Dr. Iain Stewart traces the history of climate change from its very beginning and examines just how the scientific community managed to get it so very wrong back in the Seventies. Along the way he uncovers some of the great unsung heroes of climate change science, and introduces us to a secret organisation of American government scientists, known as Jason, who wrote the first official report on global warming as far back as 1979.

Dr Iain Stewart investigates the counter attack that was launched by the global warming sceptics in the 1990s. At the start of the 1990s it seemed the world was united. At the Rio Earth summit the world signed up to a programme of action to start tackling climate change. Even George Bush was there. But the consensus didn't last. Iain interviews some of the key global warming sceptics, and discovers how their positions have changed over time.

Having explained the science behind global warming, and addressed the arguments of the climate change sceptics earlier in the series, in this third and final part Dr Iain Stewart looks at the biggest challenge now facing climate scientists. Just how can they predict exactly what changes global warming will bring? It's a journey that takes him from early attempts to model the climate system with dishpans, to supercomputers, and to the frontline of climate research today: Greenland.