 | It has been suggested that Historical climatology be merged into this article. (Discuss) Proposed since March 2019. |
Climate has affected human life and civilization from the emergence of hominins to the present day. These historical impacts of climate change can improve human life and cause societies to flourish, or can be instrumental in civilization's societal collapse.
Changes in East African climate have been associated with the evolution of hominini. Researchers have proposed that the regional environment transitioned from humid jungle to more arid grasslands due to tectonic uplift [1] and changes in broader patterns of ocean and atmospheric circulation. [2] This environmental change is believed to have forced hominins to evolve for life in a savannah-type environment. Some data suggest that this environmental change caused the development of modern homimin features; however there exist other data that show that morphological changes in the earliest hominins occurred while the region was still forested. [3] Rapid tectonic uplift likely occurred in the early Pleistocene, [2] changing the local elevation and broadly reorganizing the regional patterns of atmospheric circulation. [4] [5] This can be correlated with the rapid hominin evolution of the Quaternary period. [1] Changes in climate at 2.8, 1.7, and 1.0 million years ago correlate well with observed transitions between recognized hominin species. [2] It is difficult to differentiate correlation from causality in these paleopanthropological and paleoclimatological reconstructions, so these results must be interpreted with caution and related to the appropriate time-scales and uncertainties. [6]
Climate change has been linked to human migration from as early as the end of the Pleistocene to the early twenty-first century. [7] [8] The effect of climate on available resources and living conditions such as food, water, and temperature drove the movement of populations and determined the ability for groups to begin a system of agriculture or continue a foraging lifestyle. [7]
Groups such as the inhabitants of northern Peru and central Chile, [9] the Saqqaq in Greenland, [10] nomadic Eurasian tribes in Historical China, [11] and the Natufian culture in the Levant all display migration reactions due to climactic change. [7]
In northern Peru and central Chile climate change is cited as the driving force in a series of migration patterns from about 15,000 B.C. to approximately 4,500 B.C. Between 11,800 B.C. and 10,500 B.C. evidence suggests seasonal migration from high to low elevation by the natives while conditions permitted a humid environment to persist in both areas. Around 9,000 B.C. the lakes that periodically served as a home to the natives dried up and were abandoned until 4,500 B.C. [9] This period of abandonment is a blank segment of the archeological record known in Spanish as the silencio arqueológico. During this break, there exists no evidence of activity by the natives in the lakes area. The correlation between climate and migratory patterns leads historians to believe the Central Chilean natives favored humid, low-elevation areas especially during periods of increased aridity. [9]
The different inhabitants of Greenland, specifically in the west, migrated primarily in response to temperature change. The Saqqaq people arrived in Greenland around 4,500 B.P. and experienced moderate temperature variation for the first 1,100 years of occupation; near 3,400 B.P. a cooling period began that pushed the Saqqaq toward the west. A similar temperature fluctuation occurred around 2,800 B.P. that led to the abandonment of the inhabited Saqqaq region; this temperature shift was a decrease in temperature of about 4 °C over 200 years. [10] Following the Saqqaq dominance, other groups such as the Dorset people inhabited west Greenland; the Dorset were sea-ice hunters that had tools adapted to the colder environment. The Dorset appeared to leave the region around 2,200 B.P. without clear connection to the changing environment. Following the Dorset occupation, the Norse began to appear around 1,100 B.P. in west Greenland during a significant warming period. [12] However, a sharp decrease in temperature beginning in 850 B.P. of about 4 °C in 80 years is thought to contribute to the demise of initial Norse occupation in western Greenland. [10]
In Historical China over the past 2,000 years, migration patterns have centered around precipitation change and temperature fluctuation. Pastoralists moved in order to feed the livestock that they cared for and to forage for themselves in more plentiful areas. [11] During dry periods or cooling periods the nomadic lifestyle became more prevalent because pastoralists were seeking more fertile ground. The precipitation was a more defining factor than temperature in terms of its effects on migration. The trend of the migrating Chinese showed that the northern pastoralists were more affected by the fluctuation in precipitation than the southern nomads. In a majority of cases, pastoralists migrated further southward during changes in precipitation. [11] These movements were not classified by one large event or a specific era of movement; rather, the relationship between climate and nomadic migration is relevant from "a long term perspective and on a large spatial scale." [11]
The Natufian population in the Levant was subject to two major climactic changes that influenced the development and separation of their culture. As a consequence of increased temperature, the expansion of the Mediterranean woodlands occurred approximately 13,000 years ago; with that expansion came a shift to sedentary foraging adopted by the surrounding population. [7] Thus, a migration toward the higher-elevation woodlands took place and remained constant for nearly 2,000 years. This era ended when the climate became more arid and the Mediterranean forest shrank 11,000 years ago. Upon this change, some of the Natufian populations nearest sustainable land transitioned into an agricultural way of life; sustainable land was primarily near water sources. Those groups that did not reside near a stable resource returned to the nomadic foraging that was prevalent prior to sedentary life. [7]
The rise and fall of societies have often been linked to environmental factors. [13]
Approximately one millennium after the 7 ka slowing of sea-level rise, many coastal urban centers rose to prominence around the world. [14] It has been hypothesized that this is correlated with the development of stable coastal environments and ecosystems and an increase in marine productivity (also related to an increase in temperatures), which would provide a food source for hierarchical urban societies. [14]
Climate change has been associated with the historical collapse of civilizations, cities and dynasties. Notable examples of this include the Anasazi, [15] Classic Maya, [16] the Harappa, the Hittites, and Ancient Egypt. [17] Other, smaller communities such as the Viking settlement of Greenland [18] have also suffered collapse with climate change being a suggested contributory factor. [19]
There are two proposed methods of Classic Maya collapse: environmental and non-environmental. The environmental approach uses paleoclimatic evidence to show that movements in the intertropical convergence zone likely caused severe, extended droughts during a few time periods at the end of the archaeological record for the classic Maya. [20] The non-environmental approach suggests that the collapse could be due to increasing class tensions associated with the building of monumental architecture and the corresponding decline of agriculture, [21] increased disease, [22] and increased internal warfare. [23]
The Harappa and Indus civilizations were affected by drought 4,500–3,500 years ago. A decline in rainfall in the Middle East and Northern India 3,800–2,500 is likely to have affected the Hittites and Ancient Egypt.
Notable periods of climate change in recorded history include the Medieval warm period and the little ice age. In the case of the Norse, the Medieval warm period was associated with the Norse age of exploration and Arctic colonization, and the later colder periods led to the decline of those colonies. [24]
The Holocene is the current geological epoch. It began approximately 11,650 cal years before present, 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 period within the Pleistocene Epoch, called the Flandrian interglacial.
Climate change occurs when changes in Earth's climate system result in new weather patterns that remain in place for an extended period of time. This length of time can be as short as a few decades to as long as millions of years. Scientists have identified many episodes of climate change during Earth's geological history; more recently since the industrial revolution the climate has increasingly been affected by human activities driving global warming, and the terms are commonly used interchangeably in that context.
The Natufian culture is a Late Epipaleolithic archaeological culture that existed from around 12,000 to 9,500 BC or 13,050 to 7,550 BC in the Levant. The culture was unusual in that it supported a sedentary or semi-sedentary population even before the introduction of agriculture. The Natufian communities may be the ancestors of the builders of the first Neolithic settlements of the region, which may have been the earliest in the world. Natufians founded a settlement where Jericho is today, which may therefore be the longest continuously inhabited urban area on Earth. Some evidence suggests deliberate cultivation of cereals, specifically rye, by the Natufian culture, at Tell Abu Hureyra, the site of earliest evidence of agriculture in the world. The world's oldest evidence of bread-making has been found at Shubayqa 1, a 14,500-year-old site in Jordan's northeastern desert. In addition, the oldest known evidence of beer, dating to approximately 13,000 BP, was found at the Raqefet Cave in Mount Carmel near Haifa in Israel.
The Younger Dryas was a return to glacial conditions after the Late Glacial Interstadial, which temporarily reversed the gradual climatic warming after the Last Glacial Maximum (LGM) started receding around 20,000 BP. It is named after an indicator genus, the alpine-tundra wildflower Dryas octopetala, as its leaves are occasionally abundant in late glacial, often minerogenic-rich sediments, such as the lake sediments of Scandinavia.
The Toba supereruption was a supervolcanic eruption that occurred about 75,000 years ago at the site of present-day Lake Toba in Sumatra, Indonesia. It is one of the Earth's largest known eruptions. The Toba catastrophe theory holds that this event caused a global volcanic winter of six to ten years and possibly a 1,000-year-long cooling episode.
The Eemian was the interglacial period which began about 130,000 years ago at the end of the Penultimate Glacial Period and ended about 115,000 years ago at the beginning of the Last Glacial Period. It corresponds to Marine Isotope Stage 5e. Although sometimes referred to as the "last interglacial", it was the second-to-latest interglacial period of the current Ice Age, the most recent being the Holocene which extends to the present day. The prevailing Eemian climate was, on average, around 1 to 2 degrees Celsius warmer than that of the Holocene. During the Eemian, the proportion of CO
2 in the atmosphere was about 280 parts per million.
Dansgaard–Oeschger events are rapid climate fluctuations that occurred 25 times during the last glacial period. Some scientists say that the events occur quasi-periodically with a recurrence time being a multiple of 1,470 years, but this is debated. The comparable climate cyclicity during the Holocene is referred to as Bond events.
Pastoralism is a form of animal husbandry, historically by nomadic people who moved with their herds. The species involved include various herding livestock, including cattle, camels, goats, yaks, llamas, reindeer, horses and sheep.
An abrupt climate change occurs when the climate system is forced to transition to a new climate state at a rate that is determined by the climate system energy-balance, and which is more rapid than the rate of change of the external forcing. Past events include the end of the Carboniferous Rainforest Collapse, Younger Dryas, Dansgaard-Oeschger events, Heinrich events and possibly also the Paleocene–Eocene Thermal Maximum. The term is also used within the context of global warming to describe sudden climate change that is detectable over the time-scale of a human lifetime, possibly as the result of feedback loops within the climate system.
The timeline lists events in the external environment that have influenced events in human history. This timeline is for use with the article on environmental determinism. For the history of humanity's influence on the environment, and humanity's perspective on this influence, see timeline of the history of environmentalism. See List of periods and events in climate history for a timeline list focused on climate.
Historical climatology is the study of historical changes in climate and their effect on human history and development. This differs from paleoclimatology which encompasses climate change over the entire history of Earth. The study seeks to define periods in human history where temperature or precipitation varied from what is observed in the present day. The primary sources include written records such as sagas, chronicles, maps and local history literature as well as pictorial representations such as paintings, drawings and even rock art. The archaeological record is equally important in establishing evidence of settlement, water and land usage.
The 4.2-kiloyear BP aridification event 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 in about 2200 BC, it probably lasted the entire 22nd century BC. It has been hypothesised to have caused the collapse of the Old Kingdom in Egypt as well as the Akkadian Empire in Mesopotamia, and the Liangzhu culture in the lower Yangtze River area. The drought may also have initiated the collapse of the Indus Valley Civilisation, with some of its population moving southeastward to follow the movement of their desired habitat, as well as the migration of Indo-European-speaking people into India.
In archaeology, the classic Maya collapse is the decline of the Classic Maya civilization and the abandonment of Maya cities in the southern Maya lowlands of Mesoamerica between the 8th and 9th centuries, at the end of the Classic Maya Period. The Preclassic Maya experienced a similar collapse in the 2nd century.
Bond events are North Atlantic ice rafting events that are tentatively linked to climate fluctuations in the Holocene. Eight such events have been identified. Bond events were previously believed to exhibit a roughly c. 1,500-year cycle, but the primary period of variability is now put at c. 1,000 years.
A tipping point in the climate system is a threshold that, when exceeded, can lead to large changes in the state of the system. Potential tipping points have been identified in the physical climate system, in impacted ecosystems, and sometimes in both. For instance, feedback from the global carbon cycle is a driver for the transition between glacial and interglacial periods, with orbital forcing providing the initial trigger. Earth's geologic temperature record includes many more examples of geologically rapid transitions between different climate states.
Regional effects of global warming are long-term significant changes in the expected patterns of average weather of a specific region due to global warming. The world average temperature is rising due to the greenhouse effect caused by increasing levels of greenhouse gases, especially carbon dioxide. When the global temperature changes, the changes in climate are not expected to be uniform across the Earth. In particular, land areas change more quickly than oceans, and northern high latitudes change more quickly than the tropics, and the margins of biome regions change faster than do their cores.
The Greenlandic Inuit are the indigenous and most populous ethnic group in Greenland. Most speak Greenlandic and consider themselves ethnically Greenlandic. People of Greenland are citizens of Denmark.
The Denisovans or Denisova hominins(di-NEE-sə-və) are an extinct species or subspecies of archaic human that ranged across Asia during the Lower and Middle Paleolithic. Denisovans are known from few remains, and, consequently, most of what is known about them comes from DNA evidence. Pending consensus on their taxonomic status, they have been referred to as Homo denisova, H. altaiensis, or H. sapiens denisova.
Several expansions of populations of archaic humans out of Africa and throughout Eurasia took place in the course of the Lower Paleolithic, and into the beginning Middle Paleolithic, between about 2.1 million and 0.2 million years ago (Ma). These expansions are collectively known as Out of Africa I, in contrast to the expansion of Homo sapiens (anatomically modern humans) into Eurasia, which may have begun shortly after 0.2 million years ago.
The Medieval Warm Period (MWP) also known as the Medieval Climate Optimum, or Medieval Climatic Anomaly was a time of warm climate in the North Atlantic region lasting from c. 950 to c. 1250. It was likely related to warming elsewhere while some other regions were colder, such as the tropical Pacific. Average global mean temperatures have been calculated to be similar to early-mid-20th-century warming. Possible causes of the Medieval Warm Period include increased solar activity, decreased volcanic activity, and changes to ocean circulation.
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