Magazine article The Futurist

Climate Change: The Threat to Human Health

Magazine article The Futurist

Climate Change: The Threat to Human Health

Article excerpt

We have come a long way in recent years toward realizing how extensively global warming will jeopardize both planetary and human health.

Carbon-dioxide buildup--mainly from combustion of fossil fuels such as oil, gas, and coal, and from clearing and burning of forests--is believed responsible for about half of this worldwide warming, while chlorofluorocarbons (CFCs), methane, ground-level ozone, and nitrousoxide emissions account for the rest. Together, these gases act like glass in a greenhouse: They allow passage of incoming solar radiation but trap some of the outbound heat radiation from the earth.

One very significant aspect of global warming is the variety of effects it will have on human health--some will be subtle and indirect, others dramatic and direct. Many of the very factors contributing to global warming are themselves harmful to humans, such as the burning of fossil fuels: A typical automobile emits carbon monoxide, sulfur and nitrogen oxides, hydrocarbons, low-level ozone, and lead, all of which are hazardous to health. According to a World Health Organization (WHO) task group on the potential health effects of climate change and the Intergovernmental Panel on Climate Change (IPCC), climate change will likely worsen air pollution--especially in heavily populated urban areas--by altering the composition, concentration, and duration of chemical pollutants in the atmosphere.

Chlorine released by CFCs and bromine released by halons (used in fire extinguishers) both deplete stratospheric ozone. The use of CFCs and halons thus escalates the risk of skin cancer, eye cataracts, snow blindness, and weakened immunity to a host of other illnesses by exposing humans to increased ultraviolet B radiation from the sun. "Skin cancer risks are expected to rise most among fair-skinned Caucasians in high-latitude zones," according to the IPCC. The WHO task group reached a similar conclusion, noting that "the incidence of non-melanoma skin cancer could increase between 6% and 35% after the year 2050. These increases may be larger in the Southern Hemisphere, where total ozone depletions have been larger."

Health Inside the Greenhouse

On the basis of present trends, scientists predict that greenhouse gases will warm the earth further by about 0.3 [degrees] C in each decade of the next century This rise, faster than any experienced over the past 10,000 years, could increase the planet's mean temperature by 3 [degrees] C before the year 2100, making it warmer on average than it has been for 100,000 years.

This may not sound especially ominous, but left unchecked, global warming could alter rainfall patterns, flood vast areas of low-lying land as warmed seas rise (possibly by as much as a meter), and drive countless species to extinction as fragile ecosystems collapse. A warmed planet will affect human health by disrupting food and fresh water supplies, displacing millions of people, and altering disease patterns in dangerous and unpredictable ways.

The populations most vulnerable to the negative impacts of the greenhouse effect are in developing countries, in the lower-income groups, residents of coastal lowlands and islands, those living in semiarid grasslands, and those in the squatter settlements, slums, and shantytowns of large cities.

Present strategies for immunization, coping with disease vectors or carriers, providing safe drinking water, and improving nutrition are all based on existing climate regimes, ecosystems, and sea and solar-radiation levels. These are all expected to change, but exactly how much cannot be predicted with any certainty, making it virtually impossible to adjust health and nutritional strategies now to take possible climate changes into account.

Humans adapt well to moderate changes in temperature and to occasional extremes. But this adaptive capacity--developed over many thousands of years--is relatively low in infants and the elderly; it rises through childhood and adolescence to reach a maximum that can be maintained up to about 30 years of age, then begins to decline. …

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