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Experts forecast rise in heat-related deaths, illnesses


•United Nations warns one billion children in Nigeria, others most likely to be affected by natural disasters
•As temperatures rise, violence, aggression also go up while focus, productivity decline, researchers find

Researchers have raised fresh alarm on rising cases of heat-related deaths and illnesses. A new document from the United Nations has warned that at least one billion children in Nigeria and other countries, especially those in Sub Saharan Africa are most likely to be affected by natural disasters. Yet another study found that as temperature rises, violence and aggression also go up while focus and productivity decline.

The first study concluded that extreme heat is an increasingly common occurrence worldwide, with heat-related deaths and illnesses also expected to rise. The authors of a new two-paper Series on Heat and Health, published in The Lancet, recommended immediate and urgent globally coordinated efforts to mitigate climate change and increase resilience to extreme heat to limit additional warming, avoid permanent and substantial extreme heat worldwide, and save lives by protecting the most vulnerable people.


In alignment with the Paris Agreement, the Series authors called for global warming to be limited to 1.5°C to avoid substantial heat-related mortality in the future. Reducing the health impacts of extreme heat is an urgent priority and should include immediate changes to infrastructure, urban environment, and individual behaviour to prevent heat-related deaths. The Series was published ahead of this year’s COP26 UN Climate Change Conference in Glasgow, United Kingdom (UK).

Effective and environmentally sustainable cooling measures can protect from the worst health impacts of heat. These range from increasing green space in cities, wall coatings that reflect heat from buildings, and widespread use of electric fans and other widely available personal cooling techniques that have been shown by thermal physiologists to help people regulate their body temperature without exacerbating other types of physiological strain. While air conditioning is becoming more widely available around the world, it is unaffordable for many of the most vulnerable, is financially and environmentally costly, and leaves many defenseless against extreme heat during power outages.

According to a new Global Burden of Disease modelling study, also published in The Lancet, more than 356,000 deaths in 2019 were related to heat and that number is expected to grow as temperature rises worldwide. However, Series authors note, many heat-related deaths are preventable by mitigating climate change and reducing exposure to extreme heat.


When exposed to extreme heat stress, the body’s ability to regulate its internal temperature can be overwhelmed, leading to heat stroke. In addition, physiological thermoregulatory responses that are engaged to protect body temperature induce other types of physiological strain and can lead to cardiorespiratory events. Effects from extreme heat are also associated with increased hospitalizations and emergency room visits, increased deaths from cardiorespiratory and other diseases, mental health issues, adverse pregnancy and birth outcomes, and increased healthcare costs. Older people and other vulnerable people who may be less able to take care of themselves in extreme heat (example, people isolated at home, people who have poor mobility) are also more likely to experience the health effects of extreme heat.

Extreme heat also lessens worker productivity, especially among the more than one billion workers who are exposed to high heat on a regular basis. These workers often report reduced work output due to heat stress, many of who are manual labourers who are unable to take rest breaks or other measure to lessen the effects of heat exposure.

ALSO, the United Nations has warned that one billion children – almost half of those in the world – are at ‘extremely high risk’ from climate change.

A new report said that youngsters living in the Central African Republic, Chad, Nigeria, Guinea, and Guinea-Bissau are most likely to be affected by a ‘deadly combination’ of exposure to climate and environmental factors, plus inadequate healthcare and education.

Sub-Saharan Africa makes up 24 of the 33 countries where children are most at risk of environmental shocks including cyclones and heatwaves, as well as being particularly vulnerable to the events based on their access to essential services such as water and sanitation.

The Children’s Climate Risk Index by the UN children’s agency UNICEF is the first comprehensive analysis of climate risk from a child’s perspective.

It found that almost half of the world’s 2.2 billion children live in a country classified as ‘extremely high risk’ to climate change.


“For the first time, we have a complete picture of where and how children are vulnerable to climate change, and that picture is almost unimaginably dire,” said Henrietta Fore, UNICEF’s executive director.

“Climate and environmental shocks are undermining the complete spectrum of children’s rights, from access to clean air, food and safe water; to education, housing, freedom from exploitation, and even their right to survive.

“Virtually no child’s life will be unaffected.”

What the report also reveals is that the countries facing the worst consequences of climate change are those that have contributed the least to carbon dioxide emissions.

Collectively, the 33 ‘extremely high risk’ nations emit 9 per cent of the world’s CO2 emissions. Only India is listed among the ten biggest emitting countries, which together account for almost 70 per cent of global greenhouse gas emissions.

Meanwhile, people’s bodies aren’t built to handle heat beyond wet bulb temperatures — a combined measure of heat and humidity — of around 35° Celsius, or about 95° Fahrenheit. Mounting evidence shows that when heat taxes people’s bodies, their performance on various tasks, as well as overall coping mechanisms, also suffer. Researchers have linked extreme heat to increased aggression, lower cognitive ability and lost productivity.

With rising global temperatures, and record-breaking heat waves baking parts of the world, the effects of extreme heat on human behavior could pose a growing problem.

Scientists have been documenting humans’ difficulties coping with extreme heat for over a century. Much of that work, however, has taken place in laboratory settings to allow for a high degree of control.


For instance, a few decades ago, social psychologist Craig Anderson and colleagues showed undergraduates four video clips of couples engaged in dialog. One clip was neutral in tone, while the remaining three showed escalating tension between the duo. The undergraduate students watching the clips were each sitting in a room with the thermostat set to one of five different temperatures, ranging from a cool 14° C to a hot 36° C. The researchers then asked the students to score the couples’ hostility level. Anderson, now of Iowa State University in Ames, found that students in uncomfortably warm rooms scored all the couples, even the neutral one, as more hostile than students in rooms with comfortable temperatures did. (Interestingly, students in uncomfortably cold rooms also scored the couples as more hostile.)

Research suggests that such perceptions can give way to actual violence when people lack an escape hatch. But this “heat-aggression hypothesis” has been hard to demonstrate outside the lab because teasing out the effect of heat from other environmental or biological variables linked to aggression is tricky in the messy real world. Studies in the last few years, however, have started confirming the idea.

For instance, a July working paper out of the National Bureau of Economic Research came close to re-creating the level of control found in a lab by focusing on inmates in Mississippi prisons and jails that lack air conditioning. Economists Anita Mukherjee of the University of Wisconsin–Madison and Nicholas Sanders of Cornell University looked at rates of violence across 36 correctional facilities from January 1, 2004, to December 31, 2010. Overall, each facility averaged about 65 violent acts per year. But the pair found that on days above around 27° C — which occur about just over 60 days per year — the probability of violence among inmates rose 18 percent.

Research also suggests that violence spikes alongside heat outside of prisons. For instance, for the months May to September from 2010 to 2017, violent crime in Los Angeles was about 5.5 percent higher on days with temperatures from about 24° C to 32° C (75° to 89° F), compared with days below those temperatures, researchers reported in the May Journal of Public Economics. Violent crime was almost 10 percent higher on even hotter days, the researchers found.


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