Climate Change

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To what extent is climate change part of the Earth’s natural cycles

Since the origins of the Earth about 4.6 billion years ago the climate has be constantly changing. The Earth experienced far warmer weather and far colder weather, however it has survived and the species which existed have been continuously adapting though a process of evolution- this is all part of the Earth’s natural cycle. Recently though the changes have seemingly occurred at a more concerning pace than before; this has coincided with significant human activity. There a very few relevant experts that deny that climate change is occurring however whether it has resulted due to human caused emissions. This notion has generated a great deal of debate and it has earned significant global precedence in recent years. Consequently there has been a championing of the ultimatum that in order to ensure the continuation of our society, changes must be made- whether these changes are necessary or even if they would have any impact – remains unfounded and controversial.

For the 4.6 billion years of the Earth’s existence data (not very accurate for the early stages) is only available for the latest 10% of the history of the Earth. Consequently, it is difficult to be certain to a high degree of accuracy that what we are experiencing is not entirely normal. The pre- Cambrian period, when life is believed to have originated, is not well known to us- the data available is primarily obtained from rocks and involves larges amounts of guesswork. Even then, the oldest rocks of use are only 3.7 billion years ago- located in Northern Scotland, Greenland and Australia as well as pollen analysis. These rocks are of use because they are sedimentary, and consequently they can reveal something about the environment if the time; for instance sandstone is an indication of an arid, hot climate; while clay only forms in wet, marshy conditions. Thus the rocks inform us to a small degree about past climates and from which we know that in our past we have been 8 ºC warmer for example. From 2.5-2.2 billion years ago, there is evidence from South Africa that suggest complete coverage of the Earth in ice except at the equator; this has been termed ‘Snowball Earth’. As a result of positive feedback i.e. high albedo of snow leads to colder climate, the Earth entered a significant cold period. This period, aka ice house phase, was ended as a result of mass volcanism, which caused melting through the release of carbon. Consequently, the climate entered a warmer period or a green house phase and this relationship is what developed the connection held today between temperature change and carbon emissions Finally, there were two more ice ages between the years 800-500 ma- known today as the Sturtian and Varanger in which ice covered the entirety of the Earth save for 10 º North of the equator.

Evidently, there have been changes; it is now clear that in between these long periods of ice house or green house phases. Currently the Earth finds itself in an ice house phase; within which there are smaller periods called glacials and inter-glacials; we are in the Holecene interglacial specifically which began about 12,000 years ago. From evidence that can account for the last 500,000 years, the current period should last around 15,000 years. In one (inter)glacial, there are phases in between lasting for 300-400 years- and these tiny fluctuations in the global climate are called stadials and interstadials. Overall therefore, the Earth finds itself in an interstadial, within an interglacial, within an ice house phase. The significance of the stadial level of change is most pertinent- since based on previous periods the warming that is associated with the industrial activity of the 1850s is consistent with the ‘correct’ duration of these stadial periods. Thus regardless of what occurs now, in the next one hundred years or so the climate may cool...
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