Environmental Change at the Dawn of Human Existence
Global environmental change, as defined by the leading names in the field, is “biophysical and socioeconomic changes that are altering the structure and the functioning of the Earth System” (Steffen, Crutzen and McNeil, 2007:615). In layman’s terms this means that changes on the earth are a result of humans advancing in technology, economy and the ability to extract resources from the earth. Alterations to the Earth System, or the environment, can be catalogued into two categories: changes in state and changes in flow.
The term state refers to the physical condition of a part or a whole ecological system. Humans changed the environment primarily through state changes. Land-cover, a term that describes the state of land, has been altered by humans clearing land, farming, building, and using natural resources, such as water. In some cases, anthropogenic state change has occurred at such high levels that a return to the natural state of the land would take thousands of years (Turner 2009). The most apparent examples of these extreme state changes are cities. In cities, the natural land is changed to tremendous degrees: The ground is leveled, buildings are erected, and foreign fauna is introduced as decoration and so on and so forth. If completely abandoned, the land-cover of the city (cement, asphalt, buildings, etc) would not return to its natural state for thousands of years. State changes were the earliest form of environmental change and can be traced back as far as the end of the Pleistocene period with the die-off of mega-fauna, or large animals like the Mastadon (Karieva et al., 2007:1866). The world-wide destruction of mega-fauna at the turn of the Pleistocene period has been attributed to human activity by many scholars. It is believed that humans hunted the large mammals to extinction and so the die-of of the mega-fauna is accepted as evidence of major anthropogenic global environmental change (e.g., Dayton 2001; Goebel, Waters and O’Rourke 2008; Holdaway and Jacomb 2000). In addition to mega-fauna extinction, during the Pleistocene period humans affected their environment in various ways, which caused local environmental disturbances that, in some cases led to global effects (Karieva et al., 2007:1866). This research proves that global environmental change, in the form of state changes, can be traced clear back to our Neanderthal ancestors.
Anthropogenic global environmental changes continued throughout the Holocene, approximately 10,000 years ago, by way of various state changes including land-cover alteration for agricultural production, hunting, and population growth and concentration (Tuner and McCandless, 2004:228). State changes in these early periods of human environmental history occurred in geographically concentrated regions, which, by long-term repetition, culminated into global environmental disturbances (Foley et al., 2005:570). Researchers have found that global environmental change increased in speed and intensity in correlation with human technological advancements, which facilitated flow changes in the Earth System (Stefen 2007:617).
Flows, sometimes called cycles, are the patterns by which molecules and compounds move throughout the Earth system. Unlike states, flows are not immediately changed by human interaction. Significant changes in earth flows occur over a long period of time. For that reason, scientists have only recently recognized the affects that humans have had on the flows of the earth (Turner 2009). Changes in flows may threaten the stability of the ecosystem and therefore pose a predicament for society. The hydrological flow or the water cycle, for example, has been affected by continuous human manipulation; in result, the world’s supply of freshwater has decreased significantly (Foley et al. 2005:571). This is particularly true in regions of dry and hot climates, like the southwestern United States. This area incessantly consumes water for human enterprises, such as agriculture, resulting in reduced natural water resources.
It is important to consider the anthropogenic impact on states and flows in order to regulate human activity and to protect and preserve the ecosystem (Karieva et al. 2007:1866). The Anthropocene, or most recent era of human environmental history, marks the beginning of anthropogenic global environmental flow changes (Steffen, 2007:617). Technological advancements of the Anthropocene include the human ability to extract and burn fossil fuels for energy, which in turn releases gases into the atmosphere thus affecting natural biogeochemical flows. In conclusion, human-caused global environmental change can be traced as far back as the late Pleistocene period starting with state changes and has continued, with increased intensity, and today affects environmental flows as well as states.