James Bonsall (King Alfred’s College, United Kingdom) J.P.T.Bonsall@wkac.ac.uk
Humans have destroyed world environments during the last 10,000 years and face changes of great magnitude caused by the natural Milankovitch climatic cycle.
During the past 10,000 years we have witnessed dramatic changes on the planet, but it is only in the last few centuries that humans have been able to record such events. Fortunately, many of these events have archaeological correlates. More recent changes, are also historically documented. Humans have, over the past 10,000 years, not only modified the landscape, but also enhanced and, inherently, destroyed the environment. The effect of the Milankovitch cycles on the environment will be examined here, and we shall see how astronomical forces compare to the nature of the human need for change. This essay will cite events in the archaeological, geological and historical records as evidence for human interference and the Astronomical Theory developed by Croll and Milankovitch.
The Milankovitch theory was initially rejected upon its proposal. However, independent research carried out in the 1960’s and 70’s by W. S. Broecker, R. K. Matthews, K. J. Mesolella, and D. L. Thurber; J. Imbrie and K. P. Imbrie; and J. D. Hays and N. J. Shackelton, have now validated the theory. Their work was based upon a major reworking of our understanding of oceanography, including analysis of ocean core sequences, oxygen isotope traces from deep ocean sediments, and sea level variations (Lowe and Walker 1984). Ocean sediment records now accommodate the explanation of Quaternary climatic change, and the Milankovitch theory is now widely accepted. However, as Lowe and Walker note (ibid:13), it is hard to determine precisely what effect Astronomical Theory has on Quaternary climates.
The Astronomical Theory is based on the assumption that the Earth’s surface temperature will fluctuate as a direct result from periodic changes in the shape of Earth’s orbit, the position of the equator and Earth’s position in relation to the Sun. The eccentricity of the orbit means that Earth’s orbit changes from elliptical to circular and back again with a periodicity of 96,000 years. The axis tilt sees the equator shift 3° and back again with a periodicity of 42,000 years. The procession of the equinoxes alters the position of the Earth with a periodicity of 21,000 years (ibid:11 – 12).
These forces, known collectively as the Milankovitch Theory, after the Croatian scientist, cause massive climatic change. The change in shape of Earth’s orbit was responsible for the last glacial period alone. The changes can result in large temperature rises and a massive change in the planets environment.
An increase in climate over a long period in time can also cause sea level change. 10,000 years ago, we were at the end of the last glaciation (Loader et al. 1997:10). The expansion and contraction of the continental glaciers “caused huge and uneven rises and falls in sea levels worldwide” (Renfrew and Bahn 1996). This led to the separation of the Isle of Wight from mainland Britain, over 6000 years ago. Dr. Rob Scaife, the man responsible for looking at the features of the submerged landscape on the Wootton Quarr coastline, Isle of Wight, and sampling environmental evidence from it, dated this. By using a combination of an auger in the intertidal zone of this site, with the seismic survey of the palaeochannels found in that investigation, the gradual sea level rise resulted in the island’s separation from Britain by 4000 B.C. (Loader et al. 1997:10 – 13).
The rise in sea level goes hand in hand with the changing climate. The ultimate results of Astronomical Theory indeed change the landscape, as Wootton Quarr has demonstrated. The formation of an island and the destruction of an environment that lies under what we now know as the Solent, were due to astronomical changes. The isostatic rising of the land and the eustatic rising of the sea took place in the European Mesolithic (Mithen 1997). The rising of the sea level was due to the melted ice from the glaciers. This was not confined to Britain though, as we see a massive simultaneous global change. Another example is that of shell middens in Tokyo Bay, Japan. Research carried out on the shells shows that Japan also had a much earlier coastline before 3000 B.C. (Renfrew and Bahn 1996:216).
Changes in climate are also responsible for site formation processes. Loess, aeolian and alluviation processes are all inter-connected. They are all affected by climatic change; therefore they are all inexorably linked to astronomical cycles. These cosmic changes are not confined to land formation processes alone, but also evolution of species. Elisabeth Vrbra, a mammalian palaeontologist, noted that evolutionary change is probably most often of astronomical origin (Bennett 1997).
Humans respond to changes by changing their environments (Bell and Walker 1993). Man, it seems, does not wish to be outdone by the forces of the universe. Over the past 10,000 years, man has been modifying the planet’s landscapes to suit his needs, such as settlement, agricultural enhancement and industrial development. Unfortunately, modification on man’s behalf means significant destruction of ecosystems, ecotones and the environment. We can trace this back from as far back as 8,000 B.C., but it has never been more apparent than in the 20th Century.
In the 20th Century we need timber. From buildings to furnishings it is all around us. 10,000 years ago, there was a great deal more of it all around us, the deciduous forest regions of northern Europe covered Great Britain. Odum (1971) has cited it as “one of the most important biotic regions of the world”. His reasoning is that the biome was transformed by man, and was replaced by “cultivated” and “forest edge” communities. His point hits home rather well. If it were not for man, and his “modifications”, deciduous forests would still today cover Britain. Luckily, we don’t have to imagine forest clearance of the past. Using uniformitarian principles, we have our own 20th Century environmental change to use as a comparison.
The destruction of the tropical rainforests is the consequence of our present day need for timber. They are located almost exclusively in developing countries that are under pressure from the expansion of agriculture. The felling of the trees is not managed in a sustainable manner or with care for the ecosystem. Some tribal groups have lived for thousands of years in the tropics, and they have survived without having to destroy their environment. Yet commercial logging involves a mass modification of the ecosystem (Counsell and Rice 1992).
This is not just a 20th Century environmental change. Forest clearing has been occurring since the Mesolithic. Woodland areas were being burnt for hunting and their destruction resulted in a change in the landscape. The introduction of agriculture in the Neolithic also changed the landscape. Modification after modification to the land changes the environment in a significant way, for example colluviation. Colluviation mainly occurs as a result of forest clearance. When there are no tree roots present to bond the soil together, soil erosion appears. This is a result of the “poorly sorted or unsorted sediment”, the colluvium (Bell and Walker 1993).
Intensive agriculture in the 20th Century includes the use of chemicals which will ultimately modify the landscape in ways we do not want. Agronomy involves the determination of the nature of a soil and how its fertility may be improved by drainage, irrigation, husbandry techniques such as crop rotation, and natural or artificial fertilizers (Isaacs 1996). This is all well and good, but the environment suffers under these modifications in the form of soil erosion and pollution by excessive use of weed killers, fertilizers and insecticides. Yes we have managed to grow healthier crops with a higher yield, but the chemicals used effected the landscape in a negative manner.
Modern intensive farming methods cause problems. However during the 18th Century, the Agricultural Revolution in Britain managed to modify the landscape for mans use and had no negative effects on the environment. The open-field system of strip farming was replaced by agricultural methods and new implements could be used. Jethro Tull and Viscount Townshend’s inventions also helped speed up the more economic approach to farming. Of course, the purpose of the new system of agriculture was to avoid the “Malthus Trap” of the intensive population growth of the Industrial Revolution, as described by Rev. Thomas Malthus in his Essays (Hobsbawm 1989). The Industrial Revolution was the largest major change in Britain’s environmental history since the Romans agricultural intensification. Modification of the landscape to enable transportation of goods led to the building of railways and the extension of canals in the 18th and 19th Centuries. Major British industrial towns such as Manchester and Sheffield, sprang up over night (ibid:37).
In April 1986, radioactive particles rained down over Scandinavia, Poland, Austria, northern Italy, France, Wales, England, Canada, and what is now known as the Czech Republic. Unacceptably high levels of 137Cs were found in those areas. This posed a massive threat to the Lapps and Inuits that depended on reindeer meat for food. The reindeer fed on lichens which absorbed the radioactive isotopes (Richardson 1981). Damaging the food chain, this pollutant is extremely harmful. Lichens are a very useful way of monitoring the fallout, as they are highly susceptible to pollution. The environment surrounding the origin of the explosion was severely polluted, and after mass evacuation, twelve years on it is still a designated quarantine landscape. The small town of Chernobyl lies in northern Ukraine. In just eleven days, its pollution cloud passed over ten countries in two continents. Mans harness of nuclear power has had an extremely deadly effect on the environment. It was originally intended as modifying the environment by discontinuing the burning of fossil fuels for power supply, but like other modifications it resulted in destruction.
A final example, is that of China’s recent initiative to provide 18,000 Megawatts of electricity for the “fast developing Chinese nation state” (Greeman 1998). The Three Gorges Dam will block the Yangtze River and has flooded 1000 square kilometres of land, forcing 2 million people from their homes. The project has cost $29 billion (U.S. Dollars). Part of the Hubei province has been lost, along with it homes, wildlife habitats, ecosystems, ecotones, environmental data, and thousands of years of archaeology. It is China’s biggest engineering project since The Great Wall, and has changed the landscape forever. This large-scale operation will also be visible from space.
Astronomical data and its geological and climatic effects are hard to interpret for the period of the last 10,000 years. Geologically, 10,000 years is a very short time. It is with greater ease we can look at the Cenozoic, Mesozoic, Palaeozoic and Protozoic periods due to their longevity. The further back in time you go, the easier it is to see the patterns, and their effects, when dealing with periodicity’s of 96,000, 42,000 and 21,000 years (Bennett 1997:65 – 84). Massive global change due to astronomical cycles is undeniable, but apart from short term temperature change and land formation, there is not (readily) available any comparative material. Mans effect is all too available, and it is obvious that his effect on Earth is far greater than anything Mother Nature can throw our way. We try and adapt our environment, but all we end up doing is making it worse for future generations. Not only have we destroyed the surface of our planet, but also its pedology. Environmental data obtained from palaeosols only survive where human interference is minimal. Not only are we destroying our chances of survival in the future by deforestation, chemical use, nuclear hazards, and intense land reorganization, we are also destroying our chance to rescue the past. Humans have modified the planet in short time spans, in Revolutions, which would take an epoch for Astronomical Cycles to compete with. Cosmic changes have formed the look of the Earth for millennia, but humans change that look in the blink of an eye.
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