South Africa Climate Model predictions

South Africa Climate Model Projections:

 

What is a climate Model:

A climate Model is a mathematical representation of the climate system based on physical, biological and chemical principles which allow us to make projections on the future of the earths climate systems. These models are important as they provide solutions which are separate in time allowing for mitigation strategies to be created. Basically they are representations of past and future climates based on parameters created by scientists through studying of the current state of the earths climate.

Global Climate Change Projections:

I think most of us are aware global warming is a hot topic at the moment with it predicted that in several decades the worlds climate will become warmer than it has been for over a million years which will have unprecedented repercussions of the world. It is also important though to realize that the warming of the earth will not be uniform, with middle to high latitudes warming more than the tropics and land masses warmer than the worlds oceans. The IPPC have released some really bleak reports which project that the earth will warm between 0.9 to 5.4 degrees Celsius dependent on the different mitigation strategies implemented if any will be.

South Africa Projects:

Over the last five decades significant changes in climate have been observed in South Africa. Mean annual temperatures have increased by about 1.5 times the observed global average of 0.65°C, and hot and cold extremes have increased and decreased respectively in frequency. In almost all hydrological zones there has been a tendency towards reduced rainfall for the autumn months, though annual rainfall has not changed significantly. Instead there has been an overall reduction in the number of rainy days, implying a tendency towards an increase in the intensity of rainfall events and increased dry spell duration. Climate change projections for South Africa up to 2050 and beyond project warming as high as 5–8°C over the South African interior, and somewhat less over coastal regions, under an unmitigated global emissions scenario. With some models projecting a drastic reduction in rainfall over Limpopo with rainfall increasing however near the northeastern parts of South Africa, Zimbabwe and Mozambique. However, with all the doom and gloom that these climate model projections point towards it must be known that these projected climate changes are  within the range of historical natural variability.

The only pressing issue rather is not how the natural world will respond to these changes but rather how South Africa will with its major socio-economic issues.

   

1610 VS 1950

1610 vs 1950


I think we all have seen or heard of the movie called Jurassic park, well have you all heard of the Holocene and Anthropocene well the great debate between the two. The debate currently ongoing is when should the Anthropocene actually start, well there are two strong candidates for when it should start and we are going to look at the credibility  of each and if they fulfill the requirements defined by the International Commission on Stratigraphy.

Aztec vs Spanish Conquistadors 

Anthropocene vs Holocene:
The most important thing when it comes to dividing geological-scale time is that Earth experiences Global-scale changes to its earth systems driven by forces unique to that time period. The Holocene is often referred to the age of main while the Anthropocene has a similar meaning as it denotes the geological time period which humanity is the driving force of systems within earth. The problem arises in that when one decides to state the Anthropocene as a geological epoch, Maslin says we would be depriving the Holocene of what actually makes it unique-human- but we wont be looking into that in this blog. We are going to be discussing the credibility of 1610 and 1950 as possibly starting dates of the Anthropocene.

1610:

The earliest starting date for the Anthropocene suggested by Maslin is 1610 as it coincides with lowest carbon dioxide levels of 271.8 since the last ice age recorded   in the Law dome Ice core. The decrease in atmospheric carbon dioxide was caused by the arrival of Spanish conquistadors in the Americas in 1492, with their arrival spelling the end of the native population from roughly 61 million to 6 million by 1650. The decrease in native populations is often synonymous with colonization as Europeans went on their god ordained massacre of the natives via warfare and disease like chicken pox which wiped out the Aztec and Inca kingdoms of the old worlds. The reduction in human population as Maslin points out in his study caused the decline of farming, allowing the regrowth of native vegetation which sequestrated 7-10 ppm carbon dioxide which is documented in two high resolution Antarctic ice core records. This dip is atmospheric carbon dioxide is often referred to as the Orbis spike. The geological ice records of this Orbis spike is important as it means that both criteria of the International commission of Stratigraphy as the ice records are a GSSA and the clash of the old and new worlds signaled a shift in the dynamics of the earth as the transoceanic transport of species has no equal in geological history as Maslin points out in his study.

Great Acceleration Graphs

1950:

The next candidate for the beginning of the Anthropocene is 1950, as beyond this point in time there is clear evidence for fundamental shifts in the nature and functioning of the Earths Systems that are beyond normal variation as experienced in the Holocene as these graphs from the study conducted by Steffan et al point out. This time is often referred to as the Great Acceleration as its the time when human invention, fossil fuel consumption, deforestation and global environmental impact accelerate to levels never experienced before. A number of reasons for this increase in human impact are given as the industrial revolution had passed and two great wars had passed in Europe which allowed rapid advancement in human innovation and technology, nuclear bombs had been tested and used and the beginning of the cold war was in full swing. The Graphs of the Great acceleration point to the undeniable truth that humans are in fact in complete control of environmental change, with rates of change often unparalleled in geological time. When it comes to GSSA or GSSP the great acceleration lacks both with the only possible alternative being 1964 sediments which correlates to nuclear testing fallout which is stored in sediments as carbon 13 is dated from the nuclear bomb testing which Maslin also explores in his paper. The use of superficial sediments is being explored by Reck et al, to try and discover suitable evidence to support the starting date of 1950, however, the only criteria which 1950 ticks is that it points out the starting point in the shift of Global Earth Systems.

Both these dates are contentious and heavily debated as they have social consequences. A later starting starting date of the Anthropocene like 1950, the more diminishing the role colonization and the impacts European nations had on global climate change making it a equity issue as revealed in the Great Acceleration Graphs reinforcing the notion the notion that humanity as a whole contributed to climate change as Steffan et al explores in his study. Using 1610 as the starting date however removes is issue but raises another, being that human climate change is not new and as such we should not be that concerned about it. From my personal view 1610 would be the perfect starting date for the Anthropocene as it fulfills two criteria from the International Commission of Stratigraphy and points out the the unequal damage caused by humans to the climate, putting the burden right on the doorsteps of those who claim to be trying to better the world yet refuse to acknowledge their role in this mess.

Reference list:

 Lewis, S.L. and Maslin, M.A., 2015. Defining the anthropocene. Nature, 519(7542), pp.171-180. 

  

 Steffen, W., Broadgate, W., Deutsch, L., Gaffney, O. and Ludwig, C., 2015. The trajectory of the Anthropocene: the great acceleration. The Anthropocene Review, 2(1), pp.81-98.

 Rech, J.A., Springer, K.B. and Pigati, J.S., 2017. The Great Acceleration and the Disappearing Surficial Geologic Record. GSA Today, 27(11), pp.8-9.

Why Drink Plant Milk?

Why Drink Plant Milk?

Milk Variety: 

Humans are a truly weird species, we are the only creatures in the world that drink milk from another species and drink milk past infancy so it would only make sense that we have a variety of different milks right ? 

Diary:

The production of diary and diary products is a gold mine for anyone who can get into it but with growing concerns about the climate people are seeking alternatives to diary but still wan milk and that is where plant milk comes into the picture. The main reason behind the shift to plant milks for a lot of people is for the added health benefits plant milks have compared to milk, but a more compelling reason to drink plant milk is because of the methane produced by cows. Methane as a greenhouse gas is 23 times for potent than carbon dioxide at trapping heat even though it has a shorter life span and is easily converted to carbon dioxide in the presence of Hydroxide radical as Saunois stated in his study. Saunois study confirmed that global atmospheric methane concentrations have risen with the main contributor to this being agricultural production with ruminating animals a larger contributor as Mosier points out in his study. 

This then begs the question of how environmentally friendly are plant milks actually compared to normal cows milk? The most common non-diary milk products are almond milk, rice milk and soy milk. Now if one is trying to save the environment by substituting rice milk then your not really doing anyone any favors as rice fields are closely behind cows in their methane emissions, while also being a staple for over 3 billion people.  

Almond Milk:

So then what about almond milk ? The farming of almonds in the USA is concentrated in California were 16 000 acres of wetland where converted to almond farms and as we know wetlands are natural methane sinks and sources. The farming of Almond to produce milk is also a very water intensive practice with approximately 15 gallons of water needed to produce 16 Almonds and it takes 92 almonds to make one Litre of almond milk which equates to 384 litres of water usage, this value is however down from the 1016 litres it takes to produce one litre of cows milk. So in terms of water usage Almond milk beats cows milk but there are added environmental bonuses as almonds grow on trees which we all know take up carbon dioxide to produce oxygen. But just like any agricultural product the industrialization of the practise means that almonds also have a relatively high carbon but it seems like the farming of almonds does not produce methane or any other greenhouse gas if you do not include the use of fertilizer and pesticides.

Soy Milk:

Now for Soy Milk.The biggest issue with Soy milk is the fact that the amazon rain forest is being destroyed to convert the land into soy farms, which is also very similar to them doing it for cows. The actual farming is very similar to that of almonds as the plant itself does not produce any greenhouse gas, however the farming practices of soybeans means that they do have a negative environmental impact. When compared to almond milk soy milk requires less water to produce a litre of soy milk making it a better option than almond or cow milk but a study conducted by David Pimentel showed that 200ml of soy milk produced 0.195kg of carbon dioxide emissions.

So plant milk is better than cows milk when you look at the overall environmental impact of its farming, however the processing of the plants to create the milk means that they do in fact contribute to the emissions of greenhouse gases which are not necessarily methane. However, the really is no reason why we should be drinking milk either from plants or from cows as they are not human mothers milk and therefore could pose health risks and the habit of drinking milk past infancy is actually just a really bad habit which needs to be done away with.     

Reference list:

 Mosier, A.R., Duxbury, J.M., Freney, J.R., Heinemeyer, O., Minami, K. and Johnson, D.E., 1998. Mitigating agricultural emissions of methane. Climatic Change, 40(1), pp.39-80.

 Saunois, M., Jackson, R.B., Bousquet, P., Poulter, B. and Canadell, J.G., 2016. The growing role of methane in anthropogenic climate change. Environmental Research Letters, 11(12), p.120207.

Interaction Between Ocean-Atmospheric Cycles and their effects

Interaction Between Ocean-Atmospheric Cycles and their effects:

Indian Ocean Dipole and El Nino Southern Oscillation

Both the ENSO and the Indian Ocean Dipole are ocean atmospheric systems that consist of the relative sea-surface temperature and the global wind systems, with the ENSO a system which affects predominantly the pacific ocean and the Indian Ocean Dipole affecting the Indian ocean. These Ocean temperature and wind systems are an important control system on the nutrient cycle within the oceans but also for agriculture as they affect rainfall patterns and intensity and as such we will be looking at the effects of both these cycles within the Indian Monsoons.

ENSO: When People think of monsoons they often think of the Indian Monsoons which are also closely related to torrential rainfall within Indian. However, this is completely true as monsoons are common on other parts of the globe and monsoons are also associated with periods of drought as the monsoons as a system are related to the seasonal change in wind direction and rainfall patterns driven by shifts in temperature differences between the ocean and land causing pressure differentials as depicted in the diagram below. It is this temperature dependency of the monsoons on oceans that the Indian Ocean Dipole and ENSO become important systems to understand.   

Indian Seasonal Monsoons.

ENSO is a climatic pattern involving changes in the temperature of the waters in the central and eastern tropical Pacific Ocean. It involves the meeting of the Northern and Southern Hadley cells at the ITCZ, in which surface Easterly winds are weak causing the Western boundary of the pacific ocean surface to rise by 0.5-0.75m compared to the Eastern boundary during the normal Walker Cycle. However, under El Nino conditions the Easterly winds weaken further causing the Western boundary seal level to drop causing the warm water to be evenly spread throughout the pacific ocean increasing the depth of the thermocline and causing rain to fall over the central pacific ocean as depicted below.

El Nino Conditions over the pacific ocean.

However, the opposite occurs during La Nina conditions with the normal Walker cycle conditions becoming more exaggerated increasing rainfall over the Western boundary of the pacific ocean, (Link).

Indian Ocean Dipole: The Indian Ocean Dipole (IOD) is similar to the ENSO because it speaks about the difference in sea surface temperatures of the Eastern and Western Boundaries of the Indian Ocean. The IOD has three phases, just like the ENSO, with the three phases being neutral, positive and negative. Neutral Conditions are when sea surface temperatures over the whole Indian ocean are relatively normal but during the positive phase of the IOD the Westerly winds weaken allowing warmer waters to concentrate on the tropical Eastern boundary of Africa increasing land rainfall within this region. The IOD is also an important driver of the Australian climate having a strong impact on the agriculture of the region and more recently the bush fires which have occurred as this years positive IOD hit 2 degrees Celsius exaggerating the dry conditions experienced in Australia.

Now that we have a basic understanding of how the Indian Monsoons work, the ENSO and the IOD, how do the two ocean atmospheric systems interact in influence the Indian Monsoons. A study conducted by Cherchi, showed that rainfall decreased during the Indian summer when the El Nino and positive IOD occurred concurrently with a study by Ashok, confirming this trend. However, both studies also showed how the different phases of both system when occurring together but not in synergy either have amplifying or reducing effects on the monsoon rains, but it was also noted by Ashok, that the IOD had weakened the ENSO-monsoon relationship.  

In Conclusion each of the different ocean-atmospheric system when looked in isolation have differing effects but when occurring together have both positive and negative effects on each other depending on the feedback mechanisms of the climates they influence.

Reference List:
  Ashok, K., Guan, Z., Saji, N.H. and Yamagata, T., 2004. Individual and combined influences of ENSO and the Indian Ocean dipole on the Indian summer monsoon. Journal of Climate, 17(16), pp.3141-3155.

 Cherchi, A. and Navarra, A., 2013. Influence of ENSO and of the Indian Ocean Dipole on the Indian summer monsoon variability. Climate dynamics, 41(1), pp.81-103.

  Hashizume, M., Chaves, L.F. and Minakawa, N., 2012. Indian Ocean Dipole drives malaria resurgence in East African highlands. Scientific reports, 2(1), pp.1-6.

Oxygen isotope uses:

Oxygen Isotopes

In order to understand the different uses of Oxygn isotopes one first needs to know what an isotope is and be able to differentiate between stable and radioactive isotopes. Oxygen as an isotope is widely used within the scientific community to accomplish a number of things some of which will be explored in this blog.

What is an isotope:

An isotope is a variation of an element which either has more or less neutrons than the most abundant form of that particular element in question. This variation in the number of neutrons within the elements nucleus increases or decreases the atomic mass of the element and allow for the element to have different chemical reaction rates even though all the different elemental isotopes will have the same chemical reaction principles. There are however, two different types of isotopes namely stable and unstable isotopes. Radioactive and stable isotopes are not very different in the sense that they all contain differing numbers of neutrons however radioactive isotopes have excess nuclear energy which allows them to radioactively decay and give off that excess energy with it known that radioactive decay is responsible for the earths internal heat budget, while stable isotopes do not have excess nuclear energy and do not radioactively decay. Just as every element has an isotope each element has both stable and radioactive isotopes which is important to known since they each have different applications.

Oxygen Isotope Earth Science uses:

Oxygen has three known stable isotopes: 16-oxygen, 17-oxygen and 18-oxygen, and a number of Radioactive isotopes. The main use of oxygen isotopes specifically the ratio between 16-oxygen and 18O is in paleoclimate reconstruction studies. An example of such paleoclimate reconstruction is using the stable isotope composition of marine calcite which looks at the 18-oxygen signature of shell marine life to determine the seawater temperature which has been done by Tindal .Tindal in a study found that the use of 18-oxygen composition within shell marine life is useful as the marine life incorporates the 18-oxygen signature of the seawater with the fractionation of which is temperature dependent allowing us to reconstruct the temperature at which these marine creatures lived and therefore the temperature of the sea body. 18-oxygen is used to determine the water temperature because 16-oxygen is more readily evaporated than 18-oxygen, this relation is also important as it allows for the origin of precipitation to be found. This reaction rate differential between 16-oxygen and 18-oxygen is important in paleoclimate reconstruction studies as the lighter oxygen isotope will have a higher concentration within glaciers and terrestrial waterbodies compared to oceans which would have greater concentrations of 18-oxygen.

Oxygen isotopes are extensively used within the field of petrology because of the important role which hydrothermal fluids play in magmatic processes and metamorphic processes. Most studies that use Oxygen isotopes look at the interaction between hydrous and anhydrous minerals within whole rocks. Schiffman used 18-oxygen isotope analysis of hydrothermal zonation within the northern Troodos complex to indicate that the rock complex was formed in the upper Cretaceous within a seawater hydrothermal system. Schiffman found out that the complex is rich in subgreenschist facies mineral assemblages that contain high ratios of 18-oxygen isotopes which is indicative of rocks formed within areas where seawater diffuse recharge is an important component of rock formation.

Other uses of Oxygen Isotope:

Most Earth Science studies use the stable isotopes of oxygen within their studies to get to whatever answer they desire to however Earth Scientist are not the only users of isotopes, medical researchers like Ter-pogossian have previously used 15-oxgen to study the cerebral blood flow, blood volume, and oxygen metabolism because of the short half-life of 15-oxygen, which is 2 minutes. The use of radioactive 15-oxygen within the medical world has also been used to determine the functionality of the human respiratory system with a study by Dyson used 15-oxygen to determine the regional lung function within humans. These are two of many examples of the application of radioactive oxygen isotopes outside of the Earth sciences.

Overall the use of Oxygen isotopes goes beyond just paleoclimate reconstruction with this blog giving a number of different applications both within and outside the Earth Science stream for the different applications of both stable and radioactive oxygen isotopes. However, there are a lot more applications out there which this blog has not looked into but hopes that an interest within the topic has been ignited within my readers.

Reference List:

 Schiffman, P. and Smith, B.M., 1988. Petrology and oxygen isotope geochemistry of a fossil seawater hydrothermal system within the Solea graben, northern Troodos ophiolite, Cyprus. Journal of Geophysical Research: Solid Earth, 93(B5), pp.4612-4624.

 Tindall, J., Flecker, R., Valdes, P., Schmidt, D.N., Markwick, P. and Harris, J., 2010. Modelling the oxygen isotope distribution of ancient seawater using a coupled ocean–atmosphere GCM: implications for reconstructing early Eocene climate. Earth and Planetary Science Letters, 292(3-4), pp.265-273.

 Ter-Pogossian, M.M. and Herscovitch, P., 1985, October. Radioactive oxygen-15 in the study of cerebral blood flow, blood volume, and oxygen metabolism. In Seminars in nuclear medicine (Vol. 15, No. 4, pp. 377-394). WB Saunders.

 Dyson, N.A., Hugh-Jones, P., Newbery, G.R., Sinclair, J.D. and West, J.B., 1960. Studies of regional lung function using radioactive oxygen. British medical journal, 1(5168), p.231.

Atmospheric Composition during the Last Glacial maximum:

Atmospheric Composition during the Last Glacial maximum:

Image 1: Last Glacial Maximum Ice cover. 

The last Glacial Maximum has been studied in great detail but there does exist areas where greater research must be done and one of these areas is the composition of the atmosphere during this period compared to the current atmosphere pre-industrialization.

Most of the effort when it comes to studying the atmosphere of the last glacial maximum has been focused on atmospheric carbon dioxide and its sequestration, with little attention being paid to methane and dust and the effects they have on the global climate during this glacial period.

Carbon Dioxide vs Methane:
One of the main reasons as to why CO2 is so extensively studied is the fact that during the Devonian the drop in CO2 levels caused a major Glaciation at the end of the Devonian. However, as a Greenhouse gas CO2 is not the strongest naturally occurring greenhouse gas as methane per ton is four times more potent that CO2 however it does have a shorter life span than CO2 with a lifespan of CH4 in the order of a decade as Kaplan indicated. Kaplan found that Methane as a natural gas is not produced as rapidly as CO2 with the main producers of Methane being wetlands and boreal wetlands in the northern hemisphere.

Image 2: Natural Methane Production

Methane Importance:
Dust is an important component in the atmosphere as it plays a number of roles which range from absorbing and scattering incoming solar and outgoing infrared radiation and indirectly by acting as ice nuclei as well as providing micronutrients for organisms in the ocean affecting the biochemical cycles within the ocean which are responsible for the reduction and increase in atmospheric CO2. The priority nutrient within dust is Iron as it the main nutrient needed for phytoplankton to grow and remove CO2 from the atmosphere and store it in deep ocean sinks.

The atmosphere of the Last Glacial Maximum is known to be very different in terms of composition with studies conducted by Lambert showing that during the last glacial maximum dust deposition was 2-3 times higher in the tropics and South Pacific, 5 times higher in the South Atlantic and 20-30 times higher in polar regions than present. Lamberts study also crucially found out that the Last Glacial Maximum contained 3-4 times more dust than the Holocene. The increase in dust partial concentrations during the last glacial maximum is partially due to the increase in erosion caused by advancing glaciers which mechanically abraded underlying rock turning it into dust.

The concentration of Methane during the Last Glacial Maximum is thought to have been around 385ppb, with an increase to 450ppb from the last glacial maximum to pre-industrialization, with this figure coming from a study conducted by Kaplan. Kaplan’s study also gave the reasons as to why there was a great decrease in the concentration of methane, the biggest contributor to the low methane concentrations was the reduction in the production of methane as wetlands reduced in total land coverage so did that of plants and the number of animals.

As common knowledge the concentration of atmospheric Carbon dioxide was lower during the last Glacial maximum than pre-industrialization and present, with atmospheric CO2 concentration during the last glacial maximum being 40% lower than the Holocene which sat at 280ppm and 368ppm post-industrialization. The most intriguing aspect about the concentration of atmospheric CO2 and methane is that they have a synchronous increase and decrease pattern as Monnin found in his study, with it also being noticed today that as ice caps melt trapped methane gas is being released which adds more greenhouses gases into the atmosphere increasing temperature as it would have at the termination of the Last Glacial Maximum.

The different greenhouse gases and other atmospheric components vary depending on the climatic reign at the time, with an interconnected relation existing between dust, methane and carbon dioxide. Dust increase in atmosphere increase phytoplankton production and therefore atmospheric carbon sequestration which decreases global temperatures reducing the production of methane and shortening its lifespan as more OH is available to react with the remaining methane. All these factors contribute to the continuation of a glaciation and the termination of one and subsequent warming of the Earth.

Reference List:

 Monnin, E., Indermühle, A., Dällenbach, A., Flückiger, J., Stauffer, B., Stocker, T.F., Raynaud, D. and Barnola, J.M., 2001. Atmospheric CO2 concentrations over the last glacial termination. Science, 291(5501), pp.112-114.

 Lambert, F., Tagliabue, A., Shaffer, G., Lamy, F., Winckler, G., Farias, L., Gallardo, L. and De Pol‐Holz, R., 2015. Dust fluxes and iron fertilization in Holocene and Last Glacial Maximum climates. Geophysical Research 

 Kaplan, J.O., Folberth, G. and Hauglustaine, D.A., 2006. Role of methane and biogenic volatile organic compound sources in late glacial and Holocene fluctuations of atmospheric methane concentrations. Global Biogeochemical Cycles, 20(2).

Use of Geology to state the timing of the Great Oxidation Event:

Use of Geology to state the timing of the Great Oxidation Event:

Oxidation of the oceans.

The timing of the Great Oxidation event has been of great debate within the scientific community, because of the different number of techniques which can be used to postulate the timing of the Great Oxidation event. However, a large number of studies have focused on the use of geological data.

The exact reason as to why scholars continue to focus on geological data to create time constraints for the great oxidation event will be explored in this blog.

The most obvious reason as to why geological data is often used is the fact that geological features are physical objects which can be studied, they do however also allow for a range of data sets to be uncovered through their geochemical analysis and correlation with other geological features which have been found to have the same age. The common method of getting the date of a rock formation is through Zircon dating, however one first has to establish if the zircon is of syngenetic or epigenetic origin. The timing of deposition is only one of the major concerns when it comes to geological features and their inclusions, reworking and metamorphism can create major timing issues.

Geochemical Analysis:

Geochemical data can also be gathered which give relative dates depending on the isotopes which one chooses to study. Crowe studied the distribution of Cr isotopes of Nsuze paleosol from the Pongola Supergroup of South Africa. Crowe used Cr isotopes because they are sensitive indicators for oxidation weathering. S-isotopes have also been used to determine the timing of the Great Oxidation event, in a study Gumsley analyzed S-isotopes from the Duitschland Formation of the Transvaal Supergroup. Gumsley's study focused on the S-isotope fractionation of mass-independent fractions as they have been found to provide the tightest constraint on the timing of the Great oxidation event. These two studies studied two different geological features and used two different isotope analysis methods which yielded two different times for the great oxidation event with Crowe's study indicating that the event occurred 300-400 million years earlier than, Gumsley's study which stated that the event occurred 2.4-2.3Ga, indicating the uncertainty that still exist when using geochemical data.

Another method which has been recently adopted by scientist is the use of bio-markers within rock formations. Bio-markers are known to be sensitive to changes in climate since they were the living organisms during that specific climatic regime and as such would be the best detectors of Oxygen production during the Great Oxidation event and other atmospheric and environmental changes.

Gumsley, went beyond just studying S-isotope fraction, he also studied the assembly of large continental mass, extensive magmatism and continental migration to near-equatorial latitudes. This was done because the extensive magmatism created large igneous provinces which would have released a large amount of greenhouse gases especially carbon dioxide, while the study of the large continental mass and its migration would allow for better correlation between different rock formation. The study of the large igneous provinces was also found to be responsible for triggering a nutrient flux which would have increased the photosynthetic activity and therefore the production of Oxygen possibly signaling the beginning of the great Oxidation, 2.5-2.4 Ga.

Even though a number of challenges do exist when it comes to using geological data as evidence for the timing of the great oxidation, when the different data sets are used together as one a more accurate and coherent date is found as to when the great oxidation event occurred 2.4 Ga.  

Reference List:

 Crowe, S.A., Døssing, L.N., Beukes, N.J., Bau, M., Kruger, S.J., Frei, R. and Canfield, D.E., 2013. Atmospheric oxygenation three billion years ago. Nature, 501(7468), pp.535-538.

 Gumsley, A.P., Chamberlain, K.R., Bleeker, W., Söderlund, U., de Kock, M.O., Larsson, E.R. and Bekker, A., 2017. Timing and tempo of the Great Oxidation Event. Proceedings of the National Academy of Sciences, 114(8), pp.1811-1816.

 Sessions, A.L., Doughty, D.M., Welander, P.V., Summons, R.E. and Newman, D.K., 2009. The continuing puzzle of the great oxidation event. Current Biology, 19(14), pp.R567-R574.