Introduction

If there is one thing we can learn from the history of hominids, it is that actions leave imprints. To the surprise of many, the impacts of humans (and even pre-humans) on their surroundings is not a modern phenomenon. In fact, this trend has been happening for a remarkably long time. Charcoal remnants found in ancient hearths suggest that Homo erectus mastered the art of fire two million years ago, and stone tools date back even further. Fire and tool usage, predation, and landscape alteration have since then been trademarks of hominid presence (Steffen et al., 2007).
One of the earliest recorded impacts that humans had on their surroundings were the megafaunal extinctions occurring in the late Pleistocene. In a very predictable pattern observable in the following figure, human migration was accompanied by the extinction of vast numbers of large animal species (Steffen et al., 2007).

UC Davis Geology 120 Lecture 9

While the hunters responsible for the megafaunal extinctions thousands of years ago did indeed impact their environment, their influence was fairly localized to the regions they inhabited (Steffen et al., 2007). 

As societies advance and populations grow, human impacts on the environment increase. My goal is to explore some of the problems we humans are causing in the 21st century, and illustrate how they are amplified (or even created) by our vast numbers. I plan to elaborate on current issues including but not limited to global warming, landscape alteration, sea-level rise, threats to wildlife, shifting storm patterns, water and air pollution, and illness and disease. 

Rather than focusing on the doom and gloom aspects of humanity alone, I will also describe positive changes humans are making to lead the world into more sustainable future. I hope to share various methods humans are utilizing to cope with or slow their population growth, reduce pollution, and conserve wildlife habitats.

Essentially, I aim to illuminate the many ways in which, as my dad would say, "We are sawing off the limb we sit on,"but also spread cheer by explaining several ways in which we humans are innovatively glueing, taping and splinting our proverbial, mangled branch back to its' stump.

Works cited:

Steffen, Will, et all. The Anthropocene: Are Humans Now Overwhelming the Great Forces of Nature? Royal Swedish Academy of Sciences 36.8: 614-621.

Our Prodigious Population

From the origin of humans until the early 1900s, human population size had increased in a relatively stable manner. Around 1950, however, the pattern changed, as population size began the steep incline illustrated in the following figure.

facingthefuture.org

In just the past 60 years, four billion people have been added to the global population (Bongaarts 2009), bringing the grand total up to 7 billion individuals. The Industrial Revolution heavily contributed to this population explosion, by virtue of the innovative platform it provided, as well as the sudden expansion of fossil fuel usage. Following the Industrial Revolution, heightened public health awareness and a habitat shift from villages to cities further supported the increasing size of the population (Steffen et al., 2007).

The rapidly expanding human population quickly lead to an overwhelming human dominance over many of earth's ecosystems through direct and indirect effects. Some of the main factors contributing to increasing human dominance are agricultural and recreational land use, and overexploitation of resources (refer to the following figure) (Vitousek et al., 1997).  In fact, today, nearly 1/2 of land surfaces have been transformed by humans, and not a single ecosystem is left unaffected by the human race (Vitousek et al., 1997). 

Vitousek, et al., 1997

So many ecosystems, natural resources and species have been severely altered and damaged by human activity. It is ironic that all of the damage humans have inflicted thus far on their surroundings may eventually come full circle to damage our own race's well-being. Dr. Martin Luther King Jr. eloquently explained this concept by saying:

"Unlike plagues of the dark ages or contemporary diseases we do not understand, the modern plague of overpopulation is soluble by means we have discovered and with resources we posses. What is lacking is not sufficient knowledge of the solution but universal consciousness of the gravity of the problem and education of the billions who are its victim."

Depicting ourselves as the ultimate victims of our own actions is a powerful tool when inspiring humans to chose to live more sustainably. And like Dr. King said, we already possess a great deal of knowledge about the problem at hand: we simply need to apply it to our lifestyles.

Works cited:

Steffen, Will, et all. The Anthropocene: Are Humans Now Overwhelming the Great Forces of Nature? Royal Swedish Academy of Sciences 36.8: 614-621.

Vitousek, Peter M., et al. Human Domination of Earth's Ecosystems. Science 277.5325: 494-499.

Humans as Biological Creatures

The human capacity for innovation is truly remarkable, and has allowed us to completely escape the limits of natural selection that we were once subject to, particularly in more privileged countries like our own. However, some might argue that the extent of our innovations has become a burden on our planet. Many of these creations are responsible for improved public health, longer life spans, larger populations, and luxuries that were, up until recently, unimaginable. So, why would anyone doubt the remarkable and vast creations of "man"? What could warrant a person's disapproval when from such innovativeness stems rapid transport, modern medicine and advanced agriculture?
I would like to introduce the concept of a carrying capacity. Carrying capacity is, in essence, the population size of a given species that an ecosystem can support indefinitely without the said population or ecosystem being destroyed. The carrying capacity  for a population is determined by the food and water availability, as well as any other necessary resources provided by the ecosystem in question. In nature, population sizes often level off at their designated carrying capacity, fluctuating slightly above and below the line over time. If a population at any point exceeds its' carrying capacity, it may damage its' resource availability permanently, effectively lowering the carrying capacity. Below is are two figures illustrating the various approaches of a population towards its' carrying capacity. The first figure depicts, in yellow, a population approaching, and not exceeding, its' carrying capacity; and, in blue, a population approaching, exceeding, and fluctuating about its' carrying capacity. The second figure illustrates what can often happen to a population if it overshoots its carrying capacity too intensely for its' ecosystem to recover: a permanently lowered carrying capacity.

piranha-fury.com

paulchefurka.ca

Although the global human carrying capacity is not yet known, some scientists speculate that we humans have already exceeded (or far, far exceeded) our own carrying capacity. If this is the case, humans may already be depleting their resources at a rate faster than they can recover. In his paper "Ecological Footprints and Appropriated Carrying Capacity: What Urban Economics Leaves Out," William Rees explains that while many of us believe our species has escaped natural checks and balances with our advancing technology and "assumed mastery" of nature, we are still a biological species just like any other, and can be affected by changes in our ecosphere.
So, what resources might humans already be damaging irrevocably? What global changes are we as a species causing or exacerbating? How might the damage and change we cause impact the wellbeing of our own species, not to mention countless others? In the following entries, I will answer these questions and provide a number of examples as supporting evidence.

Our Cryptic Carrying Capacity

Nuclear waste, acid rain, rising sea levels, polluted oceans, lowering water tables, river and estuary siltation, poisonous drinking water, decreasing wetlands, desertification, deforestation, overgrazing, habitat loss, species loss, topsoil loss, arable land encroachment, ozone layer damage, and global warming are all on the list of anthropogenic environmental damages that threaten the wellbeing of humans and other living organisms on our planet (Cohen, 1997).
So, considering all of these impending and immediate ecological dangers, which are undoubtedly exacerbated as human numbers continue to rise, what is the human carrying capacity? How many of us can the Earth truly support? Can the Earth continue to support 7 billion of us, not to mention the U.N.'s projected increase, to between 7.8 and 12.5 billion individuals by 2050 (Cohen, 1997)?  The answer is very complex, relying on many variables that are subject to change.
At least 65 estimates of the maximum possible human population, ranging from less than one billion to over 1000 billion. These estimates vary so greatly because of the different methods used to calculate them. For example, food is often considered to be the single greatest limiting factor on human population size, so maximum yields and minimum nutrient requirements per person are often incorporated into carrying capacity estimates. However, the calculations get a bit convoluted when we realize that maximum food produced depends on somewhat unpredictable variables such as soil types, water availability, the length of growing seasons, crop requirements, farming technologies, farmer education, transportation of farm inputs and outputs, economic demand of the goods produced, and international politics influencing trade (Cohen, 1997).
Yet another inaccuracy of many carrying capacity approximations arises when we observe that the consumption standards vary by country. For example, the meat choices and quantities are very different from one country to the next, as can be seen in the following figures. Americans acquire about 25% of their calories from animal products, resulting in plant calorie production that is 4 times greater than the minimum amount required for our county, in order to feed both people and livestock (Cohen, 1997).

world-ostrich.org

dipasdailydumplings.blogspot.com

To skew matters yet further, some scientists are of the opinion that food is not the primary limiting factor for population, while factors such as nitrogen, phosphorous, land, fresh water, energy, sunlight, diseases, waste management, or climate change may have stronger controls over the size of our population. We must not forget that upon meeting certain natural constraints, humans may adapt and overcome them (Cohen, 1997).
So, it appears that our population limit is determined by a combination of natural limits and human actions, both of which are subject to change, and therefore exceedingly difficult to predict (Cohen, 1997). If we cannot predict these two factors, we are hard pressed to accurately determine our true carrying capacity! What we do know as of now, however, is that improving on sustainability practices- from energy usage to farming to waste management- results in decreased resource consumption per person, and increased resource availability for other members of our population.

This information guides me to, what I believe, is a logical assumption: if any of the aforementioned environmental damages occur at the hands of our species, we are effectively lowering our carrying capacity. An ecology teacher I knew once said: "We may not know the numerical value of the human carrying capacity, but might it already be upon us? In our country alone, prisons are full, schools are understaffed, and some people are, believe it or not, hungry. And let's not forget about the hunger and disease in the developing countries." The following figures depict rates of U.S. prison overfilling, U.S. hunger, and world hunger, respectively.

law.utoledo.edu

cleveland.com

onemanonebikeonefight.com

While my teacher's observations weren't based on the intensive scientific calculations mentioned above, I share her sentiments- I believe that the state of human welfare today indicates the arrival to (or even surpassing of) our carrying capacity. In the following sections, I will share stories that I believe exemplify the need for an end to human population growth.

Works cited:
Cohen, Joel E. Population, Economics, Environment and Culture: an Introduction to Human Carrying Capacity. Journal of Applied Ecology 34: 1325-1333.

The Damage: Freshwater Systems (warning: graphic imagery)

A surprising number of human activities result with waste being disposed of in nearby waterways. Hormones from birth control, sunscreen residue, pesticides, petroleum, human sewage, animal waste, and nutrient-rich fertilizers all wind up in our streams, rivers, lakes, and ultimately, oceans. Many developed countries have effective methods of treating water and regulating what enters many waterways, making drinking water relatively safe. However, many developing countries struggle more with water sanitation, because of a lack of infrastructure for keeping water clean (Nat'l Geographic).

An enlightening and sometimes startling story of pollution lies in the waters of the Ganges River, which meanders for 1,600 miles from the Himalayas through northern India, on into Bangladesh and then out into the Bay of Bengal (as can be seen in the following figure).

ncge.co

For hundreds of years, Hinduism has considered the Ganges to be a symbol of spiritual purity, and the earthly incarnation of the deity "Ganga." Because of the river's spiritual value, it is a common practice to purify one's self by touching, bathing in, or consuming its' water. Many Indian people have described the Ganges as "the river of India," reflecting upon its' rich history, great beauty, and holiness (Hammer, 2007).

ai.stanford.edu

However, the Ganges of today is, in some ways, a stark contrast to its' historical nature. In the past 30 years, India's population has risen to almost 1.2 billion, a huge number that is second only to China. Such a large and rapidly increasing population has resulted in an overwhelming amount of consequences. Higher food demand has resulted in record amounts of water being siphoned from the Ganges. Industrial dumping of chemicals into the Ganges is often severely unregulated, and when there are regulations, they are often not enforced. Today, around 400 tanneries continue to release their chemical waste into the river, and industrial leaks have been known to kill by the thousands. Today, the amount of human sewage released into the river has doubled since the 1990s, and could double again soon (Hammer, 2007).
The consequences of anthropogenic pollution in the Ganges are far reaching. So far, we know that certain parts of one of the Ganges' tributaries, the Yamuna River, has pollution-induced dead-zones, where aquatic life no longer exists. We also know that the coliform concentration in the sacred city of Varanasi is currently 3000 times higher than the safety standard determined by the U.N. Additionally, many claim that the water of the Ganges River is the main cause of increased infant mortalities, skin abnormalities, and other health ailments (Hammer, 2007).

123rf.com
"The river had turned the color of Coca-Cola" -Ramesh Chandra Trivedi of the Central Pollution Control Board (Hammer, 2007).

A source of pollution that is particularly hard for me to image is decomposing human bodies. As recent as 1997, a clean up effort lead by activist Rakesh Jaiswal recovered 180 human bodies from a mile long stretch of the river. Since then, a cemetery has been built along the riverside and a slightly stricter ban has been placed on body disposal, although it is still violated (Hammer, 2007).

all-about-india.com

In the past 20 years, government efforts have been made to shut down some of the grossest Ganges polluters, and allocating $100 million to the building of water treatment plants in 25 river cities. Unfortunately, the treatment plants have thus far been a huge disappointment: as of 2002, they have been able to process only 1/3rd of the 600 million gallons of sewage entering the Ganges River daily. Regarding this grave issue, a saddened and frustrated Jaiswal explained:
"We can send a shuttle into space, we can build the [new] Delhi Metro [subway] in record time. We can detonate nuclear weapons. So why can't we clean up our rivers? We have money. We have competence. The only problem is that the issue is not a priority for the Indian government."

If you would like to learn more or have a visual experience of the plight of the Ganges, I would recommend this short video: http://www.ft.com/cms/s/0/3b4c2046-91f6-11e2-a6f4-00144feabdc0.html#axzz2UXLhUjZ0

While the Ganges River may seem like an extreme example of water pollution to countries that are more developed, this level of pollution is actually somewhat typical for many developing countries. According to U.N. water statistics, more than 90% of wastewater used in developing countries is left untreated as it reenters waterways. This, of course, puts pressure on the availability of safe drinking and bathing water, as well as threatening food security. The strain of water pollution is often disproportionate, as some heavily polluting industries (such as leather or chemical) move from higher to lower income countries (U.N. Water).
What is humbling for developed countries is when news of how far from perfect their own freshwater systems are. In March, a study was released claiming that over 50% of U.S. rivers are too contaminated to effectively support life. This study comes from the EPA, which determined that 55% of U.S. rivers were in "poor" condition, primarily due to excess amounts of nitrogen and phosphorous runoff from agricultural land, sewer systems, and cities (Mail Online). Furthermore, 9% of the rivers and streams sampled showed bacterial counts that exceeded safe levels (Mail Online).
While countries such as our own may have comparatively modern infrastructure for dealing with pollution and contamination, there is clearly still much room for improvement. While human populations continue to increase, the pressure on our water sources grow ever greater. Continuous improvements are imperative if we plan to maintain reasonable safety standards for our own usage, and the ecological integrity of our waterways.


Works cited:

Hammer, Joshua. A Prayer for the Ganges. Smithsonian Magazine Nov. 2007. Print. 27 May 2013.

Daily Mail Reporter. More than HALF of U.S. rivers are too polluted to support life as shocking report reveals scale of water contamination. Mail Online: Daily Mail, 27 Mar. 2013. web. 27 May 2013.

Statistics: Graphs & Maps. U.N. Water, n.d. web. 27 May 2013.

Water Pollution: Find Out What's in the Water. National Geographic: Environment, n.d. web. 27 May 2013.

The Damage: Marine Systems

Human impacts do not stop with freshwater, but continue on into our oceans, often transported by the rivers themselves. These issues often arrive in the form of excess nutrients (nitrogen and phosphorous, generally) and literal garbage. Carbon emissions, which are delivered from the atmosphere rather than tributaries, also severely impact the ocean by increasing its' acidity. These issues are among others threatening the livelihood of our oceans, including habitat loss, overfishing, and other environmental problems (Diaz et al., 2008).


Oceanic Dead Zones


Eutrophication, or the addition of nutrients from the environment, shows its' first effects as water turns green due to the enhanced production of plants and algae (depicted in the following image). At this time, dissolved oxygen levels begin to decrease due to slowed or even halted photosynthesis by the organisms below the overproducing (and sunlight blocking) top layer. Many planktonic algae are unable to survive under these circumstances, and are incorporated  into the organic seabed layer and the microbial respiration that occurs there. As the dissolved oxygen concentration decreases to hypoxic conditions of around 2ml of O2/liters or less, benthic organisms begin to react by leaving their burrows and risking exposure, forming "dead zones." Then, at about 0.5ml of O2/liter (severe hypoxia) mass mortality ensues (Diaz et al., 2008).

A dead zone in the Louisiana Delta, science.nasa.gov

As organic matter and nutrients build up over time, hypoxic conditions can begin to exhibit a seasonal periodicity based on the large fluctuations among animal populations it causes. If such hypoxic events persist in regions for years, the zone can begin to expand further into the ocean, and if dissolved oxygen levels continue to decrease, H2S is released by microbes as anoxic (no oxygen) levels are reached. This is problematic because when hypoxia becomes severe on a seasonal basis, only benthic species of smaller size, shorter lifespan, and opportunistic behaviors are favored (Diaz et al., 2008).
Oxygen depletion along coasts is tightly associated with concentrated human populations and large watersheds (illustrated in the following image). Since the nitrogen fertilizer revolution in the 1940s, eutrophication has noticeably worsened in coastal ecosystems from the Baltic Sea, to the Adriatic Sea, to the Black Sea, to the Chesapeake Bay.

Diaz et al., 2008

While we are beginning to see the species specific effects of eutrophication and hypoxia, much is still unknown about the overall ecosystem impacts. So far, observations suggest that more energy is diverted into lower (microbial) trophic levels, at the loss of higher organisms in surrounding waters (depicted in the following figure).

Diaz et al., 2008

Nurseries and recruitment sites tend to suffer the most from the disproportionate energy allocations because hypoxia most often occurs in summer, which is an energy-intense season for predators. As might be predicted, regularly or seasonally hypoxic areas experience a decrease in secondary production by 1/3 to 1/2. Unfortunately, this pattern really is documented to occur near populated areas, and close to home, too: the Gulf of Mexico contains a dead zone (hypoxic area) reaching up to 15,000 square km born from the Mississippi's nutrient-rich waters. This is an unfortunate result of American farming and urbanization today, as seen in the following figure (Diaz et al., 2008).

coastalscience.noaa.gov

"Just Throw it Away"

Today, plastics easily find their way into the ocean after being dumped or spilled. Even if garbage is not deposited near a waterway, it can be picked up by rainwater and make its way into the ocean. The common misconception is that plastic does not degrade in the ocean, but accumulates in a gigantic garbage island. While these plastics do not biodegrade, they do photodegrade, producing small plastic particles and toxic chemicals in the process. Due to oceanic currents, these plastic particles accumulate in high concentrations in the five major ocean gyres shown below.

boatus.com

I recently had the pleasure of hearing Dr. Marcus Eriksen, a leading anti-plastics activist, speak of his many expeditions out into the worlds oceans. According to his website, 5gyres.org, the broken down plastic particles, including polucarbonate and polyestrene, never fully disappear, but become small enough to falsely attract marine organisms to ingest them. The United Nations Environmental Programme estimates that about 1 million seabirds and 100 thousand marine mammals die annually due to the presence of plastic in the ocean (Saido et al., 2009).
To make matters worse, these plastic particles actually attract toxins and contaminants within the water, such as PCBs (polychlorinated biphenyls) and DDT (dichlorodiphenyltrichloroethane). This means that as plastics circulate and degrade in ocean gyres, they are simultaneously acquiring more toxicity before (often) being ingested by a marine organism (5gyres.org).
Shockingly, 44% of seabirds, 22% of cetaceans, and all sea turtle species have been found with plastics in or around their bodies (as illustrated in the following images). This is ecologically damaging because ingestion or entanglement can lead to starvation, dehydration, and ultimately death (5gyres.org). 

questgarden.com

theplasticocean.blogspot.com

However, the risks of plastic in the ocean reach still further: what is plastic doing in our food web? If we eat animals who have eaten plastic, what impacts will those plastics and associated toxins have on us? The jury is still out as a great deal of research on this topic continues (5gyres.org). To me, it seems probable (and so very ironic) that the waste we so carelessly let drift out of sight and out of mind will ultimately come back to haunt human health.


From the Atmosphere to the Ocean: There is a Connection

Sources of greenhouse gas pollution, such as motor transportation and energy generation, do not only contribute to the greenhouse effect. Another major problem caused by carbon emissions is ocean acidification. In fact, according to a Scientific American article by Brian Bienowski, roughly 1/3 of carbon emissions from the burning of fossil fuels are now said to have been absorbed by the 'sponge-like' ocean water.
Ocean acidification happens when atmospheric CO2 is absorbed by the ocean, which reacts with water to form bicarbonate ions, effectively increasing the acidity. Acidic conditions in the ocean cause problems with the production of the calcium carbonate shells and skeletons of shellfish and corals. Consequently, the populations of such organisms decline, potentially causing a trophic cascade and a drastic change in species composition. This is because a huge number of fish species rely on coral reefs, and shellfish are important members of the marine food chain (Bienowski, 2013). For humans, coral is also an invaluable source of income from tourism. It might be considered even more valuable as a coastline protector from tsunamis for certain countries (Huffingtonpost.com, 2012).
Obviously both of these organisms are ecologically important, and a decline in their numbers could result in harm coming to the marine species that we rely on (shown in the following figure). 

thinkprogress.org

In his article, Bienowski claims that fish constitute an average of 6% of human protein. However, we know that seafood also traditionally composes the majority of certain diets around the world (Huffingtonpost.com, 2012). This means that any alteration to the ecologic systems that involve calciferous organisms might affect our diet. Negative affects are unfortunately already beginning to manifest in such forms as suffering oyster hatcheries, as acidity slows their growth (Huffingtonpost.com, 2012).

Oyster growth affected by ocean acidification, readthedirt.org

Hopefully the examples I have provided make it easy to see how the problems we cause can affect many other living organisms, and even come back to harm us. Eutrophication can cause severe ecological damage and decrease fish yields, economically impacting fishermen and limiting an important food source. Plastic pollution can kill marine organisms upon ingestion, and what doesn't kill them (likely) makes them toxic. This simultaneously decreases fish yields and endangers marine and human health. Ocean acidification causes disruptions in ecological systems and slows or stops the growth of economically important marine organisms. Unfortunately, the larger the human population, the further these situations can spiral out of control.

However, it is not all bad news, and there may be some improvement efforts for our oceans on the horizon. After a few more examples of why our population is the root of so many of our problems, I will explain ways in which humanity is beginning to be responsible for its actions.

Works cited:

Bienowski, Brian. U.S. Efforts on Ocean Acidification Needs to Focus on Human Impacts. Scientific American 11 Jan. 2013. Print. 27 May 2013.
Diaz, Robert J., et al. Spreading Dead Zones and Consequences for Marine Ecosystems. Science 321: 926-929.
Ocean Acidification is Climate Change's 'Equally Evil Twin,' NOAA Chief Says. Huffington Post 9 Jul. 2012. web. 27 May 2013.
Saido, Katsuhiko, et al. New Contamination Derived from Marine Debris Plastics. 238th ACS National Meeting, 2009.
What is the Problem. 5gyres.org 2013. web. 27 May 2013.

The Damage: Land

Desertification is a degradative process by which dry land regions become dryer and more arid. This process often occurs following the removal of vegetation, when soil becomes dry and easily movable by winds or floods. As the dried topsoil layer disappears, lower layers of infertile soil are exposed, making farming or reestablishment of plants and animals increasingly difficult. Processes driving desertification include deforestation, overgrazing, irrigation increasing soil salinity, agricultural tilling, and more.  However, direct human actions are not the only force behind deforestation: on a larger scale, desertification is caused by climate change, drought, poverty, inadequate infrastructure, and growing population size (Oasisglobal.net). While many of these factors can be seen as interrelated, you might be curious about poverty as a driver of desertification upon first glance at my list. Below is a very informative video explaining how drought and poverty, as well as social inequality, contribute to desertification.

http://www.alternativechannel.tv/communication-durable/videos/Conversations-with-Earth/Drought-causing-devastation-Kenya/2743/;jsessionid=82E834461041010E1203132B03A235A8

Unfortunately, the reason desertification has thus far not received much global attention is because for now, it is primarily (90%) occurring in the arid regions of developing countries, whose people are more concerned with surviving than implementing eco-friendly practices (Carrington, 2010). Additionally, economies are driven by pleasing city dwellers rather than very poor farmers, and not much thought is put into what good soil actually means to our species (Carrington, 2010). The following image illustrates the regions of the world that are at varying risks of desertification. Notice how many of the high risk regions are in developing regions, such Africa and the Middle East:

wikipedia.org

“The top 20cm of soil is all that stands between us and extinction.” This statement may seem radical, but is somewhat legitimized because it was uttered by the United Nation’s top drylands official, Luc Gnacadja. Mr. Gnacadja also believes that desertification and land degradation are the greatest threat to humanity at present. He goes on to explain that general land degradation by humans directly affects humans: desertification is connected to the Somalian political conflicts for productive land security, record Asian dust storms that impacted human health (see the following image), and the food price insecurity following a Russian drought. 

sciencedude.blog.ocregister.com

To put things in perspective, we have degraded roughly a quarter of available lands between the 1980s and today, and an additional 1% continues to be virtually ruined annually. This is particularly significant because aside from the aforementioned harm to humans, desertification plays a large role in decreasing biodiversity and climate change. This is due to the large carbon concentration in the top layers of soil that are lost during desertification. Once this layer is gone, many organisms that rely on the mineral nutrients it provides are unable to survive, including our crops! 

Today, half of the world's livestock and a third of our crops are grown on drylands. As our population continues to grow, do we want to jeopardize the livelihood or our soil, livestock, and crops, not to mention ourselves? Clearly, we need to take this issue seriously before we irreversibly damage the land and soil that we so desperately need.

The following section will be dedicated to the positive changes we have made, and what we have to look forward to, or work towards, in the future.

Works Cited

Carrington, Damian. Desertification is Greatest Threat to Planet, Expert Warns. Guardian.co.uk, 15 Dec. 2010. Web. 4 Jun. 2013.

What Causes Desertification? Oasisglobal.net, 2006. Web. 4 Jun 2013.