June 8 is World Oceans Day. It is a reminder that the oceans that cover 71% of Earth’s surface, contain 97% of Earth’s water and contain 50 – 80% of life on Earth. Although we are a water world, we know relatively little about the seafloor. The Moon, Mars and Venus are all mapped in greater detail than the ocean depths.
Amazing underwater features
The oceans are home to incredibly large features that most people do not appreciate. The oceans have:
90% of Earth’s volcanic activity
Giant mountain ranges in the mid-ocean ridge system
The world’s largest living structure – the 2,600 km long Great Barrier Reef
Deep trenches extending to 10,994 m below the surface at Challenger Deep in the Mariana Trench
The Challenger Deep in the Mariana Trench is 2 km deeper than the height of Mount Everest. (Nomi887 at English Wikipedia, Creative Commons)
Life in the seas
Some scientists estimate that the oceans contain 99% of the living space on Earth and we have only explored a small fraction of this area. Life began in the seas, moving to land around 475 million years ago. Since then, diversity on land has exploded. As terrestrial organisms, we find it easier to explore and describe life on land, biasing our knowledge of marine diversity. Some scientists think only 15% of species live in the oceans, while others think the number is much greater. Without data, we just don’t know.
The oceans contain more than 226,000 described species, but only 5% of the area has been thoroughly explored.
Oceans and climate
Ocean currents regulate global climate by moving heat around the planet. The oceanic conveyor belt transports warm water from the equator toward the poles and cold water from the poles toward the tropics. Without these currents, temperature extremes would be much greater. Surface currents like the El Niño Southern Oscillation affect short- and medium-term weather events
The major ocean currents distribute heat around the planet, influencing both weather and climate (NOAA, public domain)
Learn more about the oceans:
- Thermohaline circulation is described in this blog post and you can do the experiments shown in the video.
- Learn about mapping the ocean floor in this blog and try it yourself as shown in the video.
- Explore ocean currents with WASP activities and information.
- Analyse methods to mitigate the effect of sea level rise.
- Find out more about El Niño and La Niña in this video.
- Find out how salinity affects the solubility of carbon dioxide and how this relates to carbon sequestration in this blog and experiment with solubility and salinity as shown in this video.
- Take action with WorldOceansDay.org.
- Book a class with an expert from ANSTO about Aquaculture and Food Provenance, Coastal Ecosystems and Wetlands, or Climate Change.