CarbonTracker.com - The climate system and how it works

The Earth’s “climate system” is made up of five interactive parts:

The atmosphere (the planet’s air)
The hydrosphere (the planet’s water)
The cryosphere (the planet’s ice)
The land surface
The biosphere (plants and animals)

The climate system in detail

The atmosphere is the most rapidly changing and unstable part of the climate system. The atmosphere is made up almost entirely of nitrogen (78%) and oxygen (21%), but also contains trace amounts of other gases such as carbon dioxide, methane, nitrous oxide and ozone, as well as water vapor.

The hydrosphere is made up of all the liquid water on the planet, and includes both surface and subterranean water (groundwater). The oceans, which cover approximately 70% of the surface of the planet, play an important role in regulating temperature on the planet. Not only do they dissolve and store great quantities of carbon dioxide, they also store and transport energy around the planet.

The cryosphere is comprised of the frozen water on the planet, and includes the polar ice caps, continental glaciers and permafrost. The cryosphere is an especially important part of the climate system, as it reflects a lot of the sun’s energy back into the atmosphere and outer space. Additionally, because the polar ice sheets store a great deal of frozen water, their melting and freezing strongly influence the level and composition of the oceans.

The land surface of the Earth, or the planet’s vegetation and soils, help control how solar radiation, or energy from the sun, is absorbed or returned to the atmosphere. As solar radiation is absorbed and the land surface warms, some energy is returned to the atmosphere in the form of long-wave radiation (heat). Additionally, some energy acts to evaporate moisture, transporting water from the land surface to the atmosphere.

The biosphere strongly influences the composition of the atmosphere. Through the process of photosynthesis, both marine (water) and terrestrial (land) plants store great amounts of carbon dioxide. When those plants die and decay, most of that stored carbon dioxide is returned to the atmosphere. The amounts of other gases in the atmosphere, such as methane and nitrous oxide, are also influenced by the biosphere.

These parts of the climate system interact with one another through a variety of physical, chemical and biological processes. The interactions take place over a range of time and geographical scales. Some interactions may be localized and occur over a matter of seconds or minutes; other interactions may span the globe and happen gradually over thousands of years. Needless to say, the climate is a complex system!

Almost all life on earth is powered by the sun, either directly or indirectly. Energy from the sun arrives at earth in the form of light. Most of that light is reflected back into outer space, but about 30 percent reaches the surface of the planet and is absorbed. That heat is eventually carried aloft in the air and escapes into space. Before it escapes, however, some of that heat is trapped by greenhouse gases such as water vapor, carbon dioxide and methane. When balanced, the climate system serves to ensure that enough warmth is trapped at the surface of the planet to support life, but enough energy is reflected or released into space that the surface of the planet does not become too hot.

Next: Causes of Climate Change