The use of birth control has been an issue debated by ethicists in the United States for over a century. Until now, it’s been a moral issue, and few mainstream voices ever advocated the use of birth control for environmental reasons.
On Scientific American’s website, an Oct. 11 article by David Biello  argues that if we were able to lower the growth of the world’s population, the amount of carbon that is expected to be emitted into the atmosphere would significantly diminish. He cited a study from the U.S. National Center for Atmospheric Research  that explained demographic ties to the alleged threats of global warming.
“An additional 150 people join the ranks of humanity every minute, a pace that could lead our numbers to reach nine billion by 2050,” Biello wrote. “Changing that peak population number  alone could save at least 1.4 billion metric tons of carbon from entering the atmosphere each year by 2050, according to a new analysis – the equivalent of cutting more than 10 percent of fossil fuel burning per year.”
Biello explained that economic growth was a means of slowing population growth, but feared that the rise of “richer people” could mean more consumption, canceling out the so-called “greenhouse gas savings” from the decreased population growth.
Still, Biello explained that family planning methods could be the solution to curbing the threat of climate change.
“Ultimately, family planning alone – such as the use of condoms and other reproductive health services – in parts of the world with growing populations, including the U.S., could restrain population growth significantly, this analysis finds,” Biello wrote. “It would appear that we're trying, thanks primarily to ongoing efforts to enable women to take control of their own lives  through education and other methods. Already, birth rates the world over have halved from an average of five children per woman to just 2.6 today – a baby bust replacing the baby boom.”
However in that paragraph, he linked another Scientific American story from August 12, 2008 he wrote that referenced work by Stanford University scientists Paul Ehrlich and Robert Pringle blaming humans for the extinction of thousands of species. Their suggestion back then: Educate women about “contraception and safe abortions”:
That’s why Ehrlich and Pringle call for educating women, which has slowed or stopped population growth in the developed countries of Europe. "Education and employment – for women especially – along with access to contraception and safe abortions are the most important components," they write. Adds Ehrlich: "The most basic response is to get going on stopping population growth and starting a decline. Second is doing something about consumption. If you don't do anything about those, then you are in trouble in all the others: more people, means more greenhouse gases, which means more rapid climate change ."
Although these arguments over the need to promote the use of “birth control” for the environment’s sake raise some ethical questions, there is a belief more radical. Paul Watson, founder and president of the Sea Shepherd Conservation Society in 2007 called for  the world’s population to drop below 1 billion, meaning roughly 5.7 billion people would have to go away.