Chapter 2 Oceans And Continents

The Distribution Of Water And Land On The Earth

When viewed from space, Earth appears predominantly blue. This is because a vast majority of the planet's surface, approximately three-fourths, is covered by water. The remaining portion, a little over one-fourth, consists of land.

The largest water bodies on Earth are known as oceans. Significant continuous expanses of land are called continents.

Both oceans and continents are crucial in determining the Earth's climate and influencing all forms of life, including human societies.

The distribution of water and land is not uniform across the globe. The Northern Hemisphere contains a significantly larger proportion of land compared to the Southern Hemisphere, which is sometimes referred to as the 'water hemisphere' due to its vast oceanic areas.

Smaller water bodies connected to oceans are known by various names such as seas, bays, or gulfs.

While oceans hold the majority of the Earth's water, this water is saline and unsuitable for consumption by most land animals. Freshwater is a much smaller fraction of the total water resources, found in glaciers, rivers, lakes, the atmosphere, and underground (groundwater).

The term "marine" refers to anything related to or found in the oceans and seas.

The term "flora" refers to the plant life of a region, while "fauna" refers to the animal life.

Oceans

Conventionally, the Earth's vast interconnected water bodies are divided into five major oceans. These are:

1. The Pacific Ocean (the largest)
2. The Atlantic Ocean
3. The Indian Ocean
4. The Southern (or Antarctic) Ocean
5. The Arctic Ocean (the smallest)

Although conventionally separated on maps, the oceans are physically connected, allowing for continuous flow of seawater and the widespread presence of marine life across different regions.

Let's look at the general distribution of these oceans across the hemispheres:

The Indian Ocean is bordered by Asia to the north, Africa to the west, and Australia to the east, meeting the Southern Ocean in the south. Parts of the Indian Ocean adjacent to India are known as the Arabian Sea to the west and the Bay of Bengal to the east.

Oceans And Disasters

Oceans are a source of precipitation for land areas through the Earth's water cycle, bringing essential rain like the monsoon rains in India.

However, oceans can also be the origin of severe weather events and natural disasters that affect coastal regions.

• Storms: Oceans can generate violent storms with heavy rainfall and strong winds, such as cyclones, which can cause significant damage to coastal areas.
• Tsunamis: A tsunami is a series of very large and powerful waves, typically triggered by underwater earthquakes or volcanic eruptions. Tsunamis can travel vast distances and cause widespread destruction when they reach coastlines by flooding low-lying areas.

Given the destructive potential of events like tsunamis, early warning systems are crucial. Countries collaborate internationally to detect such events and issue timely warnings to enable protective measures, minimizing loss of life and property. The Indian Ocean Tsunami Warning System is an example of such collaboration.

Managing the impact of events that cause loss of life and property falls under the scope of disaster management. India has a dedicated authority, the National Disaster Management Authority, to handle various types of disasters.

Continents

Continents are the large, continuous landmasses on the Earth's surface. While they are clearly visible on maps, the exact number of continents recognized can vary depending on how adjacent landmasses are grouped.

Different conventions exist for counting the continents, leading to possibilities of listing four, five, six, or seven continents.

• Some views consider North and South America as a single continent called "America".
• Europe and Asia form a single large landmass but are often treated as separate continents (Europe and Asia) due to distinct historical and cultural trajectories. Geologists sometimes refer to this combined landmass as "Eurasia".
• Africa can sometimes be grouped with Eurasia.

Here's a summary of common ways to count continents:

The list of seven continents (Africa, Antarctica, Asia, Australia, Europe, North America, and South America) is the most widely accepted and used count in practice.

The Olympic rings symbol is said to represent the five inhabited continents: Africa, America, Asia, Australia, and Europe, highlighting their role in bringing together athletes globally.

Comparing the relative sizes of the seven continents:

Based on relative size (from smallest to largest):

1. Australia
2. Europe
3. Antarctica
4. South America
5. North America
6. Africa
7. Asia

Asia is the largest continent, and Australia is the smallest.

Islands

Not all landmasses are continents. Smaller pieces of land completely surrounded by water are called islands.

There are countless islands around the world, varying significantly in size.

• Greenland is the largest island globally.
• India has over 1,300 smaller islands, including the major groups of the Andaman and Nicobar Islands in the Bay of Bengal and the Lakshadweep Islands in the Arabian Sea.

India has an active presence in Antarctica, a continent with an extremely cold and harsh environment. The Indian Antarctica Programme supports scientific research there. India established its first base station, 'Dakshin Gangotri', in Antarctica in 1983.

Oceans And Life

Oceans and continents are fundamental components of the Earth's environment and profoundly influence various aspects of life on the planet.

Oceans play a critical role in the global climate system. They are essential for the water cycle, providing the moisture that leads to rainfall on continents, which is vital for agriculture and terrestrial life. Oceans also contribute significantly to the Earth's atmosphere; over half of the world's oxygen is produced by marine plant life, earning the oceans the title of "the planet's lungs."

Beyond their environmental impact, oceans have shaped human history and culture. For centuries, they have facilitated migration, trade, and even military activities. Coastal communities worldwide have developed unique cultures, traditions, and stories inspired by the sea.

However, human activities pose serious threats to the health of the oceans. Pollution, particularly from plastic waste (millions of tonnes of which enter oceans annually), is harming marine life and habitats. Overfishing, or excessive fishing, is depleting fish populations and disrupting marine ecosystems.

Protecting the oceans is a shared global responsibility, crucial for maintaining the planet's ecological balance and ensuring the well-being of future generations.

The United Nations designates June 8th as World Oceans Day to raise awareness about the ocean's importance and the need for its conservation.