Global warming has become one of the main environmental concerns of the twenty-first century, with debate spanning from the international level all the way down to the smallest local hamlet. One can hardly pick up a paper or turn on the news without seeing a story about how drastically the world is warming, or to hear that global warming is nothing but a myth caused by liberals for political purposes.
With millions of ardent supporters and detractors of the global warming theory, the facts that science presents continued to be debated and it remains to be proved whether recent warming trends are caused by human progress or natural cycles, or whether they will have long term consequences on the biosphere or have very little effect on it at all. The most accurate way to test the global warming theory is to observe the climatic changes taking place over a period of time to see what trends and changes are in effect.
As the size and scope of the entire planet makes such study difficult if not impossible, the easiest way to do this is to take a sample study of a region that could well represent the whole. The Wabash Valley Watershed in Illinois, with its rich and diverse terrain of waterways and tributaries near human populations, provides the perfect ecosystem to observe to figure out what and if any effects global warming has on it, as well as the implications these effects may have on the rest of the planet as a whole.
Wabash Valley Watershed To determine the potential warming trends in the global environment, the need to understand the temperature trends of at least a small portion of the world is necessary, and for this study, the Wabash Valley Watershed has been selected for observation, specifically the years from 1961 to 1990. The Rivers and Streams The Little Wabash River is located in Southeastern Illinois, flowing southward to the Wabash River.
The river’s headwaters are located in southwestern Coles County, and from there the Little Wabash flows approximately 237 miles south and east to its confluence with the Wabash River near New Haven, a point approximately 13 miles upstream from the Ohio River (IEPA, 2006). Altogether, there are about 5145 miles of rivers and streams in the Little Wabash River basin, and of these there are roughly 100 rivers and streams with drainage areas in excess of 10 square miles that account for 1640 of the total stream miles.
Geological Makeup of Wabash Valley Watershed In addition to the flow and direction of the rivers in the region, the geological make up is also important to understand the data properly. Based on an analysis of the topographic information, the elevation in the Wabash watershed ranges from 778 feet above mean sea level at the highest point in the watershed, in Coles County, to 404 feet in Clay County, at the downstream terminus. The change in elevation of the Little Wabash River itself, between its headwaters and the most downstream portion, is 362. 7 feet, over this approximately 114-mile stretch (IEPA, 2006).
Human Influence on Wabash Valley Watershed The characteristics of streamflow in any watershed will, over time, vary from earlier conditions because of the cumulative impact of human activities in the region. Like most locations in Illinois, the Wabash Valley Watershed has experienced considerable land-use modification since European settlement, including cultivation, drainage modification, removal of wetland areas, and deforestation. Most of these modifications occurred in the late 1800s, and most of the land in the watershed remains in agriculture, much as it did almost 100 years ago. Urbanization has affected only a very minimal percentage of land in the Wabash Valley Watershed.
While human influence on much of the region remains minimal, the larger scope of the impact of civilization can be measured best in the climatic changes the region has experienced over the years (IEPA, 2006). Overall Warming of the Environment of Wabash Watershed Based on climatic information measuring temperature in the Wabash Valley Watershed region, the average annual maximum temperature appears to be slightly increased between 1961-1990. The annual average maximum temperature in the Wabash Watershed reached a low in the late 1970s and early 1980s, but has since steadily risen to levels comparable to the peak years in the early 1960s.
The temperature fluctuated from an average annual maximum low of 60. 50 in 1978 to 65 in 1964. The average annual minimum temperature is also increasing over 1-year, 5-year, and 10-year trends. The average annual temperature for the region reached a high during the years observed in the late 1980s, with two of the hottest years recorded during that time. The 5-year and 10-year averages have also reached all-time highs and appear to be on the rise. According to the data provided about the Wabash Watershed, while there is a fluctuation over the time period studied, there is a noticeable rise in temperature in the recent years.
Pronounced Warming Of Minimum Temperatures and Reduced Range of Temperature The observed warming of the Wabash Valley Watershed suggests that global warming has had an effect on the region. To fully understand the extent of the warming, the data collected during the specific period must be analyzed and compared to the history of the region to see if the temperatures are similar to fluctuations in the past or signify a trend that requires much more analysis. Pronounce Warming of Minimum Temperatures The warming trends displayed in the Wabash Valley Watershed suggest that global warming has affected the temperature of the region.
According to the data collected from the latter half of the twentieth century, there is indeed a more pronounced warming of minimum temperatures than maximum temperatures. The minimum temperature of the Wabash Valley Watershed has reached an all-time high for the region, taking into account the entire recorded temperature history. The average annual minimum temperature reached the high of 44 degrees Fahrenheit in 1990, and highs at almost 43 degrees Fahrenheit for the 5-year span, and 42 degrees Fahrenheit for the 10-year trend.
Reduced Range of Temperatures The information gathered on the range of temperatures does suggest a trend consistent with global warming, though not as pronounced as other areas of study. The average daily temperature range in the watershed clearly shows that there is a reduced range of temperatures, though the temperature seems to have remained relatively steady around 20 degrees Fahrenheit a during the period studied. Surplus of Water and Precipitation Because many experts suggest that the globally warmed environment will see more drought and less surplus water conditions for inland or continental locations such as the Wabash Valley Watershed.
Therefore, it is expected that some trends in precipitation amounts and the frequency of certain amounts of precipitation would vary. This has been observed in the Wabash Valley Watershed, and the average annual precipitation in the watershed has increased noticeably since the 1960s. With a warming climate, precipitation in the Wabash Valley Watershed can be expected to continue on an upward trend, with 10 to 30 percent increases projected across the region by current climate trend models. Increases in the proportion of heavy and extreme precipitation appear to be very likely.
However, increased evaporation is projected to lead to a soil-moisture deficit, reduced lake and river levels, and more droughtlike conditions (Winstanley, 2006, 43). These each suggest that the area has indeed been affected by a trend of global warming. Evapotranspiration, Streamflow, and Runoff In reference to evapotranspiration, surplus/deficit conditions and runoff/streamflow, one might expect to see marked changes in each to reflect an environment in the clutches of a warming trend. In the Wabash Valley Watershed, these changes are observable.
Evapotranspiration High temperatures increase evapotranspiration rates, which tend to reduce the amount of surface water, soil moisture, and groundwater. When considering the impacts of future precipitation anomalies on water supplies, it is important also to consider the impacts of possible high temperatures (Winstanley, et al. , 2006, 9). Higher temperatures will only continue to increase the rates of evapotranspiration in the region. Streamflow Groundwater levels often are slower than streamflow to respond to precipitation deficits, only after soil moisture and streamflows are down.
Groundwater levels also recover more slowly from drought and do so only after precipitation exceeds evapotranspiration and soil moisture demands. In many places, shallow aquifers act as reservoirs from which groundwater can percolate slowly downward to recharge deep aquifers. As a result, deep aquifers are buffered from short-term droughts and only show effects during extended periods of more severe drought (Winstanley, 2006, 10). Runoff Runoff is very sensitive to precipitation changes. A decrease in precipitation by 20 percent causes a decrease in runoff of 49-55 percent.
An increase in precipitation by 20 percent causes an increase in runoff of more than 60 percent. Runoff is less sensitive to temperature change. For example, for a precipitation increase of 20 percent, runoff varies from an increase of 60 percent for a temperature increase of 7oF to 68 percent for no change in temperature. Although it is counterintuitive for runoff to increase with an increase in temperature, the slight increase shown by the model appears to be due to two factors. One, crops develops faster under warmer conditions, thus extracting soil moisture for a shorter period.
Two, high temperatures put crops under stress more frequently, which in turn causes stomates to close. It is not clear whether this reflects reality or is simply an artifact of model construction. Changes for evapotranspiration are considerably smaller: a 6-8 percent decrease for a 20 percent decrease in precipitation, and a 1-4 percent increase for a 20 percent increase in precipitation (Winstanley, 2006, 44). Trends Observed in Wabash Watershed By observing the data available, clear-cut trends can be seen in many aspects of the Wabash Valley Watershed ecosystem.
While there are many anomalies that make it difficult to predict the future and what affect, if any, current trends will have on the watershed and the rest of the world, it is clear from the data that annual temperature and precipitation is increasing. The changes and trends observed in the Wabash Valley Watershed suggest that global warming theory must continue to be a valid scientific investigation, and resources must be utilized to fully understand the scope of impact such warming trends will have on the planet.
Obvious and dramatic effects such as intensified tropical storms, polar melting, and the filling of the carbon sink in the Southern Ocean provide the public with glaring instances of global warming, but the problem still remains foreign to many that feel it does not directly affect them. Even the subtle changes in such places as the Wabash Watershed are barely detectable by the common population, and the mission of scientist should be to help examine and explain the impact.
Other Useful Environmental Data There are many other types of data that can be helpful to make a worthwhile analysis of the Wabash Valley Watershed, including ecological evaluations. By studying the animal and plant life of the region will give a better understanding as to the effect the climate changes are having. For example, if certain plants or animals native to different types of climate begin to appear in the region, this is a good indication that the characteristics of the region are changing.
Implications of Study The implications of this study clearly show that over the last half of the twentieth century, the climate in the Wabash Valley Watershed has changed slightly. Whether these changes are caused by global warming remains debatable, but the data suggests that there is a warming trend, as well as a trend of more precipitation. If it is indeed caused by global warming, there are many immediate and long-term risks associated with not trying to reverse the trend. Drought conditions run the risk of causing widespread damage to the ecosystem, as well as diminished plant and animal life in the area.
Subject: Global warming,
University/College: University of California
Type of paper: Thesis/Dissertation Chapter
Date: 7 November 2016
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