According to the prediction of the United Nations, the human population will reach 10 billion by 2050. For broadcaster and naturalist Chris Packham, our growing population and its impact on the earth is one of the most important and often neglected topics in the era of increasing environmental awareness. Chris is worried that, given that 7.7 billion people have been affected, the world of 10 billion people may be too many for the earth to bear. Chris searches for answers to difficult questions around the world, sometimes controversial. He investigated why our population growth is so rapid, what impact it has on the natural world, and whether there is anything we can do. Chris went to Brazil and found a megacity on the verge of water shortage and an expanding industry to meet our growing population - which has caused serious consequences for biodiversity. In Nigeria, by 2050, the country will surpass the United States and become the third most populous country in the world. Chris visited an extraordinary community and a school, which may solve the problem of the future decline of the birth rate. Back in the UK, Chris interviewed Sir David Attenburg - like Chris, he is also a sponsor of the charity "Population Issues". Chris also studied the role of declining birth rates around the world and the impact of population aging, and met a couple who were trying to conceive through IVF. Through interviews with several population experts, Chris finally turned his focus to the impact of our consumption level and asked whether the world could rebalance to meet the needs of more than 2 billion people.