looked at head injuries of the populations living there at that time, a commonly used proxy among archaeologists for interpersonal violence.

The researchers of this archaeological study, 'Climate Change Intensified Violence in the South-Central Andean Highlands from 1.5 to 0.5 KA (AD 470–1540)', proposed that potential competition for limited resources in the region stemming from climate change impacts likely led to the violence among people living in the highlands. The study was published in the journal Quaternary Research on June 5.

The findings of the study suggest a need for sustainable climate mitigation along with public health programmes to address intimate partner violence in climate-sensitive regions, the researchers said in their paper.

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