Chris Packham is one of the UK's most prominent natural history broadcasters, and a passionate campaigner to protect the natural world. In a wide-ranging and personal journey, he travelled the globe, witnessed the effects of overpoulation, consulted experts and discussed the issue with members of his own family.

With the Earth's resources and ecosystems struggling to cope with our current population of 7.7bn, the UN expects us to add another 3bn by the end of the century, unless action is taken.

"For me it’s been the most important thing to think about for a long time. It is undeniably, the elephant in the room."

He discusses in the programme how the global population has doubled in his lifetime, and tripled in the lifetime of his fellow patron of Population Matters, Sir David Attenborough. With the Earth's resources and ecosystems struggling to cope with our current population of 7.7bn, the UN expects us to add another 3bn by the end of the century, unless action is taken.

Sir David spoke in the programme of the devastation caused by "fantastic population growth", including the transformation of once rich ecosystems into " green deserts".

In interviews surrounding the programme, Chris talks about the tragedy of the loss of species and biodiversity that both he and Sir David have witnessed, and how our increasing numbers also drive climate change, and make it more difficult to find effective solutions.