The Quaternary: An Introduction (Introduction/ Background (-Eon:…
The Quaternary: An Introduction
Related to either
how the quaternary came about
(unlikely) or more likely,
questions on ice core/ocean core evidence
'Knowledge of the Quaternary Ice-Age is largely based on the evidence obtained from the study of ice cores and deep ocean sediment cores. Compare and contrast the evidence provided by these two sources.' 2016
'Compare and contrast the information gained from the study of ice cores in Antarctica and Greenland regarding Pleistocene environmental change' 2015
'Compare and contrast the information produced from the study of deep ocean sediment cores and ice cores' 2014
2012: Same as above
Youngest geological period; estimated to have begun 2.588 (or 2.6) million years ago
The latest of 5 identified 'ice house' worlds to have punctuated the planet's usual 'greenhouse world':
50Myr BP there was NO ice and SL was at least 70m higher than today
The cooling trend that the Quaternary is began around 50Myr ago in the late Cretaceous Period
Pre-Quaternary (up to around 2.9Myr BP), CO2 levels were similar to todays, but temperatures were 2-3C higher than today due to Earth being in the later stages of a greenhouse world - SEE FIGURE 1.1
Since the start of the Quaternary, the climatic cycles have been much higher in magnitude --> repetition of glacial/inter-glacial cycles - humans have now started influencing these cycles
To understand the present and future, we need to understand the past and to understand the past we need to identify the patterns of change, using some human and some natural techniques --> paleo-environmental/paleo-climatic reconstructions
Establishing the Nature of the Quaternary
1. Merging Evidence from Different Sources
We merge natural archives (Holocene to Present) with Human Archieves (Historic) with Observations (of the Present) to Model the Future:
Establishing how the climate and environment have varied is not easy due to:
Human have only kept
records for a limited amount of time - F and Celsius weren't established until the early/mid 18th century and standardisation criteria weren't established in the UK until the mid 19th century, and later in other places
UK's national temperature series began only in 1910
Therefore around only 110 years of reasonable records
Central England Temperature Record
providing estimates from 1659 to present using data from locations across the midlands
Nicholas and Glasspool
developed a similar estimate for rainfall stretching back to 1766
It's recognised that
prior to 1850, human records are extremely sparse
Besides some exceptional circumstances, the use of
extends back to 1,000 BP
These records are mostly from parish journals and diaries
Hulme's analysis of such records shows an increase in mass movement events (of snow and ice) between 1680 and 1750, aka the little ice age
Human's short instrumental and historical records mean we must use evidence obtained from physical deposits to provide indications of climatic and environmental conditions (
) at particular times in the past, but these need to be dated in order to provide an accurate record
The 3 Major Issues:
With age, evidence becomes increasingly fragmented
The nature of evidence changes with increasing age --> needs different techniques
A means of accurate dating has to be found
2. Proxy Measures
Scientists want an
Absolute Dating technique
to create a record of changing conditions over time BUT
erosional forces and fire
have tended to destroy evidence:
Expanding ice sheets destroy evidence of previous ones
Therefore, the search is for
preserved evidence due to accumulation beneath permanent water or burial
The buried remains of former soils
s) indicating different conditions.
(e.g. striations indicating glacial activity) and
contained in sediments.
and snail assemblages preserved in sediments.
is the male reproductive cells or microspores produced by seed producing plants. It is very durable and occurs in accumulating sediments and organic deposits (especially peat). The variations in different types of pollen with depth in a deposit can be analysed (Pollen Analysis) to reveal changing abundance of differing species of vegetation over time and, therefore, changing environmental conditions (Mannion (1999, 70)).
The study of the growth pattern of trees (Tree Rings) preserved in living and dead trees (
) (Fig.1.9) (Mannion (1999, 90 – 7)).
(Mannion (1999, 84-5)).
and varves (Mannion (1999, 67- 80))
(wind-blown silt) deposits (Mannion (1999, 82-4)).
(Mannion (1999), 50 - 63).
Ocean sediment cores
(Oxygen Isotope Record-(see Mannion (1999, 33-49)).
Out of these, the final 7 (Pollen onwards) are particularly useful as they can show continuous sequences known as
and also provide proxy information on CC
Much of the information from these sources is fragmented. The best, most complete records come from sites of
continuous long-term deposition
not subject to erosion:
(Long-lived) Lake floors and inland seas (10^5 years)
Deep ocean sediment (10^7 years+)
Ice cores from permanent ice sheets (10^5 years)
Loess deposits in Central China - up to 280m thick --> 2.6m year record (10^6 years)
Records from proxies such as tree rings can be '
' such as the 2000 years Northern Hemisphere Proxy Record (Moberg et al., 2005)
3. Recalibration of the Quaternary
The Old Scheme:
Pleistocene (1.8Myr BP - 10,000 BP)
Holocene (10,000BP - Present)
The New Scheme:
Pleistocene (2.588Myr BP - 11,700 BP)
Holocene (11,700BP - Somewhere close to BP)
Anthropocene (xxx BP - Present)?
NB: BP means before 1950
Traditionally the equivalent of 'the current ice age'
Traditionally characterised by warm conditions punctuated by 4 episodes of cold glaciations (Penck and Bryckner, 1909):
Wurm - 80Kyr BP
Riss - 150Kyr BP
Mindel - 470Kyr BP
Günz - 650Kyr BP
NB: Post 1970s research has shown it to be much more complex than this: Now known to be cold period punctuated by shorter inter-glacials
The period of time over which conditions have mostly been generally similar to those of today
Preceded by “Glacial” conditions associated with the last major ice advance (The Last Glaciation) which was thought to have reached a maximum extent at c18,000 BP where SL was around 121m lower than today
Highest temperatures of the Holocene were 8,000 years ago
The length of the Holocene has recently been changed to 11,700BP:
Previously 10,000 years - found using radiocarbon dating (after Libby, 1940, discovered radioactivty)
From the 1960s, it was shown that radiocarbon years did NOT correlate exactly with calendar years
Tree rings and other dating sources allowed radiocarbon dating to be recalibrate in the 1990s to give
indicative calibrated ages
Hence, the Holocene was recalibrate to 11,700BP, and the LGM to 21-22,000 BP
Any pre-2000 publications therefore give uncalibrated years of dating
2 Changes: The recalibration of when the quaternary started and the recalibration of when the holocene started
Human Development and Impact on the Environment
1. Human Development
The human-like Hominins were around 1Myrs ago
Homo-Sapiens (us) originated around 195,000BP
We had spread across all of SSA by 150,000BP
By 70,000BP, CC --> increased rain across the Arabian Peninsula --> humans moved up out of Africa and across the globe
Entered Australia between 45-60,000BP
No access to Europe until 22,000BP due to ice sheets
Crossed the Bearing Straight 15,000BP after the North American ice sheets receded
The Denisovans lived in Central Asia (evolved separately since 500,000BP)
The Neanderthals lived in Europe and the Middle East from at least 350,000BP
Humans (Homo Sapiens) evidently interbred with them as both are identified in modern day human genomes
Following hunter-gatherer humans came two groups:
9000BP: Neolithic Farmers
4500BP: Yamnayas in SE Asia who rode horses and utilised wheels
Mareau (2015) comments that the rise of Homo Sapiens is due to them being "Singularly collaborative and socially connected", along with their ability to use technical skills like tools and rudimentary weapons
occurred due to:
Harnessing of energy
Phases of Development:
Neolithic Revolution: c12,000BP onwards - stemming from previous discovery of fire and tools --> sedenterisation economies (i.e. villages), utilising domestication, irrigation and cultivation and trade
The Industrial Revolution: c200BP
Modernisation: past 100 years - development of transportation and dramatic urbanisation
Mccluskey and Spalding (1989) produced a map of the areas of remaining wilderness in the 1980s - areas such as the Sahara, central Australia, Siberia and Greenland
Predicts Team (2014): Showed that there's been roughly 35% ecosystem simplification in places such as eastern USA and SSA or Eastern Europe and even more in other places
2. The Human Impact
Main Influence Pre-IR: Deforestation - Fire has been used in SSA for forest clearance for around 400,000 years
The interaction of numerous biophysical and human-induced changes is now seen to result in a general evolution of environmental systems through the re-branded process of
Global Warming means that it's now thought that the only place that humans may not be affecting are some deep ocean environments
The French Division of the upper Holocene:
Upper Dustbinian (with plastic)
Lower Dustbinian (without plastic)
have been affected in terms of their character, composition and behaviour:
...and there have also been profound alterations to the:
Cryosphere (frozen conditions)
- Cumulative, diverse adverse effects on the biosphere.
Adverse alteration to the chemical composition of the atmosphere, hydrosphere and pedosphere (i.e. pollution).
Significant and progressively growing changes to environmental conditions.
Changes to climatic conditions from an uncertain commencement date.
The probability of significant future changes to climatic/ environmental conditions (Global Change) as a result of systemic (i.e. Global Warming) and cumulative influences which could have major impact on both biophysical systems and human societies
: Those directly impacting on globally functioning systems:
Industrial and land-use emissions of 'greenhouse' gases
Industrial and consumer emissions of ozone-depleting gases
Land cover changes in albedo
: Impact through worldwide distribution of change OR through magnitude of change:
Groundwater pollution and depletion
Species depletion/genetic alteration (biodiversity)
Industrial toxic pollutants
Soil depletion on prime agricultural lands
3. An Anthropocene?
Major development 3
(2002) was the original advocate for the establishment of a new geological epoch, The Anthropocene
coined the term Anthropozioc (1873), meaning the era that humans changed the course of geological history, but failed to get support from the geological community
When did it/does it start?
there is considerable disagreement as to when it should begin, including 1980, 1950, 1945, 1910, 1880, 1850 and 1800, as well as several much earlier dates going back thousands of years associated with the use of fire for hunting, the onset of forest clearance and the expansion of farming.
On the other hand, there are those who suggest we wait until the pace of Global Warming accelerates again, or when a major tipping point occurs, and use that to define the commencement of the Anthropocene.
The proposal was
formally put forward in 2008
but has yet to be ratified by
The International Commission on Stratigraphy
, although a Working Group was established to decide by the end of 2016 whether, on the basis of geological considerations:
(i) the term should be adopted, and if so, then
(ii) propose a start date for the epoch. The Group reported favourably in August 2016, suggesting a start date in the mid-C20th, but the Commission has yet to ratify. The main problem is that the significance of the “Human Impact” has varied over space and time, so defining what level of impact constitutes a sufficient change globally to warrant a new epoch will be difficult to assess.