Frumkin, 2e Part Two: Environmental Health on a Global Scale Chapter 10: Climate Change
Climate Change Climate change results from natural variability and human activity, and depends on the overall energy budget of the planet, the balance between incoming (solar) shortwave radiation and outgoing longwave radiation. This balance is affected by the atmosphere and the greenhouse gases within it, which trap in heat and result in higher average surface temperature.
Greenhouse Gases The greenhouse gas content of our atmosphere has increased by about 35% since the 1700s. Higher greenhouse gas concentrations have contributed to warming of the Earth an effect called positive radiative forcing by absorbing and reemitting infrared radiation toward the lower atmosphere and the Earth s surface. Surface temperatures in the mid-to-late twentieth century appear to have been warmer than they were during any similar period in the last 600, and this temperature increase is currently accelerating.
Earth System Changes The increase in the earth s temperature results in additional changes to the earth, such as the melting of ice caps and the increased evaporating of soil moisture. The weather patterns that result from these and other changes vary greatly from place to place and over short periods of time, emphasizing the importance of climate variability. For these reasons the term climate change is more accurate than global warming and is the accepted term for this set of changes.
Ocean Temperatures and Hurricanes Records indicate that sea surface temperatures have steadily increased over the last one hundred years, and more sharply over the last thirty-five years. These trends in turn have implications for hurricane activity. Hurricanes form only in regions where sea surface temperatures are above 26 C.
Vulnerable Regions Certain regions and populations are more vulnerable than others to the health impacts of climate change. They include: Populations within areas that with a high endemicity of climate-sensitive diseases (for example, malaria). Areas with an observed association between epidemic disease and weather extremes (for example, El Niño linked epidemics). Areas at risk from combined climate impacts relevant to health (for example, stress on food and water supplies or risk of coastal flooding). Areas at risk from concurrent environmental or socioeconomic stresses (for example, local stresses from land use practices or an impoverished or undeveloped health infrastructure) and with little capacity to adapt
Food Production and Malnutrition Climate change is likely to have major effects on crop and livestock production and on the viability of fisheries. Some changes will be positive and others negative, and the net impact on food production will likely vary from place to place. Drought due to increased temperatures could exacerbate problems of malnutrition and food production. What s more climate change, which is associated with the acidification of oceans, resulting from higher CO 2 levels may endanger fish populations.
Weather Extremes Heat waves, resulting in part from the increased temperatures caused by climate change, can cause extreme heat waves that endanger public health. A prime example of how heat waves can negatively populated environments occurs in cities due to urban heat islands. They are urban areas that generate and retain heat as a result of buildings, human and industrial activities, and other factors. These heat islands are caused by the black asphalt and other dark surfaces (on roads, parking lots, and roofs) that have a low albedo (reflectivity), and absorb and reradiate heat. It is unlikely that milder winters that occur from climate change will offset the increase in mortality caused by extreme heat waves.
Natural Disasters Natural disasters can have adverse affects on property, physical health, and mental health. Floods - The amount of rainfall during the heaviest storms in the United States has increased, which is expected to cause increased flooding. Wildfires - The potential for wildfires has increased as a result of increased temperatures and increased evaporation of moisture.
Sea-Level Rise Sea surface warming causes a rise in sea level due to thermal expansion of salt water. One expected effect is an increase in flooding and coastal erosion in low-lying coastal areas. Rising sea levels may affect human health and well - being indirectly, in addition to directly through inundation or heightened storm surges.
Air Pollution Climate change may affect exposure to air pollutants in many ways because it can influence both the levels of pollutants that are formed and the ways these pollutants are dispersed. Air quality is likely to suffer with a warmer, more variable climate. Ozone levels are expected to rise to dangerous levels in some areas because of increased warming of plants, which release isoprenes (ozone precursors) as the temperature rises. Allergenic plants are also expected to produce more pollen, which endangers people with allergies. Plants like poison ivy, which rely on increased carbon dioxide and can be harmful to humans, are expected to grow at unprecedented rates.
Infectious Diseases Waterborne and foodborne diseases are expected to be spread more as a result of temperature increases. There is concern that droughts, flooding, contamination of water supplies, and other factors will contribute to the problem of infectious diseases. What s more, the prevalence of some illnesses, like diarrhea and salmonella, has been linked to increases in temperature.
Marine Ecosystems Warm water and nitrogen favor blooms of marine algae, including two groups, dinoflagellates and diatoms, that can release toxins into the marine environment. These harmful algal blooms (HABs) previously called red tides can cause acute paralytic, diarrheic, and amnesic poisoning in humans, as well as extensive dieoffs of fish, shellfish, and marine mammals and birds that depend on the marine food web.
Vector-Borne Diseases Vector-borne diseases are caused by protozoa, bacteria, and viruses, that are spread by organisms such as mosquitoes.. Malaria and arboviruses are transmitted to humans by mosquitoes. Mosquitoes typically reproduce more quickly and survive longer in warmer environments. Some vector-borne diseases replicate more quickly during incubation when the climate is warmer. Ticks (carriers of Lyme disease), which require a minimum temperature to survive, will also likely spread further north as temperatures there increase. Plague is another climate-sensitive disease, one that is carried by fleas associated with rodents.
Land Use, Local Climate, and Infectious Disease Factors that affect disease (rainfall, biodiversity, etc.) are altered by differences in wetland and surface water levels and vegetation cover.
Mitigation and Adaptation Mitigation refers to efforts to stabilize or reduce the production of greenhouse gases. The paradigm of stabilization wedges states: If carbon dioxide emissions have traced an upward trajectory for over a century, and if we wish to redirect that trend to achieve stable or decreasing emissions, then we need to employ several technologies and behavioral changes in the areas of energy efficiency, and reduced transportation demand. Each of these solutions can be viewed as a wedge, and combining wedges is a strategy for stabilizing climate. Adaptation refers to efforts to reduce the public health impact of climate change. It is based upon the conduction of vulnerability assessments to identify at-risk populations.
Co-Benefits An important theme in both mitigation and adaptation is co-benefits, which are the multiple benefits that may occur from an act of mitigation or adaptation. For example, planting trees in cities helps reduce CO 2 levels while at the same time reducing the urban heat island effect, reducing local energy demand, improving air quality, and providing an attractive venue for physical activity and social interaction.
Unintended Consequences Steps taken to address climate change can have unintended consequences. For example, critics of biofuel production (an alternative to fossil fuel) claim that large-scale production of biofuels diverts the crops used in their production (corn, sugar cane, etc.) from use as food, creating scarcity and increasing food prices.
Public Policy and Climate Change International efforts to address climate change are carried out under the United Nations Framework Convention on Climate Change (UNFCCC). It works through agreements, like the 1997 Kyoto Protocol, in order to reduce climate change.
Ethical Considerations Climate change raises ethical concerns in several ways: First, the nations that are responsible for the lion s share of carbon emissions to date account for a small proportion of the world s population and are relatively resilient to the effects of climate change. In contrast the large population of the global south the poor countries account for a relatively small share of cumulative carbon emissions, and a very low per capita emission rate. Second, poor populations within each country will be more effected than rich populations, even though rich populations tend to use more energy. Third, current generations energy use will have disproportionate effects on future generations.