Many families who dutifully recycle, take mass transit, and have a house full of compact fluorescent light bulbs, would say they're doing their part to save the earth. However, a new study from the London School of Economics suggests that in developed countries, making the decision to have children dramatically increases your negative impact on the environment. The study shows that, on average, each baby born in the United States adds 1,644 tons of carbon dioxide to the atmosphere during their lifetime, and argues that smaller family sizes are crucial to reducing carbon emissions. "There is no possibility of drastically reducing total carbon emissions, while at the same time paying no attention whatever to the drastic increase in the number of carbon emitters," said Roger Martin, chairman of the nonprofit Optimum Population Trust. Although this argument may be shocking, smaller family sizes are nothing new. Noting the worldwide trend towards smaller families in More, Robert Engelman points out that instead of having more children, mothers want more opportunities for their children. He argues that this trend would lead to less hunger and illness, and would benefit the environment as a result--but it hinges upon society's willingness to give women the freedom to make their own decisions about reproduction. Noted scientist and author Paul Ehrlich agrees. He has been advocating for women's reproductive rights and a smaller population since the publication of his book The Population Bomb. In his newest book The Dominant Animal, he makes the case that now, more than ever, our decisions about family size will have far-reaching impacts on our culture and our environment. The authors of the upcoming book A Pivotal Moment make a similar point, arguing that to build a sustainable future, both men and women need access to voluntary family planning, education, and employment; and, just as importantly, the need to address the deep inequalities that come with rapid population growth and unsustainable resource consumption. The issue of what to do about population growth has been and will be debated for decades, but scientists agree there is no question about its impact on climate change. Population is an integral part of the discussion on reducing greenhouse gas emissions. With global warming becoming a more pressing concern every day, we can't afford not to discuss it. This post was originally sent to our email subscribers. Sign up for the next one!