Oceanography

Our water did not come from space

Where did the oceans really come from?

Most scientists think they came from water-rich asteroids and comets raining down on the planet in its youth. Just after the Earth formed, it was very hot and dry. Prevailing theory suggests that millions of water-rich comets and asteroids bombarded our planet around 3.8 billion years ago, neatly explaining why oceans later appeared.

Also, the ratio of deuterium—or “heavy hydrogen” because it contains a neutron in addition to a proton—to hydrogen in our sea water matches the value found in water-rich asteroids, suggesting a common origin.

The black lava sand is one of the characteristics of Bali. It makes the colour of these nudibranchs stand out too.

Why are the Balinese waters so rich?

It all starts east of the Philippines where the constant blowing of the tradewinds and the ocean currents forces huge masses of water up against the Philippines, where it is trapped and forced southwards. 

Most of this current is directed by ocean bottom morphology to flow into the Sulawesi basin and down between Borneo and Sulawesi—the fat red arrow on the figure above. The only thing sitting in this giant current’s way is the lesser Sunda Islands, predominantly Bali, Lombok, Sumbawa, Flores and Timor—with Bali sitting right in the ideal position to benefit from this flow.

Twilight Zone

Dominic Andradi-Brown using the stereo video system. Photo by Ally McDowell.

The pressure builds, causing ears to pop as they equalise. The temperature drops and the light starts to fade. However, bubbles are not an issue for the researchers from the University of Oxford, as they descend in the waters off the Honduran island of Utila. Researching efficiently in the twilight zone requires rebreathers, and the summer of 2015 saw the first-ever expedition led by doctoral students using this technology.

Hydrothermal vents

Hydrothermal vents are places in the Earth’s crust where very hot water arises from vents in the cold, deep-sea floor. This hot, mineral-laden water is a rich environment for the development of an exotic marine life, previously unknown before the discovery of hydrothermal vents. This marine life uses a quite different chemistry from other animal life, be it marine life in the upper sea levels, or terrestrial life.

Crossing the Altantic

“The subject of oceanology is the study and research of the totality of events taking place in oceans, seas and lakes,” wrote geographer, academician and founder of Russian oceanology, Juli Shokalskiy, in 1917. Oceanology, or oceanography1 as it is more commonly called in the West, is an integral part of natural sciences. The ratio of water to land on the planet Earth is approximately 71 to 29 percent.

Ocean conveyor belt - the thermohaline circulation

The thermohaline circulation is also known as the meridional overturning circulation.

Can global warming trigger a shutdown or slowdown the circulation in the world’s oceans?

The globe is encircled by a pattern of ocean currents known as the ocean conveyor belt. Heat is transported from the equator towards the poles by both the atmosphere and by ocean currents, with warm water near the surface and cold water at deeper levels. As such, the state of the circulation has a large impact on the climate of our planet.