0 OCEAN LITERACY Essential Principles & Fundamental Concepts of Ocean Science PRINCIPLE 1

1 REVISION HISTORY DateVersionRevised ByDescription Aug 25, VLOriginal

2 ESSENTIAL PRINCIPLE 1 1 The Earth has one big ocean with many features.

3 1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES 1(a) The ocean is the dominant physical feature on our planet Earth – covering approximately 70% of the planet’s surface. There is one ocean with many ocean basins, such as the North Pacific, South Pacific, North Atlantic, South Atlantic, Indian and Arctic. One Ocean The ocean covers approximately 70% of Earth with the five great ocean basins (Atlantic, Pacific, Indian, Arctic, and Southern) holding 97% of Earth’s water. The water vapor the ocean releases into the atmosphere returns as rain, sleet and snow, replenishing the planet with freshwater. All life, including our own, is dependent on the ocean. Understanding the ocean is integral to comprehending the planet upon which we live. Ocean Features  Enormous, dynamic body of water  Covers many “basins” (Atlantic, Pacific, Indian, Arctic & Southern)  Basins are variably shaped – different contours, depths  Basin sea floor moves due to tectonic plate movement  One interconnected circulation system  Sea level changes due to movement of the sea floor  Water Cycle – interconnected water systems  Enormous body of water but nonetheless finite & limited

4 1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES 1(b) An ocean basin’s size, shape and features (islands, trenches, mid-ocean ridges, rift valleys) vary due to the movement of Earth’s lithospheric plates. Earth’s highest peaks, deepest valleys and flattest vast plains are all in the ocean.

5 1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES 1(c) Throughout the ocean there is one interconnected circulation system powered by wind, tides, the force of the Earth’s rotation (Coriolis effect), the Sun, and water density differences. The shape of ocean basins and adjacent land masses influence the path of circulation. One Interconnected Circulation System The circulation system is driven by the: Wind Tides Coriolis Effect (force of Earth’s rotation) Sun Water density differences Circulation Path Influenced By Ocean Basin Shapes Shape of ocean basins & land masses influence the circulation path

6 1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES 1(d) Sea level is the average height of the ocean relative to the land, taking into account the differences caused by tides. Sea level changes as plate tectonics cause the volume of ocean basins and the height of the land to change. It changes as ice caps on land melt or grow. It also changes as sea water expands and contracts when ocean water warms and cools. Sea Level Average height of the ocean relative to land Sea Level Changes Plate tectonics change the volume of ocean basins Ice caps melt or grow Sea water expands and contracts

7 1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES 1(e) Most of Earth’s water (97%) is in the ocean. Seawater has unique properties: it is saline, its freezing point is slightly lower than fresh water, its density is slightly higher, its electrical conductivity is much higher, and it is slightly basic. The salt in seawater comes from eroding land, volcanic emissions, reactions at the seafloor, and atmospheric deposition. 97% of Earth’s water is in the ocean Seawater 96% pure water 3% sodium chloride (common salt or halite) 1% other elements (e.g. magnesium, calcium, potassium) Seawater Properties it is saline its freezing point is slightly lower than freshwater its density is slightly higher that freshwater its electrical conductivity is much higher than fresh it is slightly basic (or alkaline)

8 1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES 1(f) The ocean is an integral part of the water cycle and is connected to all of the earth’s water reservoirs via evaporation and precipitation processes. Water Cycle Water is cycled and recycled via evaporation (heating) and precipitation (cooling) processes.

9 1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES 1(g) The ocean is connected to major lakes, watersheds and waterways because all major watersheds on Earth drain to the ocean. Rivers and streams transport nutrients, salts, sediments and pollutants from watersheds to estuaries and to the ocean. Ocean Is Connected To Major Watersheds The ocean is connected to major lakes, watersheds and waterways because all major watersheds on Earth drain to the ocean. Rivers & Streams Transport & Drain Substances To The Ocean Rivers and streams transport nutrients, salts, sediments and pollutants from watersheds to estuaries and to the ocean.

10 1 | THE EARTH HAS ONE BIG OCEAN WITH MANY FEATURES 1(h) Although the ocean is large, it is finite and resources are limited. Water Is Finite All the water we will ever have is already here on Earth in one form or another (except possibly for ice-laden comets striking the Earth). Freshwater Is Limited Of the total supply almost 97% of the total is saline. Of the 3% freshwater, ~69% is locked up in ice and glaciers while ~30% of freshwater is in the ground. Only 1% is readily available for drinking. Fresh surface-water sources, such as rivers and lakes, only constitute 1/700th of 1% of the total water. Yet, rivers and lakes are the sources of water most people use.