Climate system

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The five components of the climate system all interact. They are the atmosphere, the hydrosphere, the cryosphere, the lithosphere and the biosphere.[1]

Earth's climate system is a

Solar radiation is the main driving force for this circulation. The water cycle also moves energy throughout the climate system. In addition, certain chemical elements are constantly moving between the components of the climate system. Two examples for these biochemical cycles are the carbon and nitrogen cycles
.

The climate system can change due to

feedback processes
in the different climate system components.

Components

The atmosphere envelops the earth and extends hundreds of kilometres from the surface. It consists mostly of inert

greenhouse gases which allow visible light from the Sun to penetrate to the surface, but block some of the infrared radiation the Earth's surface emits to balance the Sun's radiation. This causes surface temperatures to rise.[6]

The

hydrological cycle is the movement of water through the climate system. Not only does the hydrological cycle determine patterns of precipitation, it also has an influence on the movement of energy throughout the climate system.[7]

The hydrosphere proper contains all the liquid water on Earth, with most of it contained in the world's oceans.[8] The ocean covers 71% of Earth's surface to an average depth of nearly 4 kilometres (2.5 miles),[9] and ocean heat content is much larger than the heat held by the atmosphere.[10][11] It contains seawater with a salt content of about 3.5% on average, but this varies spatially.[9] Brackish water is found in estuaries and some lakes, and most freshwater, 2.5% of all water, is held in ice and snow.[12]

The

snow cover. Because there is more land in the Northern Hemisphere compared to the Southern Hemisphere, a larger part of that hemisphere is covered in snow.[13] Both hemispheres have about the same amount of sea ice. Most frozen water is contained in the ice sheets on Greenland and Antarctica, which average about 2 kilometres (1.2 miles) in height. These ice sheets slowly flow towards their margins.[14]

The Earth's crust, specifically mountains and valleys, shapes global wind patterns: vast mountain ranges form a barrier to winds and impact where and how much it rains.[15][16] Land closer to open ocean has a more moderate climate than land farther from the ocean.[17] For the purpose of modelling the climate, the land is often considered static as it changes very slowly compared to the other elements that make up the climate system.[18] The position of the continents determines the geometry of the oceans and therefore influences patterns of ocean circulation. The locations of the seas are important in controlling the transfer of heat and moisture across the globe, and therefore, in determining global climate.[19]

Lastly, the biosphere also interacts with the rest of the climate system.

Carbon assimilation from seawater by the growth of small phytoplankton is almost as much as land plants from the atmosphere.[23] While humans are technically part of the biosphere, they are often treated as a separate components of Earth's climate system, the anthroposphere, because of human's large impact on the planet.[20]

Flows of energy, water and elements

Earth's atmospheric circulation is driven by the energy imbalance between the equator and the poles. It is further influenced by the rotation of Earth around its own axis.[24]

Energy and general circulation

The climate system receives energy from the Sun, and to a far lesser extent from the Earth's core, as well as tidal energy from the Moon. The Earth gives off energy to outer space in two forms: it directly reflects a part of the radiation of the Sun and it emits infra-red radiation as

Earth's Energy Imbalance is positive and the climate system is warming. If more energy goes out, the energy imbalance is negative and Earth experiences cooling.[25]

More energy reaches the tropics than the polar regions and the subsequent temperature difference drives the global circulation of the

Monsoons, seasonal changes in wind and precipitation that occur mostly in the tropics, form due to the fact that land masses heat up more easily than the ocean. The temperature difference induces a pressure difference between land and ocean, driving a steady wind.[29]

Ocean water that has more salt has a higher

ocean circulation. The thermohaline circulation transports heat from the tropics to the polar regions.[30] Ocean circulation is further driven by the interaction with wind. The salt component also influences the freezing point temperature.[31] Vertical movements can bring up colder water to the surface in a process called upwelling, which cools down the air above.[32]

Hydrological cycle

The hydrological cycle or water cycle describes how it is constantly moved between the surface of the Earth and the atmosphere.[33] Plants evapotranspirate and sunlight evaporates water from oceans and other water bodies, leaving behind salt and other minerals. The evaporated freshwater later rains back onto the surface.[34] Precipitation and evaporation are not evenly distributed across the globe, with some regions such as the tropics having more rainfall than evaporation, and others having more evaporation than rainfall.[35] The evaporation of water requires substantial quantities of energy, whereas a lot of heat is released during condensation. This latent heat is the primary source of energy in the atmosphere.[36]

Biochemical cycles

Carbon is constantly transported between the different elements of the climate system: fixed by living creatures and transported through the ocean and atmosphere.

Chemical elements, vital for life, are constantly cycled through the different components of the climate system. The

acidic, this rain can slowly dissolve some rocks, a process known as weathering. The minerals that are released in this way, transported to the sea, are used by living creatures whose remains can form sedimentary rocks, bringing the carbon back to the lithosphere.[40]

The

fossil fuels has displaced carbon from the lithosphere to the atmosphere, and the use of fertilizers has vastly increased the amount of available fixed nitrogen.[42]

Changes within the climate system

Main article: Climate change

Climate is constantly varying, on timescales that range from seasons to the lifetime of the Earth.

climate feedbacks (e.g. albedo changes), producing many different effects (e.g. sea level rise).[47]

Internal variability

See also: Climate variability and change
Difference between normal December sea surface temperature [°C] and temperatures during the strong El Niño of 1997. El Niño typically brings wetter weather to Mexico and the United States.[48]

Components of the climate system vary continuously, even without external pushes (external forcing). One example in the atmosphere is the

North Atlantic Oscillation (NAO), which operates as an atmospheric pressure see-saw. The Portuguese Azores typically have high pressure, whereas there is often lower pressure over Iceland.[49] The difference in pressure oscillates and this affects weather patterns across the North Atlantic region up to central Eurasia.[50] For instance, the weather in Greenland and Canada is cold and dry during a positive NAO.[51] Different phases of the North Atlantic oscillation can be sustained for multiple decades.[52]

The ocean and atmosphere can also work together to spontaneously generate internal climate variability that can persist for years to decades at a time.[53][54] Examples of this type of variability include the El Niño–Southern Oscillation, the Pacific decadal oscillation, and the Atlantic Multidecadal Oscillation. These variations can affect global average surface temperature by redistributing heat between the deep ocean and the atmosphere;[55][56] but also by altering the cloud, water vapour or sea ice distribution, which can affect the total energy budget of the earth.[57][58]

The oceanic aspects of these oscillations can generate variability on centennial timescales due to the ocean having hundreds of times more mass than the

attribute recent climate change to greenhouse gases.[59]

External climate forcing

See also: Climate variability and change § External climate forcing

On long timescales, the climate is determined mostly by how much energy is in the system and where it goes. When the Earth's energy budget changes, the climate follows. A change in the energy budget is called a forcing, and when the change is caused by something outside of the five components of the climate system, it is called an external forcing.[60] Volcanoes, for example, result from deep processes within the earth that are not considered part of the climate system. Off-planet changes, such as solar variation and incoming asteroids, are also "external" to the climate system's five components, as are human actions.[61]

The main value to quantify and compare climate forcings is radiative forcing.

Incoming sunlight

The

varies on shorter time scales, including the 11-year solar cycle[63] and longer-term time scales.[64] While the solar cycle is too small to directly warm and cool Earth's surface, it does influence a higher layer of the atmosphere directly, the stratosphere, which may have an effect on the atmosphere near the surface.[65]

Slight variations in the Earth's motion can cause large changes in the seasonal distribution of sunlight reaching the Earth's surface and how it is distributed across the globe, although not to the global and yearly average sunlight. The three types of

interglacial periods.[66]

Greenhouse gases

Main article: Greenhouse effect

Greenhouse gases trap heat in the lower part of the atmosphere by absorbing

emissions by humans are the cause of increasing concentrations of some greenhouse gases, such as CO2, methane and N2O.[67] The dominant contributor to the greenhouse effect is water vapour (~50%), with clouds (~25%) and CO2 (~20%) also playing an important role. When concentrations of long-lived greenhouse gases such as CO2 are increased and temperature rises, the amount of water vapour increases as well, so that water vapour and clouds are not seen as external forcings, but instead as feedbacks.[68] The weathering of carbonates and silicates removes carbon from the atmosphere.[69]

Aerosols

Liquid and solid particles in the atmosphere, collectively named aerosols, have diverse effects on the climate. Some primarily scatter sunlight and thereby cool the planet, while others absorb sunlight and warm the atmosphere.

volcanoes, but humans also contribute[70] as human activity such as the combustion of biomass or fossil fuels releases aerosols into the atmosphere. Aerosols counteract a part of the warming effects of emitted greenhouse gases, but only until they fall back to the surface in a few years or less.[72]

El Niño
is a separate event, from ocean variability.

Although volcanoes are technically part of the lithosphere, which itself is part of the climate system, volcanism is defined as an external forcing agent.

volcanic eruptions per century that influence Earth's climate for longer than a year by ejecting tons of SO2 into the stratosphere.[74][75] The sulfur dioxide is chemically converted into aerosols that cause cooling by blocking a fraction of sunlight to the Earth's surface. Small eruptions affect the atmosphere only subtly.[74]

Land use and cover change

Changes in land cover, such as change of water cover (e.g.

rising sea level, drying up of lakes and outburst floods) or deforestation, particularly through human use of the land, can affect the climate. The reflectivity of the area can change, causing the region to capture more or less sunlight. In addition, vegetation interacts with the hydrological cycle, so that precipitation is also affected.[76] Landscape fires release greenhouse gases into the atmosphere and release black carbon, which darkens snow making it easier to melt.[77][78]

Responses and feedbacks

Some effects of global warming can either enhance (positive feedbacks) or inhibit (negative feedbacks) warming.[79][80] Observations and modeling studies indicate that there is a net positive feedback to Earth's current global warming.[81]
Main article:
Climate change feedback

The different elements of the climate system respond to external forcing in different ways. One important difference between the components is the speed at which they react to a forcing. The atmosphere typically responds within a couple of hours to weeks, while the deep ocean and ice sheets take centuries to millennia to reach a new equilibrium.[82]

The initial response of a component to an external forcing can be

damped by negative feedbacks and enhanced by positive feedbacks. For example, a significant decrease of solar intensity would quickly lead to a temperature decrease on Earth, which would then allow ice and snow cover to expand. The extra snow and ice has a higher albedo or reflectivity, and therefore reflects more of the Sun's radiation back into space before it can be absorbed by the climate system as a whole; this in turn causes the Earth to cool down further.[83]

References

  1. ^ a b c Planton 2013, p. 1451.
  2. ^ Planton 2013, p. 1450.
  3. ^ "Climate systems". climatechange.environment.nsw.gov.au. Archived from the original on 2019-05-06. Retrieved 2019-05-06.
  4. ^ "Earth's climate system". World Ocean Review. Retrieved 2019-10-13.
  5. ^ Barry & Hall-McKim 2014, p. 22; Goosse 2015, section 1.2.1.
  6. ^ Gettelman & Rood 2016, pp. 14–15.
  7. ^ Gettelman & Rood 2016, p. 16.
  8. ^ Kundzewicz 2008.
  9. ^ a b Goosse 2015, p. 11.
  10. ^ Gettelman & Rood 2016, p. 17.
  11. ^ "Vital Signs of the Plant: Ocean Heat Content". NASA. Retrieved 2022-02-12.
  12. ^ Desonie 2008, p. 4.
  13. ^ Goosse 2015, p. 20.
  14. ^ Goosse 2015, p. 22.
  15. ^ Goosse 2015, p. 25.
  16. ^ Houze 2012.
  17. ^ Barry & Hall-McKim 2014, pp. 135–137.
  18. ^ Gettelman & Rood 2016, pp. 18–19.
  19. ^ Haug & Keigwin 2004.
  20. ^ a b Gettelman & Rood 2016, p. 19.
  21. ^ Goosse 2015, p. 26.
  22. ^ Goosse 2015, p. 28.
  23. ^ Smil 2003, p. 133.
  24. ^ Barry & Hall-McKim 2014, p. 101.
  25. ^ Barry & Hall-McKim 2014, pp. 15–23.
  26. ^ Bridgman & Oliver 2014, p. 131.
  27. ^ Barry & Hall-McKim 2014, p. 95.
  28. ^ Barry & Hall-McKim 2014, pp. 95–97.
  29. ^ Gruza 2009, pp. 124–125.
  30. ^ Goosse 2015, p. 18.
  31. ^ Goosse 2015, p. 12.
  32. ^ Goosse 2015, p. 13.
  33. ^ "The water cycle". Met Office. Retrieved 2019-10-14.
  34. ^ Brengtsson et al. 2014, p. 6.
  35. ^ Peixoto 1993, p. 5.
  36. ^ Goosse 2015, section 2.2.1.
  37. ^ Goosse 2015, section 2.3.1.
  38. ^ Möller 2010, pp. 123–125.
  39. ^ Aiuppa et al. 2006.
  40. ^ Riebeek, Holli (16 June 2011). "The Carbon Cycle". Earth Observatory. NASA.
  41. ^ Möller 2010, pp. 128–129.
  42. ^ Möller 2010, pp. 129, 197.
  43. ^ National Research Council 2001, p. 8.
  44. ^ Nath et al. 2018.
  45. ^ Australian Academy of Science (2015). "1. What is climate change?". www.science.org.au. The science of climate change - Questions and Answers. Retrieved 2019-10-20.
  46. ^ National Geographic (2019-03-28). "Climate Change". Retrieved 2019-10-20.
  47. ^ Mauritsen et al. 2013.
  48. ^ Carlowicz, Mike; Uz, Stephanie Schollaert (14 February 2017). "El Niño: Pacific Wind and Current Changes Bring Warm, Wild Weather". Earth Observatory. NASA.
  49. ^ "North Atlantic Oscillation". Met Office. Retrieved 2019-10-03.
  50. ^ Chiodo et al. 2019.
  51. ^ Olsen, Anderson & Knudsen 2012.
  52. ^ Delworth et al. 2016.
  53. ^ Brown et al. 2015.
  54. ^ Hasselmann 1976.
  55. ^ Meehl et al. 2013.
  56. ^ England et al. 2014.
  57. ^ Brown et al. 2014.
  58. ^ Palmer & McNeall 2014.
  59. ^ Wallace et al. 2013.
  60. ^ Gettelman & Rood 2016, p. 23.
  61. ^ Planton 2013, p. 1454: "External forcing refers to a forcing agent outside the climate system causing a change in the climate system. Volcanic eruptions, solar variations and anthropogenic changes in the composition of the atmosphere and land use change are external forcings. Orbital forcing is also an external forcing as the insolation changes with orbital parameters eccentricity, tilt and precession of the equinox."
  62. ^ Roy 2018, p. xvii.
  63. ^ Willson & Hudson 1991.
  64. ^ Turner et al. 2016.
  65. ^ Roy 2018, pp. xvii–xviii.
  66. ^ "Milankovitch Cycles and Glaciation". University of Montana. Archived from the original on 2011-07-16. Retrieved 2 April 2009.
  67. ^ McMichael, Woodruff & Hales 2006.
  68. ^ Schmidt et al. 2010.
  69. ^ Liu, Dreybrodt & Liu 2011.
  70. ^ a b Myhre et al. 2013.
  71. ^ Lohmann & Feichter 2005.
  72. ^ Samset 2018.
  73. ^ Man, Zhou & Jungclaus 2014.
  74. ^ a b Miles, Grainger & Highwood 2004.
  75. ^ Graf, Feichter & Langmann 1997.
  76. ^ Jones, Collins & Torn 2013.
  77. ^ Tosca, Randerson & Zender 2013.
  78. ^ Kerr 2013.
  79. ^ "The Study of Earth as an Integrated System". nasa.gov. NASA. 2016. Archived from the original on November 2, 2016.
  80. ^ Fig. TS.17, Technical Summary, Sixth Assessment Report (AR6), Working Group I, IPCC, 2021, p. 96. Archived from the original on July 21, 2022.
  81. ^ Stocker, Thomas F.; Dahe, Qin; Plattner, Gian-Kaksper (2013). IPCC AR5 WG1. Technical Summary (PDF). Archived (PDF) from the original on 16 July 2023. See esp. TFE.6: Climate Sensitivity and Feedbacks at p. 82.
  82. ^ Ruddiman 2001, pp. 10–12.
  83. ^ Ruddiman 2001, pp. 16–17.

Sources

  • Peixoto, José P. (1993). "Atmospheric energetics and the water cycle". In Raschke, Ehrhard; Jacob, Jacob (eds.). Energy and Water Cycles in the Climate System. Springer-Verlag Berlin Heidelberg.
    ISBN 978-3-642-76957-3
    .

External links
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