A startling and honestly distressing view is beginning to receive serious consideration in both academic and popular discussions of climate change ethics. According to this view, having a child is a major contributor to climate change. The logical takeaway here is that everyone on Earth ought to consider having fewer children.
Although culturally controversial, the scientific half of this position is fairly well-established. Several years ago, scientists showed that having a child, especially for the world's wealthy, is one of the worst things you can do for the environment. That data was recycled this past summer in a paper showing that none of the activities most likely to reduce individuals' carbon footprints are widely discussed.