BBC Two’s epic tale of the Earth’s history continues this week with the story of the oceans.
The oceans are almost as ancient as the planet itself and are much more than huge reservoirs of water – the oceans have transformed the planet. Their brute force carves the coastline, leaving an extraordinary legacy. They transfer energy around the planet and drive the climate.
Dr Iain Stewart’s journey begins in Hawaii – a surfer’s paradise. Here, he shows how the oceans capture and store energy from the wind, eventually delivering it to the coastline and creating some of the most powerful waves on the planet.
In the Amazon, Iain rides the biggest, longest tidal bore in the world. This annual event demonstrates how the oceans also gain energy from gravity – in this case, the gravitational pull of the Sun and Moon.
Iain then travels to Ethiopia, the only place in the world where one can see a new ocean forming. Cracks are opening in the ground that will eventually form an ocean basin. One day, this basin will fill with water and, over time, become a new ocean, separating East Africa from the rest of the continent.
Many years ago, the Straits of Gibraltar closed and the Mediterranean disappeared. To prove this, Iain visits the extraordinary salt deposits that were formed when the Straits closed and the sea evaporated. He also discovers fossils of dwarf elephants that evolved when the returning Mediterranean cut them off on Sicily.
Iain tells the story of the ocean’s great currents, how they distribute heat around the planet and how they interact with the atmosphere, creating the phenomena of El Nino. Most critical of all is a global network of currents called the Great Ocean Conveyor – this distributes nutrients, oxygen and warmth around the planet. When this failed 250 million years ago, it led to the greatest mass extinction in the history of the planet.
Finally, Iain investigates what will happen to the oceans in the future as global warming takes hold. He discovers that as well as the oceans warming, they will begin to acidify as they absorb carbon dioxide from the atmosphere.
Tuesday 11 December
9.00-10.00pm BBC TWO
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