Dunn: Human Health Effects of Global Warming Article

Human Health Effects of Global Warming

International Conference on Climate Change

March 2-4, New York City

John Dale Dunn MD JD

Emergency Medicine Faculty

Carl R. Darnall Army Medical Center

Fort Hood, Texas

Background on warming and health

Public health authorities have asserted that global warming has a detrimental effect on human health. Officials affiliated with the World Health Organization claimed that global warming killed 150,000 people in 2000 and that warmer temperatures will put 65 % of the world’s population at risk for insect borne tropical diseases. WHO scientist Campbell-Lendrum asserted in 2003 that the year 2000 warming death effect of 150,000 will be doubled by 2030. (Unstoppable Global Warming Singer and Avery 2007, page 201)

Daily change in temperature in any location on the planet is more than the warming projection changes of the IPCC: Epidemiologists should know better than to run with silly “associations” and sky is falling scenarios, given that the human species has wonderful adaptive mechanism for temperature, and has demonstrated an ability to live at extremes of temperature far greater than a few degrees from an average.

I assert that warm is good for human health, and that global warming even in the most extreme estimates will not create heat illness or death increases, and certainly no changes that are more important than basic public health measures of vector control, water, nutrition, sewage and housing quality, and the impact of modern medical measures and technology.

Is warm good for health?

The answer is yes, and most people do what they can to mitigate the effects of stressful cold weather. People take the hot springs cure, people vacation in warm places to ease their ills and they move “down south” where the living is easy. As long as you stay in the warm 1st world you will live better and longer. Older Americans move to Phoenix in the winter instead of Cleveland, Buffalo or International Falls. Consider just the risk of falling on the ice in Minneapolis. In Texas we call sensible retirees snow birds.

People die more often during cold winter months. People of all ages get sick in the winter more than summer. I get sick in the winter—same for you and your kids. The WHO proposes we consider warmth as the enemy. Are they goofy or what?

WHO makes heat wave death effects into an argument that global warming will kill 150,000 or twice that number? Warm is good for circulation, arthritis, respiratory health, and well being.

Ask a pediatrician what time of year kids are sick. The public health community would have you believe that global warming is a killer? I say it’s good for the roses, the trees, the horses, the crocodiles, the snakes, even the polar bears. The issue for polar bears is food, not temperature. They do quite well in the San Antonio zoo, they take a dip when they’re hot. A bear’s body temperature is close to ours, so they can live in moderate climes, just like humans, for cold they have some fat and fur that protects better than the naked human skin on the ice flows. Bears could still do the mint julep tour.

Surveillance in the United States Department of Defence shows increases in respiratory illnesses during the winter months. (MSMR (Monthly Surveillance Monthly Report) Dec, 2007, published by the Armed Forces Health Surveillance Center. January is consistently the month of highest mortality rates in the northern hemisphere. Being born in the winter puts children at higher risk for infectious disease. Summertime babies have it easy.

A study by Keatinge published September 16, 2000 in the British Medical Journal showed a tenfold increase in deaths in the elderly (age 65-74) from cold waves versus heat waves (2000 deaths per million attributed to cold stress, 200 deaths per million attributed to heat stress.) Cold wave death effects are not only more severe, but last longer than heat wave effects, probably because of physiological and infectious tails.

The rates of stroke and other cardiovascular events like myocardial infarction are higher in cold weather, explained by the effects of cold on blood vessels.

Climate has no significant effect on the general health of the population. Period. Global temperature changes of a few degrees are in the range of human tolerance and typical of a normal day, not deadly or even stressful.

There are some seasonal and temperature infectious disease patterns, and all of them are improved with warming. RSV, croup, enteroviruses, Rotovirus, parainfluenza, and influenza, probably related to close living and transmission. Global warming of a degree, even up to 5 degrees as predicted by the IPCC fanatics, is not going to change the seasonal pattern except maybe to moderate it.

Global warming will moderate, not exaggerate temperature extremes. It’s a physical principle related to air circulation. The pleasant weather without cold snaps blows a hole in the theory of catastrophe proposed by the WHO.

Heat Illness

So the remaining global warming crusader problem and hobgoblin is heat illness. Consider the rash of elderly deaths in the 1995 Chicago heat wave or the French August heat wave and there is the WHO case for panic in a nutshell.

The human organism operates in a controlled, very small range of internal temperature, regardless of ambient temperature. We are not lizards or snakes. That’s why the public health global warming panic mongers are off the mark to say human health would be impacted by global average changes of a few degrees. Humans live with daily temperature changes of more than 5 degrees and except for the terminally ill and dying, we have no problem keeping body temperature in the right range. That’s what mammals do. People are about 99.6 F rectally , dogs 102 F, horses at 100.5. F. Ambient temperature is not a factor.

The only threat that might produce heat illness is extreme heat waves that exceed 95 F degrees but that is not the effect of global warming, those things occur for other reasons. For the ill and debilitated temperature of 95 F or higher is a problem. 100 F is an emergency if no air conditioning or ventilation is available.

People who are at risk of heat illness or effects can avoid the risk by being quiet, drinking fluids and staying in a well ventilated place. That’s why heat didn’t kill off the primitive tribes in the first few thousand years of man’s existence on this planet. It’s not rocket science. Take a break, take a drink of water when you’re thirsty. Live under the shade of the coconut tree and relax when the temperatures seem pretty high, even if you don’t have a thermometer. The WHO seems to think that people who live in hot places are on a chain gang, but they are drinking water in the shade of the tree and waiting for it to cool down.

Let’s eliminate right off the bat heat stress for the healthy active person, since acclimatization and adjusting work schedules and activities can circumvent the heat stress problems of the seriously active player. Heat deaths are of the isolated innocents who are ill, who get into trouble without attention. Otherwise only rarely does heat stress cause illness or death.

Extreme heat waves occur for various reasons, and are not affected by slight changes in average global temperature. The heat shock does cause an initial surge in deaths, particularly in high density populations where people live in buildings without air conditioning or ventilation, but those deaths quickly dissipate, and research shows a successive period with a much lessened death effect.

General improvements in heat wave deaths in Germany and United States studies and across the 1st world countries are due to awareness, prevention, and most important, air conditioning.

Evaporation of sweat, the most important mode of “wet” heat dissipation, and air convection, the most effective “dry” heat loss mechanism are affected by hydration status, ventilation, and cardiovascular conditioning as well as medication effects. High humidity and ambient temperature are the most serious factors for producing heat illness.

The various stages of heat illness are fatigue, cramps; progressing to exhaustion and then, when core temperature increases to more than 102 F, heat confusion and “stroke” or progressive brain dysfunction. Heat illness in the otherwise healthy is purely a thermoregulatory failure, do to imbalance of energy production and the lack of cooling from convection, radiation or evaporation, producing dehydration and core temperature increase. The core temperature rise causes diffuse organ heat damage and progressive dehydration that produces circulatory failure and death.

The typical high risk range for the healthy human is temperature and heat index factors in excess of 100 with the margin at 105 F, humidity 10% or more. In the tropics temperature rarely rises to heat index danger levels because of limits on temperature rise caused by humidity. It’s hot and humid in the tropics but the heat index is less than dangerous.

Dry desert produces the extremes of heat. The desert summer temperatures of Iraq, at more than 120 F, are an excellent laboratory for heat illness in the healthy American soldier. Heat illness is a risk when ambient temperatures are above 100 degrees and subjects have a compromise of adaptive fluid intake, ventilation, and no opportunity for heat loss, or an increase in core heat production because of activity.

American Soldiers in training in the Southeast United States repeatedly undergo heat stress challenges with heat illness limited to a few cases every year. At Fort Hood the last two years training of thousands of soldiers, has produced less than 50 cases of heat illness per year in 2006 and 2007.

In Iraq where summer daytime temperatures can reach 130 F, American soldiers in full battle gear, including Kevlar body armor, helmet, 50 pound burdens of arms equipment and munitions, are operating in the full sun, walking and running or closed up in heavily armored vehicles. They survive and function with proper fluid intake, conditioning and training with no significant losses, down time, or removal for heat illness.

Acclimatization is the key to heat stress. Lack of physiological accommodation and confinement or lack of ventilation and fluid intake is the reason for heat illness in the elderly without air conditioning.

Heat stress and severe heat conditions are not the product of global warming, but local conditions, and there is no reason for the WHO to project thousands of deaths from a change in average temperature on the planet—one, because any warming is moderate and distributive and doesn’t create extremes; and two, because heat illness and deaths are not about the temperature as much as failure to acclimatize and address the special needs of the infirm and debilitated.

Proper prevention and modern adaptations make warm weather beneficial, only extreme heat events are a risk at all, and such conditions are not the result of any global warming trends.


The Copenhagen Consensus group placed basic public health as high priority and global warming as low priority for addressing the problems of the planet. I am outraged at the attitude of the European and American snobs who place global warming on the top of their list of priorities over the welfare of the poor and deprived of the third world.

Here we are fussing and worrying about whether one, two or three degrees of global warming is a catastrophe, when we can see serious problems for innocent people dying or suffering from water borne diseases, poor nutrition, and parasites. The WHO and the international public health community are pathetic debating societies; they should be ashamed that they can’t get the basics right on humanitarian needs.

Biography John Dale Dunn MD JD

Dr. Dunn is a civilian emergency medicine faculty physician at Carl R. Darnall Army Medical Center, Fort Hood, Texas. Fort Hood is the largest United States Army base and the home of the 1st Cavalry and 4th Infantry Divisions. Dr. Dunn served as public health authority for Brown County, Texas for more than ten years and is the Brown County Sheriff’s Medical Officer. He has lectured and written on environmental and public health issues for more than ten years. He is a policy advisor for the Heartland and the American Council on Science and Health.