Rapid US Population Growth - Food and the Environment
By David Pimentel
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The U.S. population has doubled in the past six decades to over 300 million people. Currently, the U.S. population growth rate is now more than twice that of China. In about 100 years, at our current growth rate, the U.S. population is projected to reach 1.2 billion -- or nearly the population of China. Is this what we want for future America?
Like it or not, our natural resources, from land to wood to oil to water, are finite and cannot sustain an infinite population growth without seriously impacting our quality of life. The time has come for government planners and citizens alike to begin weighing the impacts of unabated population growth.
More than 99% of all our food comes from the land and less than 1% from the oceans and other aquatic ecosystems. Each American consumes more than 2,200 lbs of food per year, and to produce this food requires more than 3.6 acres of agricultural land. Most U.S. cropland is now in production and little is available for expanding food production. Moreover, approximately 1 additional acre is required per person for urbanization, highways, and for supporting industry.
Along with land, an ample supply of freshwater is essential for food and other human needs. Water shortages already exist in many parts of the nation, especially in western and southern states - and such shortages will become more acute if population growth continues unabated. Each American uses about 530,000 gallons of water per year, with about 80% used just for food production. For example, an acre of corn requires 500,000 gallons of water during the growing season.
More than 90% of U.S. oil reserves have already been pumped, and currently more than 63% of U.S. oil has to be imported from other nations at a cost of more than $120 billion/year. Yearly, each American uses energy in the equivalent to 2,800 gallons of oil, with 500 gallons devoted just for food production.
Fossil energy is a non-renewable resource, which means that Americans will require renewable energy sources in the future. Depending on the geographic region, the renewable energy technologies with the greatest potential are photovoltaics, hydropower, wind energy, biomass (thermal), solar thermal, and passive solar. Yet, even when all solar-based technologies become operational, they are expected to provide only half of the current U.S. energy consumption. These renewable energy technologies will require about 17% of U.S. land area for their production -- and this is equal to current cropland area in use.
The U.S. is now producing 5 billion gallons of ethanol per year. This uses 20% of the U.S. corn crop but the yield represents only 1% of U.S. petroleum use. If 100% of U.S. corn were used, the estimated ethanol yield would provide only about 6% of U.S. petroleum needs.
The continued expansion of the human population not only is depleting fossil fuels, it is reducing the numbers of native species of plants, animals, and microbes throughout the U.S., many of which are vital to agricultural production processes, such as pollination, and essential for a quality environment.
Converting land to development and highways not only takes away valuable cropland acreage. For example, in California 240,000 acres of farmland was lost during last year to development.
Highway construction also destroys many thousands of acres of natural habitat for survival of native species. Nearly 4 million miles of highways cover our land. The area being blacktopped each year is 1.3 million acres (an area equal to the State of Delaware). No species lives under the blacktop. Rapid, unabated population growth, including legal and illegal immigrants, also is stressing school systems. Some schools have three times the number of students that they can handle with the available teachers and support staff. Overall this lowers our effectiveness of the education system, which in turn reduces the economic viability and competitiveness of the United States in the global market.
Similarly, the rapid increase in the population is crowding medical facilities in the United States. In the past two decades the number of outpatients in hospitals has increased more than two fold, and continues to increase. Some hospitals have been forced to close due to the pressure on their emergency and outpatient facilities.
The rapid population increa
se in the United States is challenging our food production system, the economy in general, and the environment. As humans and their diverse activities expand, the sustainability of the natural environment is threatened and diminished for the future.
We, as a nation, must come to grips with the harsh reality that our land, energy, food and water are finite. The quality of life for us, and especially for our children and future generations, is closely linked to the number of people who live in our 50 states.
David Pimentel
Professor
College of Agriculture and Life Sciences
Cornell University
Ithaca, New York
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