Introduction: Earth - the Power of the Planet: Oceans (02:31)

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Iain Stewart will examine the four powerful forces that created Earth. Oceans carve the coastline, transfer energy around the planet, and control the climate.

Oceans Carry Energy (04:18)

Water separates Earth from other planets in the solar system. A gentle breeze creates waves far out to sea. The base of the wave slows when it comes closer to shore; the peak topples over, releasing energy.

Tides (04:48)

The moon's gravity and the rotation of the Earth causes tidal currents. Stewart watches Pororoca's unusual tidal surges on the Amazon river.

Erosion (02:38)

Sea stacks are all that remains of a coastline eroded by the Atlantic Ocean. The English coast has retreated more than a half-mile in the past 500 years.

Earth's History (02:31)

Volcanic eruptions create steam; rain falls for thousands of years. Comets deliver half of the oceans' water. Scientists discover that a comet contained over six million gallons of water.

Earth's Next Ocean (03:31)

As continents move, oceans form and vanish. In Ethiopia, the Afar Depression will cause a separation of Africa. Stewart discusses why armies have fought over the Straits of Gibraltar.

Mediterranean Sea (05:59)

Continents collide, closing the Straits of Gibraltar. Evaporation leaves behind salt and gypsum geodes. Stewart explores a salt mine in Sicily where workers carved a chapel.

Evolution of Animals (02:30)

In Sicily, experts have found fossilized remains of an elephant species the size of a goat. The Mediterranean Sea will evaporate again, when the Straits of Gibraltar close.

Ocean System (07:01)

Phytoplankton blooms that produce oxygen appear around the world, feeding fish and other sea animals. The accidental dumping of 28,000 bath toys helps scientists understand how currents connect the world's oceans.

Gulf Stream (03:28)

The warmest areas are located near the equator. Warm Caribbean air travels toward the Isles of Scilly. Oceanic currents are the driving force that affects the weather.

El Niño (03:48)

South America experiences torrential rain while Australia and Indonesia experience droughts. The "Great Ocean Conveyor" transports nutrients and oxygen around the world. Water becomes cold and dense at the poles, causing it to sink.

Natural Catastrophe (03:55)

The continual rise of global temperatures causes the extinction of animals. "The Great Ocean Conveyor" ceases to function and oxygen does not circulate. Remains of creatures have been discovered in the Dolomite Mountains.

Great Ocean Conveyor Failure (03:34)

Hydrogen sulfide increases in the oceans and seeps into the atmosphere, killing 90% of all life on Earth. Conditions in the oceans have barely changed since human evolution.

Climate Change (07:37)

Rising levels of carbon dioxide affect the oceans. In 1998, increased sea temperatures cause swarms of golden jellyfish in Palau to die. Ocean acidification threatens the seas.

Credits: Earth - the Power of the Planet: Oceans (00:30)

Credits: Earth - the Power of the Planet: Oceans