Since the 1968 publication of Stanford University biologist Dr. Paul Ehrlich's classic book The Population Bomb, the potential consequences of the human population explosion have been a heated matter of debate. Today, the effects of overpopulation are merely becoming more and more apparent. Beyond the phenomenon's obvious impacts on human societies-poverty, hunger, disease and the breakdown of social structures-its effect on our environment and the world's animals is worsening. From problems such as the destruction of forest habitat to the die-off of coral reefs, our increasing population and consumption is largely to blame. Indeed, there is not an ecosystem on the planet that is not adversely impacted directly or indirectly by human population growth.
The latest figures from the United Nations (UN) predict the world's current population of over 6 billion people will rise to 9.1 billion by 2050, adding more than 80 million people each year. Can the planet cope with the ever-burgeoning human population? While future technologies will provide some of the tools needed to feed, clothe and provide water to increasing numbers of people in both the developed and developing world, the space and resources required to sustain numbers are finite. And with only a fraction of the Earth's species identified, current human impacts on this planet's biodiversity are already unprecedented.
As noted by Harvard Professor E.O. Wilson, one of the most respected biologists in the United States, "species are vanishing 100 times faster than before the arrival of Homo sapiens." The loss of forest habitats is devastating orangutans, the nearly extinct Sumatran tiger, gibbons, Asian elephants, a host of bird species and a variety of other forest-dwelling species around the globe. Throughout the world, amphibian populations-the modern day "canaries in the coal mine"-are in decline due to the effects of global warming, habitat loss and disease. Within the Kashmir region between Pakistan and India, disappearing forests have led to a change in bird migration routes, a significant decline in wild deer, and a reduction in snow leopards from an estimated 80 to merely 20.
In total, 484 animal and 654 plant species have gone extinct since the year 1600 because of human activity. In addition to species becoming extinct before we even learn of their existence, today it is estimated that up to 25 percent of all species may become extinct over the next 25 years. At present, 11 percent of birds, 20 percent of reptiles, 25 percent of amphibians, 25 percent of mammals and 34 percent of all fish species are threatened with extinction, according to the World Conservation Union. Habitat destruction is the biggest threat to these animals, and it is almost entirely anthropogenic. A report by the UN states that an average of 85 percent of original wildlife habitat has been lost in countries with a human population density of over 189 people per square kilometer. Even when human density was only 29 people per square kilometer, an average of 41 percent of original wildlife habitat was lost.
This problem is not just about population numbers, since our consumption of resources is the real concern. While people living in developed countries are known to use far more resources than people in developing countries, the expanding economies in the developing world are feeding an explosion in the number of people increasingly consumptive lifestyles. This trend is placing an even greater demand on finite resources. While we cannot blame those with newfound wealth for wanting to live a Western lifestyle, the implications for the planet are severe. According to the UN, if the Earth's entire human population were to have consumption levels equal to the average American, it would take three Earths to supply the necessary resources.
For example, with world meat production having quadrupled to nearly 220 million tons annually over the past 50 years, significant quantities of land and water are necessary to grow the biomass needed to feed the world's livestock. Due to the inefficiency of converting plant products to animal protein, over 40 percent of the grain grown worldwide is fed to livestock. While the demand for meat from animals who are raised organically and humanely has increased, the world's growing appetite for meat has led to habitat destruction to create additional lands for grazing and livestock grain production. It has also substantially increased the number of animals raised in deplorable conditions on feedlots and other factory-style operations.
In the ocean, our insatiable demand for fish products is destroying marine species and habitats. Another recent UN report shows that in the past 42 years, the capture of wild fish has increased from 20 to 85.4 million tons. As a result, over 75 percent of fish populations are fully exploited or overexploited, not even taking into account the effects of mounting pollution levels. Many fish are captured by trawlers, who scour up to 5.8 million square miles of ocean bottom each year, resulting in millions of tons of bycatch. Meanwhile, bodies of water such as the Aral Sea have receded dramatically and become too salty to sustain fish populations, as the rivers feeding the sea are diverted for human use. For the same reasons, the headwaters of the Yellow and Yangtze rivers in China are drying up and threatening thousands of people and animals. Deserts everywhere are expanding; the Gobi Desert grows by 4,000 sq. miles each year, and in Nigeria, over 1,350 sq. miles of land annually become desert.
The planet is facing serious environmental crises, but there is hope for the future. At present, there is sufficient food to feed the entire human population, while scientific and technological advances will likely reduce our per capita use of resources, extending the availability of critical resources such as water and productive soils. Population growth and fertility rates in many countries have declined in response to increased availability of family planning opportunities and improvements in women's rights, education, literacy and health care. Attitudes regarding our responsibilities toward the earth and animals are also improving.
However, what good news may exist is not reason for complacency, and there are steps we can all take to improve the situation. Reduce your consumption of products and energy. Walk or use public transportation instead of driving, purchase organic and locally produced products, avoid overpackaged goods, and select energy efficient products. Avoid becoming part of the "throw-away society" by reusing, repairing and refurbishing products you purchase, and recycle what you can. While reducing our use of resources will not solve the overpopulation crisis, it will minimize our human footprints on the environment.