
In the US, the 1960s had been a very dynamic period for ecology, in both theory
and practice. It was in the mid-1960s that Congress passed the sweeping Wilderness
Act, and Supreme Court Justice William O. Douglas asked, "Who speaks for
the trees?" Pre-1960 grassroots activism against DDT in Nassau County,
New York, had inspired Rachel Carson to write her shocking bestseller Silent
Spring (1962).
Ralph Nader began talking about the importance of ecology in 1970.
Responding to widespread environmental degradation, Gaylord Nelson, a United
States Senator from Wisconsin, called for an environmental teach-in, or Earth
Day, to be held on April 22, 1970. Over 20 million people participated that
year, and Earth Day is now observed each year on April 22 by more than 500 million
people and national governments in 175 countries.

Senator Nelson, an environmental activist, took a leading role in organizing
the celebration, hoping to demonstrate popular political support for an environmental
agenda. He modeled it on the highly effective Vietnam War protests of the time.
The concept of Earth Day was first proposed in a memo to JFK written by Fred
Dutton.
According to Santa Barbara, California Community Environmental Council:
The story goes that Earth Day was conceived by Senator Gaylord Nelson
after a trip he took to Santa Barbara right after that horrific oil spill off
our coast in 1969. He was so outraged by what he saw that he went back to Washington
and passed a bill designating April 22 as a national day to celebrate the earth.
Senator Nelson selected Denis Hayes, a Harvard University graduate student,
as the national coordinator of activities. Hayes said he wanted Earth Day to
"bypass the traditional political process." Garrett DuBell compiled
and edited The Environmental Handbook the first guide to the Environmental Teach-In.
Its symbol was a green Greek letter theta, "the dead theta".

Gaylord Nelson
One of the organizers of the event said:
"We're going to be focusing an enormous amount of public interest
on a whole, wide range of environmental events, hopefully in such a manner that
it's going to be drawing the interrelationships between them and, and getting
people to look at the whole thing as one consistent kind of picture, a picture
of a society that's rapidly going in the wrong direction that has to be stopped
and turned around.
"It's going to be an enormous affair, I think. We have groups operating
now in about 12,000 high schools, 2,000 colleges and universities and a couple
of thousand other community groups. It's safe to say I think that the number
of people who will be participating in one way or another is going to be ranging
in the millions."

The nationwide event included opposition to the Vietnam War on the agenda,
but this was thought to detract for the environmental message. Pete Seeger was
a keynote speaker and performer at the event held in Washington DC. Paul Newman
and Ali McGraw attended the event held in New York City.
In 2000, Ron Bailey, the scientific editor of Reason Magazine, wrote an article
considering predictions and warnings made at the time of the inaugural Earth
Day and progress that had been made since then, suggesting that much of the
alarmism of the environmental movement was unfounded. In particular, he mentioned
these quotes:
Denis Hayes, the chief organizer for the first Earth Day, wrote, "It is
already too late to avoid mass starvation."

Senator Gaylord Nelson, the founder of Earth Day, stated, "Dr. S. Dillon
Ripley, secretary of the Smithsonian Institute, believes that in 25 years, somewhere
between 75 and 80 percent of all the species of living animals will be extinct."
Peter Gunter, a professor at North Texas State University, stated, "... by
1975 widespread famines will begin in India; these will spread by 1990 to include
all of India, Pakistan, China and the Near East, Africa. By the year 2000, or
conceivably sooner, South and Central America will exist under famine conditions....
By the year 2000, thirty years from now, the entire world, with the exception
of Western Europe, North America, and Australia, will be in famine."

Denis Hayes
Paul Ehrlich, author of The Population Bomb, predicted that between 1980 and
1989, 4 billion people, including 65 million Americans, would starve to death.
Life Magazine wrote, "... by 1985 air pollution will have reduced the
amount of sunlight reaching earth by one half."
Ecologist Kenneth Watt stated, "The world has been chilling sharply for about
twenty years. If present trends continue, the world will be about four degrees
colder for the global mean temperature in 1990, but eleven degrees colder in
the year 2000. This is about twice what it would take to put us into an ice
age."

Watt also stated, "By the year 2000, if present trends continue, we will
be using up crude oil at such a rate…that there won’t be any more
crude oil."
Later, these quotes, and others like them, would be highlighted by skeptics
such as Glenn Beck with the suggestion that they undermined other predictions
by environmentalists.
The most notable organization to protest the event was the Daughters of the
American Revolution.
Earth Day proved popular in the United States and around the world. 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
across the United States. More importantly, it "brought 20 million Americans
out into the spring sunshine for peaceful demonstrations in favor of environmental
reform."

Senator Nelson stated when that Earth Day "worked" because of the spontaneous
response at the grassroots level. Twenty-million demonstrators and thousands
of schools and local communities participated. He directly credited the first
Earth Day with persuading U.S. politicians that environmental legislation had
a substantial, lasting constituency. Many important laws were passed by the
Congress in the wake of the 1970 Earth Day, including the Clean Air Act, wild
lands and the ocean, and the creation of the United States Environmental Protection
Agency.

It is now observed in 175 countries, and coordinated by the nonprofit Earth
Day Network, according to whom Earth Day is now "the largest secular holiday
in the world, celebrated by more than a half billion people every year."
Environmental groups have sought to make Earth Day into a day of action which
changes human behavior and provokes policy changes.