An environment is a complex of external factors. It acts on a system and determines its course and form of existence. Generally, the environment or milieu of some object, action, or individual consists of the substances, circumstances, objects, or conditions by which the object or person is surrounded or in which the action occurs.

An environment may be thought of as a superset, of which the given system is a subset. An environment may have one or more parameters, physical or otherwise. The environment of a given system must interact with that system in order for it to sustain and develop.

Although the two terms are interchangeable, some disciplines prefer the term milieu to avoid confusion with the more widely used meanings of environment in ecology, politics, and sociology. Either word may be used with specialized meaning in various contexts.

Wikipedia

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Natural Environment

The natural environment comprises all living and non-living things that occur naturally on Earth. In its purest sense, it is thus an environment that is not the result of human activity or intervention. The natural environment may be contrasted to "the built environment."

For some, there is a difficulty with the term "natural environment" in that nearly all environments have been directly or indirectly influenced by humans at some point in time. In order to address this concern, some level of human influence is thus allowable without the status of any particular landscape ceasing to be "natural." The term's meaning, however, is usually dependent more on context than a set definition. Many natural environments are the product of the interaction between nature and humans. For this reason, the term ecosystem has been used to describe an environment that contains nature, and includes people. It follows then that environmental problems are human or social problems. Some also consider it dangerously misleading to regard "environment" as separate from "people."

It is the common understanding of natural environment that underlies environmentalismÑa broad political, social, and philosophical movement that advocates various actions and policies in the interest of protecting what nature remains in the natural environment, or restoring or expanding the role of nature in this environment.

While wilderness is increasingly rare, wild nature (e.g., unmanaged forests, uncultivated grasslands, wildlife, wildflowers) can be found in many locations previously inhabited by humans.Goals commonly expressed by the environmentalists include: reduction and clean up of man-made pollution, with future goals of zero pollution; reducing societal consumption of non-renewable fuels, development of alternative, green, low carbon or renewable energy sources; conservation and sustainable use of scarce resources such as water, land and air; protection of representative or unique or pristine ecosystems; preservation and expansion of threatened or endangered species or ecosystems from extinction; the establishment of nature and biosphere reserves under various types of protection, and, most generally, the protection of biodiversity and ecosystems upon which all human and other life on earth depends.

More recently, there has been a strong concern about climatic changes caused by anthroprogenic releases of greenhouse gases, most notably carbon dioxide, and their interactions with human uses and the natural environment. Efforts here have focused on the mitigition of greenhouse gases that are causing climatic changes (i.e., through the Climate Change Convention and the Kyoto Protocol), and on developing adaptative strategies to assist species, ecosystems, humans, regions and nations in adjusting to these climatic changes.

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Built Environment

The term Earth Changes describes a belief prevalent in certain segments of the New Age movement. Believers in the Earth Changes theory believe that the world will soon enter on a series of catastrophic changes that will begin a major alteration in human life on the planet.

While apocalyptic beliefs of this sort are common across a variety of religious traditions, the Earth Changes theory is particular to the New Age movement, and is often associated with the predictions of people claiming to have psychic abilities.

The term 'Earth Changes' to describe this apocalyptic sequence of events originates with the American psychic Edgar Cayce who made many prophesies of cataclysms involving the whole planet. He claimed the polar axis would shift and that many areas now land would become Ocean floor.

The belief that the California coast would slip into the sea - a common feature of Earth Changes predictions - originated with Cayce's alleged prophecies. In more recent times, self-proclaimed psychic Gordon Michale Scallion has issued a variety of prophecies centering on the concept of 'Earth Changes' that mimic Cayce's.

Scallion also believes that a series of major tectonic events will re-shape the globe, and herald a new age in human life. Scallion and his predictions were featured on a number of documentaries that appeared prior to the year 2000, highlighting millenarian beliefs in both world and New Age religious traditions. Many less notable believers in a variety of psychic phenomena report similar prophecies.

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Environmentalism

Environmentalism is the support of or involvement with the environmental movement by environmentalists. It is a social movement which seeks to influence the political process by lobbying, education, activism and setting an example in order to protect natural resources and ecosystems. They can also promote alternative ways or social change in society with day by day actions. Some of the issues of concern for the environmental movement are pollution, species extinction, waste reduction, recycling, the threat of global warming and ozone depletion, and genetically engineered crops.

Timeline of Environmental Events

The timeline of environmental events is a historical account of events that have shaped humanity's perspective on the environment. This timeline includes some major natural events, man-made disasters, environmentalists that have had a positive influence, and environmental legislation. Earlier Events and Periods ...

Earth's First Arctic Ozone Hole Recorded   Live Science - October 3, 2011

The high atmosphere over the Arctic lost an unprecedented amount of its protective ozone earlier this year, so much that conditions echoed the infamous ozone hole that forms annually over the opposite side of the planet, the Antarctic, scientists say.

Arctic ozone loss at record level   BBC - October 3, 2011
Ozone loss over the Arctic this year was so severe that for the first time it could be called an "ozone hole" like the Antarctic one, scientists report. About 20km (13 miles) above the ground, 80% of the ozone was lost, they say. The cause was an unusually long spell of cold weather at altitude. In cold conditions, the chlorine chemicals that destroy ozone are at their most active. It is currently impossible to predict if such losses will occur again, the team writes in the journal Nature.

First North Pole Ozone Hole Forming?   National Geographic - March 23, 2011

"Put on your sunscreen" - damaging air mass could drift far south. Spawned by strangely cold temperatures, "beautiful" clouds helped strip the Arctic atmosphere of most of its protective ozone this winter, new research shows. The resulting zone of low-ozone air could drift as far south as New York, according to experts who warn of increased skin-cancer risk.

'Archeologists of the air' isolate pristine aerosol particles in the Amazon   PhysOrg - September 16, 2010
Environmental engineers who might better be called "archeologists of the air" have, for the first time, isolated aerosol particles in near pristine pre-industrial conditions.

All About the Environment   National Geographic - May 18, 2010

Klondike Holds Clues to Ancient Environment   Live Science - October 30, 2009

  Dust Turns Sydney Red   National Geographic - September 24, 2009

What is a 100-Year Storm?   Live Science - September 22, 2009