The Holocene ( ) is the current
geological epoch
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochr ...
. It began approximately 11,650
cal Cal or CAL may refer to:
Arts and entertainment
* ''Cal'' (novel), a 1983 novel by Bernard MacLaverty
* "Cal" (short story), a science fiction short story by Isaac Asimov
* ''Cal'' (1984 film), an Irish drama starring John Lynch and Helen Mir ...
years
Before Present
Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Becaus ...
(), after the
Last Glacial Period, which concluded with the
Holocene glacial retreat.
The Holocene and the preceding
Pleistocene together form the
Quaternary period. The Holocene has been identified with the current warm period, known as
MIS 1. It is considered by some to be an
interglacial
An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene i ...
period within the Pleistocene Epoch, called the
Flandrian interglacial The Flandrian interglacial or stage is the name given by geologists and archaeologists in the British Isles to the first, and so far only, stage of the Holocene epoch (the present geological period), covering the period from around 12,000 years ago ...
.
[Oxford University Press – Why Geography Matters: More Than Ever (book) – "Holocene Humanity" section https://books.google.com/books?id=7P0_sWIcBNsC ]
The Holocene corresponds with the rapid proliferation, growth and impacts of the
human species worldwide, including
all of its written history,
technological revolutions, development of major
civilization
A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system).
Ci ...
s, and overall significant transition towards
urban living in the present. The human impact on modern-era
Earth and its
ecosystems may be considered of global significance for the future evolution of living species, including approximately synchronous
lithospheric evidence, or more recently
hydrospheric and
atmospheric
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
evidence of the human impact. In July 2018, the
International Union of Geological Sciences split the Holocene Epoch into three distinct
ages based on the climate,
Greenlandian (11,700 years ago to 8,200 years ago),
Northgrippian
In the geologic time scale, the Northgrippian is the middle one of three ages or stages of the Holocene Epoch or Series. It was officially ratified by the International Commission on Stratigraphy in June 2018 along with the earlier Greenlan ...
(8,200 years ago to 4,200 years ago) and
Meghalayan (4,200 years ago to the present), as proposed by
International Commission on Stratigraphy.
The oldest age, the Greenlandian was characterized by a warming following the preceding ice age. The Northgrippian Age is known for vast cooling due to a disruption in ocean circulations that was caused by the melting of glaciers. The most recent age of the Holocene is the present Meghalayan, which began with extreme drought that lasted around 200 years.
Etymology
The word is formed from two
Ancient Greek words. ''Holos'' () is the Greek word for "whole". "Cene" comes from the Greek word ''kainos'' (), meaning "new". The concept is that this epoch is "entirely new". The suffix '-cene' is used for all the seven epochs of the
Cenozoic
The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configurat ...
Era.
Overview
It is accepted by the
International Commission on Stratigraphy that the Holocene started approximately 11,650
cal Cal or CAL may refer to:
Arts and entertainment
* ''Cal'' (novel), a 1983 novel by Bernard MacLaverty
* "Cal" (short story), a science fiction short story by Isaac Asimov
* ''Cal'' (1984 film), an Irish drama starring John Lynch and Helen Mir ...
years
BP (9,700 BCE).
The Subcommission on Quaternary Stratigraphy (SQS) observes the terms ‘recent’ to be an incorrect way of referring to the Holocene, and the term ‘modern’ may be used instead to describe current processes. It also observes the term ‘Flandrian’ may be used as a synonym for Holocene, although it is becoming outdated. The International Commission on Stratigraphy, however, considers the Holocene an epoch following the
Pleistocene and specifically the
last glacial period. Local names for the last glacial period include the
Wisconsinan
The Wisconsin Glacial Episode, also called the Wisconsin glaciation, was the most recent glacial period of the North American ice sheet complex. This advance included the Cordilleran Ice Sheet, which nucleated in the northern North American Cord ...
in North America,
the
Weichselian
The Weichselian glaciation was the last glacial period and its associated glaciation in northern parts of Europe. In the Alpine region it corresponds to the Würm glaciation. It was characterized by a large ice sheet (the Fenno-Scandian ice sheet ...
in Europe,
the Devensian in Britain,
the
Llanquihue in Chile
and the Otiran in New Zealand.
The Holocene can be subdivided into five time intervals, or
chronozones, based on climatic fluctuations:
*
Preboreal
The Preboreal is an informal stage of the Holocene epoch. It is preceded by the Tarantian and succeeded by the Boreal. It lasted from 10,300 to 9,000 BP in radiocarbon years or 8350BC to 7050BC in Gregorian calendar years (8th millennium BC). ...
(10 ka–9 ka BP),
*
Boreal
Boreal may refer to:
Climatology and geography
*Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch
*Boreal climate, a climate characterized by long winters and short, cool to mild ...
(9 ka–8 ka BP),
*
Atlantic (8 ka–5 ka BP),
*
Subboreal
The Subboreal is a climatic period, immediately before the present one, of the Holocene. It lasted from 3710 to 450 BCE.
Etymology
The composite scientific term ''Subboreal'', meaning "below the Boreal," is derived from the Latin ''sub'' (b ...
(5 ka–2.5 ka BP) and
*
Subatlantic
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 temp ...
(2.5 ka BP–present).
: ''Note: "
ka BP" means "kilo-annum
Before Present
Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Becaus ...
", i.e. 1,000 years before 1950 (non-calibrated
C14 dates)''
Geologists working in different regions are studying sea levels, peat bogs and
ice core
An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains i ...
samples by a variety of methods, with a view toward further verifying and refining the
Blytt–Sernander sequence. This is a classification of climatic periods initially defined by plant remains in
peat moss
''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, peat moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store wa ...
es. Though the method was once thought to be of little interest, based on
14C dating of peats that was inconsistent with the claimed chronozones, investigators have found a general correspondence across
Eurasia and
North America. The scheme was defined for
Northern Europe, but the
climate changes were claimed to occur more widely. The periods of the scheme include a few of the final pre-Holocene oscillations of the last glacial period and then classify climates of more recent
prehistory.
Paleontologists
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...
have not defined any
faunal stages for the Holocene. If subdivision is necessary, periods of human technological development, such as the
Mesolithic,
Neolithic, and
Bronze Age
The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second prin ...
, are usually used. However, the time periods referenced by these terms vary with the emergence of those technologies in different parts of the world.
According to some scholars, a third division, the
Anthropocene
The Anthropocene ( ) is a proposed geological epoch dating from the commencement of significant human impact on Earth's geology and ecosystems, including, but not limited to, anthropogenic climate change.
, neither the International Commissio ...
, has now begun. This term is used to denote the present time interval in which many geologically significant conditions and processes have been profoundly altered by human activities.
The 'Anthropocene' (a term coined by
Paul J. Crutzen
Paul Jozef Crutzen (; 3 December 1933 – 28 January 2021) was a Dutch meteorologist and atmospheric chemist. He was awarded the Nobel Prize in Chemistry in 1995 for his work on atmospheric chemistry and specifically for his efforts in studyin ...
and Eugene Stoermer in 2000) is not a formally defined geological unit. The Subcommission on Quaternary Stratigraphy of the
International Commission on Stratigraphy has a working group to determine whether it should be.
In May 2019, members of the working group voted in favour of recognizing the Anthropocene as formal chrono-stratigraphic unit, with stratigraphic signals around the mid-twentieth century CE as its base. The exact criteria have still to be decided upon, after which the recommendation also has to be approved by the working group's parent bodies (ultimately the International Union of Geological Sciences).
Geology
The Holocene is a geologic epoch that follows directly after the Pleistocene. Continental motions due to
plate tectonics are less than a kilometre over a span of only 10,000 years. However, ice melt caused world
sea levels to rise about in the early part of the Holocene and another 30 m in the later part of the Holocene. In addition, many areas above about
40 degrees north latitude had been depressed by the weight of the Pleistocene glaciers and rose as much as due to
post-glacial rebound
Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound a ...
over the late Pleistocene and Holocene, and are still rising today.
The sea-level rise and temporary
land depression allowed temporary marine incursions into areas that are now far from the sea. For example, marine fossils from the Holocene epoch have been found in locations such as
Vermont and
Michigan. Other than higher-latitude temporary marine incursions associated with glacial depression, Holocene fossils are found primarily in lakebed,
floodplain, and
cave deposits. Holocene marine deposits along low-latitude coastlines are rare because the rise in sea levels during the period exceeds any likely
tectonic uplift of non-glacial origin.
Post-glacial rebound in the
Scandinavia region resulted in a shrinking
Baltic Sea
The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain.
The sea stretches from 53°N to 66°N latitude and from ...
. The region continues to rise, still causing weak
earthquakes across Northern Europe. An equivalent event in North America was the rebound of
Hudson Bay, as it shrank from its larger, immediate post-glacial
Tyrrell Sea
The Tyrrell Sea, named after Canadian geologist Joseph Tyrrell, is another name for prehistoric Hudson Bay, namely as it existed during the retreat of the Laurentide Ice Sheet.
Roughly 8,000 years BP, the Laurentide Ice Sheet thinned and split i ...
phase, to its present boundaries.
Climate
The climate throughout the Holocene has shown significant variability despite ice core records from Greenland suggesting a more stable climate following the preceding ice age. Marine chemical fluxes during the Holocene were lower than during the Younger Dryas, but were still considerable enough to imply notable changes in the climate. The Greenland ice core records indicate that climate changes became more regional and had a larger effect on the mid-to-low latitudes and mid-to-high latitudes after ~5600 B.P. During the transition from the last glacial to the Holocene, the
Huelmo–Mascardi Cold Reversal
The Huelmo–Mascardi Cold Reversal (HMCR) is a cooling event in South America between 11,400 and 10,200 14C years BP. This cooling began about 550 years before the Younger Dryas cooling in the Northern Hemisphere, and both periods ended at abo ...
in the
Southern Hemisphere began before the Younger Dryas, and the maximum warmth flowed south to north from 11,000 to 7,000 years ago. It appears that this was influenced by the residual glacial ice remaining in the
Northern Hemisphere until the later date.
The
Holocene climatic optimum
The Holocene Climate Optimum (HCO) was a warm period that occurred in the interval roughly 9,000 to 5,000 years ago BP, with a thermal maximum around 8000 years BP. It has also been known by many other names, such as Altithermal, Climatic Optimu ...
(HCO) was a period of warming throughout the globe. It has been suggested that the warming was not uniform across the world. Ice core measurements imply that the sea surface temperature (SST) gradient east of New Zealand, across the subtropical front (STF), was around 2 degrees Celsius. This temperature gradient is significantly less than modern times, which is around 6 degrees Celsius. A study utilizing five SST proxies from 37°S to 60°S latitude confirmed that the strong temperature gradient was confined to the area immediately south of the STF, and is correlated with reduced westerly winds near New Zealand. From the 10th-14th century, the climate was similar to that of modern times during a period known as the Medieval climate optimum, or the Medieval warm period (MWP). It was found that the warming that is taking place in current years is both more frequent and more spatially homogeneous than what was experienced during the MWP. A warming of +1 degree Celsius occurs 5-40 times more frequently in modern years than during the MWP. The major forcing during the MWP was due to greater solar activity, which led to heterogeneity compared to the greenhouse gas forcing of modern years that leads to more homogeneous warming. This was followed by the
Little Ice Age
The Little Ice Age (LIA) was a period of regional cooling, particularly pronounced in the North Atlantic region. It was not a true ice age of global extent. The term was introduced into scientific literature by François E. Matthes in 1939. Ma ...
, from the 13th or 14th century to the mid-19th century.
The temporal and spatial extent of climate change during the Holocene is an area of considerable uncertainty, with
radiative forcing recently proposed to be the origin of cycles identified in the North Atlantic region. Climate cyclicity through the Holocene (
Bond events) has been observed in or near marine settings and is strongly controlled by glacial input to the North Atlantic.
Periodicities of ≈2500, ≈1500, and ≈1000 years are generally observed in the North Atlantic. At the same time spectral analyses of the continental record, which is remote from oceanic influence, reveal persistent periodicities of 1,000 and 500 years that may correspond to solar activity variations during the Holocene Epoch.
A 1,500-year cycle corresponding to the North Atlantic oceanic circulation may have had widespread global distribution in the Late Holocene.
Ecological developments
Animal and plant life have not evolved much during the relatively short Holocene, but there have been major shifts in the richness and abundance of plants and animals. A
number of large animals including
mammoths and
mastodons,
saber-toothed cat
Machairodontinae is an extinct subfamily of carnivoran mammals of the family Felidae (true cats). They were found in Asia, Africa, North America, South America, and Europe from the Miocene to the Pleistocene, living from about 16 million unt ...
s like ''
Smilodon
''Smilodon'' is a genus of the extinct machairodont subfamily of the felids. It is one of the most famous prehistoric mammals and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely relat ...
'' and ''
Homotherium'', and
giant sloth
Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbea ...
s went extinct in the late Pleistocene and early Holocene. The extinction of some megafauna in America could be attributed to the Clovis people; this culture was known for "
Clovis points" which were fashioned on spears for hunting animals. Shrubs, herbs, and mosses had also changed in relative abundance from the Pleistocene to Holocene, identified by permafrost core samples.
Throughout the world, ecosystems in cooler climates that were previously regional have been isolated in higher altitude ecological "islands".
The ''
8.2-ka event'', an abrupt cold spell recorded as a negative excursion in the record lasting 400 years, is the most prominent climatic event occurring in the Holocene Epoch, and may have marked a resurgence of ice cover. It has been suggested that this event was caused by the final drainage of
Lake Agassiz, which had been confined by the glaciers, disrupting the
thermohaline circulation of the
Atlantic. This disruption was the result of an ice dam over
Hudson Bay collapsing sending cold
lake Agassiz water into the
North Atlantic ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe a ...
.
Furthermore, studies show that the melting of
Lake Agassiz led to sea-level rise which flooded the North American coastal landscape. The
basal peat plant was then used to determine the resulting local sea-level rise of 0.20-0.56m in the
Mississippi Delta
The Mississippi Delta, also known as the Yazoo–Mississippi Delta, or simply the Delta, is the distinctive northwest section of the U.S. state of Mississippi (and portions of Arkansas and Louisiana) that lies between the Mississippi and Yazo ...
.
Subsequent research, however, suggested that the discharge was probably superimposed upon a longer episode of cooler climate lasting up to 600 years and observed that the extent of the area affected was unclear.
Human developments
The beginning of the Holocene corresponds with the beginning of the
Mesolithic age in most of
Europe. In regions such as the
Middle East and
Anatolia, the term
Epipaleolithic is preferred in place of Mesolithic, as they refer to approximately the same time period. Cultures in this period include
Hamburgian,
Federmesser
''Federmesser'' group is an archaeological umbrella term
including the late Upper Paleolithic to Mesolithic cultures of the Northern European Plain, dating to between 14,000 and 12,800 years ago (the late Magdalenian). It is closely related t ...
, and the
Natufian culture, during which
the oldest inhabited places still existing on Earth were first settled, such as
Tell es-Sultan
Tell es-Sultan ( ar, تل السلطان, ''lit.'' Sultan's Hill), also known as Tel Jericho ( he, תל יריחו) or Ancient Jericho, is a UNESCO-nominated archaeological site in the West Bank, in the State of Palestine, located adjacent to th ...
(Jericho) in the
Middle East. There is also evolving archeological evidence of
proto-religion at locations such as
Göbekli Tepe, as long ago as the
9th millennium BCE
The 9th millennium BC spanned the years 9000 BC to 8001 BC (11 to 10 thousand years ago). In chronological terms, it is the first full millennium of the current Holocene epoch that is generally reckoned to have begun by 9700 BC (11.7 thousan ...
.
The preceding period of the Late Pleistocene had already brought advancements such as the bow and arrow, creating more efficient forms of hunting and replacing spear throwers. In Holocene, however, the domestication of plants and animals allowed human civilization to develop villages and towns in centralized locations. Archaeological data shows that between 10,000 to 7,000
BP rapid domestication of plants and animals took place in tropical and subtropical parts of
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
,
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
, and
Central America
Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. C ...
.
The development of farming allowed
human civilization
A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system).
Civ ...
to transition away from
hunter-gatherer nomadic cultures, which did not establish permanent settlements, to a more sustainable sedentary lifestyle. This form of lifestyle change allowed human civilization to develop towns and villages in centralized locations, which gave rise to the world known today. It is believed that the domestication of plants and animals began in the early part of the Holocene in the tropical areas of the planet.
Because these areas had warm, moist temperatures, the climate was perfect for effective farming. Culture development and human population change, specifically in South America, has also been linked to spikes in hydroclimate resulting in climate variability in the mid-Holocene (8.2 - 4.2 k cal BP). Climate change on seasonality and available moisture also allowed for favorable agricultural conditions which promoted human development for Maya and Tiwanaku regions.
Extinction event
The
Holocene extinction, otherwise referred to as the ''sixth mass extinction'' or ''Anthropocene extinction'', is an ongoing
extinction event of
species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
during the present Holocene
epoch (with the more recent time sometimes called Anthropocene) as a result of
human activity
Human behavior is the potential and expressed capacity ( mentally, physically, and socially) of human individuals or groups to respond to internal and external stimuli throughout their life. Kagan, Jerome, Marc H. Bornstein, and Richard M ...
.
The included
extinctions
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
span numerous families of
bacteria,
fungi,
plants and
animal
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...
s, including
mammals,
birds,
reptiles,
amphibian
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arborea ...
s,
fish and
invertebrates
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
. With widespread degradation of
highly biodiverse habitats such as
coral reefs and
rainforests, as well as other areas, the vast majority of these extinctions are thought to be undocumented, as the species are undiscovered at the time of their extinction, or no one has yet discovered their extinction. The current rate of extinction of species is estimated at 100 to 1,000 times higher than
natural background extinction rates.
Gallery
See also
* 4.2-kiloyear event
The 4.2-kiloyear (thousand years) BP aridification event (long-term drought) was one of the most severe climatic events of the Holocene epoch. It defines the beginning of the current Meghalayan age in the Holocene epoch.
Starting around 2200& ...
* 8.2-kiloyear event
In climatology, the so-called "8.2-kiloyear event" was a sudden decrease in global temperatures that occurred approximately 8,200 years before the present ( BP), that is, 6,251 BC. It defines the start of the Northgrippian age in the Holocen ...
* 10th millennium BC
* Blytt–Sernander system
The Blytt–Sernander classification, or sequence, is a series of north European climatic periods or phases based on the study of Danish peat bogs by Axel Blytt (1876) and Rutger Sernander (1908). The classification was incorporated into a seque ...
* Holocene calendar
* African humid period
The African humid period (AHP) (also known by other names) is a climate period in Africa during the late Pleistocene and Holocene geologic epochs, when northern Africa was wetter than today. The covering of much of the Sahara desert by grasses ...
* Older Peron
The Older Peron was the name for a period identified in 1961 as an episode of a global sea-level (i.e. eustatic) high-stand during the Holocene Epoch
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years B ...
* Outburst flood
In geomorphology, an outburst flood—a type of megaflood—is a high-magnitude, low-frequency catastrophic flood involving the sudden release of a large quantity of water. During the last deglaciation, numerous glacial lake outburst floods were ca ...
* Piora Oscillation
The Piora Oscillation was an abrupt cold and wet period in the climate history of the Holocene Epoch; it is roughly dated to c. 3900-3000 BC. Some researchers associate the Piora Oscillation with the end of the Atlantic climate regime, and the sta ...
* Quaternary extinction event
The Quaternary period (from 2.588 ± 0.005 million years ago to the present) has seen the extinctions of numerous predominantly megafaunal species, which have resulted in a collapse in faunal density and diversity and the extinction of key ecolog ...
References
Further reading
*
*
*
External links
The Holocene epoch explained by the BBC
{{Authority control
Geological epochs
Quaternary geochronology
Interglacials
Historical eras