Environment

Overpopulation has substantially adversely impacted the environment of Earth starting at least as early as the 20th century.There are also economic consequences of this environmental degradation in the form ofecosystem services attrition. Beyond the scientifically verifiable harm to the environment, some assert the moral right of other species to simply exist rather than become extinct. Environmental author Jeremy Rifkin has said that "our burgeoning population and urban way of life have been purchased at the expense of vast ecosystems and habitats. ... It's no accident that as we celebrate the urbanization of the world, we are quickly approaching another historic watershed: the disappearance of the wild."

Says Peter Raven, former President of the American Association for the Advancement of Science (AAAS) in their seminal work AAAS Atlas of Population & Environment, "Where do we stand in our efforts to achieve a sustainable world? Clearly, the past half century has been a traumatic one, as the collective impact of human numbers, affluence (consumption per individual) and our choices of technology continue to exploit rapidly an increasing proportion of the world's resources at an unsustainable rate. ... During a remarkably short period of time, we have lost a quarter of the world's topsoil and a fifth of its agricultural land, altered the composition of the atmosphere profoundly, and destroyed a major proportion of our forests and other natural habitats without replacing them. Worst of all, we have driven the rate of biological extinction, the permanent loss of species, up several hundred times beyond its historical levels, and are threatened with the loss of a majority of all species by the end of the 21st century."

Further, even in countries which have both large population growth and major ecological problems, it is not necessarily true that curbing the population growth will make a major contribution towards resolving all environmental problems.However, as developing countries with high populations become more industrialized, pollution and consumption will invariably increase.

The Worldwatch Institute said the booming economies of China and India are planetary powers that are shaping the global biosphere. The report states:

The world's ecological capacity is simply insufficient to satisfy the ambitions of China, India, Japan, Europe and the United States as well as the aspirations of the rest of the world in a sustainable way.

It said that if China and India were to consume as much resources per capita as United States or Japan in 2030 together they would require a full planet Earth to meet their needs. In the longterm these effects can lead to increased conflict over dwindling resources and in the worst case a Malthusian catastrophe.

Overpopulation

Overpopulation is a condition where an organism's numbers exceed thecarrying capacity of its habitat. In common parlance, the term often refers to the relationship between the human population and its environment, theEarth.

Overpopulation does not depend only on the size or density of the population, but on the ratio of population to available sustainable resources. It also depends on the way resources are used and distributed throughout the population If a given environment has a population of 10 individuals, but there is food or drinking water enough for only 9, then in a closed system where no trade is possible, that environment is overpopulated; if the population is 100 but there is enough food, shelter, and water for 200 for the indefinite future, then it is not overpopulated. Overpopulation can result from an increase in births, a decline in mortality rates due to medical advances, from an increase in immigration, or from an unsustainable biome and depletion of resources. It is possible for very sparsely-populated areas to be overpopulated, as the area in question may have a meager or non-existent capability to sustain human life (e.g. the middle of the Sahara Desert).

The resources to be considered when evaluating whether an ecologicalniche is overpopulated include clean water, clean air, food, shelter, warmth, and other resources necessary to sustain life. If the quality of human life is addressed, there may be additional resources considered, such as medical care, education, proper sewage treatment and waste disposal. Overpopulation places competitive stress on the basic life sustaining resources, leading to a diminished quality of life.The rapid increase in human population over the course of the 20th century has raised concerns about the Earth's ability to sustain a large number of inhabitants. In 2009, the estimated annual growth rate was 1.10%, and the world population stood at roughly 6.7 billion. Current projections show a steady decline in the growth rate, and a population of around 9 billion by the year 2050. The scientific consensus is that the current population expansion and accompanying increase in usage of resources is linked to threats to the ecosystem. The InterAcademy Panel Statement on Population Growth, which was ratified by 58 member academies in 1994, called the expansion in human numbers "unprecedented", and stated that many environmental problems were aggravated by the population expansion. At the time, the world population stood at 5.5 billion, and optimistic scenarios predicted a peak of 7.8 billion by 2050, a number that current estimates show will be reached around 2030.