System Earth
Chapter 2 - Society
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Welcome to the System Earth page
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Key takeaways
- Not only do the Earth systems overlap, they are also interconnected; what affects one can affect another
- Our social and economic systems are now embedded within the Earth system
- Life affects the carbon, nitrogen, water, oxygen and many other cycles and processes
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Core ideas
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Earth system definition
The term “Earth system" refers to Earth´s interacting physical, chemical, and biological processes. The system consists of the land, oceans, atmosphere and poles. It includes the planet's natural cycles — the carbon, water, nitrogen, phosphorus, sulphur and other cycles — and deep Earth processes. Life too is an integral part of the Earth system. Life affects the carbon, nitrogen, water, oxygen and many other cycles and processes.
The Earth system now includes human society, Our social and economic systems are now embedded within the Earth system. In many cases, the human systems are now the main drivers of change in the Earth system.
| Content source |
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| International Geosphere-Biosphere Program |
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Dive deeper
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The biosphere
The biosphere (from Ancient Greek βίος (bíos) 'life' and σφαῖρα (sphaîra) 'sphere'), also called the ecosphere (from Ancient Greek οἶκος (oîkos) 'settlement, house' and σφαῖρα (sphaîra) 'sphere'), is the worldwide sum of all ecosystems.
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The zone of life on the Earth.
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- The biosphere (which is technically a spherical shell) is:
- regard to matter, a closed system, with minimal inputs and outputs.
- regarding energy, it is an open system, with photosynthesis capturing solar energy at a rate of around 100 terawatts.
By the most general biophysiological definition, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, cryosphere, hydrosphere, and atmosphere.
| Wikipedia |
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| https://en.wikipedia.org/wiki/Biosphere |
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The hydrosphere
The hydrosphere (from Ancient Greek ὕδωρ (húdōr) 'water' and σφαῖρα (sphaîra) 'sphere').
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The combined mass of water found on, under, and above the surface of our Earth.
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Although Earth's hydrosphere has been around for about 4 billion years, it continues to change in shape. This is caused by seafloor spreading and continental drift, which rearranges the land and ocean.
It has been estimated that there are 1.386 billion cubic kilometres of water on Earth. This includes water
- in gaseous, liquid and frozen forms as soil moisture, groundwater and permafrost in the Earth's crust (to a depth of 2 km);
- oceans and seas, lakes, rivers and streams, wetlands, glaciers, ice and snow cover on Earth's surface;
- vapour, droplets and crystals in the air;
- and part of living plants, animals and unicellular organisms of the biosphere.
The total mass of Earth's hydrosphere is about 1.4 × 1018 tonnes, which is about 0.023% of Earth's total mass. At any given time, about 2 × 1013 tonnes of this is in the form of water vapor in the Earth's atmosphere (for practical purposes, 1 cubic metre of water weighs 1 tonne). Approximately 71% of Earth's surface, an area of some 361 million square kilometres, is covered by ocean.
- Saltwater accounts for 97.5% of this amount. The average salinity of Earth's oceans is about 35 grams of salt per kilogram of sea water (3.5%)
- Fresh water accounts for only 2.5%. Of this fresh water, 68.9% is in the form of ice and permanent snow cover in the Arctic, the Antarctic and mountain glaciers; 30.8% is in the form of fresh groundwater; and only 0.3% of the fresh water on Earth is in easily accessible lakes, reservoirs and river systems.
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| Wikipedia |
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| https://en.wikipedia.org/wiki/Hydrosphere |
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The cryosphere
The cryosphere is an umbrella term for those portions of Earth's surface where water is in solid form. This includes sea ice, ice on lakes or rivers, snow, glaciers, ice caps, ice sheets, and frozen ground (which includes permafrost). Thus, there is an overlap with the hydrosphere. There are several fundamental physical properties of snow and ice that modulate energy exchanges between the surface and the atmosphere. The most important properties are the surface reflectance (albedo), the ability to transfer heat (thermal diffusivity), and the ability to change state (latent heat). These physical properties, together with surface roughness, emissivity, and dielectric characteristics, have important implications for observing snow and ice from space. For example, surface roughness is often the dominant factor determining the strength of radar backscatter. Physical properties such as crystal structure, density, length, and liquid water content are important factors affecting the transfers of heat and water and the scattering of microwave energy.
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| https://en.wikipedia.org/wiki/Cryosphere |
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The atmosphere
The atmosphere (from Ancient Greek ἀτμός (atmós) 'vapour, steam' and σφαῖρα (sphaîra) 'sphere').
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The layer of gases that envelop the Earth, held in place by its gravity.
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The current composition of the atmosphere of the Earth is the product of billions of years of biochemical modification of the paleo-atmosphere by living organisms. The atmosphere of Earth is composed of:
- nitrogen (78%),
- oxygen (21%),
- argon (0.9%),
- carbon dioxide (0.04%)
- and trace gases.
Most organisms use oxygen for respiration; lightning and bacteria perform nitrogen fixation which produces ammonia that is used to make nucleotides and amino acids; plants, algae, and cyanobacteria use carbon dioxide for photosynthesis. The layered composition of the atmosphere minimises the harmful effects of sunlight, ultraviolet radiation, solar wind, and cosmic rays and thus protects the organisms from genetic damage.
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| https://en.wikipedia.org/wiki/Atmosphere_of_Earth |
| https://en.wikipedia.org/wiki/Atmosphere |
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The geosphere
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The geosphere refers to the solid parts of the Earth.
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In modern texts and in Earth system science, it is used along with atmosphere, hydrosphere, and biosphere to describe the systems of the Earth (the interaction of these systems with the magnetosphere is sometimes listed). In that context, sometimes the term lithosphere is used instead of geosphere or solid Earth. The lithosphere, however, only refers to the uppermost layers of the solid Earth (oceanic and continental crustal rocks and uppermost mantle).
"Geosphere" may also be taken as the collective name for the lithosphere, the hydrosphere, the cryosphere, and the atmosphere. The different collectives of the geosphere are able to exchange different mass and/or energy fluxes (the measurable amount of change). The exchange of these fluxes affects the balance of the different spheres of the geosphere. An example is how the soil acts as a part of the biosphere, while also acting as a source of flux exchange.
| Wikipedia |
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| https://en.wikipedia.org/wiki/Geosphere |
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Do you want to know more?
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| Earth as a System |
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| While Earth is also nested within much larger systems, like our Solar System and Milky Way Galaxy, Earth is also made up of five major parts or subsystems: the Atmosphere, Hydrosphere, Biosphere, Cryosphere, and Geosphere. |
| https://mynasadata.larc.nasa.gov/basic-page/about-earth-system-background-information |
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| Earth's System |
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| Not only do the Earth systems overlap, they are also interconnected; what affects one can affect another. |
| https://education.nationalgeographic.org/resource/earths-systems/ |
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| Two major ecological shifts shaped 60 million years of ungulate faunal evolution - Fernando Blanco - Nature Communications - 2025 |
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| The fossil record provides direct evidence for the behavior of biological systems over millions of years, offering a vital source for studying how ecosystems evolved and responded to major environmental changes |
| https://www.nature.com/articles/s41467-025-59974-x |
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