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18.8: Human Impact on the Environment

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    Learning Objectives
    • Discuss the impact humans have had on climate change
    A man feeding a squirrel a french fry
    Figure 1. The ecosystem of public parks often includes humans feeding the wildlife.

    Human impact on the environment includes impacts on biophysical environments, biodiversity, and other resources. The term is sometimes used in the context of pollution emissions that are produced as a result of human activities but applies broadly to all major human impacts on the environment.

    Technology

    Environmental impacts caused by the application of technology are often perceived as unavoidable for several reasons. First, the purpose of many technologies is to exploit, control, or otherwise “improve” upon nature for the perceived benefit of humanity. At the same time, the myriad of processes in nature have been optimized, and are continually adjusted, by evolution: any disturbance of these natural processes by technology is likely to result in negative environmental consequences. Second, the conservation of mass principle and the first law of thermodynamics (i.e., conservation of energy) dictate that whenever material resources or energy are moved around or manipulated by technology, environmental consequences are inescapable. Third, according to the second law of thermodynamics, order can be increased within a system (such as the human economy) only by increasing disorder or entropy outside the system (i.e., the environment). Thus, technologies can create “order” in the human economy (i.e., order as manifested in buildings, factories, transportation networks, communication systems, etc.) only at the expense of increasing “disorder” in the environment. According to a number of studies, increased entropy is likely to be correlated to negative environmental impacts.

    Agriculture

    The environmental impact of agriculture can vary widely—ultimately, environmental impact of agriculture depends on the production practices of the system used by farmers. There are two types of indicators of environmental impact: means-based, which is based on the farmer’s production methods, and effect-based, which is the impact that farming methods have on the farming system or on emissions to the environment. An example of a means-based indicator would be the quality of groundwater, that is effected by the amount of nitrogen applied to the soil. An indicator reflecting the loss of nitrate to groundwater would be effect-based.

    The environmental impact of agriculture involves a variety of factors from the soil, to water, the air, animal and soil diversity, plants, and the food itself. Some of the environmental issues that are related to agriculture are climate change, deforestation, genetic engineering, irrigation problems, pollutants, soil degradation, and waste.

    Irrigation

    The water in the stream has become brown and mucky, with particles collected on the surface of the water, almost like a film.
    Figure 2. Water pollution in a rural stream due to runoff from farming activity in New Zealand.

    The environmental impact of irrigation includes the changes in quantity and quality of soil and water as a result of irrigation and the ensuing effects on natural and social conditions at the tail-end and downstream of the irrigation scheme. The impacts stem from the changed hydrological conditions owing to the installation and operation of the scheme. An irrigation scheme often draws water from the river and distributes it over the irrigated area. As a hydrological result it is found that:

    • the downstream river discharge is reduced
    • the evaporation in the scheme is increased
    • the groundwater recharge in the scheme is increased
    • the level of the water table rises
    • the drainage flow is increased

    Land Loss and Soil Erosion

    Lal and Stewart estimated global loss of agricultural land by degradation and abandonment at 12 million hectares per year.[1] In contrast, according to Scherr, GLASOD (Global Assessment of Human-Induced Soil Degradation, under the UN Environment Programme) estimated that 6 million hectares of agricultural land per year had been lost to soil degradation since the mid-1940s, and she noted that this magnitude is similar to earlier estimates by Dudal and by Rozanov et al.[2] Such losses are attributable not only to soil erosion, but also to salinization, loss of nutrients and organic matter, acidification, compaction, water logging and subsidence. Human-induced land degradation tends to be particularly serious in dry regions.

    Energy Industry

    The environmental impact of energy harvesting and consumption is diverse. In the real world, consumption of fossil fuel resources leads to global warming and climate change. However, little change is being made in many parts of the world. If the peak oil theory proves true, more explorations of viable alternative energy sources could minimize the environmental impact of human energy demands, leading to a more ‘environmentally friend’ resource consumption.

    In recent years there has been a trend towards the increased commercialization of various renewable energy sources. Rapidly advancing technologies can achieve a transition of energy generation, water and waste management, and food production towards better environmental and energy usage practices using methods of systems ecology and industrial ecology.

    Invasive Species

    Introductions of species, particularly plants into new areas, by whatever means and for whatever reasons have brought about major and permanent changes to the environment over large areas. Examples include the introduction of Caulerpa taxifolia into the Mediterranean, the introduction of oat species into the California grasslands, and the introduction of privet, kudzu, and purple loosestrife to North America. Rats, cats, and goats have radically altered biodiversity in many islands. Additionally, introductions have resulted in genetic changes to native fauna where interbreeding has taken place, as with buffalo with domestic cattle, and wolves with domestic dogs.

    Transport

    The environmental impact of transport is significant because it is a major user of energy, and burns most of the world’s petroleum. This creates air pollution, including nitrous oxides and particulates, and is a significant contributor to global warming through emission of carbon dioxide, for which transport is the fastest-growing emission sector. By subsector, road transport is the largest contributor to global warming.

    Two interstates overlapping one another
    Figure 3. Interstate 10 and Interstate 45 near downtown Houston, Texas in the United States.

    Environmental regulations in developed countries have reduced the individual vehicles emission; however, this has been offset by an increase in the number of vehicles, and more use of each vehicle. Some pathways to reduce the carbon emissions of road vehicles considerably have been studied. Energy use and emissions vary largely between modes, causing environmentalists to call for a transition from air and road to rail and human-powered transport, and increase transport electrification and energy efficiency.

    Other environmental impacts of transport systems include traffic congestion and automobile-oriented urban sprawl, which can consume natural habitat and agricultural lands. By reducing transportation emissions globally, it is predicted that there will be significant positive effects on Earth’s air quality, acid rain, smog and climate change.

    5 Human Impacts on the Environment

    In this video, we’ll learn about the important services the ecosystem provides (including biogeochemical cycles and food) as well as the top five negative impact humans have had on the environment: deforestation, desertification, global warming, invasive species, and overharvesting.

    Thumbnail for the embedded element "5 Human Impacts on the Environment: Crash Course Ecology #10"

    A YouTube element has been excluded from this version of the text. You can view it online here: pb.libretexts.org/fob1/?p=592

    1. Lal, R. and B. A. Stewart. 1990. Soil degradation. Springer-Verlag, New York. ↵
    2. Scherr, S. J. 1999. Soil degradation: a threat to developing country food security by 2020? International Food Policy Research Institute. Washington, D. C. ↵

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    • 5 Human Impacts on the Environment: Crash Course Ecology #10. Authored by: CrashCourse. Located at: https://youtu.be/5eTCZ9L834s. License: All Rights Reserved. License Terms: Standard YouTube License
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    18.8: Human Impact on the Environment is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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