‘Heat Ages People’: As Temperatures Rise, Scientists Study How Humans React

Workers at the Three Mile Island nuclear plant were the focus of W. Larry Kenney's research when he was a professor at Pennsylvania State University.

In the decades that followed, Dr. Kenney has looked at how heat stress affects a range of people, from football players to soldiers in protective suits.

Ordinary people have been the focus of his research in the last few months. It's doing things every day. Climate change is making a difference.

There were excessive heat warnings and heat advisories in effect for much of the eastern interior of the United States on Monday. According to the National Weather Service, the heat will move further Northeast in the next few days.

Scientists are trying to figure out how life in a hotter world will affect us. The aim is to get a better idea of how many people will suffer from heat related illnesses and how often. To learn how to protect the most vulnerable.

Scientists say that the heat waves of the past two decades aren't good predictors of the risks that will confront us in the decades to come. The link between greenhouse-gas emissions and hot temperatures is so clear that some researchers may no longer be able to determine if the most extreme heat waves of the past were caused by humans. They couldn't have.

The hottest heat wave many people have ever experienced will be their new summertime norm if global warming isn't slowed. It won't be something you can escape from.

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It is difficult for scientists to pin down how these climate shifts will affect human health and well-being on a large scale in the developing world. Projection of future effects with any precision is difficult because of the wide range of harms caused by heat stress.

There isn't enough research on living full time in a warmer world. He doesn't know what the long-term consequences of getting up every day are.

The growing importance of these issues is drawing in researchers like Dr. Kenney, who didn't always think of themselves as a climate scientist. Young, healthy men and women were placed in specially designed chambers, where they pedaled an exercise bike at low intensity, for a recent study. The researchers adjusted the temperature and humidity.

Under steam-bath conditions, our bodies absorb heat from the environment more quickly than we can sweat. We don't pump out a lot more sweat to keep up

Climate change is at its most devastatingly intimate and devastating at the depths of the individual human body.

The victims of heat die alone in their homes. It can cause cardiovascular collapse and even death. Our organs and cells are damaged by it. In people with high blood pressure, asthma, multiplesclerosis, and other conditions, its harms are magnified.

We aren't as effective when the mercury is high. Motor functions are impaired. Depression and suicide are also linked to excessive heat.

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Personal toll on the body can be striking. An experiment years ago with a large group of people was recalled by George Havenith. They wore the same clothes and worked in the same place for an hour. Their body temperature ranged from 100 degrees to 102.6 degrees.

He said that they are trying to understand why one person ends up on one side of the spectrum and another on the other.

A professor of environmental health at a university in India has been studying what heat does to workers in India's steel plants, car factories and brick kilns. Severe dehydration causes many of them to suffer from stone diseases.

A decade ago, she met someone. The steelworker had been working near the furnace for 20 years. He told her he was 38 to 40.

She was certain she'd been deceived. His hair was not straight. His face looked smaller. He looked like he was 55 years old.

When he got married, how old was his child? There was a check out of the math.

It was a turning point for the group. That is when we began to think about the effects of heat.

A researcher at the Aga Khan University is studying the effects of heat on pregnant women and newborn babies. Women walk long hours in the sun to fetch water for their families in communities there. There are studies linking heat exposure to premature births and low birth weights.

Women who suffered after giving birth are the most heartbreaking. Babies develop blisters on their bodies and mouths when they are walking with their 1-day-old on their backs.

She wondered if the progress Africa has made on reducing newborn and childhood mortality was being reversed by climate change.

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According to a professor of heat and health at the University of Sydney, societies need to find more sustainable defenses given how many people don't have access to air-conditioning.

Dr. Jay has studied the body's responses to sitting near an electric fan and wearing wet clothing. He recreated a Bangladesh garment factory in his lab to test low-cost ways of keeping workers safe.

Humans are able to adapt to hot environments. When our heart rate goes down, more blood is pumped into us. The sweat glands are active. Dr. Jay said that scientists don't understand how our bodies adapt to heat in the real world because it's in controlled laboratory settings.

In the lab, inducing such changes requires exposing people to uncomfortable strain for hours a day over weeks.

He said it was not nice. It's not a practical solution to live in a future that's oppressive. On the time scale of human evolution, there will be more profound changes in the body's ability to adapt.

India is a hot country, so what's the big deal?

People don't ask what the big deal is when your body is in a state of heatstroke.

The doctor said that that is human physiology. You can't change that