To Print: Click your browser's PRINT button



NOTE: To view the article with Web enhancements, go to:



[pic]

Public Health Perspective

Global Warming: A Public Health Crisis Demanding Immediate Action -- Part 1

Martin Donohoe, MD, FACP

Medscape Public Health & Prevention.  2007; ©2007 Medscape

Posted 01/12/2007

[pic]

Introduction

This column is the first part in a 2-part series on global warming. Part 1 will provide an overview of the causes and environmental and health consequences of global warming. Part 2 will describe how corporations have employed unsound science and legislative influence to attempt to refute the existence of -- and to impede progress toward curtailing -- global warming; how the media have obfuscated the issue of global warming; and the roles of individuals, governments, and health professionals in confronting this major environmental crisis.

Overview: Climate Change and the Greenhouse Effect

Although cooling and heating shifts in the earth's climate occur with somewhat predicable frequency on geological time scales, it is now accepted that we are in the midst of a dramatic and rapid warming of the planet consequent to the combustion of fossil fuels.[1-3] [Donohoe MT. Roles and responsibilities of health professionals in confronting the health consequences of environmental degradation and social injustice. Submitted to: Social Medicine, May 2006.] This warming, which began with the advent of industrialization in the late 19th and early 20th centuries, has accelerated over the last few decades and bodes ill for the earth's ecosystems and for human health.

Causes of Global Warming

Climate change and the greenhouse effect. Planetary temperature has increased 1° over the last century -- a number that might seem small yet has dramatic consequences.[4] The last 24 years have been the hottest in the last century and a half, and 2005 was the hottest year since weather record-keeping began in 1856. If no action is taken to reduce carbon emissions, the concentration of atmospheric greenhouse gasses could reach double its pre-Industrial Era level within the next 30 years, leading to a temperature rise of at least 2° C.[4] Recent estimates from the International Panel on Climate Change place the rise as high as 10° C over the next century.[1]

The greenhouse effect refers to the tendency of carbon dioxide (CO2), methane, nitrous oxide, sulfur compounds, and chlorofluorocarbons to trap that portion of the sun's heat energy which is reflected off the earth.[5] Without a greenhouse effect, the earth's average surface temperature would be -18° C instead of 15°C, and our frozen planet would not be able to sustain human life. The presence of the major greenhouse gasses is a consequence of both natural processes (eg, cellular respiration) and man-made technologies (the burning of fossil fuels and methane production from agricultural activities such as growing rice and raising cattle).[5] Large industrialized countries are the greatest contributors to global warming.

Contributors to Global Warming

The top one fifth of the world's nations account for over 60% of global CO2 emissions; the lowest fifth accounts for just 2%.[5] Although the United States contains just 5% of the world's population, it is responsible for 25% of the world's energy consumption (as well as 33% of paper use and 72% of hazardous waste production).[3] The countries likely to be most affected by global warming, primarily the developing nations of the Southern hemisphere, are those least responsible for the increases in global temperature.

Industrialization and automobiles. Since preindustrial times, the atmospheric concentration of CO2 has increased 31%.[2] The major cause of increased greenhouse gas production is the burning of fossil fuels such as coal, oil, and natural gas. Transportation, electricity generation, and heating and cooling for industrial processes contribute almost equally.[5] Industrialization and the ever increasing number of fuel-inefficient automobiles have also significantly contributed to air pollution and the destruction of the protective ozone layer.

Automobile use provides a graphic illustration of just 1 current inequity in contribution to global warming. For every gallon of gasoline manufactured, distributed, and then burned in a vehicle, 25 pounds of CO2 are produced.[3] In the United States, there is 1 car for every 2 people; in Mexico, 1 for every 8; and in China, 1 for every 100. The number of miles driven per person continues to grow as urban sprawl leads to longer commute distances.[6,7] US fuel economy standards have changed very little since the Model-T, due in large part to lobbying by car manufacturers and the oil industry.[3] Globally, the automobile population is expected to double in the next 25-50 years.

The military and oil use. The world's militaries are the planet's single largest polluter, responsible for 8% of global air pollution and 6% of raw material use.[8] Even prior to the current wars in Iraq and Afghanistan, the US Defense Department was the world's largest consumer of oil and the Pentagon generated half a billion tons of toxic waste per year -- more than the 5 top chemical companies combined.[9] Ironically, the Pentagon has deemed global warming a "vastly greater threat than terrorism," with enormous consequences for US national security and the potential to cause global anarchy.[10]

Deforestation. Deforestation, spurred by overpopulation, poverty, unsustainable farming practices, and rapacious logging to satisfy an increasing demand for paper products, has in turn augmented global warming, degraded soil quality, and contributed heavily to species loss.[1-3] Deforestation destroys the plant life which serves as the planet's CO2 sink. Half of all tropical forests have been destroyed; by 2010, three quarters may be lost.[3] Also, an estimated 20% to 50% of global wetlands have been destroyed.[3] Areas most affected by deforestation are the Amazon, sub-Saharan Africa, the Philippines, and most recently the Pacific Northwest and British Columbia (the "Amazon of the North").

The factors that lead to deforestation are need for new agricultural settlements, spurred by overpopulation, poverty, and unsustainable farming practices; urban sprawl; logging for building materials and paper; cattle ranching; and drug cultivation in countries like Peru, Bolivia, and Columbia.[3] With deforestation and global warming have come shifts in the ranges and behaviors of plant and animal species. One example of this is the increased range of mosquitoes that carry malaria to higher elevations, which in turn has contributed to an increased prevalence of this deadly disease.

Combustion for cooking and heating. Another important contributor to global warming and pollution is the combustion, by almost 3 billion people worldwide, of coal and biomass (wood, charcoal, crop residues, and animal dung) for cooking, heating, and food preservation.[11] Health consequences of released pollutants are magnified when such combustion is carried out in enclosed spaces, a common occurrence in many developing countries.

Consequences of Global Warming

Melting and flooding. Consequences of global warming include the melting of polar icecaps and glaciers and the rise of global sea levels.[1,2,4,5] Over the next 100 years, sea levels are predicted to rise between 9 cm and 88 cm. This rise is likely to result in more coastal erosion and flooding during storms, and water may inundate Male (the capital of the Maldives) and South Pacific islands like Tuvalu and Vanuatu. Low-lying countries like Bangladesh will be threatened, and aquifers in New Orleans and San Francisco could be destroyed.

Large portions of the Antarctic ice shelf have calved into the sea and the Greenland ice sheet is rapidly receding. With less ice to reflect sunlight, the earth absorbs more heat, which accelerates melting. If the layer of permafrost covering the Siberian tundra continues to melt, huge amounts of CO2 could be released, further accelerating global warming.

Extreme weather events. Global warming augments the effects of extreme weather patterns, including El Niño and La Niña, and may have contributed to the recent dramatic increase in severe hurricanes and costly flood damage in the United States.[1,2,4,5] With higher temperatures would come more heat waves, resulting in more deaths from hyperthermia (although deaths from hypothermia should decrease). Due to the additive effects of global warming, overpopulation, and water pollution, supplies of fresh water have decreased -- with limitations making it a resource over which future wars will likely be fought.[12]

Air Pollution: Ramifications for Human Health

There are many actual or potential adverse effects of global warming for both individual and public health. Some have already been briefly mentioned and others have been implied. It is beyond the scope of this column to address or even to list all such effects; however, numerous studies have documented the links between greenhouse gasses, air pollution, ozone depletion, and acute and chronic health problems.

Greenhouse gasses are major contributors to air pollution -- and pollution levels have been strongly linked to morbidity and mortality from cardiopulmonary and cerebrovascular disease, lung cancer, and infant mortality in the United States.[13-18] Higher ambient temperatures increase smog and ground level ozone, thus exacerbating symptoms in those suffering from asthma and chronic obstructive pulmonary disease. Higher levels of CO2 favor growth of ragweed and other pollen-producing plants that in turn exacerbate allergies.

Furthermore, due to pollution-induced destruction of ozone in the upper atmosphere (as well as cooling of the upper atmosphere, a consequence of more heat being trapped in the lower atmosphere), the ozone layer, which provides protection from the sun's harmful ultraviolet radiation, is being depleted. This depletion has been associated with an increase in cataracts, a consequence of ultraviolet-light induced damage to the eye's lens, and a predicted increase in the lifetime risk of malignant melanoma, the most virulent form of skin cancer.[19] Scientists at the World Health Organization have estimated that about 160,000 people die each year from the side effects of global warming, and that this number could double by 2020.[20]

Conclusion

The next column in this 2-part series will focus on how data from corporate-funded studies and legislative influence have impeded recognition and response to global warming. Suggestions for ways to confront global warming, as individuals and as health professionals, will also be offered.

References

|Report of the Intergovernmental Panel on Climate Change, 2001. Available at: Accessed November 3, 2006. |

|Gore A. An Inconvenient Truth. New York: Rodale/Melcher Media; 2006. |

|Donohoe MT. Causes and health consequences of environmental degradation and social injustice. Soc Sci Med. 2003;56:573-587. |

|Abstract |

|Report of the Stern Commission on Climate Change, United Kingdom. Available at: |

| Accessed October 30, 2006. |

|Staff. Frequently asked questions about global warming. Union of Concerned Scientists. Available at: |

| Accessed November 3, 2006. |

|Mark J, Morey C. Rolling smokestacks. Nucleus (Union of Concerned Scientists). 2000;(Summer):1-3. |

|Staff. Driving ourselves crazy. Amicus Journal. 1999;(Summer):21 |

|Sidel VW, Shahi GS. The impact of military activities on development, environment, and health. In: Shahi GS, Levy BS, Binger A, |

|Kjeustrom T, Lawrence R, eds. International Perspectives on Environment, Development, and Health: Toward a Sustainable World. New|

|York: Springer Publishing Company; 1997. |

|Thomas W. Scorched earth: the military's assault on the environment. Philadelphia: New Society Publishers; 1995. |

|Townsend M, Harris P. Now the Pentagon tells Bush: climate change will destroy us. The Guardian. 2004 Feb 22. Available at: |

| Accessed November 3, 2006. |

|Ezzati M, Kammen D. The health impacts of exposure to indoor air pollution from solid fuels in developing countries: knowledge, |

|gaps, and data needs. Env Hlth Persp. 2002;110:1057-1068. |

|Leslie J. Running dry - what happens when the world no longer has enough freshwater? Harper's Magazine. 2000 Jul:37-52. |

|Samet JM, Dominici F, Curriero FC, et al. Fine particulate air pollution and mortality in 20 U.S. cities, 1987-1994. N Engl J |

|Med. 2000;343:1742-1749. Abstract |

|Dockery DW, Pope CA, Xu X, et al. An association between air pollution and mortality in six U.S. cities. N Engl J Med. |

|1993;329:1753-1759. Abstract |

|Morris RD, Naumara EN, Muasmghe RL. Ambient air pollution and hospitalization for congestive heart failure among elderly people |

|in seven large U.S. cities. Am J Public Health. 1995;85:1361-1365. Abstract |

|Morgan G, Corbett S, Wlodarczyk J. Air pollution and hospital admissions in Sydney, Australia, 1990 to 1994. Am J Public Health. |

|1998;88:1761-1766. Abstract |

|Ponka A, Virtanen M. Low-level air pollution and hospital admissions for cardiac and cerebrovascular diseases in Helsinki. Am J |

|Public Health. 1996;86:1273-1280. Abstract |

|Bobak M, Leon DA. Air pollution and infant mortality in the Czech Republic, 1986-88. Lancet. 1992;340:1010-1014. Abstract |

|Whited JD, Grichnik JM. Does this patient have melanoma? JAMA. 1998;279:696-701. |

|Staff. Global warming deaths on the rise. Available at Accessed November |

|3, 2006. |

[pic]

Martin Donohoe, MD, FACP, Adjunct Lecturer, Community Health, Portland State University, Portland, Oregon; Staff Physician, Department of Internal Medicine, Kaiser Sunnyside Medical Center, Portland, Oregon

Disclosure: Martin Donohoe, MD, FACP, has disclosed no relevant financial relationships.

Public Health and Social Justice Website



martindonohoe@

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download