User:Nataliekozlowski/sandbox

Source evaluation
Chapter 5: Information from Paleoclimate Archives from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) is written for individuals with a considerable background in climate science. This chapter is a brief outline of various types of forcing factors that have caused climate change in the past, along with the resulting change that is observed in paleoclimatic records, such as variations in temperature. Developments in climate models allow for the assessment of the applicability and reliability of paleoclimatic records. By using both methods of climate reconstruction, it is possible to get a more comprehensive image of past climate. Direct observations have been made through the use of paleoclimatic records and climate models, particularly for the late Holocene, in order to reconstruct temperature, glacial and atmospheric behavior, weather patterns, and changes in sea level. Environmental features may have multiple equilibrium states, meaning the changes occurring in the present may be of a more permanent nature, until equilibrium shifts again. While progress has been made in the ability to reconstruct past environments using paleoclimatic records and climate models, there is still progress to be made, particularly for regions of the world that are lacking in adequate proxy records.

Article evaluation
The majority of the references used in the current "Paleoecology" article have working links, and all citations are valid and support the information provided in the article. All of the articles used are either published in an academic journal or on a website that is academic in nature. While some academic papers may be biased in their research aims, the citation of multiple studies helps solve this problem, as it shows that the statements being made are reputable and common. There are some articles cited that are from the last decade, but many are from the 1980s and 1990s; the reference section could use more updating with current findings. Most sections that require a citation include one, but the "Major principles" section could need a reference.

Some potential things that could be added to this article are: regions of the world that have been reconstructed using paleoecological records, or regions that haven't been studied, and the limitations to using paleoecological records. The 'Applications' section exists, but could be expanded with more citations included. It appears that there isn't much conversation surrounding this particular article, and that there may only be two people who have contributed in any significant way; one being a past student of this course. The article is currently rated as Start-Class and is a level-5 vital article. It is part of the WikiProject Geology and within the scope of the WikiProject Ecology.

Research paper outline
The use of the term "Anthropocene" became more common starting in the early 2000s. This term is disputed in society generally and is a topic of debate, but the timing of the onset of the Anthropocene is also disputed in the academic world, as well what should be considered as an indicator of the start of the Anthropocene. The broader geologic community agrees that an indicator of a new geologic time would have to be worldwide stratigraphic change. Because the name "Anthropocene" implies that it is considered a new Epoch, researchers are looking for evidence that the Holocene has ended, and distinct new conditions exist. Human alteration of the environment is undoubtedly a main factor in determining when the Anthropocene began, but dates back so far in time, that it's difficult to determine when human beings became a dominant force on Earth. This paper primarily focuses on the data behind the argument in favor of the early onset of the Anthropocene. Additionally, a brief review of the arguments for different onsets times of the Anthropocene and the general reluctance to use the term is provided.

Stratigraphic indicators

The geologic academic community plays a large role in determining what should be considered a new geologic time period. Some events that could result in a significant change in the stratigraphic record include deposits directly from humans, biotic turnover, orbital forcing, geochemical indicators, or a catastrophic event. This list serves as a guideline and motivation for the new characterization of the Anthropocene.

Things to focus on in this section:


 * Determining the end of the Holocene
 * Explain Anthropogenic changes in stratigraphy in more detail/give examples

Onset in the 1700, 1800, or 1900s

Arguments are made in support of the onset of the Anthropocene shortly after the Industrial Revolution in the early 1800s. Evidence backing this claim includes increased CO2 levels seen in ice cores and significant changes in anthropogenic deposits. Others claim that the start of the Anthropocene aligns with the time period when urbanization increased around 1750. Another period argued for the late onset of the Anthropocene is around the 1950s, after the end of World War II.

Things to focus on in this section:


 * Brief evidence for each time period
 * Alteration of the atmosphere didn't occur until the Industrial Revolution
 * Arguments against this view – Industrial Revolution did not occur at the same time worldwide

Early Onset Evidence

Some research supports the idea that the Anthropocene started much earlier than others argue. Widespread change on a local level begin to occur in the stratigraphic record around 4,000 ka. These changes are likely caused by early agriculture occurring in discrete places around the world. Another study claims that the Anthropocene originated when humans mastered the use of fire, dating back to approximately 1.8 million years ago. (This will be the longest and most detailed section)

Things to focus on in this section:


 * Describe CO2 and CH4 emission changes during the Holocene
 * Evidence: CO2 and CH4 increase began 8,000 and 5,000 ka respectively, rejection of natural forcing, early agriculture
 * "Early", "Middle", and "Late Anthropocene"
 * Arguments against early onset

Pushback to the use of "Anthropocene"

Some academics argue that the process of determining when the Anthropocene officially started is unlike any other past geologic-time-naming because this is the first time the human race is alive for the time period of interest. Because of this, it is not necessary to define an exact date when the Anthropocene started; instead we should take a more hands-off approach and let conditions develop further.

Things to focus on in this section:


 * Anthropocene may have already ended if it is just considered the time period when humans became dominant on Earth
 * Political agenda behind defining the Anthropocene
 * Using the term informally (with a small "a")
 * Why is there a need to base the start off of a clear change in stratigraphy when the Anthropocene is more complicated than that?

Introduction
The use of the term "Anthropocene" became more common starting in the early 2000s. This term is disputed in society generally and is a topic of debate, but the timing of the onset of the Anthropocene is also disputed in the academic world, as well what should be considered as an indicator of the start of the Anthropocene. The broader geologic community agrees that an indicator of a new geologic time would have to be worldwide stratigraphic change. Because the name "Anthropocene" implies that it is considered a new Epoch, researchers are looking for evidence that the Holocene has ended, and distinct new conditions exist. Human alteration of the environment is undoubtedly a main factor in determining when the Anthropocene began, but dates back so far in time, that it's difficult to determine when human beings became a dominant force on Earth. This paper primarily focuses on the data behind the argument in favor of the early onset of the Anthropocene. Additionally, a brief review of the arguments for different onsets times of the Anthropocene and the general reluctance to use the term is provided.

Stratigraphic Indicators
In order to determine whether or not a new geologic time period has begun, the time of interest must reach certain qualifications posed by the International Commission on Stratigraphy in the late 1960s. The Anthropocene Working Group (AWG), a group within the Subcommission on Quaternary Stratigraphy (SGS), specifically focuses on determining when the Anthropocene started. When to delineate a new time period is based off of the following characteristics:


 * 1) Appearance and increased abundance of anthropogenic deposits
 * 2) Biotic turnover
 * 3) Geochemical changes
 * 4) Climate change
 * 5) Catastrophic events

Some events that would contribute evidence to a new geologic time period include anthropogenic structures or infrastructure, extinctions of a number of species, significant change in sea level, and volcanic eruptions. It is notable that these changes do not occur in any one specific ecosystem type or location; the observed changes must be all-encompassing and deal with the entire Earth system. Because there isn't one overarching and blatant characteristic that helps identify when a new geologic time period may have started, there tends to be disagreement among members of this group on when the Anthropocene started.

All of the currently named geologic time boundaries appear in the Earth's stratigraphy and display some sort of major event that caused a change in conditions. The relatively recent boundaries identified have been done using high-resolution dating methods that allow for the clear distinction of time period boundaries. The start of the Anthropocene is particularly difficult to determine due to the uneven rate of human development across the world, as well as changes observed on a regional scale. In addition to determining if the relatively recent past displays enough significant change to be considered on its own, scientists also must decide whether the new time is an Epoch or age; the nature of the name "Anthropocene" suggests that it is a Epoch, since this classification usually ends with "-cene". Ages typically end with "-ian" and displays less change compared to an Epoch. If the Anthropocene were to be named a new age, it would be considered a subset of the Holocene.

Period of Increased Urbanization – 1750s and on
Some groups of researchers argue for increased urbanization that occurred during the 18th century to be considered as the start of the Anthropocene. Extensive landcover change occurred during this time due to the construction of urban areas and roadways. In addition to landcover change and the expansion of a constructed environment, the natural environment also went through significant change. Acidification of freshwater lakes in Europe due to human behavior show support for considering this time period one of rapid change. Humans along with domesticated animals outnumbered megafauna, and humans also began to introduce non-native plant species for profit.

Industrial Revolution – early 1800s
The period directly following the Industrial Revolution is accepted by many groups as the start of the Anthropocene. During this time period, societies departed from primarily depending on agriculture for work, and began using fossil fuels for energy. An industrialized society allowed for the rate of manufacturing goods to expand rapidly. It is argued that this was the first time humans began to alter the environment and atmosphere; an increase in CO2, CH4, and N2O was observed. While the rate of manufacturing was increasing, the human population was also increasing at a rate that had never been observed before.

Support for using the Industrial Revolution as the start of the Anthropocene includes a change in recovered anthropogenic deposits, such as infrastructure, manufactured goods, and increased human alteration of the Earth's depths. Despite this support, using this time period as the start of the Anthropocene has received criticism due to the asynchronous nature of the Industrial Revolution; societies across the world experienced these changes at very different times, making it unlikely that industrialization focused in Europe had a significant worldwide impact.

Post-World War II – 1950s
This period is known as the Great Acceleration due to the rate at which human development increased, which was unprecedented at that time. Human population, cities, consumption, infrastructure, travel, Neo-liberalism, and technology all grew during this time period. The rate of deforestation increased due to increased need for space and resources. In addition to these changes to society and the lifestyles of individuals, CO2 concentrations also continued to rise. Despite this long trend of increasing CO2, the cause did not gain widespread attention until the 1990s.

Evidence of Early Onset
Some research supports the idea that the Anthropocene started much earlier than other findings argue. Widespread change on a local level begin to occur in the stratigraphic record around 4,000 ka. These changes are likely caused by early agriculture occurring in discrete places around the world. Another study claims that the Anthropocene originated when humans mastered the use of fire, dating back to approximately 1.8 million years ago. The evidence supporting the early onset of the Anthropocene will be presented on a case-study basis.

Ruddiman 2003
Evidence of an earlier onset of the Anthropocene during the mid-Holocene is supported by obsersved trends in carbon dioxide (CO2) and methane (CH4) over the past few thousand years as well as physical and historical records that support the idea that humans began significantly altering their surroundings much earlier than once believed. Orbital forcing and its effects on climate have been extensively studied.

Scientists agree that the emission of CH4 is related to orbital precession and changes in solar insolation. As solar insolation increases, localized air masses rise and eventually cool, resulting in the release of precipitation. Extensive precipitation results in flooded wetlands and and increase in the release of CH4. This insolation and monsoonal cycle occurs over 23,000 years; during the mid-Holocene, the cycle was theoretically in a state of decreasing solar insolation, meaning CH4 emissions would also be decreasing. Despite this, CH4 began slowly increasing around 5,000 years ago. Palynology studies done do not attribute this increase in CH4 to monsoonal conditions, making it not likely that this change was naturally caused. CO2 also shows similar patterns to CH4. During interglacials, CO2 typically peaks at the time of ice minimum. This peak in CO2 was observed around 11,000-10,000 years ago, began to decrease, but then started to increase around 8,000 years ago, eventually rising 20-25 ppm.

Increased cultivation of crops during the mid-Holocene, as well as rice irrigation can help explain the observed increase in CH4. Additionally, deforestation and land-use change that occurred around 8,000 years ago may be directly related to the increase in CO2 that occurred during the mid-Holocene. As agriculture continued to spread throughout Africa, Asia, Europe, and North and South America, CO2 levels continued to rise and had increased significantly around 2,000 years ago, which is much earlier than the Industrial Revolution.

Glikson 2013
It is proposed that the discovery of fire by humans should be considered the time at which the Anthropocene started. The ice age during the Pleistocene can be argued as the driving factor behind why humans studied and replication natural fire ignitions, such as lightning strikes. Because fire was likely discovered at different times on local levels, different techniques were also developed. "Firestick farming" was a type of mosaic farming that led to changes in land use and the disappearance of suitable habitat types for certain animals, and may have contributed to the extinction of megafauna. The use of fire by humans has resulted in entropy levels that rival acute destructive events, such as volcanic eruptions or asteroid impacts; total anthropogenic fire and fossil fuel consumption up until the 21st century totals 9.2 billion tons of carbon. It is evident that human-induced fires dating back thousands of years have resulted to increased levels of carbon dioxide in the atmosphere.

It is recognized that many different teams of researchers propose the start of the Anthropocene at different times. This researcher proposes a categorization of the Anthropocene into three groups: the Early Anthropocene, the Middle Anthropocene, and the Late Anthropocene. The Early Anthropocene coincides with the discovery of fire by humans (approximately 2 million years ago). The Middle Anthropocene is the time in which agriculture developed and expanded in use. The Late Anthropocene is characterized by the industrialization of some societies on a widespread scale (around the 1800s).

Evaluation and Relevance of the Use of "Anthropocene"
Groups of researchers strive to pinpoint the start of the Anthropocene in order to determine when humans began having a large and dominant impact on their environment. It is important to recognize the consequences of human activity in the past, but the process of identifying the start of the Anthropocene is likely a way for society to determine exactly which actions resulted in humans becoming the dominant variable, which then helps guide us how to reverse those effects. The relationship between humans and the environment is not this simple; humans have had a significant impact on the since their origin. Although the use of the term Anthropocene is justifiable, it does not necessarily mean that an exact date or time period needs to be identified. Several arguments against the use of the term "Anthropocene", or a specific start date are discussed. Discourse around this topic is productive, as it emphasizes the idea that human history on Earth is complicated and interwoven.

The Anthropocene is a particularly unique geologic time classification, because it is the first one to be considered when the researchers are still alive. This makes the consideration and timing of the Anthropocene information that is relevant to political positionality and environmental causes. It is also a relatively short time scale compared to past geologic time periods named, making it hard to obtain a fine enough resolution to adequately understand exactly when humans may have started to make an impact on Earth and how they may have impacted or interrupted deposition. Referring to the term "Anthropocene" with the use of a small "a-" can help address concern about the complexities of this time in the Earth's history. By doing so, it allows freedom in using the term for various time periods or observed changes in the Earth.