Heat Stress May Impact More than 1.2 Billion People Annually By 2100: Study
Sat, April 10, 2021

Heat Stress May Impact More than 1.2 Billion People Annually By 2100: Study


Heat stress from extreme humidity and heat may impact more than 1.2 billion people annually by 2100, a new study finds.

Heat stress is an illness that occurs when the body cannot get rid of excess heat in response to a hot environment. When it happens, the core temperature of the body rises and the heart rate also increases as the body is unable to properly cool down through sweating. The person suffering from heat stress starts to lose concentration and finds it difficult to focus on a certain task. They may become sick or irritable and lose the desire to drink. As the body temperature rises, it can likewise damage vital organs in the body. The most common serious heat-related illness is heatstroke.

In a recent study conducted by Rutgers University researchers, they focused on heat stress caused by extreme humidity and heat and not the other factors that contribute to heat stress, such as strenuous physical activities and direct physical contact with hot objects. The shocking figure of more than 1.2 billion people is more than four times the number of people affected by heat stress this year, the researchers added.

Dawei Li, a former Rutgers post-doctoral associate and lead author of the study, said that global warming makes humid and hot days more intense and frequent. He cited that the most humid and hottest day in a typical year in New York, for instance, now occurs nearly 11 times more frequently than in the 19th century. Without emergency treatment, heat-related illness can cause permanent disability or even death, according to the Centers for Disease Control and Prevention.

In their study titled “Escalating global exposure to compound heat-humidity extremes with warming,” the authors explained that heat stress harms the environment, economy, agriculture, and human health in a broader concept. Most studies that assess the future of heat stress focused on the surface air temperature but the main drivers of heat stress are the compound extremes of humidity and heat. This is why they focused on these key drivers in their study.


The experiment using a global climate model

To know the statistics on rare events, the team used 40 climate simulations and focused on the measure of heat stress caused by humidity, temperature, and other environmental factors, such as infrared and solar radiation, sung angle, and wind speed. They found that annual exposure to extreme humidity and heat will affect locations that are home to nearly 500 million people if the Earth warms by 1.5 degrees Celsius or 2.7 degrees Fahrenheit. If it warms at 2 degrees Celsius or 2.2 degrees Fahrenheit, it is expected to impact about 800 million people worldwide. The number of people that will be affected will increase to 1.2 billion people it the planet warms by 3 degrees Celsius or 5.4 degrees Fahrenheit.

The research was co-authored by Jiacan Yuan and Robert (Bob) Koop.



The World Health Organization also shared public health advice, emphasizing that population exposure to heat continues to increase because of climate change and the trend is not likely to end soon. Extreme temperature events worldwide are observed to be increasing in magnitude, duration, and frequency. In 2015, there were 175 million additional people exposed to heatwaves compared to average years.


Working hours lost due to heat stress, by sector

The share of working hours lost in the US because of heat stress is forecast to double between 1995 and 2030, from 0.11% to 0.21% of total working hours, according to German database company Statista. The most affected economic sectors are the following: agriculture -in shade (from 0.58% in 1995 to 1.18% by 2030), construction -in shade (0.58% in 1995 to 1.18% by 2030), and services (0.03% in 1995 and 0.09% by 2030).

US nonprofit National Safety Council (NSC) also mentioned those who are most at risk of heat-related illness and death and these include infants and young children (especially if left in hot cars), people 65 and older, people who are ill, people who have chronic health conditions or are on certain medications, and people who are overweight. Signs and symptoms of heat exhaustion are sweating, pale, moist or ashen skin, muscle cramps, especially for people exercising or working outdoors in high temperatures), exhaustion, weakness, or fatigue, vomiting or nausea, rapid heart rate, and dizziness, headache, or fainting.

Uncontrolled heat exhaustion can quickly evolve into heatstroke. Victims should be quickly moved to the air-conditioned or shaded areas and given water or other non-alcoholic cool beverages. Someone should apply wet towels on them or have the victims take a cool shower. If the person is suffering from heatstroke, seeking medical help immediately is advised. Calling 911, moving the victim to a cool place, removing unnecessary clothing, and monitoring the victim’s breathing and being ready to give CPR if needed are some of the immediate reactions that the NSC provided. In 2017, the NSC recorded 87 deaths in the US caused by exposure to excessive heat.



WHO recommends that people keep their homes cool. The room temperature should be checked between 08:00 and 10:00, at 13:00, and at night after 22:00. The room should be ideally kept below 24 °C during the night and 32 °C during the day. This is most important for infants or people more than 60 years of age or those diagnosed with chronic health conditions.


Greenhouse gas emissions

Meanwhile, the Environmental Protection Agency ranked the economic sectors that contribute to greenhouse gas emissions in 2016. These were electricity (28%), industry (22%), commercial and residential (11%), and agriculture (9%). Greenhouse gas traps heat within the atmosphere, causing global temperatures to rise. Transportation is one of the largest contributors to global warming. US commuters travel by driving alone (76%), cycling (60%), public transit (9%), carpooling (5%), walking (3%), and taking a taxi or motorcycle (1%), while others work from home (5%). This data was provided by nonprofit public policy organization The Brookings Institution. Industrialization, deforestation, livestock production, factory farming, consumerism, overuse of electricity, and overfishing are only some of the ways humans contribute to climate change.

Human-caused global warming may remain for years but the magnitude can be reduced gradually. We are all capable of combating global warming in our little ways. By saving the environment from destruction, we are also protecting ourselves against heat stress.