The debate is over; nearly all scientists (and politicians) agree that climate change is real, is here, and is the result of human activity. Experts also agree that the consequences of global warming are serious and far-reaching. All too often, though, these consequences are framed in terms of the threat to polar bears, exotic wildlife, and beautiful glaciers. Without minimizing the value of stately bears and snow-covered peaks, many people find it hard to make lifestyle changes and economic sacrifices to protect such distant assets. But climate change threatens more than the earth’s vistas. It also threatens human health — and as Ondoy showed last year, it’s already causing problems here in the Philippines.
How Global Warming Is Produced
Sunshine warms the earth. When solar radiation enters the atmosphere, a portion is bounced back into space, and another portion is absorbed by clouds and water vapors, but the majority strikes the planet’s surface. This solar energy warms the earth, but it’s also reflected back into the atmosphere in the form of infrared radiation. Some of the infrared penetrates through the atmosphere into space but some bounces off the atmospheric gases and heads back to earth, where it adds warmth (see figure on Page D-1).
The atmospheric gases that reflect infrared radiation back to earth are known as greenhouse gases. Without them, too much solar energy would be lost, and the earth would be ice cold. But since the industrial revolution, the concentration of atmospheric greenhouse gases has increased, and the increase has accelerated in the past 50 years. That means more infrared energy is reflected back to earth, where it produces global warming. Scientists report that the earth’s temperature increased by 0.6°C during the 20th century, and they project an additional rise by as much as 4.4°C during this century.
Greenhouse Gases
Heat-trapping greenhouse gases are formed on earth by natural processes and human activities, and then enter the atmosphere. Here is a primer on the major gases:
• Carbon dioxide (CO2). A tiny amount of CO2 enters the atmosphere every time you breathe out. But the CO2 produced as a waste product of the body’s metabolism is dwarfed by the CO2 generated when wood and fossil fuels such as oil, natural gas, and coal burn. A variety of other industrial reactions also produce CO2. Plants remove CO2 from the air as part of the biological cycle. But as fossil fuel combustion has increased and the world’s forests have shrunk, atmospheric CO2 climbed from about 280 parts per million (ppm) in 1750 to 315 ppm in 1958, and then to today’s level of nearly 380 ppm. Carbon dioxide bears much of the blame for global warming — and at the rate we’re going, atmospheric CO2 levels could double as early as 2050.
• Methane. Like CO2, methane is emitted during the production and transport of oil, gas, and coal. But methane also enters the air from the gastric emissions and “tailpipe” of cattle, and from decomposing manure and organic wastes in solid-waste landfills. The concentration of methane in the atmosphere has more than doubled since the industrial revolution.
• Nitrous oxide. This gas enters the atmosphere from agricultural and industrial activity, including fossil fuel combustion.
• Fluorinated gases (halocarbons). All fluorinated gases result strictly from human industrial activities, not natural sources. Although only tiny amounts are present in the atmosphere, they are very potent greenhouse gases.
While all these gases contribute to worrisome global warming, CO2 and methane are particularly concerning. And since CO2 lingers in the atmosphere for 50 to 200 years and methane for 12 years, prompt action is needed to control gas emissions, mitigate global warming, and protect human health.
Health Consequences
Climate change can affect human health in many ways. The direct effect of exposure to hot weather is the most obvious example. For example, in the 1980s and ’90s, heat stroke killed about 200 Americans a year, but the average toll is now close to 700 a year. Heat-related illnesses and deaths will increase as the earth warms up. And climate change involves more than warming; typhoons, floods, and wildfires are expected to increase, causing injury, death, psychological trauma, and damage to the public health infrastructure.
Many insects thrive in warm weather. That means more insect-borne diseases, including viral encephalitis, malaria, and dengue. Tropical diseases may also spread to temperate zones. An example was the 2007 Italian epidemic of Chikungunya virus (a viral infection normally found in the Indian Ocean region) which reminds us that global warming can make our small world even smaller.
If unchecked, polar melting will have devastating effects on the earth and its peoples. The sea level will rise, displacing millions of people. Human suffering and economic stress are obvious consequences. In addition, disruptions in sanitation, the supply of fresh water, and food production may cause health problems that extend far beyond receding shorelines. Food- and water-borne infections and malnutrition are evident threats, but the combination of population shifts and socioeconomic hardships could also trigger political instability and international conflict.
The worst-case scenario may make the health consequences of global warming sound like science fiction or Al Gore’s bad dream. One example is depletion of the stratospheric ozone layer, which has increased exposure to UVB radiation, which contributes to skin cancer, cataracts, and immune suppression. Air pollution is another threat whose time has already come. Particulate emissions and noxious gases spewed from tailpipes, smokestacks, and burning forests contribute to heart and lung diseases. Experts blame poor air quality for the fourfold increase in asthma since 1980.
Global warming may inhibit the growth of some important food crops, and it has already promoted the growth of some pesky plants. Ragweed and similar plants now produce twice as much pollen as they did 100 years ago, and rising CO2 levels will boost pollen counts even further in the years ahead. It’s another reason for the increase in asthma, as well as hay fever and allergies.
And just in case you still think climate change is just a problem for polar bears, consider this: The World Health Organization estimates that climate change is already responsible for 150,000 deaths a year worldwide, and the toll is expected to double by 2030.
Cooling It
Climate change is a huge problem, so big that it may seem insolvable. But instead of throwing up your hands and continuing to turn fossil fuels into CO2, we can take steps to control the problems. Success will depend on a combination of scientific research, new public policies, and informed personal choices.
Government policy proposals are beyond the scope of this column. Still, we all can make small steps that can add up to a long march to progress. Here are things we can do:
• Take steps. Walk (or bike) for transportation. You’ll cut your gas bill and generate less CO2. Of equal importance, you’ll get exercise that will lower your risk of heart disease, high blood pressure, stroke, dementia, depression, colon cancer, and osteoporosis.
• Eat for a cooler planet. Cows are living smokestacks that generate methane and nitrous oxide, two powerful greenhouse gases. The world’s farm animals make 18 percent of the emissions that produce global warming. If you eat less meat and dairy, you’ll reduce the demand for cows, and you’ll take in less cholesterol-raising saturated fat. Substitute meat with healthful fruits, vegetables, whole grains, beans, and fish for the health of your planet and your body.
• Make home improvements. Choose renewable energy, if available to you. Switch to compact fluorescent light bulbs. Turn off your computer when it’s not in use. Unplug TV sets, printers, fax machines, and other electronics when you’re away for a day or two.
• Reduce wasteful consumption, reuse whatever you can, and recycle whatever you can’t reuse. Health is everyone’s concern, and climate change is everyone’s problem. Do what it takes to reduce your carbon footprint and to prod our leaders to reduce global warming. It’s not only the cool thing to do. Your life and that of your children may depend on it!
— Sources: “Where will global warming hit home?” Frontiers of Science, US News and World Report, August 4-11, 2008
“9 tips for your health and the planet’s,” Harvard Health Publications, April 2007, www.earth911.org