The world population increased from 3 billion individuals in 1959 to 6 billion by 1999, a doubling that occurred over 40 years. The Census Bureau's latest projections imply that population growth will continue into the 21st century, although at a slightly slower pace. The world population is projected to grow from 7 billion in 2011 to 9 billion by 2040 (2). To put this in perspective, every minute, an average of 255 human births and 106 deaths occur – this is a net gain of 149 people. At this rate, the human population is increasing by roughly 8,940 people every hour (3).
The primary causes of today’s environmental imbalances are the consumption and waste of the industrialized and newly industrializing nations. With just 4.5% of the human population, the U.S. consumes 25% of the world’s produced oil. The U.S. is also the world's second largest emitter of greenhouse gases behind China, which produces a large quantity of goods purchased by U.S. consumers. While other countries such as India have much larger populations than the U.S., they currently have a smaller total impact on ecosystems. This is because a country’s environmental impact is determined by its per capita consumption and disposal of resources multiplied by the total amount of people. Although countries like India currently don’t consume on the level of Americans, if India and the rest of the world adopted the consumption and pollution patterns of the U.S., we would need 5.3 Earths to sustain everyone (4).
Our impact on this earth is measured by Ecological Footprint (EF) assessments. An EF is the biologically productive area (land, rivers, lakes, sea) required to produce the resources (food, energy, materials) and absorb the wastes of a population. The largest portion of our global Ecological Footprint comes from the burning of fossil fuels, followed by the use of crop and pastureland. Since the late 1980s, our global Ecological Footprint has exceeded the Earth’s biocapacity – as of 2007 by about 50% (5). Humanity as a whole is running an ecological deficit.
UN Interactive Population Center,
U.S. Census Bureau,
Air Pollution and Ozone Depletion
Clean air is one of the building blocks necessary for a heath eco-system, but currently our air quality is at risk. The U.S. Environmental Protection Agency’s (EPA) air quality monitoring network indicates that almost 127 million Americans live in counties with unhealthy air due to one or more criteria air pollutants (6).
The EPA is required under The Clean Air Act of 1970 to set National Ambient Air Quality Standards for six common air pollutants. These commonly found air pollutants (also known as criteria pollutants) are found all over the United States. They are particle pollution (often referred to as particulate matter), ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead. Exposure to these pollutants is associated with numerous effects on human health, including increased respiratory symptoms, heart or lung diseases, and even premature death (7). The number one source of industrial air pollution is the burning of fossil fuels (coal, oil, and gas) for electricity production (8).
The ozone layer in the earth’s atmosphere is our layer of protection against deadly ultraviolet-B radiation from the sun. Therefore, ozone depletion is a very serious problem resulting primarily from the production of chlorofluorocarbons (CFC’s). CFC’s were discovered in 1928, proven to deplete the ozone layer in 1974, and in 1978 were banned in aerosols in the U.S. By the mid-1980s, concern over CFC’s grew worldwide when the Antarctic Ozone Hole was measured, revealing its depletion, a catastrophe if left unabated. In 1987, 57 industrial nations signed the Montreal Protocol, the first global environmental agreement. The developed countries agreed to stop all production of CFC’s on January 1, 1996, and the other countries committed to end production by 2006. Today, several CFC-substitutes are in use, and more are expected from manufacturers. As a result, the ozone layer has already shown signs of recovery. It is believed that if the international agreement is adhered to, the ozone layer is expected to recover by 2050 (9). The global solution to end CFC production and slow ozone depletion provides hope that humans can come together to solve other environmental threats such as global warming (link).
Water pollution is divided into two categories: point source pollution and non-point source pollution. Point sources of water pollution are stationary locations such as sewage treatment plants, factories and ships. Non-point sources are more diffuse and include agricultural runoff, mining activities and runoff from paved roads.
Current farming practices often result in the release of sediment, fertilizers, pesticides and animal wastes into local watersheds. The local impact has often worsened as smaller family farms have been replaced by factory operations such as Concentrated Animal Feeding Operations (CAFO’s). Factory farms have multiplied in recent years, spreading into many states that lack adequate environmental controls. Every year almost two trillion pounds of animal waste are produced nationally from 1.5 billion cattle, hogs, poultry and sheep (10). Livestock grazing in riparian zones - the thin ribbons of green vegetation that border rivers, streams and other water bodies - is responsible for degraded water quality, increased erosion and runoff, damaged fish and wildlife habitat, and decreased recreational opportunities. With controlled grazing strategies or restricting livestock completely from these sensitive areas, many of the detrimental impacts to water quality can be minimized or greatly reduced.
In 2004, states reported that about 44% of assessed stream miles, 64% of assessed lake acres, and 30% of assessed bay and estuarine square miles were not clean enough to support uses such as fishing and swimming. About 16% of U.S. waters were assessed by the states for this report. Leading causes of impairment in assessed waters include excess levels of nutrients, metals (primarily mercury), sediment and organic enrichment. Top sources of impairment include agricultural activities, hydrologic modifications, atmospheric deposition, industry, and unknown or unspecified sources (11).
Natural Resources Defense Council,
U.S. Environmental Protection Agency,
Healthy forest ecosystems benefit people in many ways. They provide food, water and materials, regulate floods, drought, support soil formation and nutrient cycling, provide habitat for wildlife and supply recreational and other nonmaterial benefits. For hundreds of millions of years, forests have covered much of the Earth’s surface (12).
Over the past 8,000 years, nearly half of the Earth’s forests have been destroyed. Globally, only 20% of the original forests remain pristine and undisturbed (13). In the U.S., only 4% of the ancient forests remain standing. The world’s rainforests are clear-cut at a rate of 214,000 acres per day, an area larger than New York City. If deforestation continues at current rates, nearly all tropical rainforest ecosystems will be destroyed by 2030 (12).
The primary cause for deforestation is the consumption patterns of the industrialized nations. In the rainforests, logging, cattle ranching, mining, oil extraction, hydroelectric dams, and subsistence farming are the leading causes of habitat destruction.
According to some estimates, less than 10% of forests worldwide can be considered old growth, or undisturbed for more than a century. And that is not just a tragedy for the plants and animals that require mature forests—it is also a tragedy for the world's climate, as old-growth forests are highly effective carbon sinks (14). Solutions to deforestation include reducing our consumption of raw materials, increasing use of reused and recycled materials, and buying wood products that come with the Forest Stewardship Council Certification.
World Resources Institute,
USDA Forest Service: Roadless Area Conservation,
Food and Agriculture Organization,
World Resources Institute,
Forest Stewardship Council
Soil Degradation & Desertification
U.S. croplands are eroding up to seven times faster than they are naturally created (15). Soil takes hundreds of years to form and is naturally removed by the action of water or wind. Such “background” soil erosion has been occurring for millions of years. But “accelerated” soil erosion is a much more recent problem. It is a result of human activities such as overgrazing or unsuitable cultivation practices, which leave the land vulnerable during times of strong rainfall or windstorms.
It is estimated that topsoil erosion currently reduces productivity on 29% of U.S. cropland and negatively affects 39% of rangeland (16). The loss of soil from farmland can lower surface water quality, damage drainage networks and reduce crop production through the loss of nutrients and degradation of the physical structure. (17).
A related environmental concern is desertification: the change of fertile land into desert. This process takes place in drier climates where the Earth is especially fragile, where rainfall is low and the climate harsh. Climatic changes can trigger the desertification process, but frequently human activities are the primary cause. Over-cultivation exhausts the soil, deforestation removes trees that prevent soil erosion, and overgrazing of livestock strips the land of grasses that prevent soil erosion (18).
Certain conservation measures can reduce soil erosion and desertification, such as contour plowing, strip cropping, terracing, or using trees for wind barriers.
UN Convention to Combat Desertification,
UNEP World Conservation Monitoring Centre,
U.S.D.A. Natural Resources Conservation Service,
Extinction & Loss of Biodiversity
Over the course of geologic history, the Earth has experienced at least five mass extinctions where two-thirds or more of existing species disappear. The primary causes of these mass extinctions include global temperature and sea level changes, volcanic activity and meteor impacts. Many scientists believe we are now undergoing the sixth such mass extinction since life began, only this one is caused by humans (19).
Species are estimated to be heading toward extinction at a rate of about one every 20 minutes, a pace that is one thousand times faster than the Earth has ever experienced in its long history (20).
A diverse ecosystem is important. Biodiversity actually boosts ecosystem productivity where each species, no matter how small, all have an important role to play. It is this combination that enables the ecosystem to possess the ability to prevent and recover from a variety of disasters. Healthy biodiversity provides other natural services including protection of water resources, soils formation and protection, nutrient storage and recycling, pollution breakdown and absorption, and a contribution to climate stability (21).
World Wildlife Fund Global Network,
Rainforest Action Network,
Endangered Species Coalition,
World Resources Institute: Global Biodiversity Assessment,
The Earth’s weather and climate originate from the sun. Solar rays enter through the atmosphere and warm the Earth’s surface. The Earth’s surface then radiates infrared heat back into the atmosphere. Some of this heat escapes into space, and some is trapped by greenhouse gases. Certain greenhouse gases occur naturally including water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Without the natural greenhouse effect, temperatures would be much lower than they are now, and life as we know it on Earth would not be possible. However, certain human activities add to the levels of most greenhouse gases. Excess greenhouse gases in the atmosphere is now causing global climate change to occur at rates faster than ecosystems can adapt. Climate change refers to long-term fluctuations in temperature, precipitation, wind, and other elements of the Earth’s climate system.
A record of Earth’s climate, dating back 400,000 years, has been decoded from air bubbles within ice core samples from Greenland and Antarctica. Beginning as much as 8,000 years ago, atmospheric levels of carbon dioxide began to rise at abnormal rates as humans started clearing forests, planting crops, and raising livestock. Carbon that was once stored in the biomass of forests, was freed up to enter the atmosphere in gaseous forms such as carbon dioxide. In the late 18th century, air pollution from human industrialization began to dramatically change the chemical composition of the atmosphere.
The primary sources of greenhouse gases have been the combustion of fossil fuels for automobiles, electricity, and heat (8). Other causes include industrial agriculture, deforestation, landfills, industrial production, and mining. Since the Industrial Revolution, concentrations of carbon dioxide have increased 37.5%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 18% (22). The U.S. is the second largest producer of greenhouse gas pollution, contributing about 20% of total emissions. The buildup of greenhouse gases is causing the Earth’s surface temperature to rise at an accelerated rate. Greenhouse gases are expected to be on the rise for many decades to come. Even after greenhouse gas concentrations have been stabilized, sea level and ice sheets will continue to respond to warming for many centuries.
The 2000 IPCC Special Report on Emissions Scenarios projects an increase of global GHG emissions by 25-90% between 2000 and 2030, with fossil fuels maintaining their dominant position in the global energy mix to 2030 and beyond. More recent scenarios without additional emissions mitigation are comparable in range (23).
Climate change can affect human health directly by more frequent floods and storms. Indirect impacts from climate change include increases in disease transmission by mosquitoes and water-borne pathogens, lower quality water and air, and famine. Recent regional changes in climate, particularly increases in temperature, have already affected hydrological systems as well as terrestrial and marine ecosystems in many parts of the world. Overall, climate change is projected to increase threats to human health, particularly in lower income populations, predominantly within tropical and subtropical countries. Solutions to global warming and climate change include expanding renewable and non-polluting energy infrastructure, reforestation, and limiting greenhouse gas pollution (24).