Paleoclimatology

upright=1.4|thumb|Global distribution of Drylands|dryland areas based on the [[aridity index computed over a 30-year average during 1981 to 2010. Typical deserts are indicated by the hyper-arid category (light yellow).]] thumb|right|234px|Extreme desertification in Somalia Desertification is a type of gradual land degradation of fertile land into arid desert due to a combination of natural processes and human activities.

Paleoclimatology (British spelling, palaeoclimatology) is the scientific study of climates predating the invention of meteorological instruments, when no direct, artificial measurement data were available. As instrumental records only span a tiny part of Earth's history, the reconstruction of ancient climate is important to understand natural variation and the evolution of the current climate.

periodic changes in the orbital movements of the earth

worldwide glaciation episodes during the Cryogenian Period of the Neoproterozoic Era

thumb|upright=0.5|Fulgurite

measurement of how much temperature will rise given an increase in CO2

thumb|upright=1.4|Cave labeled with the six most common types of speleothems: flowstone, columns, drapery, [[stalagmites, stalactites and straws]] A speleothem (; ) is a geological formation made by mineral deposits that accumulate over time in natural caves. They can take a variety of forms, depending on their depositional history and environment. Common forms include stalagmites, stalactites, and flowstones.

rapid (in geological terms) global warming, profound changes in ecosystems, and major perturbations in the carbon cycle which started about 55.0 million years ago

interglacial period

alternating warm and cool periods in the Earth's paleoclimate, deduced from oxygen isotope data

form of climate change

preserved physical characteristics allowing reconstruction of past climatic conditions

warmest and moistest Blytt-Sernander period, pollen zone and chronozone of Holocene northern Europe

The Subboreal is a climatic period, immediately before the present one, the subatlantic period. Both are part of the Holocene epoch. It lasted from 3710 to 450 BCE. During this time, conditions on earth were somewhat warmer and drier than the present with lower levels of carbon dioxide. There were important changes to vegetation, sea level, and the expansion of human civilizations, and the first instances of human recorded history.

thumb|496px|Variation of tree ring width translated into summer temperature anomalies for the past 7000 years, based on samples from holocene deposits on [[Yamal Peninsula and Siberian now living conifers.]]

The Subatlantic is the current climatic age of the Holocene epoch. It started about 2,500 years BP and is still ongoing. Its average temperatures are slightly lower than during the preceding Subboreal and Atlantic. During its course, the temperature underwent several oscillations, which had a strong influence on fauna and flora and thus indirectly on the evolution of human civilizations. With intensifying industrialisation, human society started to stress the natural climatic cycles with increased greenhouse gas emissions.

hypothesis about migration of species between Africa and Eurasia

Paleolimnology (from Greek: παλαιός, palaios, "ancient", λίμνη, limne, "lake", and λόγος, logos, "study") is a scientific sub-discipline closely related to both limnology and paleoecology. Paleolimnological studies focus on reconstructing the past environments of inland waters (e.g., lakes and streams) using the geologic record, especially with regard to events such as climatic change, eutrophication, acidification, and internal ontogenic processes.

rapid climate fluctuation in the last glacial period

natural phenomenon in which large groups of icebergs traverse the North Atlantic

stadial period

climatic period

series of north European climatic periods

In geochemistry, paleoclimatology, archaeology, and paleoceanography '''δC''' (pronounced "delta carbon thirteen") is a normalized ratio of the two stable isotopes of carbon—C and C—reported in parts per thousand (per mille, ‰).

anoxic extinction events in the Cretaceous period, occurring at 91.5 ± 8.6 Ma

Paleotempestology is the study of past tropical cyclone activity by means of geological proxies as well as historical documentary records. The term was coined by American meteorologist Kerry Emanuel.

Alkenones are long-chain unsaturated methyl and ethyl n-ketones produced by a few phytoplankton species of the class Prymnesiophyceae. Alkenones typically contain between 35 and 41 carbon atoms and with between two and four double bonds. Uniquely for biolipids, alkenones have a spacing of five methylene groups between double bonds, which are of the less common E configuration. The biological function of alkenones remains under debate although it is likely that they are storage lipids. Alkenones were first described in ocean sediments recovered from Walvis Ridge and then shortly afterwards in c

scientific journal

timeline

type of zone

Chemostratigraphy, or chemical stratigraphy, is the study of the chemical variations within sedimentary sequences to determine stratigraphic relationships. The field is relatively young, having only come into common usage in the early 1980s, but the basic idea of chemostratigraphy is nearly as old as stratigraphy itself: distinct chemical signatures can be as useful as distinct fossil assemblages or distinct lithographies in establishing stratigraphic relationships between different rock layers.

thumb|222px|The nature of sediments can vary in a cyclic fashion, and these cycles can be displayed in the sedimentary record - here visible in the colouration and resistance of strata thumb|Milankovitch variations, solar forcing, and glacial cycles. Image by Robert A. Rohde, under the CC BY-SA 3.0 license. Cyclostratigraphy is a subdiscipline of stratigraphy that studies astronomically forced climate cycles within sedimentary successions.

thumb|Molecular structures and High-performance liquid chromatography|HPLC detection of GDGTs. Retrieved from Tierney and Tingley (2015).|433x433px

cyclical variations in the ratio of the abundance of oxygen

period of either rapid or just accelerated post-glacial sea level rise

thumb|The Pale Orange Dot: an artist's interpretation of what the Earth may have looked like when haze built up in its atmosphere. A paleoatmosphere (or palaeoatmosphere) is an atmosphere, particularly that of Earth, at some unspecified time in the geological past.

change in glacial cycles occurring 1 Mya (Pleistocene), from 41000-year glacial cycles (Milankovitch forcing) to 100000-year asymmetric cycles

Suggested composition of the ocean in the middle to late Proterozoic

period of rapid post-glacial sea level rise