To attempt to understand the driving motivation behind these environmental organizations and the individuals involved, it is helpful to read their statements in their own words.

Wild Earth magazine, a journal promoting radical environmentalism, included a manifesto for the extinction of the human race, written under the pseudonym "Les U. Knight." The article said, "If you haven't given voluntary human extinction much thought before, the idea of a world with no people in it may seem strange. But, if you give it a chance, I think you might agree that the extinction of Homo sapiens would mean survival for millions, if not billions, of Earth-dwelling species. . . . Phasing out the human race will solve every problem on earth, social and environmental" ("Voluntary Human Extinction," Wild Earth, Vol. 1, No. 2, 72).

“We must make this an insecure and inhospitable place for capitalists and their projects. We must reclaim the roads and plowed land, halt dam construction, tear down existing dams, free shackled rivers and return to wilderness millions of acres of presently settled land.”
- David Foreman, co-founder of Earth First!

“Isn’t the only hope for the planet that the industrialized civilizations collapse? Isn’t it our responsibility to bring that about?”
- Maurice Strong, founder of the UN Environment Programme

“A massive campaign must be launched to de-develop the United States. De-development means bringing our economic system into line with the realities of ecology and the world resource situation.”
- Paul Ehrlich, Professor of Population Studies

“The only hope for the world is to make sure there is not another United States. We can’t let other countries have the same number of cars, the amount of industrialization, we have in the US. We have to stop these Third World countries right where they are.”
- Michael Oppenheimer, Environmental Defense Fund

“Global Sustainability requires the deliberate quest of poverty, reduced resource consumption and set levels of mortality control.”
- Professor Maurice King

“Complex technology of any sort is an assault on human dignity. It would be little short of disastrous for us to discover a source of clean, cheap, abundant energy, because of what we might do with it.”
- Amory Lovins, Rocky Mountain Institute

“The prospect of cheap fusion energy is the worst thing that could happen to the planet.”
- Jeremy Rifkin, Greenhouse Crisis Foundation

“Giving society cheap, abundant energy would be the equivalent of giving an idiot child a machine gun.”
- Prof Paul Ehrlich, Stanford University

“Our insatiable drive to rummage deep beneath the surface of the earth is a willful expansion of our dysfunctional civilization into Nature.”
- Al Gore, Earth in the Balance

“The big threat to the planet is people: there are too many, doing too well economically and burning too much oil.”
– Sir James Lovelock, BBC Interview

“My three main goals would be to reduce human population to about 100 million worldwide, destroy the industrial infrastructure and see wilderness, with it’s full complement of species, returning throughout the world.”
-Dave Foreman, co-founder of Earth First!

“Current lifestyles and consumption patterns of the affluent middle class - involving high meat intake, use of fossil fuels, appliances, air-conditioning, and suburban housing - are not sustainable.”
- Maurice Strong, Rio Earth Summit

“All these dangers are caused by human intervention and it is only through changed attitudes and behaviour that they can be overcome. The real enemy, then, is humanity itself.”
- Club of Rome, The First Global Revolution

“Mankind is the most dangerous, destructive, selfish and unethical animal on the earth.”
- Michael Fox, vice-president of The Humane Society

“Humans on the Earth behave in some ways like a pathogenic micro-organism, or like the cells of a tumor.”
- Sir James Lovelock, Healing Gaia

“The Earth has cancer and the cancer is Man.”
- Club of Rome, Mankind at the Turning Point

"A cancer is an uncontrolled multiplication of cells, the population explosion is an uncontrolled multiplication of people.  We must shift our efforts from the treatment of the symptoms to the cutting out of the cancer.  The operation will demand many apparently brutal and heartless decisions."
- Prof. Paul Ehrlich, The Population Bomb

"A reasonable estimate for an industrialized world society at the present North American material standard of living would be 1 billion.  At the more frugal European standard of living, 2 to 3 billion would be possible."
- United Nations, Global Biodiversity Assessment

“A total population of 250-300 million people, a 95% decline from present levels, would be ideal.”
- Ted Turner, founder of CNN and major UN donor

“… the resultant ideal sustainable population is hence more than 500 million but less than one billion.”
- Club of Rome, Goals for Mankind

"One America burdens the earth much more than twenty Bangladeshes.  This is a terrible thing to say in order to stabilize world population, we must eliminate 350,000 people per day.  It is a horrible thing to say, but it's just as bad not to say it."
- Jacques Cousteau, UNESCO Courier

“If I were reincarnated I would wish to be returned to earth as a killer virus to lower human population levels.”
- Prince Philip, Duke of Edinburgh, patron of the World Wildlife Fund

“I suspect that eradicating small pox was wrong. It played an important part in balancing ecosystems.”
- John Davis, editor of Earth First! Journal

“The extinction of the human species may not only be inevitable but a good thing.”
- Christopher Manes, Earth First!

"Childbearing should be a punishable crime against society, unless the parents hold a government license.  All potential parents should be required to use contraceptive chemicals, the government issuing antidotes to citizens chosen for childbearing."
- David Brower, first Executive Director of the Sierra Club

“In searching for a new enemy to unite us, we came up with the idea that pollution, the threat of global warming, water shortages, famine and the like would fit the bill.”
- Club of Rome, The First Global Revolution

“We need to get some broad based support, to capture the public’s imagination… So we have to offer up scary scenarios, make simplified, dramatic statements and make little mention of any doubts… Each of us has to decide what the right balance is between being effective and being honest.”
- Stephen Schneider, Stanford Professor of Climatology, lead author of many IPCC reports

“Unless we announce disasters no one will listen.”
- Sir John Houghton, first chairman of IPCC

“It doesn’t matter what is true, it only matters what people believe is true.”
- Paul Watson, co-founder of Greenpeace

"We've got to ride this global warming issue.  Even if the theory of global warming is wrong, we will be doing the right thing in terms of economic and environmental policy."
- Timothy Wirth, President of the UN Foundation

"No matter if the science of global warming is all phony, climate change provides the greatest opportunity to bring about justice and equality in the world."
-Christine Stewart, fmr Canadian Minister of the Environment

"The climate crisis is not a political issue, it is a moral and spiritual challenge to all of humanity.  It is also our greatest opportunity to lift Global Consciousness to a higher level."
- Al Gore, accepting the Nobel Peace Prize

"The only way to get our society to truly change is to frighten people with the possibility of a catastrophe."
- emeritus professor Daniel Botkin

"We are on the verge of a global transformation.  All we need is the right major crisis."
- David Rockefeller, Club of Rome executive manager

"Humanity is sitting on a time bomb.  If the vast majority of the world's scientists are right, we have just ten years to avert a major catastrophe that could send out entire planet's climate system into a tail-spin of epic destruction involving extreme weather, floods, droughts, epidemics and killer heat waves beyond anything we have ever experienced - a catastrophe of our own making."
- Al Gore, An Inconvenient Truth

"By the end of this century, climate change will reduce the human population to a few breeding pairs surviving near the Arctic."
- Sir James Lovelock, Revenge of Gaia

"Climate Change will result in a catastrophic, global seal level rise of seven meters.  That's bye-bye most of Bangladesh, Netherlands, Florida and would make London the new Atlantis."
- Greenpeace International

"Climate change is real.  Not only is it real, it's here, and its effects are giving rise to a frighteningly new global phenomenon - the man-made natural disaster."
- Barack Obama, US Presidential Candidate

"We are close to a time when all of humankind will envision a global agenda that encompasses a kind of Global Marshall Plan to address the causes of poverty and suffering and environmental destruction all over the earth."
- Al Gore, Earth in the Balance

"In Nature organic growth proceeds according to a Master Plan, a Blueprint.  Such a 'master plan' is missing from the process of growth and development of the world system.  Now is the time to draw up a master plan for sustainable growth and world development based on global allocation of all resources and a new global economic system.  Ten or twenty years from today it will probably be too late."
- Club of Rome, Mankind at the Turning Point

"The concept of national sovereignty has been immutable, indeed a sacred principle of international relations.  It is a principle which will yield only slowly and reluctantly to the new imperatives of global environmental cooperation."
- UN Commission on Global Governance report

"Democracy is not a panacea.  It cannot organize everything and it is unaware of its own limits.  These facts must be faced squarely.  Sacrilegious though this may sound, democracy is no longer well suited for the tasks ahead.  The complexity and the technical nature of many of today's problems do not always allow elected representatives to make competent decisions at the right time."
- Club of Rome, The First Global Revolution

"In my view, after fifty years of service in the United National system, I perceive the utmost urgency and absolute necessity for proper Earth government.  There is no shadow of a doubt that the present political and economic systems are no longer appropriate and will lead to the end of life evolution on this planet.  We must therefore absolutely and urgently look for new ways."
- Dr. Robert Muller, UN Assistant Secretary General

"Nations are in effect ceding portions of their sovereignty to the international community and beginning to create a new system of international environmental governance as a means of solving otherwise unmanageable crises."
- Lester Brown, WorldWatch Institute

"A keen and anxious awareness is evolving to suggest that fundamental changes will have to take place in the world order and its power structures, in the distribution of wealth and income."
- Club of Rome, Mankind at the Turning Point

"Adopting a central organizing principle means embarking on an all-out effort to use every policy and program, every law and institution, to halt the destruction of the environment."
- Al Gore, Earth in the Balance

"Effective execution of Agenda 21 will require a profound reorientation of all human society, unlike anything the world has ever experienced - a major shift in the priorities of both governments and individuals and an unprecedented redeployment of human and financial resources.  This shift will demand that a concern for the environmental consequences of every human action be integrated into individual and collective decision-making at every level."
- UN Agenda 21

"The earth is literally our mother, not only because we depend on her for nurture and shelter but even more because the human sepcies has been shaped by her in the womb of evolution.  Our salvation depends upon our ability to create a religion of nature."
- Rene Dubos, board member Planetary Citizens

The National Animal Interest Alliance has a large collection of quotes from animal rights extremists, providing some insight into how that relates to environmentalism..