Earth is the only living world we know of, but a new force threatens our perfect planet. That force is us. Humans are changing our planet so rapidly, it's affecting Earth's life support systems: our weather, our oceans and the living world. To understand what is going wrong, we must look to the past. Earth has been through at least five mass extinction events, most of which have been caused by cataclysmic volcanic eruptions. It's not the lava or ash that wiped out life, but an invisible gas released by volcanoes: carbon dioxide. Through compelling, animal-led stories and expert interviews, we discover how CO2 is destabilising our planet. We meet rescued orphaned elephants in Kenya, victims of ever worsening droughts, and join ocean patrols off the coast of Gabon fighting to save endangered sharks. In the Amazon, we witness wildlife teams saving animals in the shrinking forests, and in San Diego we enter a cryogenic zoo preserving the DNA of endangered species before they become extinct. Almost every part of modern life depends on energy created by burning fossil fuels, and this produces CO2 in huge amounts. Humans are now acting like a super-volcano, releasing carbon dioxide at an even greater rate than the prehistoric mega-eruptions that extinguished life in the past. Globally, we now release 100 times more carbon dioxide into the atmosphere than all of Earth's volcanoes combined. The greatest change to be made is in how we create energy, and the planet is brimming with natural power that can help us do just that. It's these forces of nature — the wind, the sun, waves and geothermal energy — that hold the key to our future.