Paleoclimatology (in English spelling, palaeoclimatology ) is the study of climate change taken on the whole scale of Earth's history. It uses various methods of proxy from Earth and life sciences to obtain previously preserved data in such things as rocks, sediments, ice sheets, tree circles, corals, shells, and microfossils. Then use the notes to determine the past conditions of various Earth's climate regions and atmospheric systems. Studies of past changes in the environment and biodiversity often reflect the current situation, particularly the impact of climate on mass extinction and biotic recovery.
Video Paleoclimatology
Histori
The field of paleoclimate scientific studies began to form in the early 19th century, when discoveries about glaciations and natural changes in Earth's past climate helped to understand the greenhouse effect. The first observations that have a real scientific basis may be those by John Hardcastle in New Zealand, in the 1880s. He noted that the loess deposit at Timaru on the South Island recorded changes in climate; he calls the loess 'climate register'.
Maps Paleoclimatology
Reconstructing the ancient climate
Paleoclimatologists use various techniques to infer the ancient climate.
Ice
Mountain glaciers and polar ice/ice sheets provide much data in paleoclimatology. Ice-ice accumulation projects in Greenland and Antarctic ice sheets have produced data back several hundred thousand years, over 800,000 years in the case of the EPICA project.
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- The air trapped in falling snow becomes wrapped in tiny bubbles as the snow is compressed into ice on the glacier under the snow load of subsequent years. Trapped air has proven to be an invaluable resource for the direct measurement of air composition from time of ice formed.
- Layering can be observed because of seasonal pauses in ice accumulation and can be used to define chronology, connecting to specific depths of core with time span.
- Layer thickness changes can be used to determine changes in precipitation or temperature.
- The oxygen-18 (? 18 O) change in the ice layer represents the change in mean sea surface temperature. Water molecules containing heavier O-18s evaporate at higher temperatures than water molecules containing normal Oxygen-16 isotopes. The ratio of O-18 to O-16 will be higher with increasing temperature. It also depends on other factors such as water salinity and the volume of water locked in the ice sheet. Various cycles on the isotope ratios have been detected.
- The pollen has been observed on ice cores and can be used to understand which plants are present when layers are formed. Pollen is produced in large quantities and its distribution is usually well understood. The amount of pollen for a given layer can be produced by observing the total amount of pollen categorized by type (shape) in the controlled samples of that layer. Changes in the frequency of plants over time can be plotted through statistical analysis of the amount of pollen in the core. Knowing which plants exist leads to an understanding of rainfall and temperature, and the type of fauna that exists. Palynology includes a pollen study for this purpose.
- Volcanic ash is contained in several layers, and can be used to define the time of layer formation. Each volcanic event distributes ash with a unique set of properties (particle shape and color, chemical signature). Setting the ash source will form a time range to be associated with the ice sheet.
Dendroclimatology
Climate information can be obtained through an understanding of changes in tree growth. Generally, trees respond to changes in climate variables by accelerating or slowing growth, which in turn is generally reflected by greater or lower thickness in growth rings. Different species, however, respond to changes in climate variables in different ways. The record of tree rings is made by collecting information from many live trees in a particular area.
Older, intact wood that has escaped decay can extend the time covered by the records by matching the change in ring depth in contemporary specimens. Using that method, some areas have circular records of trees dating back several thousand years. Older woods not connected to contemporary records can be dated generally by radiocarbon techniques. A tree ring recording can be used to produce information on precipitation, temperature, hydrology, and fire associated with a particular area.
Sediment content
On longer time scales, geologists should refer to the sedimentary records for the data.
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- Sediments, sometimes thought to form rocks, may contain remnants of preserved vegetation, animals, plankton, or pollen, which may characterize certain climatic zones.
- Biomarker molecules such as alken can produce information about the temperature of its formation.
- Chemical signatures, in particular the Mg/Ca calcite ratio in Foraminifera testing, can be used to reconstruct past temperatures.
- The isotope ratio can provide more information. Specifically, ? 18 O record responds to changes in temperature and ice volume, and ? 13 The C record reflects many factors, which are often difficult to decipher.
- sedan facies
- On longer time scales, rock records may show signs of sea level rise and decline, and features such as "fossil" dunes can be identified. Scientists can gain an understanding of the long-term climate by studying sedimentary rocks that will return billions of years. The division of earth's history into separate periods is largely based on visible changes in sedimentary rock layers that limit large changes in conditions. Often, they include major changes in climate. Sclerochronology> Sclerochronology
- Coral (see also sclerochronology)
- Coral "rings" are similar to tree rings except that they respond to different things, such as water temperature, freshwater entry, pH change, and wave action. From there, certain equipment can be used to lower sea surface temperatures and water salinity from several centuries ago. " 18 O from coralline red algae provides a useful proxy of combined sea surface temperatures and sea level salinity in high latitudes and tropical regions, where many traditional techniques are limited.
- Sunless paradox (early)
- Huronian glaciation (~ 2400 Mya Earth is completely covered with ice possibly due to Great Oxygenation Event)
- Neoproterozoic Snow Balls (~ 600 Mya, Cambrian Explosion Precursors)
- Andean-Saharan Glaciation (~ 450 Mya)
- Carbon Rain Forest Dies (~ 300 Mya)
- Permian-Triassic deletion event (251.4 Mya)
- Marine anoxic incidents (~ 120 Mya, 93 Mya, and more)
- Cretaceous-Paleogene (66 Mya) extinction event
- Thermal Paleocene-Thermal Eocene (Paleocene-Eocene, 55 Mya)
- Dryas Young/Big Freeze (~ 11000 BC)
- Climate optimal Holocene (~ 7000-3000 BC)
- Extreme weather event 535-536 (535-536 AD)
- Medieval Warm Period (900-1300)
- Little Ice Age (1300-1800)
- The Year Without Summer (1816)
- Huronian glaciation, is the first known glaciation in Earth history, and lasted from 2400-2100 million years ago.
- Cryogenian glaciers lasted from 720 to 635 million years ago.
- The Andean-Saharan Glacial lasts from 450-420 million years ago.
- Glossary Karoo lasted from 360-260 million years ago.
- Quaternary Glaciation is the current glaciation period and started 2.58 million years ago.
- Thermohaline circulation (Hydrosphere)
- Life (Biosphere)
- The Milankovitch cycle determines the distance and position of the Earth to the Sun. Solar insolation is the total amount of solar radiation received by the Earth.
- Volcanic eruptions are considered external coercion.
- Human change from atmospheric composition or land use.
- Paleoceanography
- Paleothermometry, the study of ancient temperatures
- Paleotempestology, a study of previous tropical cyclone activity
- Paleomap Maps of different ages and climates of the earth
- Historical and prehistoric climate indicator tables
Landscapes and landscapes
In climate geomorphology, one approach is to study the ruins of landforms to infer the ancient climate. Being often worried about the climate of climate geomorphology past is sometimes considered to be the theme of historical geology. Climatic geomorphology is of limited use to study recent major climate change (Quaternary, Holocene) because it is rarely seen in geomorphological records.
Limitations
A multinational consortium, the European Project for Ice Cores in Antarctica (EPICA), has drilled ice cores in Dome C in the East Antarctic ice sheet and took ice from about 800,000 years ago. The international ice core community has, under the auspices of the International Partnership on Ice Core Sciences (IPICS), set a priority project to obtain the oldest possible ice core record from Antarctica, ice core records that reach back to or towards 1.5 million years ago. Deeply marine records, the source of most isotope data, exist only on the oceanic plate, which is subcontracted eventually: the oldest waste material is 200 million years long. Older sediments are also more prone to corruption by diagenesis. Resolution and belief in data decreases over time.
Climate event is important in Earth's history
Knowledge of precise climate events decreases as time goes back, but some important climate events are known:
Atmosphere history
Earliest atmosphere
The first atmosphere consists of gas in the solar nebula, especially hydrogen. In addition, there may be simple hydrides as they are now found in gigantic gases like Jupiter and Saturn, especially moisture, methane, and ammonia. When the solar nebula disappears, the gas will escape, partly driven by the solar wind.
Second atmosphere
The next atmosphere, consisting mostly of nitrogen, carbon dioxide, and inert gas, is produced by outgassing of volcanism, coupled with the gas produced during the final heavy bombardment of Earth by large asteroids. Most carbon dioxide emissions soon dissolve in water and build carbonate sediments.
Water-related sediments have been discovered since about 3.8 billion years ago. About 3.4 billion years ago, nitrogen was a major part of a stable "second atmosphere". The influence of life must be taken into account in atmospheric history, since the indications of early life forms have been set since 3.5 billion years ago. The fact that it is not perfectly aligned with the 30% lower sunlight (compared today) of the early Sun has been described as "the vague young Sun paradox".
However, geological records show a relatively warm surface during Earth's initial temperature record that is complete with the exception of a cold glacial phase about 2.4 billion years ago. At the end of the Archaean month, the oxygen-containing atmosphere began to evolve, apparently from photosynthesizing cyanobacteria (see Great Oxygenation Event) which has been discovered as a stromatolite fossil of 2.7 billion years ago. The initial baseline carbon isotopes (the proportion of isotope ratios) are consistent with what is found today, suggesting that the basic features of the carbon cycle have been formed since 4 billion years ago.
Third atmosphere
Continuous rearrangement of the continents by tectonic plates affects the evolution of the long-term atmosphere by transferring carbon dioxide to and from large continental carbonate stores. Free oxygen did not exist in the atmosphere until about 2.4 billion years ago, during the Great Oxygenation Event, and its appearance was shown by the end of the iron formation. Until then, the oxygen generated by photosynthesis is consumed by the oxidation of the reduced material, especially iron. Free oxygen molecules do not begin to accumulate in the atmosphere until the level of oxygen production begins to exceed the availability of the reduction material. That point is a shift from the reduced atmosphere to the oxidizing atmosphere. O 2 shows the main variation until it reaches a steady state of more than 15% at the end of Precambrian. The following time span is a Phanerozoic eon, where the metazoan-breathing life forms of oxygen begin to appear.
The amount of oxygen in the atmosphere fluctuates over the past 600 million years, reaching a 35% peak during the Carbon period, much higher than the current 21%. Two major processes govern atmospheric change: plants use carbon dioxide from the atmosphere, release oxygen, and pyrite solubility and volcanic eruptions release sulfur into the atmosphere, which oxidizes and therefore reduces the amount of oxygen in the atmosphere. However, volcanic eruptions also release carbon dioxide, which plants can be converted into oxygen. The exact cause of variations in the amount of oxygen in the atmosphere is unknown. Periods with much oxygen in the atmosphere are associated with rapid animal development. Today's atmosphere contains 21% oxygen, which is high enough for fast animal development.
Climate during geological age
Precambrian Climate
The final Precambrian climate shows some of the major glacial events scattered throughout most of the earth. At this time the continents are united in the super continent of Rodinia. Massive deposits of seedlings and anomalous isotope marks are found, which gives rise to the Snowball Earth hypothesis. When the Eon Proterozoic is almost over, the Earth starts to warm up. Toward the dawn of the Cambrian and Fanerozoic, life forms abound in the Cambrian explosion with an average global temperature of about 22 ° C.
Phanerozoic climate
The main drivers for pre-industrial times are variations of sun, volcanic ash and respiration, relative motion of the earth to the sun, and induced tectonic effects such as large ocean currents, watersheds, and oscillations of oceans. At the beginning of Phanerozoic, an increased concentration of atmospheric carbon dioxide has been linked to driving or strengthening global temperature increases. Royer et al. 2004 finds climate sensitivity for the remainder of Phanerozoic which is calculated to be similar to today's modern value range.
The global average temperature difference between a fully glacial Earth and an ice-free Earth is estimated at about 10 ° C, although much larger changes will be observed at higher and lower latitudes at lower latitudes. One of the requirements for the development of large-scale ice sheets seems to be the arrangement of the mass of continental land at or near the poles. Continuous rearrangement of the continent by tectonic plates can also form a long-term climate evolution. However, the presence or absence of polar ground masses is not sufficient to ensure glacial or excluding polar ice. Evidence there is a past warm period in the Earth's climate when a polar plane similar to Antarctica is home to a deciduous forest rather than a sheet of ice.
Relatively warm local minimums between Jurassic and Cretaceous are in line with increased subduction volcanism and mid-ocean ridge due to the breakup of the Pangea superbenua.
Superimposed on the long-term evolution between hot and cold climates are many short-term fluctuations in a climate similar to, and sometimes more severe than, the various glacial and interglacial conditions of the current ice age. Some of the most severe fluctuations, such as the Paleocene-Eocene Maximum Thermal, may be linked to rapid climate change due to the sudden collapse of the natural methane clay reservoirs in the oceans.
A similar singular event due to severe climate change after the impact of meteorites has been proposed as an excuse for the Cretaceous-Paleogene extinction event. The other major thresholds are the Permian-Triassic extinction event, and Orcordova-Silurian for a variety of reasons.
Quaternary Climate
The Quaternary sub-era includes the current climate. There is an ice age cycle over the last 2.2-2.1 million years (beginning before Quaternary in the Late Neogenic Period).
Notice in the graph to the right of the 120,000-year-old periodicity of a strong cycle, and the asymmetry of a fascinating curve. This asymmetry is believed to result from the complex interaction of feedback mechanisms. It has been observed that the ice age is deepened by progressive steps, but the restoration of interglacial conditions occurs in one major step.
The graph on the left shows temperature changes over the past 12,000 years, from various sources. The thick black curve is average.
Climate Forcings
Coercion is the difference in radiation energy (sunlight) received by the Earth and long-wave radiation that goes back out into space. Radiation coercion is calculated based on the amount of CO 2 in tropopause, in units of watts per square meter to the surface of the Earth. Depending on the balance of incoming and outgoing energy radiation, the Earth will warm or cool. Earth's radiation balance comes from changes in solar insolation and greenhouse gas concentrations and aerosols. Climate change may be caused by internal processes within the Earth's sphere and/or follow external forcings.
Internal processes and forcings
The Earth's climate system involves the study of the atmosphere, the biosphere, the cryosphere, the hydrosphere, and the lithosphere, and the summing of processes from the globe of the Earth is considered a process that affects the climate. Greenhouse gases act as an internal force of the climate system. Special interest in climate science and paleoclimatology focuses on the study of Earth's climate sensitivity, in response to the sum of forcings.
Example:
External Forcings
Mechanism
Over a period of millions of years, upgrading of mountains and subsequent weathering of rock and soil and subduction of tectonic plates, is an important part of the carbon cycle. Absorption of CO 2 weathering, by mineral reactions with chemicals (especially silicate coating with CO 2 ) and thus removing CO 2 from the atmosphere and reducing coercion of radiation. The opposite effect is volcanism, responsible for the natural greenhouse effect, by emitting CO 2 into the atmosphere, thus affecting the glaciation cycle (Ice Age). James Hansen suggested that humans emit CO 2 10,000 times faster than natural processes that have been done in the past.
The dynamics of ice sheets and the position of the continents (and associated vegetation changes) have been important factors in the long-term evolution of the Earth's climate. There is also a close correlation between CO 2 and temperature, where CO 2 has strong control over global temperatures in Earth history.
See also
References
Note
Bibliography
External links
Quintana, Favia et al., 2018? Multiproks response to climate change and humanity in remote lakes in southern Patagonia (Laguna Las Vizcachas, Argentina) for the last 1.6 kyr, BoletÃÆ'n de la Sociedad GeolÃÆ'³gica Mexicana, Mexico, VOL. 70 NO. 1 P. 173 - 186 https://dx.doi.org/10.18268/BSGM2018v70n1a10
Source of the article : Wikipedia
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