History of the climate

Taking into account the existence of another article treating époque contemporaine, this article voluntarily completes its descriptions at the year 1850.

---- To recall the History Climate until the contemporary time and the anthropic appearance of the phenomenon of the Climate warming amounts examining the events of the Histoire of the world and their correlation with the various phases of warming and glaciation punctuating the successive Climate changes.

Origins of the subject

the great myths of humanity are not free from such bringings together; one can quote for example the revelation of Noah, parabola of a Déluge due to a divine fury, which, except context of the beliefs, would constitute the memory of one destabilizing Transgression marinades in the biblical corpus.
In its work Of the spirit of the laws , Montesquieu was devoted to a Théorie of the climate (Citations) trying to correlate ambient heat on the level of development of the autochtones: the cold would be inciting of dynamism, where heat and moisture would impose on the man only few efforts to implement the Agriculture of subsistence. However, this theory has the defects of its qualities, since she does not explain why the Inuit S did not conquer planet.
Louis Agassiz in 1837 will be the first to put forth the assumption of a great glaciation. Its theory was known as mono-glacialiste bus it affirmed that only one glaciation had prevails on the surface of the ground. Its observations were based on the displacement of large erratic blocks far from their initial substrates, under the action of the ice.
Albrecht Penck and Eduard Brueckner in 1901-1909 will cancel the mono-glacialiste assumption and will put forth an assumption pluri-glacialist. They will describe and name the great alpine glaciations according to the affluents of the the Danube, that is to say Günz, Mindel, Riss and Würm. If it were employed a long time like reference for the northern hemisphere, it is from now on allowed that this classification is valid only with the regional scales of the alpine arc. The development of the methods of dating based on the Radioactivity and of the Stratigraphie made it possible to prove scientifically that several glaciations had followed one another the Pléistocène.
the astrophysicist Milutin Milankovitch will push the theories further on the glaciations by publishing a astronomical Théorie from the climates, which will be allowed only in 1976. This theory affirms that the great glaciations are engaged by orbital parameters and that the solar quantity of flow which strikes the northern hemisphere is determining in the development of Inlandsis. Its theory was proven by the Stratigraphie and the radiometric datings which illustrate that the variations of eccentricity start glaciations recurringly.

Items 1 and 2 illustrate, in spite of their lack of direct link with the subject of this article, the interest of the men to connect, with more or less happiness, their observations with the historical Téléologique. The fact that one bases oneself on the content of the Air to ensure this description, and not ground like before (discipline of the Stratigraphie, archaeological excavations), constitutes an innovative approach very with fact.

The current appearance of a history of the temperature of the sphere going back to 650.000 years before the present makes today possible such a retrospective, bringings together between Science of the climate and historical Science which this time raises neither of eschatologic mythology nor of a humanistic ideology.

Phasage

the phases former to the Human history concern the Paléoclimatologie . They make it possible to follow, with the wire of the successive periods of Glaciation S, the variations related to the Climate change having affected the grounds and the species, according to their nature. The Cycle of carbon in is from now on recipient; the frequency of study of this phase is thus comparable with the geological time scale.
1. an example: Precambrian.
the Glaciation S: the cycle of the Climate changes makes it possible today to detail the seven former glaciations:
1. ()
2. until 450.000 years behind: Interglacial of Waal
3. until 400.000 years behind: Glaciation of Günz or Nébraskien
4. until 350.000 years behind: Interglacial of Cromer or Aftonien
5. until 320.000 years behind: Glaciation of Mindel, or or Kansien
6. until 270.000 years behind: Interglacial of Holstein or Yamouthien
7. until 200.000 years behind: Glaciation of Riss, or Saal, or of the Illinoien
8. until 125.000 years behind: Interglacial of Eem or Sangamonien
9. until 70.000 years behind: Glaciation of Würm, or Weichsélien or Wisconsinien
10. until 11625 years behind: Interglacial of Holocene the, () sometimes indicated like “the new warming” of the Holocene
Beginning of the written human history and observation of the climatic variations by the chroniclers.
1. 535 - 536: Climate change of 535-536 () , noted by the Byzantine Procope de Césarée
2. 10th century - 14th century: Optimum climatic of the Middle Ages () , a warming located with the Europe, even with the North America
3. Years 1550 - Years 1850: Petit Ice Age
the last phase is contemporary and attempts to describe the multiples Effets of climate warming; it is to be separated from the remainder taking into account the constant anthropic interference on climatic balances since the advent of the Industrial revolution and controls it energy S Polluant are by Humanity.
1. Retreat of the glaciers since 1850

Effects of the climate on the species

One of the theories former to the current awakening connects the Extinction of the dinosaurs to an abrupt glaciation: it is about that of the Crétacé.

August 1st

Effects of the climate on the Human history

before 1850.

After this year, lira the article Effects of climate warming.

Reconstitution of the paleoclimates

Radiometric datings

The lakes varves

With the average latitudes, the sediments present at the bottom them lakes can constitute an extremely relevant information source. The lakes most interesting to study are the lakes Dimictique S, i.e. which mix twice in the year. In this context, it is possible to study the varvées layers, during a carrotage. Each Varve form a verse which represents one year of Sédimentation. In spring, the Sédiments are pale and come from the rivers which flow. In winter, the dark particles and more fines elutriate and will settle on the bottom. The thickness of varves is thus variable and makes it possible to know if a summer were longer or a colder winter. If the varvée sequence moves more towards a prevalent varve, it that the lake moves more towards a side Amictique, i.e. is covered with ice at the long year and only one mixture of water annual.

Stratigraphy

The succession of the layers of Substrat S is an excellent climatic indicator. It is possible, for example, to see indices indicating the transition from a forest medium about a more arid middle or more cold. The vestiges collected using a Carrotage thus deliver extremely relevant information. Let us imagine a river in lose speed and process of exhaustion: initially, its marshy zone extends and is colonized by the forest which is subjacent for him. Then, the marshy zone is colonized more and more by the forest. However, a draining of the climate leads the forest to become more Arbustive and in the form of Lichen and to be transformed more into Tourbière, place of decomposition of the vegetable elements. The stratigraphic Coupe will be able to illustrate this transition. At the beginning, one finds the Argiles, witnesses of the hotter and wet period. Then, one finds Alluvions of river terraces, with vegetable remains. Come then wood and the peat, witnesses of the colder period, mixed with Lichen. In the case, of a place under influence of Ice cap, these vestiges could be covered with Till, i.e. rocks torn off and compacted, crushed in fine granules and very compact, set up under the action of the ice. The Moraine S are also Faciès which are found with the face of the ice caps and are often made up of till. However, the erosion of a layer exposed, under the action of the wind or of the ice can skew the results. It is also possible to date the vegetable elements as wood and the peat to discover on which date the environmental conditions of the climate were present. It is also possible to compare two layers, to obtain absolute datings for each one of them and to determine in how long the transition was carried out.

Glacial coring vs marine coring

Drillings of large the caps of ice present at the poles are very good climatic indicators, since the polar Inlandsis are in place since thousands of years. It is thus an incredible bank of climatic data which is trapped in the ice. Drillings SPICED and Vostok in the Antarctic or with the Greenland is mainly carried out with an aim of reconstituting the paleoclimates. It is also possible to make oceanic carrotage, to compare the results resulting from the glacial and oceanic carrotage.

The proportions between the two natural isotopes of the Oxygen O16 and O18 are also very interesting to study. The Oxygène 16 accounts for 99,76% of terrestrial oxygen, while oxygen 18 accounts for 0,2% of them. During a glaciation report/ratio O18/O16 is weaker in the glaciers and higher in the oceans. The O16 isotope is prisoner in the ice and evaporates oceans, being lightest. As the water of precipitations is immobilized in the form of ice during one glacial period, the sea level drops and the ice caps increase their volume. During a warming of the climate, the process is reversed. The glaciers found and oxygen 16, lighter than the 18, runs out towards the ocean making increase ratio O18/O16. In the ocean the effect is opposite there, the oxygen 16 addition due to the cast iron of the glaciers, makes decrease report/ratio O18/O16 and makes increase the marine level.

The content of Methane and Carbon dioxide of the ocean and the glaciers is also interesting. During a glaciation, the content of CO₂ is weak in the atmosphere and the glaciers. However, the cool water incorporates tons of CO₂, by its thermodynamic Pompe and the biological Pompe. The content of CO₂ is thus very high in the ocean. In the case of a warming, water releases from CO₂ towards the atmosphere, cause a drop in the oceanic content but to increase the atmospheric content. Water is then less productive and less rich in rock salt. The activity of methane is similar: when the weather is hotter, the content methane is very high in the atmosphere, sight the strongest decomposition. In the ocean, it is the reverse: as the biomass is higher there during one glacial period, the decomposition is more intense there too.

It is possible to make datings Isotopique S in a layer of ice or a oceanic carrot. The bubbles of airs present inside the ice can be dated by the use of the Isotopes. Even thing, in the oceans the ic organizations Plankton, like the Foraminifera with calcareous shell and the Diatomée S with silica shell can be dated.

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