The concept of population growth is tricky because populations can grow exponentially – similar to the way a bank or credit card company compounds interest. The formula for exponential population growth is N=N0ert where N0 is the starting population, e is a logarithmic constant (2.71828), r is the rate of growth (birth rate minus death rate), and t is time. If you plot this equation, you see a curve arching upward over time as the population increases exponentially, assuming no change in the rate.
This concept might be easier to visualize with actual figures. From the beginning of time on Earth to the start of the 20th century, the population of the planet grew from zero to 1.6 billion. Then, thanks to many factors, the population increased to 6.1 billion in just 100 years, which is an almost fourfold increase in the number of humans over a relatively short period.
More people require more resources, which means that as the population increases, the Earth’s resources deplete more rapidly. The result of this depletion is deforestation and loss of biodiversity as humans strip the Earth of resources to accommodate rising population numbers. Population growth also results in increased greenhouse gases, mostly from CO2 emissions. For visualization, during that same 20th century that saw fourfold population growth, CO2 emissions increased twelvefold. As greenhouse gases increase, so do climate patterns, ultimately resulting in the long-term pattern called climate change.
The use of resources and the impact of environmental issues are not equal around the globe. People in developed countries require substantially more resources to maintain their lifestyles compared with people in developing countries. For example, the United States, which contains 5 percent of the world’s population, currently produces a full 25 percent of CO2 emissions.
People in developing countries tend to feel the impacts of environmental problems more acutely, especially if they live in coastal areas directly affected by sea level rise and the extreme weather events that accompany climate change. The most vulnerable populations also experience decreased access to clean water, increased exposure to air pollution and diseases – which may result from decreased biodiversity – and may feel the impact more immediately as local resources including plants and animals deplete.
While the interconnected problems of population growth and environmental issues seem overwhelming, it is important to remember that humans can make changes that positively impact the planet. One good starting point is understanding and applying the concept of sustainability, which is the opposite of resource depletion. Sustainability describes a model of resource usage in which the current generation uses only the resources the Earth provides indefinitely (like solar or wind power instead of burning fossil fuels) to ensure that future generations inherit resources.
A sustainable economy must be fundamentally supported by the wise use of renewable resources, meaning they are not used more quickly than their rate of regeneration. For these reasons, the term sustainable development should refer only to progress being made toward a sustainable economic system. Progress in sustainable development involves the following sorts of desirable changes:
· increasing efficiency of use of non-renewable resources, for example, by careful recycling of metals and by optimizing the use of energy
· increasing use of renewable sources of energy and materials in the economy (to replace non-renewable sources)
· improving social equity, with the ultimate goal of helping all people (and not just a privileged minority) to have reasonable access to the basic necessities and amenities of life
Despite abundant public rhetoric, our society has not yet made much progress toward true sustainability. This has happened because most actions undertaken by governments and businesses have supported economic growth, rather than sustainable development.
Sustainable development is a lofty and necessary goal for society to pursue. But if a sustainable human economy is not attained, then the non-sustainable one will run short of resources and could collapse. This would cause terrible misery for huge numbers of people and colossal damage to the biosphere.
The notion of sustainability can be further extended to that of ecologically sustainable development. This idea includes the usual aspect of sustainable development in which countries develop without depleting their essential base of natural resources, essentially by basing their economy on the wise use of renewable sources of energy and materials. Beyond that, however, an ecologically sustainable economy runs without causing an irretrievable loss of natural ecosystems or extinctions of species, while also maintaining important environmental services, such as the provision of clean air and water. Ecological sustainability is a reasonable extension of sustainability, which only focuses on the human economy. By expanding to embrace the interests of other species and natural ecosystems, ecological sustainability provides an inclusive vision for a truly harmonious enterprise of humans on planet Earth. Identifying and resolving the barriers to ecological sustainability are the fundamental objectives and subject matter of environmental studies. It provides a framework for all that we do.
NOTE: Take MidTerm Exam before proceeding to next Chapter.