Within the last 50 years, the world has experienced incredible changes thanks to human innovation and creation. Now home to over seven billion people, Earth continues to allow humans to thrive and develop in ways that no other species before has ever been able to. However, because no other species has ever been able to accomplish the social and technological advances that humans have, this is the first time that the planet has ever had to withstand the pressure of putting up with so much rapid growth and development. Within our relatively short occupancy of the Earth, we have managed to domesticate over one third of dry land, cut down over one quarter of tropical forests, and raise atmospheric CO2 levels past 400 ppm (Steffen W., et al. 2015). All of these things were done for the sake of progress; we needed electricity so we burned fossil fuels, we needed wood for building and land for development so we cut down forests, and we needed to sustain a growing population so we did these things more and more. We have now reached a pivotal point in the history of mankind; the tipping point of the Earth’s ability to sustain us. Mankind’s actions have put too much pressure on the delicate planet, and changes are beginning to occur as a result of these accumulating actions. If humanity doesn’t slow down and begin taking steps to slow our planetary impact, then we will need to learn to quickly adapt to the conditions of a planet that has been continually altered and ravaged by a single species in the name of progress.
An article published in the magazine Science in January of 2015 lists 9 planetary boundaries that outline “ a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth System” (Rockström J., et al. 2015). These boundaries, if adhered to, provide the necessary restrictions for mankind’s planetary degradation if we are to keep the Earth in the stable state that it has been in for the past 11,700 years of the Holocene. The 9 planetary boundaries relate to the following Earth System processes: climate change, change in biosphere integrity (rate of biodiversity loss), stratospheric ozone depletion, ocean acidification, biogeochemical flows (P and N cycles), land-system change, freshwater use, atmospheric aerosol loading, and introduction of novel entities (chemical pollution) (Rockström J., et al. 2015). Of these 9, mankind has already surpassed the boundaries placed for climate change, change in biosphere integrity, biogeochemical flows, and land-system changes. As time moves forward, humans must make any and all attempts that they can to prevent any more of these boundaries from being exceeded. The goal of this research paper will be to explain each of the 4 planetary boundaries that we have already exceeded, and to explain what the average person can do in their own lives to prevent the further destabilization of our so-far hospitable home, Earth.
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| Our lovely planet. |
Climate change, in terms of the proposed planetary boundary, refers directly to two control variables: atmospheric carbon dioxide levels and radiative forcing. Atmospheric carbon dioxide levels, measured in parts per million (ppm), measure the total concentration of carbon dioxide in the Earth’s atmosphere. (Rockström J., et al. 2015) As this concentration increases, so too does the amount of heat trapped on Earth from the sun’s radiative waves; waves of infrared radiation from the sun reflect off of the Earth’s surface, and as they travel through the atmosphere CO2 molecules absorb their energy and prevent many of these IR waves from escaping. Similar to CO2’s effect, radiative forcing “expresses the change in energy in the atmosphere due to GHG [greenhouse gas] emissions” (CORE, 2016). Radiative forcing is directly connected to CO2 concentration; more CO2 in the atmosphere means that more heat gets trapped, which increases the energy in the atmosphere (known as positive radiative forcing). While radiative forcing is affected by other greenhouse gases as well, carbon dioxide is the most significant contributor to the atmosphere’s greenhouse gas concentration. The boundary for atmospheric CO2 concentration is “no more than 350 ppm” in order to keep the planet and its ecosystems stable; currently, atmospheric CO2 levels are at about 403 ppm (ESRL, 2016).
Today, the biggest contributors to CO2 and other greenhouse gases in the atmosphere (depending on who you ask) are the burning of fossil fuels (EPA, “Global Greenhouse Gas Emissions Data”) and the process of animal agriculture (me). The burning of oil and coal (reportedly) are responsible for 74% of the United States’ greenhouse gas emissions (EESI, 2016). Unfortunately, only about 3% of oil consumption in the U.S. can be attributed to residential use, and residential coal use accounts for roughly 0% of consumption in the U.S. (EIA, 2016). This means that on an individual level, there is very little that the average person can do to affect the consumption of these carbon-rich fuels. However, the EPA defines the transportation sector (which accounts for about 79% of U.S. oil consumption) as anything that “ includes the movement of people and goods by cars, trucks, trains, ships, airplanes, and other vehicles” (EPA, “Source of Greenhouse Gas Emissions”). Therefore, the best thing that the average American can do to reduce the emissions produced by oil consumption in the U.S. is to travel less and travel more efficiently; drive electric cars, use public transportation, and vacation locally rather than traveling across the globe to stay in some hotel near some beach. In regards to animal agriculture (which is reported as accounting for nearly 51% of global greenhouse gas emissions), individuals can make steps to change their diet that can have a huge impact on the emissions related to the animal agriculture industry (Goodland R. & Anhang J., 2009). By cutting meat, dairy, and eggs out of the standard diet, individuals can reduce the need for more meat, dairy, and egg production, reducing the amount of CO2 and other harmful greenhouse gases produced from livestock, as well as reducing the amount of land and water that is needed for the animal agriculture industry. Reducing the amount of land needed for agricultural development has the added benefit of preserving forested areas, which remove carbon dioxide from the atmosphere in large quantities. Choosing a vegetarian or vegan diet is essentially preventing more carbon dioxide from being released, while simultaneously preserving carbon sinks.
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Total U.S. energy-related carbon dioxide (CO2) emissions were 5,271 million metric tons in 2015.
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The next boundary, which we’ve also surpassed, is the change in biosphere integrity. Biosphere integrity relates to the extinction rate of species today, as well as the Biodiversity Intactness Index (BII). Extinction rates are measured in extinctions per million species-years (E/MSY for short), with the planetary boundary set at 10 E/MSY, which means that only 10 species should go extinct for every million species-years. Unfortunately, in our expansion of mankind we have surpassed this boundary by a frightening amount; current estimates put the current extinction rate between 100 to 1,000 E/MSY, between 10 and 100 times higher than the specified boundary. The BII measures the percent of decline of all populations (plant and animal) in a specific region, compared to their pre-modern rate of 100%. The boundary is set at 90%, meaning that populations of plants and animals should remain at at least 90% of their pre-modern levels. The BII has only been applied to southern Africa so far, but with that region reporting a BII of 84%, which is below the minimum of 90% (Rockström J., et al. 2015).
What can individuals do in their everyday lives to prevent extinction rates from rising further and to maintain plant and animal populations? This seems like a tough question to answer when most people today don’t go out hunting rare animal species, nor do they purposely destroy plant populations in their backyards. Today, the largest driver of extinction rates and population decreases is habitat destruction by humans (Hogan C., 2014). Habitat destruction is mainly carried out in natural habitats for agricultural or logging purposes; we are destroying plant and animal’s natural habitats because we need more food, more space, and more structures to support our constantly growing population. Therefore, the best thing that individuals can do on their own to help slow habitat destruction is to support companies who have adapted responsible, sustainable business practices in regards to food and lumber. Buying locally, where you know where your food is coming from, is one of the best options from an agricultural standpoint. This not only doesn’t support the expansion of big food corporations in countries rich in biodiversity, but it also promotes small farmers, who tend to have more sustainable and ethical business practices anyway. While (depending on your area) this is more difficult to do when it comes to lumber, making an attempt to purchase wood that hasn’t been imported from another country prevents funds from going to large off-shore logging operations, helping to prevent further expansion by those big corporations.
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| A local produce market. |
The third of the planetary boundaries that have already been surpassed is biogeochemical flows, specifically referring to the phosphorous and nitrogen cycles. Currently, phosphorus and nitrogen are both utilized in fertilizers across the globe; as two of the major plant nutrients, fertilizers containing these elements (usually in the form of ammonia or phosphoric acid) are known to promote plant growth and development (The Essential Chemical Industry Online, 2016). Now more than ever, we use and overuse fertilizer globally because of our need to support our rising population. However, excess amounts of phosphorus or nitrogen in marine environments can cause huge algal blooms, which leads to “dead zones” as a result of the water becoming oxygen-deficient from the photosynthesizing of algae. The global planetary boundary for the P cycle (phosphorus) is 11 teragrams (1 teragram = 1 billion grams) per year, and the boundary for the N cycle (nitrogen) is 62 teragrams per year (these numbers are assumably different because nitrogen is much more commonly used in fertilizer than phosphorus is). Today, it has been calculated that about 22 teragrams of phosphorus are used and about 150 teragrams of nitrogen are used per year globally (Rockström J., et al. 2015). These numbers are frighteningly high; both are at least twice the placed limit, with use only likely to increase as we continue to attempt to grow food to feed the planet.
As has been discussed, the main use of phosphorus and nitrogen today is in fertilizer. So when it comes to attempting to figure out how to use less fertilizer, the question is: are there any farming techniques that don’t use fertilizer? The answer: yes. Organic farming “refers to agricultural production systems that do not use genetically modified (GM) seed, synthetic pesticides or fertilizers” (Organic Farming Research Foundation, 2016). When it comes to worldwide use of nitrogen and phosphorus, the most effective decision that the average human can make is to buy only organically grown produce. By buying from producers who follow organic procedures, people can assist in the producer’s efforts to make organic farming more common, which would greatly help in reducing our planet’s disruption of the phosphorus and nitrogen cycles.
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| Unnatural looking, nitrogen-based fertilizer. |
The fourth and final of the already-exceeded limits pertains to land-system change. Specifically, this boundary relates to the area of forested land as a percent of the original forest cover. The global boundary (minimum global forest coverage) is currently set at 75%; today, humans have cut down or disturbed 38% of once-forested land, leaving our area of forested land at 62% (Rockström J., et al. 2015). As a massive carbon sink and habitat for animal and plant species, forests are incredibly important to the balance of the Earth’s ecosystems; chopping them down contributes to three of the four exceeded limits (and chances are a lot of that land is being filled with fertilizer for agricultural applications). As with habitat destruction, the biggest cause of deforestation is for conversion into cropland and pastures (NASA, 2016). In order to affect change on an individual level, the most effective step for people to take (as with habitat destruction) is to buy locally. If you know where your food is coming from, then you can be sure that it isn’t coming from a plantation on a plot of land that used to be filled with rainforest and thriving animal and plant life.
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| Land that has been cleared and burned for agricultural use. |
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