Deforestation is one of the leading causes of habitat and biodiversity loss. The rainforests contain at least half of the Earths species and the clearance of these rainforests is causing a dramatic loss of biodiversity. Primate species are highly threatened because of their dependence on large expanses of tropical forest. The accelerating worldwide loss of biodiversity is alarming, no one knows how many species inhabit the Earth, and species are disappearing so fast that many of them are not even named. The fundamental solution to halting biodiversity declines is slowing population growth and over consumption. Levels of biodiversity are said to decrease as population increases, and it is estimated that we lose one or more entire species of plant or animal every twenty minutes. Human numbers and lifestyles compel habitat destruction, and the pressure on land for building and agriculture further contributes to the concerns for biodiversity. As wetlands are drained or filled to create farmland, commercial and residential real estate, more species are being lost. Urbanisation has dramatically increased the rate of biodiversity decline through habitat loss and change. The construction of roads and new towns destroy and alter vast areas of natural habitats worldwide. According to a study of fifty countries by Paul Harrison, those with the greatest population density retain the least wildlife habitat.
Many marine ecosystems are also in decline and threatened due to human numbers and their behaviour, factors influencing this are water diversion, pollution, sedimentation from upstream soil erosion, over-harvesting, coastal development and introduced species. With population increasing and half of the world’s population living within one hundred kilometres of coastlines many environmentalists are saying that coastal development is one of the most pressing issues that are damaging biodiversity. Marine species provide a large percentage of humans protein supply, they also absorb large amounts of CO2 and are said to hold the important pharmaceutical advances. Shrinking fish stocks, extinction of freshwater species, and the decline of coral reefs are all indicators showing the increasing threat to marine biodiversity due to human activities. Lack of fish will put more pressure on the land to feed the population and intensive farming will create even more environmental problems.
Population growth has a negative impact on the Earths atmosphere due to the release of pollution that causes smog, acid rain, and depletion of the ozone layer. All of these have impacts on the health of human beings, and of ecosystems. Human numbers and activities are directly related to this because it is largely a result of emissions from automobiles and industrial plants. With population growth meaning more people needing more automobiles air pollution will increase further. Carbon emissions are also linked to global warming, and climate change, these are what may be the most serious long-time threat to humanity. The air quality in Mexico City is said to be the worst in the world, because of its population density. It is said that just breathing the air in Mexico City is the equivalent of smoking two packs of cigarettes a day. China has seen death rates increase nearly twenty-five percent in the last ten years due to respiratory diseases. In Shanghai, the air reportedly contains three hundred and two different types of chemicals, and it is estimated that over three hundred people die each year due to poor air quality. The United States environmental protection agency estimates that sixty thousand people die each year from respiratory problems linked to emissions, and an average of fourteen people die each day from asthma aggravated by air pollution.
Air pollution is evident as acid rain, when these airborne acids fall on Earth in the form of precipitation, they can kill fish in lakes and streams, damage forests and crops, and corrode metals. In Europe, the United Nations estimates that nearly one quarter of total forests have been damaged by acid rain. In Great Britain well over half of the total forest area has been damaged. Global air pollution appears in two different forms; ozone depletion and global warming, these are the most critical environmental impacts imposed on the atmosphere by human pollution. Depletion of the ozone layer allows more ultraviolet radiation to hit the world’s surface; scientists believe that this will cause damage to plants, mammals, insects, birds, and will be a direct link to an increase in skin cancer for humans. It is also believed that global warming will lead to rising sea levels and natural disasters such as hurricanes, heat waves, storms, flooding and droughts that will threaten people, communities and global food supplies. People in industrialized countries generate the majority of carbon emissions, but as the developing countries are where the majority of population growth will occur in the next several decades the emissions will significantly increase. The United Nations Population Fund projects that developing countries will double their carbon dioxide emissions by 2025.
The connection between population growth and environmental damage is easy to see and understand. When we have more people, we need more food, more housing, and more fuel. If population grows faster than resources scarcities will occur, people will go hungry, be homeless and without wood for fuel many will be cold. Resource scarcities due to population growth can cause a number of problems such as migration, social, religious, and ethnic tensions and wars. It seems that over population will lead to loss of life in many ways; the loss of bio-diversity, our forests, and human beings. It seems as though virtually every important issue we confront today is caused or contributed to, by population growth.
