World population is currently growing by over 80 million people each year, and is projected to exceed six billion people by around the year 2000. Human numbers are expected to increase by around 80 million people annually for roughly the next 30 years, leading to a global population in 2030 of over 8.5 billion. This level of increase and of total population are unprecedented in human history, and create challenges to the environment and the quality of human life previously unimagined.
When nomadic people first came down into the great river valleys to create permanent settlements, the earth's population was perhaps five to ten million. That number was relatively stable, because life was hazardous. Life expectancy was short-perhaps 25 to 30 years-and about, as many people died each year from hunger, accidents, or disease as were born. Population growth, therefore, was approximately zero.
Beginning with the Age of Agriculture some 10,000 to 12,000 years ago, life spans lengthened. Farming provided more stable food supplies, and the relative security of a settled existence allowed more people to survive. As mortality decreased, population increased, and it may be that birth rate also increased. Overall, life expectancy appears to have improved only slightly, however.
By the First Dynasty in Egypt (circa 3000 BCE) global population reached around 100 million. By the height of the Roman Empire and the birth of Christ, that number was perhaps 250 million almost the size of the United States today.
As productivity increased, fostered by inventions such as the plow and the water wheel, as well as a greater understanding of raising plants and animals, food supplies also increased. In response to available food supplies, human numbers also increased. More people then required more land for fields and towns, which in turn led to greater prosperity and productivity and again to more people. By 1,500 CE, world population had reached, perhaps, one-half billion. It was around this time that the era of western colonial expansion began, driven in large part, by the demands of more people for more resources.
Population growth was not always linear. Famine, war or disease often decimated local cultures. In fact, as population grew, another pattern of human history emerged that of overpopulation, which led, unfortunately, to over-exploitation of resources.
Civilizations can grow when resources are available, whether fertile soils and good water, minerals for metalwork, or forests for fuel and building. In the prosperous times that followed, population tended to increase. At some point a threshold was reached, beyond which demand exceeded supply, and the resource base could no longer supply the population. The resulting disruption then generated problems similar to those we see from severe overpopulation today social and economic collapse, hunger, migration and war.
Human numbers were also limited by disease. Bubonic Plague (the Black Death) devastated large parts of China as early as the third century BCE, then spread west to ravage Constantinople in 542 CE. During the fourteenth century, it killed one third of the population of Europe. Other diseases were equally devastating, if more localized. When the conquistadors invaded Mexico in 1517, the native population was some 25 million. In less than a century, it had fallen to just over one million. The remainder succumbed to introduce disease, just as the Inca Empire was conquered more by smallpox than Pizarro's few soldiers.
Despite these setbacks, however, population continued to grow overall. On the eve of the industrial revolution in 1750, humans numbered around 750 million, and just after 1800, world population reached one billion.
As population increased, identifiable side effects associated with that growth became more apparent, most notably migration either to cities or to other lands and conflict. Internal migration increased as rural populations grew in size and it became increasingly difficult to absorb younger people into the labor force. The onset of mechanization also displaced many workers, who then were forced to move to cities in search of jobs.
As rural families grew over the generations, it often became impossible to divide hereditary lands among all those in need, and more people were forced to leave. Lack of work, economic instability, local food scarcity and lack of available land all contributed to large-scale migration in the past, just as those factors drive migration today.
International migration occurred in the form of colonization particularly by European nations as expanding countries looked beyond their borders for sources of raw materials and wealth. Individual colonists migrated in search of a better life, including access to land and economic opportunity. In virtually every case, population-driven international migration led to conflict.
Conflict between nations increase as competing powers fought over colonies and access to resources in North and South America, Asia and Africa. Conflict also occurred on a more local scale, as the new arrivals clashed with indigenous populations. As European settlers expanded across North America. For example, they displaced or dispossessed Native inhabitants. Those peoples were then forced to migrate, and subsequently displaced the tribes onto whose lands they were driven, (or failed to do so, and vanished as a culture).
As Americans pushed further west in search of more land and resources to supply a growing population, more clashes followed. By the time the western edge of the continent was reached, the majority of land and resources were controlled by the new immigrants, and most surviving indigenous populations were relegated to reservations. Population growth continued through the nineteenth century, spurred by a general economic and immigration expansion, and increased food production. The Industrial Revolution generated a great economic boom, as machine power made mass manufacturing possible. Steam-powered transportation systems allowed people to move easily from one place to another, while mechanization made it possible for fewer farmers to work more land. As the possibility of working for cash wages opened up, opportunities to accumulate capital, and to move it easily, increased.
Despite a drop in birth rates, population growth continued. Advances in medicine and sanitation lowered mortality and increased life expectancy.
During the Civil War, health care workers demonstrated that steps as simple as doctors washing their hands between operations and sterilizing instruments dramatically reduced infection. Development of safe water sources, sewer systems and food preservation technologies also improved general health.
The work of Lister and Pasteur provided improved understanding of infectious agents, while the development of general anesthetics, X- rays and corrective surgery saved countless lives. The invention of antibiotics, such as sulfonamides and penicillin in the 1930's allowed treatment of many previously fatal infections and vaccinations protected people against diseases such as smallpox, typhoid and measles.
After World War II, relief workers from the United Nations and other organizations introduced public health measures to the less developed regions of the world. Without the historic constraints of hunger and disease, population growth in those regions has been dramatic - so dramatic, in fact, that the term "explosion" has sometimes been used to describe it. In some regions growth rates reached three to four percent annually, which equates to a doubling of population every 17 to 23 years.
Despite the fact that global birth rates have declined in recent years, population increases will continue for the foreseeable future because of a factor known as population momentum. This means that even if people have fewer children on average, there are so many more people having children overall that population continues to grow. Today, roughly one third of the world's population - nearly two billion people -are under the age of 15. As those young people - most of who live in developing regions -start families in the future, world population will soar.
After taking all of human history for population to reach one billion, it took only a little over a century to reach two billion in 1930. The third billion was added in just 30 years and the fourth in only 15 years. Today, we're adding another billion people, and projections indicate that at the current rate of increase, world population will double again in just 47 years.
Less developed regions in particular face a difficult future. Africa is growing at a rate which, if maintained, will lead to a doubling of population in just 24 years. At its current rate of growth, Asia -excluding China, which has slowed growth through its controversial "one child" policy - will double its population in 36 years.
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The extent of the alteration of the natural environment through human activity has increased dramatically in the last three centuries. The Scientific Revolution that began in the 1700s was more than just an Industrial Revolution - it transformed medicine, agriculture, settlement, and sanitation. Taken together, these changes enabled people to live longer and more prosperous lives. As a consequence, total population and per capita resources used began to grow exponentially, though not at the same rate everywhere. Total material flow from the resource base, through the human economy and back into the environment as waste, has multiplied many times over and is threatening the environmental systems upon which life on Earth depends. Opinions among scientists, politicians, and citizens are deeply divided as to what the future holds.
The purpose of this unit on "The World Population Explosion" is to develop an awareness of the seriousness of the problems of over population. The unit is designed for use in grades 5-12. The unit will provide a conceptual framework on how to deal with fundamental problems through integrating reading, writing, collaborative activities, science and mathematics. Students will be exposed to subject content and lessons plans that enhance critical thinking and inquiry. A hands-on approach to learning about problem with population growth will be utilized.
This unit introduces students to some of the fundamental questions about the connections among population, resources and energy use, and environmental impacts. What factors have caused the enormous growth of population and energy use in the past? To what extent is population growth responsible for the environmental problems we see today? What opportunities are there for slowing population growth, per capita energy use, or the environmental harm caved by each unit of energy use?
The unit will become an invaluable aid in programs for motivated students. It provides clear guidelines and procedures for involving these children in significant learning experiences in research and high level thinking skills, while not neglecting challenging learning within the respective basic disciplines of science, mathematics, social studies, and writing. The approach is one that engages the interests of children at a deep level.
One of the most exciting things about independent learning is that students can become an "expert" about a subject that their friends may not understand. "Kids Teaching Kids" allows students to share their knowledge with others. The process of teaching requires you to do much more than acquire knowledge, however, and that is what research is all about. Students will be synthesizing information, which means that they will take facts that are known and build them into something that has not existed before. Students may going to create something new!
With “The World Population Explosion” you may require students to conduct research. Few children, however, possess the necessary skills to complete this type of project successfully. The Research Guide is designed to help them learn and practice some basic skills: how to locate, record, organize, and present information about topics they study. Even though the handouts are detailed, students will need some guidance and instructional support from you as they undertake their first research projects.
The activity on poverty, can be in preparation for the CAPT Interdisciplinary Assessment. Students use knowledge and skills they have gained through their social studies, science, mathematics, language arts and other classes. Students are presented with several source materials (e.g., newspaper or magazine articles, government documents, editorials, political cartoons, maps, charts or graphs) related to a significant issue. The lesson begins with a brief group discussion. The purpose of this collaborative activity is to give students the opportunity to begin thinking about the topic and to share their ideas with others before starting the task.
For the graphing activity "Where in the United States Are You," we can use the number line and ordered pairs to locate points on a plane. 1. Construct the United States geographic coordinate system (2 number lines one vertical, one horizontal) on your map of the United States. 2. Use this system to locate points on the map of the United States.
The activity on projecting the rate of population growth can be in preparation for the CAPT Mathematics Assessment. It will assess students understanding of important skills and knowledge in mathematics. The questions will require students to apply their understanding of mathematics to real situations that occur in everyday living. Students will be able to use a calculator for all of the problems in this activity and on the actual test.
The Mathematics CAPT Assessment will consist of two types of questions, open-ended and grid items. For the open-ended questions, students response may be to write an explanation, fill out a form, create a graph, or draw a diagram. For the grid questions, students will solve a problem and then record their answer in a number grid. For many of these questions, there may be more than one acceptable answer, depending on how they solve them.
The unit provides students with the concepts and tools needed to make sense of the often contradictory and contested information on population, energy, and environment, and to encourage them to draw their own conclusions based on a comprehensive understanding of the linkages among demographic, economic, environmental, and resource systems. The activities are designed to develop students' appreciation of the global linkages among population, energy usage, and environmental impacts understanding of the basic concepts and dynamics of population growth' understanding of energy usage and links to economic activity and growth and assessment of the enormous and value-changed complexity of the population-environment relationship. Throughout, students are challenged to think critically and practically about the own habits and lifestyles.
