Earth Day, April 22, is a secular holiday celebrated in many English-speaking countries. Its founding organizer, U.S. Senator Gaylord Nelson, intended it to be a day that focuses on political efforts to fight pollution, perform conservation, biodiversity, and other environmental concerns to protect the Earth.
The symbol for Earth Day is a green T (Greek theta) on a white background:
Earth Day History
Earth Day was first celebrated in 1970. Senator Nelson, an environmental activist in the U.S. Senate, organized it to demonstrate popular political support for an environmental agenda. The holiday proved extremely popular. The first Earth Day had participants and celebrants in two thousand colleges and universities, roughly ten thousand primary and secondary schools, and hundreds of communities.
Senator Nelson directly credits Earth Day with persuading U.S. politicians that environmental legislation had a substantial, lasting constituency. The result of this persuasion was a series of U.S. environmental acts (laws), including the Clean Air Act, the Water Quality Improvement Act, the Water Pollution and Control Act Amendments, the Resource Recovery Act, the Resource Conservation and Recovery Act, the Toxic Substances Control Act, the Occupational Safety and Health Act, the Federal Environmental Pesticide Control Act, the Endangered Species Act, the Safe Drinking Water Act, the Federal Land Policy and Management Act, and the Surface Mining Control and Reclamation Act. In a 1980 article, Sen. Nelson credited the same political pressure for "the most important piece of environmental legislation in our history, the National Environmental Policy Act (NEPA)", signed into law on January 1, 1970.
The United Nations celebrates Earth Day each year on the vernal equinox (around March 21). On February 26, 1971, Secretary-General U Thant signed a proclamation to that effect. At the moment of the equinox, the Peace Bell is rung at the UN headquarters in New York.
A sizable minority - around 2.5 of a total of 6.3 billion people - live in urban surroundings. Urbanisation is expected to rise drastically during the 21st century. Problems for humans in cities include various forms of pollution, crime and poverty, especially in inner city and suburban slums.
Humans living on Antarctica, under the ocean, or in space are part of scientific, military, or industrial expeditions, and habitation of these environments is temporary.
Life in space has thus far been temporary living, with up to ten humans in space at a given time (seven on the Space Shuttle, three on Mir) and currently around three in the International Space Station. This is a direct result of humans' vulnerability to ionizing radiation. Prior to 1961, all humans were restricted to the earth; Yuri Gagarin was the first human to travel into space. At various periods between 1969 and 1974, up to two humans spent varying amounts of time on the Moon. As of yet, residencies or human explorations on other planets have not come to be.
The original habitat in which humans evolved is the African savannah (see Vagina gentium, Environment of Evolutionary Adaptedness). Culturally transmitted technology has allowed humans to colonize all of the continents and adapt to all climates. Within the last few decades, humans have been able to temporarily inhabit Antarctica, the ocean depths, and outer space, although permanent habitation of these three environments is not yet possible. Humans, with a population of about six billion, are one of the most numerous mammals on Earth.
Most humans (61%) live in the Asian region. The vast majority of the remainder live in the Americas (14%), Africa (13%) and Europe (12%), with only 0.3% in Australia.
Humans' original life style is hunting/gathering, which is adapted to the savannah where they evolved. Other human life styles are nomadism (often linked to animal herding) and permanent settlements made possible by the development of agriculture. Humans have a great capacity for altering their habitats by various methods, such as agriculture, irrigation, urban planning and construction, and activities accessory to those, such as transportation and manufacturing goods.
Permanent human settlements are dependent on proximity to water and, depending on the lifestyle, other natural resources such as fertile land for growing crops and grazing livestock or, seasonally by populations of prey. With the advent of large-scale trade and transportation infrastructure, immediate proximity to these resources has become less necessary, and in many places these factors are no longer the driving force behind growth and decline of population.