Hydrological Cycle (Water Cycle): The continuous movement of water on the land, in the atmosphere and in the oceans.
The hydrological cycle is said to be a closed system because water can not be added or lost. Although water can not be added or lost it can be found in different states and in different locations. Despite the planet being covered in water, the vast majority is sea water (97.5%). Of the remaining 2.5% the majority is held in glaciers and ice sheets. Only a very small amount of the world's water is easily accessible in rivers and lakes (0.00069%).
Because of rising global temperatures the storage of water is changing. This is particularly true of water held as ice either as permafrost or in giant ice sheets and ice shelves.
Permafrost: Ground that is permanently frozen. For permafrost to exits the ground temperature must be below freezing for the whole year, Permafrost contains large amounts of methane which is released when it melts. Glacier: A slow moving river of ice ages. many of the world's glaciers are melting. The melting of glaciers at their snouts is known as ablation. Ice sheet: Also known as a continental glacier, ice sheets are areas of ice over 50,000 square kilometres found on land. The world's only ice sheets are found on Antarctica and Greenland. Iceberg: A large piece of ice that has broken off a glacier or ice shelf. 90% of icebergs are submerged underwater Ice shelf: Thick floating platforms of ice. Ice shelves are between 100, and 1,000m thick Sea ice: Frozen sea water. Seas like the Baltic Sea freeze during winter.
Because ice shelves and icebergs already make up part of the ocean's volume, their melting does not contribute to rising sea levels. However, because ice sheets are found on land, their melting does contribute to rising seal levels. In addition because the density of liquid water is greater than frozen water, as icebergs and ice shelves melt, they do not take up a grater volume of space. The melting of ice sheets will cause eustatic sea levels changes. This is a global rise in the level of the sea. It is possible for the height of the land to change relative to the sea (e.g. rebound from last ice age). These local changes in the height of the land are known as isostatic sea level changes. As well as melting ice sheets and glaciers, it must also be remembered that global warming causes thermal expansion i.e. the density of water reduces and causes an increase in the volume of water and therefore sea levels.
The hydrological cycle
Hydrological Cycle (Water Cycle): The continuous movement of water on the land, in the atmosphere and in the oceans.
The hydrological cycle is said to be a closed system because water can not be added or lost. Although water can not be added or lost it can be found in different states and in different locations. Despite the planet being covered in water, the vast majority is sea water (97.5%). Of the remaining 2.5% the majority is held in glaciers and ice sheets. Only a very small amount of the world's water is easily accessible in rivers and lakes (0.00069%).
Glacier: A slow moving river of ice ages. many of the world's glaciers are melting. The melting of glaciers at their snouts is known as ablation.
Ice sheet: Also known as a continental glacier, ice sheets are areas of ice over 50,000 square kilometres found on land. The world's only ice sheets are found on Antarctica and Greenland.
Iceberg: A large piece of ice that has broken off a glacier or ice shelf. 90% of icebergs are submerged underwater
Ice shelf: Thick floating platforms of ice. Ice shelves are between 100, and 1,000m thick
Sea ice: Frozen sea water. Seas like the Baltic Sea freeze during winter.
Greenland ice loss accelerating - BBC article
Maldives cabinet to hold underwater meeting - BBC article
New York set to be big loser as sea levels rise - BBC article