This large format photo book features hundreds of stunning images highlighting the effects that our global population of 7 billion (and growing) has on the Earth.

There's one very touchy subject in environmental circles that seems to be particularly polarizing, and which is often glossed over or avoided in favor of other, more comfortable topics, but this elephant in the room is at the root of most of our planetary ills. This somewhat taboo subject is the issue of human population, or to be more precise, human overpopulation (there are now more than 7 billion of us on the planet), and which is behind almost every other environmental issue.

Overpopulation takes a toll on human health and civil rights, on clean water and food supplies, on the climate and on our oceans and forests, and yet most of us never get to see those negative impacts because they seem so far away from our everyday lives. Perhaps if we got to see more of the devastating environmental and social effects we're all ultimately responsible for, we'd be more inclined to talk about the issue, but even as environmental disasters such as major oil spills get quite a bit of attention from the media, those incidents are all too often seen as isolated events, with no connection made to the underlying cause: our population explosion.

In order to bring more awareness to the question of global overpopulation, a new book from the 2015 Global Population Speakout campaign starts by asking the question, "Isn't it time to start talking about the equation that matters most to the future of people and the planet?" The book OVER: Overdevelopment, Overpopulation, Overshoot then proceeds to do just that with a series of hundreds of stunning photos accompanied by essays and insights from experts in the field.