In your course, turn to Lesson 4. Skim through it to refresh your memory. Next, carefully study and review the section titled, “Ecological Challenges Facing Humanity.” Skim through that and then focus on the topic of deforestation.

Directions: Be sure to make an electronic copy of your answer before submitting. Unless otherwise stated, answer in complete sentences, and be sure to use correct English spelling and grammar. Sources must be cited in APA format. Your response should be four (4) pages in length; refer to the “Assignment Format” page for specific format requirements.
In your course, turn to Lesson 4. Skim through it to refresh your memory. Next, carefully study and review the section titled, “Ecological Challenges Facing Humanity.” Skim through that and then focus on the topic of deforestation.
Using your own words, write a short descriptive essay that defines and explains selected environmental impacts of deforestation. As you write, imagine you are talking to a friend who has no knowledge of this topic. In short, write the way you speak, using a conversational tone. Also, try to alternate short sentences and longer sentences to make your writing more readable.
Be sure to create a title and cite yourself as the author. For example:
Environmental Impacts of Deforestation
Jennifer Croft
Your essay should include five paragraphs, as follows:
Paragraph 1 is your lead paragraph. It will contain an overview of what you have to say about these three topics: disruption of the carbon cycle, disruption of the hydrologic (water) cycle, and the reduction of species diversity.
Paragraphs 2, 3, and 4, are your body paragraphs.
Paragraph 2 should describe how deforestation disrupts the carbon cycle.
In paragraph 3, you’ll write about how deforestation disrupts the hydrologic (water) cycle.
In paragraph 4, you’ll explain how deforestation is related to declining species diversity.
Paragraph 5 is your conclusion paragraph. Here, you can describe how you feel about the three effects of deforestation discussed, and what we might do about it.
It’s permissible to use direct quotes from your reading, but don’t use too many. One to three such quotes should be your limit. Be sure to put a direct quote in quotation marks. For example: According to Smith, “Carbon dioxide is both our friend and our enemy.”
Begin by writing a first draft. Then, edit and rework your material to make it clear and concise. After you have reached a final draft, proofread the essay one last time to locate and correct grammar and spelling errors.
Rubric Name: Assignment 4 Rubric
This table lists criteria and criteria group name in the first column. The first row lists level names and includes scores if the rubric uses a numeric scoring method.
Criteria
Exemplary
Satisfactory
Unsatisfactory
Unacceptable
Criterion Score
Lead Paragraph
10 points
Student provides a clear, logical overview of the disruption of the carbon cycle, disruption of the hydro (water) cycle, and the reduction of species diversity.
8 points
Student provides a mostly clear, logical overview of the disruption of the carbon cycle, disruption of the hydro (water) cycle, and the reduction of species diversity.
5 points
Student provides a weak or unclear overview of the disruption of the carbon cycle, disruption of the hydro (water) cycle, and the reduction of species diversity.
0 points
Student provides a poor overview of the disruption of the carbon cycle, disruption of the hydro (water) cycle, and the reduction of species diversity.
/ 10
Paragraph 2: How deforestation disrupts the carbon cycle
20 points
Student provides a clear, logical description of how deforestation disrupts the carbon cycle.
15 points
Student provides a mostly clear, logical description of how deforestation disrupts the carbon cycle.
10 points
Student provides a weak or unclear description of how deforestation disrupts the carbon cycle.
0 points
Student provides a poor description of how deforestation disrupts the carbon cycle.
/ 20
Paragraph 3: How deforestation disrupts the hydro (water) cycle
20 points
Student provides a clear, logical description of how deforestation disrupts the hydro (water) cycle.
15 points
Student provides a mostly clear, logical description of how deforestation disrupts the hydro (water) cycle.
10 points
Student provides a weak or unclear description of how deforestation disrupts the hydro (water) cycle.
0 points
Student provides a poor description of how deforestation disrupts the hydro (water) cycle.
/ 20
Paragraph 4: How deforestation is related to declining species diversity
20 points
Student provides a clear, logical description of how deforestation is related to declining species diversity.
15 points
Student provides a mostly clear, logical description of how deforestation is related to declining species diversity.
10 points
Student provides a weak or unclear description of how deforestation is related to declining species diversity.
0 points
Student provides a poor description of how deforestation is related to declining species diversity.
/ 20
Paragraph 5: Conclusion
10 points
Student provides a clear, logical explanation of how he/she feels about the three (3) effects of deforestation and what could be done about it.
8 points
Student provides a mostly clear, logical explanation of how he/she feels about the three (3) effects of deforestation and what could be done about it.
5 points
Student provides a weak or unclear explanation of how he/she feels about the three (3) effects of deforestation and what could be done about it.
0 points
Student provides a poor explanation of how he/she feels about the three (3) effects of deforestation and what could be done about it.
/ 10
Mechanics – Grammar, Punctuation, Spelling
5 points
Student makes no errors in grammar, punctuation, or spelling that distract the reader from the content.
4 points
Student makes 1-2 errors in grammar, punctuation, or spelling that distract the reader from the content.
2 points
Student makes 3-4 errors in grammar, punctuation, or spelling that distract the reader from the content.
0 points
Student makes more than 4 errors in grammar, punctuation, or spelling that distract the reader from the content.
/ 5
Writing Style – Organization, Transitions, Tone
5 points
The assignment is written with excellent organization, thoughtful transitions, and the appropriate tone.
4 points
This writing assignment is adequately organized, but has some errors in the transitions or the tone.
2 points
This writing assignment is poorly organized, or it contains ineffective transitions and/or inappropriate tone.
0 points
This writing assignment displays little to no organization or transitions, and/or does not use the appropriate tone.
/ 5
APA Format – Margins, Font, Spacing, Headings and cover page.
5 points
The margins, font, spacing, headings, and cover page are all formatted properly.
4 points
There are 1-2 errors in the formatting of the margins, font, spacing, headings, or cover page.
2 points
There are 3-4 errors in the formatting of the margins, font, spacing, headings, or cover page.
0 points
There are more than 4 errors in the formatting of the margins, font, spacing, headings, or cover page.
/ 5
APA Format – Citations and References
5 points
All sources used for quotes and facts are credible and cited, and the references and in-text citations are all properly formatted. Each reference has an in-text citation and in-text citation has a reference.
4 points
All sources used for quotes and facts are credible and cited, but slight errors are present in the format of the in-text citations or references. Or there may be one in-text citation or reference missing.
2 points
Some sources used for quotes and facts are either not credible or there are significant errors in the in-text citations and/or references. Or there are multiple missing in-text citations or references.
0 points
The sources used for quotes and facts are not credible and/or not cited. The in-text citations and/or references are not present.
/ 5
Rubric Total Score
Total
/ 100
Overall Score
Overall Score
A
90 points minimum
B
80 points minimum
C
70 points minimum
F
0 points minimum
Deforestation
Humans have been engaging in deforestation practices for a long time in history. Industrialization has marched hand in hand with the clearing of forests. In fact, in the continental United States, about 90 percent of indigenous forests have been destroyed since 1600.
As already noted, most remaining indigenous boreal forests are located in central Canada, Alaska, northern Russia, northern Japan, and northern Mongolia. The largest remaining indigenous tropical forests are found in the northwestern Amazon Basin and in the Guyana Shield of South America. This region includes Guyana, Surinam, Venezuela, Colombia, and Ecuador. Other regions with extensive tropical forests include Indonesia, Cambodia, Vietnam, Thailand, southern India, and the Congo Basin in the Democratic Republic of the Congo.
Global forests act as carbon sinks by absorbing carbon dioxide while also uploading oxygen into the atmosphere. Carbon sink capacity is vital—and obviously reduced as forests are cleared. This adds heavily to global greenhouse gas production and contributes to global warming. Additionally, trees and other kinds of vegetation emit carbon dioxide when they die.
To learn more about how carbon sinks work, watch this video:
According to the EPA, the most significant anthropogenic (human-caused) source of global warming is the burning of fossil fuels. The second major cause is deforestation, particularly the destruction of tropical forests. According to NASA, if the current rate of deforestation isn’t curbed radically, the world’s rainforests may be completely destroyed in as few as 100 years.
Deforestation clearly affects the carbon cycle. However, it also disrupts the hydrologic (water) cycle. Trees, especially those in tropical forests, emit water vapor. Global climate is regulated by water vapor in the atmosphere. This vapor is also considered the world’s chief greenhouse gas. Thus, changes to the water cycle inevitably lead to changes in global climate patterns.
Deforestation is also a major factor in the global decline of species diversity. According to the National Geographic Society, some 70 percent of Earth’s plants and animals are impacted by the destruction of native habitats. Some species can adapt to changes in their native habitats. Some may be able to migrate to other locations. But others can’t adapt and become extinct.
Finally, deforestation leads to soil erosion. Tree roots serve as anchors. When these roots are destroyed, soil may be washed or blown away. According to the World Wildlife Fund (WWF), upward of one-third of the planet’s arable land has been lost to deforestation just since 1960. Part of the problem is clear-cutting forests to grow cash crops like coffee, palm oil, and soy. These crops don’t have root systems capable of anchoring the soil. That makes erosion more likely.
Desertification
From an ecological perspective, all of Earth’s biomes are headed in the wrong direction. That’s clearly evident when it comes to the process called desertification. This is the process by which fertile land becomes desert. According to UNESCO, globally, “Twenty-four billion tons of fertile soil disappears annually. Over the past 20 years, the surface area lost is equal to all of the farmland of the United States.” This means roughly one-third of the world’s land surface is threatened by desertification. This threatens food production, which is particularly problematic for soaring populations, especially in less developed nations.
Desertification is caused by the destruction or removal of “green” coverage. Although there are many reasons for this, the two primary causes are human activity and climate change.
Globally, desertification results from human overexploitation of natural resources. For example, in regions like Africa and the Middle East, the burning of firewood for energy is a major problem. In the long term, these drought-plagued regions must turn to renewable energy sources based on solar, hydrological, and wind technologies. In the short term, the use of natural gas and petrol is preferable to stripping the land for firewood.
In semi-arid environments prone to desertification, three human activities are of major concern.
Overcultivation exhausts the soil, reducing vital nutrients.
Overgrazing by poorly managed livestock strips away the vegetation cover. Overgrazing encourages erosion and deforestation.
Improper irrigation leads to an increase in salt levels of croplands. (This is called salinization.) The salty environment is hostile to healthy plants.
Desertification is especially problematic in certain parts of the world. Over many decades, political and economic instability has wreaked havoc in Western Asia and North Africa. Unfair trade practices that impact oil-producing nations in Western Asia have been part of the problem.
Evidence of Global Warming and Climate Change
Are humans facing extinction? This is not a rhetorical question. Mounting evidence from various scientific sources suggests that humans are in denial about their peril. Scientific reports are dire, but experts believe we still have time to address these issues and reverse the situation.
Experts rely on information provided by observable data. Studies show that land and ocean surfaces are warming at an unprecedented rate. We can observe rising sea levels, accelerating desertification, and a higher frequency of weather patterns like tornadoes, hurricanes, and tsunamis. We can also observe unnatural patterns of desertification and precipitation. This evidence shows that global warming and climate change are observable.
Greenhouse Effect
(NASA public domain image)
Earth’s natural environment is changing due to the greenhouse effect. To understand the greenhouse effect, study the image below. On the left you’ll see that the surface of the planet is warmed even as a surplus of heat is radiated back into space. On the right you’ll see how greenhouse gas molecules absorb infrared (heat radiation) and scatter it over the planet.
Greenhouse gases include water vapor, carbon dioxide, and nitrogen oxides emitted by burning fossil fuels like coal and petroleum. Methane (CH4) is another greenhouse gas. Methane is a component of natural gas that is used in a number of industrial processes. Foremost among these are the gas and petroleum industries.
Methane also gets into the atmosphere from other sources. For example, landfills emit methane, as do wetlands and areas of cattle ranching. Methane stored in long-buried vegetation is being released into the atmosphere as the arctic permafrost has melted due to global warming.
We don’t know exactly what this means. However, the ratio of methane to other greenhouse gases has been increasing at an alarming rate. This is a serious issue. Although methane doesn’t linger for a long time in the atmosphere, it’s eight times more potent than carbon dioxide over the short term.
The Mechanics of Global Warming
How does global warming work? Water vapor is our planet’s “thermostat.” It’s also our chief greenhouse gas and the key to regulating Earth’s temperature. However, as NASA researchers have established, an increase in carbon dioxide and other greenhouse gases amplify the “thermostat” setting. At its current rate of emissions, carbon dioxide alone can double the heat retention of water vapor in the atmosphere. As global warming increases the amount of water vapor in the atmosphere, we observe a positive feedback loop. (This means the rise in temperature is accelerated.) As a result, we end up with a “new normal,” like daily temperatures exceeding 120 degrees Fahrenheit in parts of Pakistan.
Let’s look at the Keeling curve.
The Keeling Curve
(NOAA public domain image)
The Keeling curve is a graph used to plot the ongoing change in carbon dioxide in Earth’s atmosphere. It is one of the best-known, ongoing studies of the relationship between carbon dioxide and global warming. The Keeling curve is named for Charles David Keeling. He was a scientist who began tracking carbon dioxide levels at Mauna Loa, Hawaii, in 1958. He continued to direct the study until his death in 2005.
Notice on the graph that the the carbon dioxide level in Earth’s atmosphere exceeded 400.00 parts per million (ppm) in 2013. The last time carbon dioxide exceeded this rate was millions of years ago—long before the emergence of the human species.
Another important indicator of global warming is the rate of arctic ice melt. That rate is known to correlate to rising levels of carbon dioxide in the atmosphere. Study the image provided by the National Oceanic and Atmospheric Administration (NOAA).
Average Sea Ice Concentration on Earth
NOAA public domain image
The image shows that the rate of polar cap melt is another positive feedback loop. That is, as the Arctic polar ice melts due to global warming, dark ocean surface areas expand. This causes more heat to be stored in the polar environment, leading to more ice melt, and so on. The feedback loop is called “positive” because it amplifies changes in a system.
Species Extinction
You had a brief preview on species extinction during the discussion of urban sprawl. There you learned that human destruction of natural habitats is the main cause of species loss in the United States. This observation can also be applied worldwide.
A number of recent studies make it clear that humans are responsible for the extinction of many species. However, the topic is extremely complex. It’s difficult to establish current species extinction rates for a number of reasons. For one, experts cannot accurately determine the actual number of species on the planet. Consider this quote from the World Resources Institute as reported by the World Wildlife Fund:
“Scientists were startled in 1980 by the discovery of a tremendous diversity of insects in tropical forests. In one study of just 19 trees in Panama, 80 percent of the 1,200 beetle species discovered were previously unknown to science . . . Surprisingly, scientists have a better understanding of how many stars there are in the galaxy than how many species there are on Earth.”
Extinction is a natural phenomenon. In fact, it’s been estimated that 99 percent of all species that have lived on Earth are now extinct. However, this extinction occurred at a natural background rate of about one to five species per year. Scientists now conservatively estimate that the planet is losing species at 100 to 1,000 times this rate. That means dozens of species are going extinct every day.
Scientists generally agree that extinction rates have reached levels not seen since the dinosaurs died out 66 million years ago. Some theories claim that dinosaurs died out after a huge asteroid hit the planet near the Yucatan Peninsula. Humans are the current “asteroid.” The rate of species extinction in the human (anthropogenic) era is much faster than in the era of the dinosaurs.
According to your required reading (in Science Advances), species are dying off due to
Clearing of land for farming, logging, and settlement
Introduction of invasive species to native habitats
Release of carbon emissions that drive climate change and ocean acidification
Introduction of toxins that alter and poison ecosystems
Paul Ehrlich, author of The Population Bomb, was one of the scientists who wrote the article in Science Advances. According to the authors, there’s still hope for the future. “Avoiding a true sixth mass extinction will require rapid, greatly intensified efforts to conserve already threatened species, and to alleviate pressures on their populations—notable habitat loss, overexploitation for economic gain and climate change.”
Ocean Acidification
Although the burning of fossil fuels has increased carbon dioxide levels in the atmosphere, the oceans have helped slow down the inevitable impacts of the greenhouse effect. In effect, the oceans act as huge carbon sinks. About 50 percent of human-generated carbon dioxide is being stored in the world’s oceans. Recent studies have shown that, as a result, the oceans are becoming more acidic. When carbon dioxide dissolves in water, it produces carbonic acid. The increase of carbonic acid in ocean waters has caused oceanic pH to drop.
pH is a measure of acidity and alkalinity of a substance. The pH scale ranges from 0 to 14, with 7 being considered neutral. A pH reading below 7 is considered acidic. A pH reading above 7 is considered alkaline (base).
The average ocean pH has dropped from 8.2 to 8.1. That doesn’t sound like much, but even small changes impact marine life. For example, some types of marine life depend on calcification. This is the process by which organisms form shells. Oysters, shrimp, clams, mussels, lobsters, and some species of fish corals all engage in calcification. Coral reefs depend upon calcification to grow. High acidity of ocean water makes it more difficult for these species to produce their shells.
Additionally, acidic water can have a dramatic impact on plankton and phytoplankton, which are the base of the oceanic food chain. These microscopic organisms drift or float and are eaten by many larger organisms. For example, whales thrive on plankton, as do many other oceanic species. An increase in acidity is expected to spur a range of responses in plankton and phytoplankton. Some species will die out, while others will begin to flourish. This dynamic can seriously change the marine ecosystem that produces 50 percent of our oxygen on the planet.
References
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Biello, David. “Risks of Global Warming Rising: Is It Too Late to Reverse Course?” Scientific American, February 27, 2009. Retrieved May 22, 2018, from http://www.scientificamerican.com/article/risks-of-global-warming-rising/
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