The pushing to the Overton Window to the right, ever to the right, over the past few decades have made many topics seemingly near taboo in ‘polite company’. Zero Population Growth seemingly was part of the common lexicon decades ago, with serious concern about The Population Bomb part of the general cultural conversation space. As we face every more serious pressures on the global ecosystem, not least of which is climate change, ZPG seems unlikely to ring bells with most Americans in 2010. And, sadly, we still spend orders of magnitude more on fertility research then on contraceptives. We spend how much more on cosmetics as on family planning. And, yet, when it comes to our long term solutions getting a handle on population and, in fact, turning back from the 9 billion or so humans that could be on the planet in 2040 is critical.
The Center for Biological Diversity evidently looked to the relative obscurity in which population issues seem to reside, and has chosen to try to shine some light on the issue via Endangered Species Condoms. 
The earth’s population has nearly doubled since the original Earth Day in 1970. In those days, it was well understood that human overpopulation was causing the many environmental challenges cropping up around the world. Today, on the 40th anniversary of the original Earth Day, unsustainable human population growth is too often ignored, even though it continues to drive all the major environmental problems that plague our planet.
At 6.8 billion people, the human race is not only the most populous large mammal on Earth but the most populous large mammal that has ever existed. Providing for the needs and wants of this many people — especially those in high-consumption, first-world nations — has pushed homo sapiens to absorb 50 percent of the planet’s freshwater and develop 50 percent of its landmass. As a result, other species are running out of places to live.
By our actions — including our decisions about when (major difference between becoming a parent at age 16 and age 36 in terms of population growth) to have children and how many — we affect all around us. And, when we’re talking 6.8 billion and growing, well that cumulative impact becomes oppressive.
If the planet is headed for another mass extinction like the previous five, each of which wiped out more than 75 percent of all species on the planet, then North American mammals are one-fifth to one-half the way there … the perfect storm of global warming and environmental degradation — both the result of human activity is leading to a sixth mass extinction equal to the “Big Five” that have occurred over the past 450 million years, the last of which killed off the dinosaurs 68 million years ago.
As the CBD summarizes, “Human overpopulation is the driving force behind the current 
mass-extinction crisis, endangering:
- 12 percent of mammals
- 12 percent of birds
- 31 percent of reptiles
- 30 percent of amphibians
- 37 percent of fish”
As CBD notes, “wrap with care, save a polar bear”.