Understanding the complexity of our planet can be simplified by viewing the Earth as a set of four spheres that interact via matter and energy. These four spheres are the lithosphere, atmosphere, hydrosphere, and the biosphere. Human activities create changes to all four of these interconnected spheres, often detrimentally, and as the population continues to increase these activities are driving even larger environmental impacts.
The lithosphere represents the stony or rocky matter that makes up the majority of the Earth’s surface. Humans mine the lithosphere for precious metals and fossil fuels to make infrastructure and technological products as well as the energy that powers them, but these resources take millions of years to replace. Agriculture also utilizes lithosphere topsoil which leads to erosion that can take thousands of years to replace. These products are generally considered nonrenewable resources because of these long replenishment cycles (McKinney, et al. 2019, 46). While agriculture could shift to non-soil requiring methods like hydroponics, precious metals are increasing in use and have no current alternatives which creates larger long-term issues.
These lithosphere activities, like mining and fossil fuel use, also creates large amounts of carbon emissions that directly impact the atmosphere. The atmosphere represents all the gaseous envelope around Earth. The combustion of materials, like fossil fuels, creates smog at the local level, acid rain regionally, and global warming and ozone loss at the global level (McKinney, et al. 2019, 18). These impacts are difficult to reverse and can persist for thousands of years after cessation of these activities (Stager 2012). Atmospheric pollution not only impacts human health, but it can also lead to ocean acidification as the water absorbs the carbon dioxide.
The hydrosphere represents the liquid water on the surface of the Earth. Atmospheric pollution can impact the acidity and temperature of the oceans, but humans are also polluting water sources in additional ways as well. Mining waste is often dumped into fresh water sources like rivers and streams. Polluting fresh water sources from human waste and other industrial activities also leads to a lack of clean drinking water and unsanitary conditions that are responsible for millions of deaths in Africa each year for example (McKinney, et al. 2019, 42). With only around 3% of the water being vital fresh water, human activities reduce freshwater habitats and drinking water sources at alarming rates (World Wildlife Foundation n.d.).
All these impacts lead to critical issues to the biosphere, the sphere that represents all the living organisms on the planet. Human activities like logging and agriculture reduce habitat for terrestrial organisms, while carbon emissions lead to atmospheric pollution and ocean acidification that impacts aquatic organisms. It is estimated that humans are creating 100 to 10,000 times the background extinction rate for organisms on the planet (Rafferty 2019). Unlike the other spheres where resources and issues can be neutralized over thousands or millions of years, the loss of species and biodiversity is effectively permanent. When looking at those timescales, human impacts to the biosphere create issues of the highest severity, followed by the lithosphere, atmosphere, and hydrosphere respectively.
Author: Logan Callen
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Stager, Carl. 2012. “What Happens AFTER Global Warming?” Nature. Accessed June 18, 2021. https://www.nature.com/scitable/knowledge/library/what-happens-after-global-warming-25887608/.
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