The University of Iowa
Department of Chemical and Biochemical Engineering
052:163 Atmospheric Chemistry and Physics
TASK #1: Introduction to Climate Change
The first task was created to offer individuals insight on
climate change and its potential impacts on the globe. The web provides a number of sights that describe global warming from different perspectives. Although most scientists agree that climate change will have significant effects on the earth, many people question the severity of global warming and the resulting impacts that will follow. Climate change has become a complex political issue do to the significant health, economic, and environmental implications that have been projected. Delegates from 150 industrialized nations are currently participating in a global warming conference in Kyoto, Japan to reach an agreement to control the Earth's greenhouse gasses. Take a look at the recommended sights to compare and contrast predictions on global climate change.Task #1 Question: After contrasting the different views on global warming, what is your position? What impacts of climate change will be the most significant? What stance do you think the United States should take on the issue?
TASK #2: El Niño. A Look into the Future of Global Change?
One of the most influential sources of yearly climate variation in the United States is the
El Niño phenomena of the tropical Pacific Ocean. The El Niño is a naturally occurring but highly unpredictable condition that results from complex interplay among clouds and storms, regional winds, oceanic temperatures, and ocean currents along the equatorial Pacific. During El Niño, the pacific trade winds are disrupted resulting in a reduction of the upwelling of cool waters in the Eastern Pacific. This occurrence permits the warm water pools in the west Pacific to drift easterly towards South America. As the waters of the Central and East Pacific warm, the powerful tropical storms begin to form further east than usual. As the distribution of the storms spreads east along the equator, the jet stream over the North Pacific is pulled further south than usual, where it collects moisture and storms and carries them to the Southwestern United States. The particular effects of the El Niños are widespread; however, flooding and drought are strongly influenced by the increased precipitation generally associated with El Niño events.The rivers of the United States, Southwest in particular, experience increased streamflow during the winter phase of El Ni
ño. Although there are a number of factors that influence the flooding, specific rivers whose source of streamflow is strictly precipitation are greatly influenced by El Niño events. Since El Niños increase the chance of receiving tropical storms from the eastern Pacific, those rivers that respond to these types of storms usually have rapid flood response. El Niño conditions tend to yield the largest floods in these particular types of rivers.Although large floods have been associated with past El Niños, the onset of an El Niño does not guarantee flooding and not all floods occur during El Niño years. However, it can be concluded that El Niños affect the odds of flooding in a given river and given winter over the course of many El Niño episodes. For example, more floods have occurred in Arizona during El Niños than other years. This supports the fact that atmospheric disruptions can and will promote noticeable climate change.
In addition to flooding, El Niños often result in severe drought in some regions of the world. In East and Southern
Africa, agricultural experts have advised the farming community to take necessary contingency measures to mitigate the effects of the El Niño weather phenomenon. El Niño is threatening to cause famine due to expected drought in some regions and flooding in others. While much of Ethiopia is experiencing severe flooding, the El Niño phenomenon has resulted in the scarcity of rainfall in other parts of the country, particularly in July. El Niño's occurrence in1957, 1964,1969,1982,1983, and 1993 shows that it is nothing new to Ethiopia. On average, El Niño recurs every 2-8 years and lasts for approximately l-2 years; however, authorities excepted this year to be more severe. It has been predicted that some 4.25 million people in the country will require food assistance in 1998 due to irregularities of the rainy season and the resulting damage to crops. In addition to famine, the El Niño phenomenon has caused an increased spread of malaria and air born bacteria.The El Niño phenomena offer insight into the potential severity of global change. El Niño is the best-studied example of a global climate change that has coherent influences that arise from recognized physical origins. The ways in which water and land resources are managed in the presence of El Niños provides an outlook on the kinds of response that might be necessary in a climate-changing world.
Task #2 Question: Explain the El Niño phenomena and describe what potential impacts it has on humans and agriculture.
TASK #3: Exploring the Effects of Global Change on Agriculture
The level of agricultural production is important to the United States. Agriculture represents approximately 17.5% of the U.S, gross national product and generates $771 billion on average per year in revenues. In addition, U.S. agriculture acts as the primary food source for this country and many foreign countries dependent on U.S. agricultural surplus. Agriculture would be extremely sensitive to permanent changes in climate, atmospheric composition, soils, precipitation, and temperature predicted to occur with of global change. Do to the potential impacts of global change on agriculture, it is worthwhile to explore predictions on the factors essential to the production of crops and livestock.
Global warming will effect agriculture directly through changes such as length of the growing season, frequency of severe weather and heat waves, rainfall, top soil management techniques, and irrigation demands. The impacts of the greenhouse effect on U.S. crop yields and productivity vary according to region and severity of the climate change. For this reason, scientific predictions range from worse case scenarios similar to the Dust Bowl of the 1930's, when corn and wheat yields dropped by up to 50 percent, to best case scenarios of increased crop productivity. Nevertheless, change is inevitable and indisputable as the concentrations of greenhouse gasses in the atmosphere continue to rise and changes in the climate become more evident.
The Unites States EPA and Department of Agriculture recognize the sensitivity of agriculture to a changing climate and are currently researching new techniques, land management practices, and agricultural technology to help combat the potentially negative impacts of global warming. We encourage you to visit these and other web sites you may find to help you in answering the following question.
Task #3 Question: Based on what you have learned about climate change, what is your prediction for the future of agricultural production?
TASK #4: Analysis of Agricultural production models: Adaptation to Global Climate Change at the Farm Level
The previous three tasks have introduced climate change and its potential impacts on agricultural productivity. For the next two tasks, we will review models that predict the specific effects of climate change on agriculture. For Task #4, we will explore a model created by Kaiser, Riha, Wilks, and Sampath, all of Cornell University. These four professors created an integrated model that consists of the following:
This model differs from others in that climate change here is modeled as a gradual, dynamic process. The model looks at a change in climate under three scenarios over a 100-year period from 1979 to 2079.
The first climate scenario is no change in climate over the 100-year period. The second scenario increases the temperature by 2.5° C and a 10% average linear precipitation increase by year 2060. The third and most severe climate scenario increases the temperature by 4.5° C and a 20% average linear precipitation decrease by 2060. The three scenarios are compared in two different farming regions of the United States, a 600 acre farm in Minnesota and a 900 acre farm in Nebraska to compare and contrast the effects accordingly.
The model also assumes that agricultural adaptation to changing climate will occur in several forms. Three types of farm-level adaptation are considered in the analysis. The first is the possibility of switching cultivars for a particular crop. In the model, the three cultivars included for each crop differ by length of time to maturity and potential yield. If climate change affects the length of the growing season, the farmer could use the adaptation strategy of switching to longer growing, higher yielding cultivars.
The second farm-level adaptation strategy is to alter crop mix in response to the changing climate. If climate change affects the relative yield and profitability of one crop in favor of another, then farmers should respond by making the appropriate change in crop mix.
Finally, farmers may also make adjustments in scheduling of the field operations in response to climate change. If climate change increases or decreases the amount of time that farmers can be in the field, this will affect planting and harvesting dates, and therefore yield levels indirectly.
The following are graphical results of the 100-year agricultural modeling for both Minnesota and Nebraska:
Minnesota Results
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2)
Net Revenue for Minnesota Farm as a Percentage of its 1980 Level by Climate Scenario and Percentage Difference in Net Revenue Between the Adaptation and No Adaptation Scenario. 1980-20703)
Optimal Mix of Crop Acreage for Minnesota Farm Under Climate Scenarios 2 and 3Nebraska Results
1) Nebraska Crop Yields as a Percentage of Their 1980 Levels. 1980-2070. Climate Scenarios 2 and 3.
3)
Optimal Mix of Crop Acreage for Nebraska Farm Under Climate Scenarios 2 and 3Task #4 Question:
Compare the graphical results of the model. What are the major differences you noted. Is the particular agricultural region a significant factor? What conclusions can be drawn from the results of these models?
TASK #5: Who Will Feed Us?
The preceding tasks introduced global warming and its effects on agriculture. In task 5 we will explore the future demand for agricultural production. During the 1990's, the growth in world crop production has slowed dramatically, while demand has continued to climb, driven by the addition of nearly 90 million people per year. The gap in this trend has been filled in recent years by drawing down carryover stocks of grain, which is the amount left in the world's grain bins at the start of each new harvest. By 1996, these had fallen to 50 days of consumption, the lowest level on record.
There are a number of trends that are influencing the creation of food scarcity. With all oceanic fisheries at or beyond capacity, growth in the oceanic fish catch came to a halt in 1989. For the first time in history, farmers cannot count on fisheries for help. In addition, farmers have to deal with the future of global warming. The 11 warmest years on record, since 1866, have all occurred since 1979 and the three warmest have all occurred in the nineties. Crop-withering heat waves like those that shrank harvests in 1995 across the United States, Canada, several European countries, the Ukraine, and Russia could become more severe if the level greenhouse gasses in the atmosphere continues to rise.
Task #5 Question: Although most experts say that food scarcity is more of a problem of distribution than of productivity keeping up with population, few seem to have considered the potential effects of climate change. If the world population were to increase by 50% in the next 45 to 50 years, under the worse case scenario of climate change, would the world be able to feed itself? Re-visit some of these sites, as well as the model predictions, and make a prediction based on what you've learned.
