climate, Earth system science, entropy, glacial cycles, glaciation, greenhouse, Law of Thermodynamics, reflectivity, surroundings Thermodynamic
Earth system is maintained in a state so far away from TE (Equilibrium thermodynamics) despite the natural direction towards mixing matter and depleting sources of free energy. The Exchange of energy and mass with the surroundings is a critical component that allows systems to evolve away from TE without violating the second law of thermodynamics. The evolutionary direction of the Earth systems away from TE can thus be understood as a consequence o the MEP principle (Maximum Entropy Production).
Life affects climate through its role in the carbón and water cycles and through such mechanisms as albedo, evapotranspiration, cloud formation and weathering.
The glacial and inerglacial periods of the Quaternary Ice Age were named after characteristic geological features.
Geological time scale:
ERA PERIOD EPOCA Millions of years ago
Nomenclaturte of Quaternary glacial cycles
1ST Würm glacial period 12-71 Ka
Riss-Würm interglacial 115-130
2ND Riss glacial period 130-200
Mindel-Riss interglacial 374-424
3RD-6TH Mindel glacial period 424-478
Günz-Mindel interglacial 478-563
7TH-8TH Günz glacial peiod 621-676
The second ice age, and posibly most severe, is estimated to have ocurred from 850 to 635 Ma agen, in the Neoproterozoic Era. A minor series of glaciations occurred from 460 Ma to 430 Ma. There were extensive glaciations from 350 to 250 Ma. The current ice age, called the Quaternary glaciation, has seen more or less extensive glaciation on 40.000 and later, 100.000 year cycles.
The planet seems to have three main setting and colon:
“snowball”: when planet´s entrie surface is frozen over
“icehouse”: when there is some permanent ice
“greenhouse”: when tropical temperaturas extend to the poles
- 4 to 2.1 billion years ago: snowball Earth, the Huronian glaciation is the oldest ice age we know about. Home only to unicelular life-forms.
- 850 to 630 million years ago: deep freeze, the evolution of large cells, and possibly also multicelular organisms, this would have sucked CO2 out of the atmosphere, weakening the greenhouse effect and thus lowering global temmperatures.
- 460 to 430 million years ago: mass extinction, the late Ordovician period, the plants becoming common over the course of the Silurian period.
- 360 to 260 million years ago: plants invade the land, expansión of land plants that followe the Cryogenian. As plants spread over the planet, they aboserved CO2, from the atmosphere and releaxed oxygen.
- 14 million yearse ago: Antarctica freezes ago, increased weathering, which sucked CO2, out of the Atmosphere and reduced the greenhouse effect.
- 50 million years ago: lateste advance of the ice, the main trigger for the Quaternary glaciation was the continuing fall in the level of CO2 in the atmosphere due to the weathering of the Himalayas.
- 000 to 12.000 yearse ago: our ice age, the cool temperaturas of the Quaternary may have allowed our brains to become much larger than those of our of hominid ancestors. As the glacial period drew to a close and temperaturas began to rise, there were two final cold snaps.
Changes in the sun´s energy affect how much energy reaches Earth´s system
Changes in the sun´s intensivity have influenced Earth´s climate in the past. Changes in Earth´s orbit have had a big impact in climate over tens to hundreds of thousands of years. Primary cause of past cycles of ice ages, long periods of cold temperatures (ice ages), as well as shorter interglacial periods of relatively warmer temperatures. Changes in solar energy continue to affect climate. Changes in the shape of Earth´s orbit as well as the tilt and position of Earth´s axis affect temperature on very long timescales (tens to hundreds of thousands of years), and therefore cannot explain the recent warming. Sunlight reaches Earth, it can be reflected or absorbed, snow and clouds tend to reflect most sunlight, darker objects and surfaces, like the ocean, forests, or soil, tend to absorb more sunlight. Earth as a whole has an albedo of about 30%, meaning that 70% of the sunlight that reaches the planet is absorbed. Absorbed sunlight warms Earth´s land, water, and atmosphere. Processes such as deforestation, reforestation, desertification, and urbanization often contribute to changes in climate in the places they occur. Human activities have generally increased the number of aerosol particles in the atmosphere. Reductions in overall aerosol emissions can therefore lead to more warming.
Affects climate through its role in the carbón and water cycles and through such mechanisms as albedo, evapotranspiration, cloud formation, and weathering:
- Glaciation 2,3 billion years ago triggered by the evolution of oxygenic photosynthesis, which depleted the atmosphere of the greenhouse gas carbón dioxide and introduced free oxygen.
- Another glaciation 300 million years ago ushered in by long-term burial of descomposition-resistant detritus of vascular land-plants (creating a carbón sink and forming coal)
- Termination of the Paleocene-Eocene Thermal Maximum 55 million years ago by flourishing marine phytoplankton.
- Reserval of global warming 49 million years ago by 800.000 years of arctic azolla blooms.
- Global cooling over hte past 40 million years driven by the expansión of grass-grazer ecosystems.
Human and natural sources:
Methane: is produced through both natural and human activities. Natural wetlands, agricultural activities and fossil fuel extraction and transport all emit CH4. CH4 concentrations increased sharply during most of the 20th century and are now more than-and-a-half times preindustrial levels.
Nitrous oxide: Nitrous oxide is produced through natural and human activities, mainly through agricultural activities and natural biological processes. Concentrations of N20 have risen approximately 20% since the start of the Industrial Revolution.
Water vapor: is the most abundant greenhouse gas and also the most important in terms of its contribution to the natural greenhouse effect, despite having a short atmospheric lifetime.
Tropospheric ozone (O3), which also has a short atmospheric lifetime, is a potent greenhouse gass.
Thermodynamic and Earth´s Climate
The particular ítem or collection of ítems tht is interesting is called the system, everything that´s not included in the system , everything that´s not included in the system we´ve defined is called the surroundings.
There are three types of systems in thermodynamics: open, closed and isolated.
- An open system: can Exchange both energy and matter with its surroundings.
- A closed system: on the other hand, can Exchange only energy with its surroundings, not matter.
- Isolated system : is one that cannot Exchange either matter or energy with its surroundings.
The total amount of energy in the universo, and in particular, it states that this total amount does not change. The First Law of Thermodynamics states that energy cannot be created or destroyed. It can only be change formo r be transferred from one object to another. Heat that doesn´t do work goes towards increasing the randomness of the Universe. The degree of randomness or disorder in a system is called its entropy. We can state a biology-relevant versión of the Second Law of Thermodynamics: every energy transfer that takes place will increase the entropy of the universo and reduce the amount of usable energy available to do work. In other words, any process, such as a chemical reaction or set of connected reactions, wil proceed in a direction that increases the oerall entropy of the Universe.
The cells are organized into tissues, and the tissues into organs; and entire body maintains a carefull system of transport, exchange, and commerce that keeps the live. Chemical energy from complex molecules such as glucose and converting it into kinetic energy, a large fraction of the energy from fuel sources is simply transformed into heat. Much of it dissipates into the surrounding environment.
Earth´s atmosphere is far from thermodynamic equilibrium (TE). Entropy can be use as a measure for the lack of gradients and free energy. By depleting gradients and sources of free energy, these processes are directed towards the state of thermodynamic equilibrium (TE) at which the entropy of the system and its surroundings is maximized. The temperatura of the gas refers to the mean kinetic energy of the molecules, pressure describes the average intensity by which the molecules collidle with the walls of the volumen, and density measures the average number of molecules per unit volume. The most probable macroscopic state by definition is the state of máximum entropy, as stated by
Boltzman´s equation: S= K log W, S is the entroy and W the statical weight of a macrostate
The distinction between macroscopic and microscopic dynamics applies to understanding the large-scale behaviour of environmental systems and ecosystems.
Strong atmospheric circulation and the global cycles of wáter and carbón require engines to continuosly. Solar radiation also provides the photochemical energy to drive photosynthesis, which in turn provides the major source of free energy to drive geochemical cycles within the Earth system. States that thermodynamic process in non-equilibrium systems asume steady states at which their rates of entropy production are maximized.
Using the estándar thermodynamic definition of entropy change,
dS = dQ/T, extra increase in entropy of dS = dQ(1/Tb-1/Ta) results in an overall increase of the entropy of the whole system as stated by the second law (dS >0)
Some scientists think nowadays that we are living in Anthropocene Epoch and human influence is important. “Global Glacier recession continues”. A natural glacial may have seen just before to the Industrial Revolution, as a result of high late Holocene (the last 11.000 years on Earth) CO2 and the low orbital of the Earth, corrent interglacial climate would likely continue for another 50.000 years, making this an unisually long interglacial period.
- Bethan Davies. antarcticglaciers.org. 2016
- UC. Davis ChemWiki, “A system and its surroundings”.2015
- Melillo, Jerry M., Terese Richmong, and Gary W.Yohe, Eds. “Climate Change Impacts in the United States: The Third National Climate Assesment”. 2014
- Reece, J.B., Urry, L.A., Cain, M.L, Wasserman, S.A., Minorsky, P.V., and Jackson, R.B. “The laws of energy transformation”. Campbell biology (10th ed., pp 143-145) 2011.
- Michael Marshall , “The history of ice on Earth”.2010
- A.Kleidon, “A basic introduction to the thermodynamics of the Earth system far from equilibrium and máximum entropy production”. 2010
- National Research Council. The National Academies Press, Washington, “Advancing the Science of Climate Changes”. 2010
- Van Andel, Tjeerd H. “New Views on an Old Planet: A History of Global Change”. Cambridge UK. 1994
The laws of thermodynamic