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 examines the scientific arguments that developed as the global warming sceptics took on the climate change consensus. The sceptics attacked almost everything that scientists held to be true. They argued that the planet wasn't warming up, that even if it was it was nothing unusual, and certainly whatever was happening to the climate was nothing to do with human emissions of greenhouse gases. 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, Dr Iain Stewart concludes the series by looking 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. Most worryingly he discovers that scientists are becoming increasingly concerned that their models are actually underestimating the speed of changes already underway.

The search for climate change solutions requires passion, resources and a sense of urgency -- three qualities Bill Gates clearly possesses. Bill has founded a start-up called TerraPower. After extensive computer modelling, the idea showed promise. Its new reactor greatly reduced the chance of human error. Fuelled by depleted uranium, the travelling wave reactor functions like a slow-burning candle and requires refuelling only once every decade. Bill and his team believed they had finally developed the ideal energy source, a reactor that was clean, efficient, and most importantly, safe.

As tides rise and fall twice a day, vast amounts of water swirl around the earth. This is a huge energy source that's currently largely untapped. An estimated 3000 gigawatts are available to be harvested globally, enough to power a third of the earth's homes. Yet compared to wind and solar, the technology needed to harness tidal power is still in its infancy. The power of the ocean’s tides is the last great untapped energy source on Earth. From sub-sea kites to floating platforms, teams of engineers are racing to perfect the technology to harness the vast flows of water.

Will explore the strategy, deception and feats of engineering plants use to thrive in the changing weather of different seasons. In the face of conditions ranging from ice and snow to raging fires, survival is often a question of perfect timing - particularly when contending with intense competition and surprising predators.
In this episode, David Attenborough travels to Finland to show one of the most extreme examples of seasonal plant life in the Arctic Circle. He also travels to California to see how climate change is affecting giant sequoias. These ancient trees like all other seasonal plants depend on the predictability of the seasons and our current changing climate threatens their survival.

Even as the science grew more certain, the oil industry continued to block action to tackle climate change in the new millennium. In a revelatory interview, Christine Todd Whitman, George W. Bush's former environment chief, tells the story of how the industry successfully lobbied President Bush to reverse course on his campaign promise to regulate carbon emissions.
Tensions grew between two of the world's biggest oil companies, ExxonMobil and BP, after the latter publicly called for action to tackle climate change. The election of Barack Obama provided hope for supporters of climate action, but the billionaire Koch brothers made an effort to block the new president's attempts to pass climate change legislation, and climate denialism became the mainstream position of the Republican Party. A lawyer who worked for Koch brothers through this period speaks on camera for the first time.