The word Holocene was formed from two
Ancient Greek words. Holos (ὅλος) is the Greek word for "whole". "Cene" comes from the Greek word kainos (καινός), meaning "new". The concept is that this epoch is "entirely new". The suffix '-cene' is used for all the seven epochs of the
International Commission on Stratigraphy has defined the Holocene as starting approximately 11,700 years before 2000
BP, or 9,700 BCE). The Subcommission on Quaternary Stratigraphy (SQS) regards the term 'recent' as an incorrect way of referring to the Holocene, preferring the term 'modern' instead to describe current processes. It also observes that the term 'Flandrian' may be used as a synonym for Holocene, although it is becoming outdated.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 to be an epoch following the
Pleistocene and specifically following the
last glacial period. Local names for the last glacial period include the
North America, the
Weichselian in Europe, the Devensian in Britain, the
Llanquihue in Chile and the Otiran in New Zealand.
Geologists working in different regions are studying sea levels, peat bogs and
ice-core samples, using 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 mosses. 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
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
Paleontologists have not defined any
faunal stages for the Holocene. If subdivision is necessary, periods of human technological development, such as the
Bronze Age, 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 epoch of the Quaternary, the
Anthropocene, 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 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 determined, after which the recommendation also has to be approved by the working group's parent bodies (ultimately the International Union of Geological Sciences).
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 35 m (115 ft) 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 180 m (590 ft) due to
post-glacial rebound 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
Michigan. Other than higher-latitude temporary marine incursions associated with glacial depression, Holocene fossils are found primarily in lakebed,
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 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 phase, to its present boundaries.
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 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. From 8,500 BP to 6,700 BP, North Atlantic climate oscillations were highly irregular and erratic because of perturbations from substantial ice discharge into the ocean from the collapsing Laurentide Ice Sheet. 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.
Human activity through land use changes was an important influence on Holocene climatic changes, and is believed to be why the Holocene is an atypical interglacial that has not experienced significant cooling over its course. From the start of the
Industrial Revolution onwards, large-scale anthropogenic greenhouse gas emissions caused the Earth to warm. Likewise, climatic changes have induced substantial changes in human civilisation over the course of the Holocene.
During the transition from the last glacial to the Holocene, the
Huelmo–Mascardi Cold Reversal 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 (HCO) was a period of warming throughout the globe but was not globally synchronous and uniform. 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 (LIA), from the 13th or 14th century to the mid-19th century. Following the Industrial Revolution, warm decadal intervals became more common relative to before as a consequence of anthropogenic greenhouse gases, resulting in progressive global warming. In the late 20th century, anthropogenic forcing superseded solar activity as the dominant driver of climate change.
North Africa, dominated by the
Sahara Desert in the present, was instead a savanna dotted with large lakes during the Early and Middle Holocene, regionally known as the
African Humid Period (AHP). The northward migration of the
Intertropical Convergence Zone (ITCZ) produced increased monsoon rainfall over North Africa. The lush vegetation of the Sahara brought an increase in
pastoralism. The AHP ended around 5,500 BP, after which the Sahara began to dry and become the desert it is today.
A stronger East African Monsoon during the Middle Holocene increased precipitation in East Africa and raised lake levels.
Kalahari Desert, Holocene climate was overall very stable and environmental change was of low amplitude. Relatively cool conditions have prevailed since 4,000 BP.
During the Late Holocene, the coastline of the
Levant receded westward, prompting a shift in human settlement patterns following this marine regression.
Xinjiang, long-term Holocene warming increased meltwater supply during summers, creating large lakes and oases at low altitudes and inducing enhanced moisture recycling. In the
Tien Shan, sedimentological evidence from Swan Lake suggests the period between 8,500 and 6,900 BP was relatively warm, with steppe meadow vegetation being predominant. An increase in Cyperaceae from 6,900 to 2,600 BP indicates cooling and humidification of the Tian Shan climate that was interrupted by a warm period between 5,500 and 4,500 BP. After 2,600 BP, an alpine steppe climate prevailed across the region. Sand dune evolution in the Bayanbulak Basin shows that the region was very dry from the Holocene's beginning until around 6,500 BP, when a wet interval began. In the Tibetan Plateau, the moisture optimum spanned from around 7,500 to 5,500 BP.
The sediments of Lonar Lake record dry conditions around 11,400 BP that transitioned into a much wetter climate from 11,400 to 11,100 BP due to intensification of the Indian Summer Monsoon (ISM). Over the Early Holocene, the region was very wet, but during the Middle Holocene from 6,200 to 3,900 BP, aridification occurred, with the subsequent Late Holocene being relatively arid as a whole.
Coastal southwestern India experienced a stronger ISM from 9,690 to 7,560 BP, during the HCO. From 3,510 to 2,550 BP, during the Late Holocene, the ISM became weaker, although this weakening was interrupted by an interval of unusually high ISM strength from 3,400 to 3,200 BP.
From 900 to 1,200 AD, during the MWP, the ISM was again strong as evidenced by low δ18O values from the Ganga Plain.
Northern China experienced abrupt aridification around 4,000 BP. Eastern and southern China, the monsoonal regions of China, were wetter than present in the Early and Middle Holocene. Lake Huguangyan's TOC, δ13Cwax, δ13Corg, δ15N values suggest the period of peak moisture lasted from 9,200 to 1,800 BP and was attributable to a strong East Asian Summer Monsoon (EASM). Late Holocene cooling events in the region were dominantly influenced by solar forcing, with many individual cold snaps linked to solar minima such as the Oort,
Maunder Minima. Monsoonal regions of China became more arid in the Late Holocene.
Before 7,500 BP, the Gulf of Thailand was exposed above sea level and was very arid. A marine transgression occurred from 7,500 to 6,200 BP amidst global warming.
During the Middle Holocene, western North America was drier than present, with wetter winters and drier summers. After the end of the thermal maximum of the HCO around 4,500 BP, the
East Greenland Current underwent strengthening. A massive megadrought occurred from 2,800 to 1,850 BP in the
Eastern North America underwent abrupt warming and humidification around 10,500 BP and then declined from 9,300 to 9,100 BP. The region has undergone a long term wettening since 5,500 BP occasionally interrupted by intervals of high aridity. A major cool event lasting from 5,500 to 4,700 BP was coeval with a major humidification before being terminated by a major drought and warming at the end of that interval.
During the Early Holocene, relative sea level rose in the
Bahia region, causing a landward expansion of mangroves. During the Late Holocene, the mangroves declined as sea level dropped and freshwater supply increased. In the
Santa Catarina region, the maximum sea level highstand was around 2.1 metres above present and occurred about 5,800 to 5,000 BP. Sea levels at
Rocas Atoll were likewise higher than present for much of the Late Holocene.
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 during the HCO. 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. Since 7,100 BP, New Zealand experienced 53 cyclones similar in magnitude to
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
saber-toothed cats like Smilodon and Homotherium, and
giant sloths 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
δ18O 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. 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. 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.
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 the Holocene, however, the
domestication of plants and animals allowed humans 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
Central America. The development of farming allowed humans 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 humans 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.
^Schrøder, N.; Højlund Pedersen, L.; Juel Bitsch, R. (2004). "10,000 years of climate change and human impact on the environment in the area surrounding Lejre". The Journal of Transdisciplinary Environmental Studies. 3 (1): 1–27.
abKravchinsky, V.A.; Langereis, C.G.; Walker, S.D.; Dlusskiy, K.G.; White, D. (2013). "Discovery of Holocene millennial climate cycles in the Asian continental interior: Has the sun been governing the continental climate?". Global and Planetary Change. 110: 386–396.
^Ripple WJ, Wolf C, Newsome TM, Galetti M, Alamgir M, Crist E, Mahmoud MI, Laurance WF (13 November 2017).
"World Scientists' Warning to Humanity: A Second Notice"(PDF). BioScience. 67 (12): 1026–1028.
10.1093/biosci/bix125. Archived from
the original(PDF) on 15 December 2019. Retrieved 4 October 2022. Moreover, we have unleashed a mass extinction event, the sixth in roughly 540 million years, wherein many current life forms could be annihilated or at least committed to extinction by the end of this century.
^Hollingsworth, Julia (June 11, 2019).
"Almost 600 plant species have become extinct in the last 250 years". CNN. Retrieved January 14, 2020. The research -- published Monday in Nature, Ecology & Evolution journal -- found that 571 plant species have disappeared from the wild worldwide, and that plant extinction is occurring up to 500 times faster than the rate it would without human intervention.