Earth is often called the “Blue Planet,” a designation that suggests a world dominated by liquid water. Understanding the planet’s composition requires distinguishing between the submerged ocean basins and the exposed continental landmasses. The solid, rocky surface provides the foundation for terrestrial ecosystems and human civilization. Measuring the proportion of the Earth’s total surface area covered by solid ground is a key geographical and scientific interest.
The Global Land-Water Ratio
The Earth’s total surface area is roughly 510 million square kilometers. The accepted global metric shows that water covers approximately 70.8% of this area, primarily through the interconnected bodies of the global ocean. The remaining portion, consisting of continental landmasses and islands, is approximately 29.2%. This ratio, often rounded to 71% water and 29% land, represents the balance between the hydrosphere and the exposed crust.
Defining Earth’s Land Surface
The 29.2% figure encompasses all continental landmasses and the myriad of islands scattered across the globe. This surface is fundamentally the Earth’s crust, consisting of rock, soil, and various geological formations that rise above sea level. When defining this land area, scientists consider the underlying solid earth, even where it is covered by features like permanent ice sheets. For instance, the Antarctic Ice Sheet rests on a continental landmass, and the area of that underlying ground is counted as part of the total land percentage.
A significant distinction exists between exposed land and the submerged continental shelves. These shelves are geologically part of the continents, representing the edge of the continental crust that extends outward from the coastline. However, because they are covered by relatively shallow seawater, they are included in the 70.8% water measurement, not the land percentage. Therefore, the land surface area measurement specifically isolates the segments of the crust that are emergent from the ocean. This calculation provides a precise measure of the physical area available for terrestrial life and geological processes.
Distribution of Land Area
The landmass that makes up the 29.2% of the Earth’s surface is not evenly distributed across the planet. A profound imbalance exists between the Northern and Southern Hemispheres, divided by the Equator. The vast majority of the world’s land is situated north of the Equator. Specifically, the Northern Hemisphere contains approximately 68% of the Earth’s total land area.
This concentration means the Southern Hemisphere is overwhelmingly dominated by water, holding only about 32% of the global landmass. The Northern Hemisphere includes the entirety of North America and Europe, most of Asia, and a large portion of Africa. In contrast, the Southern Hemisphere contains the whole continents of Antarctica and Australia, along with the majority of South America. This uneven distribution has significant implications for global climate patterns and ocean circulation.