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PATH: HelpWeb Home ->EnviroSTART Home -> Environmental Crises -> How Humans Harm the Environment
In this section you can learn about the main ways that human activities adversely impact the environment adversely
All of these human impacts can contribute to the increase in droughts, floods, fires, extreme storms, rising sea levels, acid rain, heat waves, mass species extinction, and more extreme events
Definition: Deforestation, the systematic harvesting of forests for lumber, or clearing land for agricultural use (farming), or for other uses such as building infrastructure,
Deforestation harms the natural ecosystem in many ways, because since in deforestation the trees are not replanted, this could have disastrous effects. Deforestation will result in habitat loss for many species, it will reduce tree cover for prey (to avoid predators) and predators(to avoid being seen by prey), and it will collapse the local ecosystem's food web by removing the main producers, and eliminate a source of food for many primary consumers. Deforestation will also result in an imbalance in the carbon cycle: trees convert carbon dioxide to oxygen via photosynthesis, and deforestation, combined with increased carbon emissions, will increase the carbon dioxide concentration in the air and reduce the oxygen concentration. This contributes to the greenhouse effect, see Anthropogenic Climate Change
Definition: It explains itself - none required
The creation of roads, buildings and other infrastructure will cause serious harm to the environment: Firstly the creation of these will result in habitat loss, and most likely needs deforestation to clear the land necessary for them. Secondly, roads being paved will harm the surface soil, and kill organisms living in it, as well as cause natural drainage problems and flooding: as water cant infiltrate (see Water Cycle) into the soil thats blocked by roads (and other infrastructure), and also this will disrupt the water table. in addition, the intensive mining and refining process for the resources needed to construct roads, buildings, and other infrastructure will not only deplete the resources necessary to construct them, but will also change the landscape, disturbing and harming many organisms, release pollution into the air and water, and release carbon emissions. The buildings and infrastructure will release pollution: air, water and light pollution too, (which harms animals which use the natural light to navigate and for other important purposes) and the buildings and infrastructure will also release much carbon emissions.
Definition: A change in long term weather patterns (climate change) caused specifically by human industrial activities starting from the Industrial Revolution in the mid 1800s.
Climate change is common in the natural world, true. But not at the rate that it is right now. This is because of human caused, or anthropogenic impacts. There are many causes for anthropogenic climate change including deforestation, pollution, artificial altering of the landscape, but the main reason is "greenhouse gas" emissions. Greenhouse gases are gases which are retained in the atmosphere and prevent more of the Sun's heat from escaping into space, retaining more of the heat, warming up the Earth. (see the diagram below this section to see how greenhouse gases work)
The main greenhouse gases include:
Nitrous oxide (N2O ), which is a part of the nitrogen cycle (See Chapter 3), and is emitted from agricultural land use and industrial activities, as well as wastewater treatment;
Methane (CH4), which is released by wetlands naturally, as well as from livestock and other agricultural practices, land use, and waste decay
Water vapour (H2O) which is a part of the water cycle (See Chapter 3)
Ozone ( O3), which is a natural layer of the atmosphere which helps deflect harmful UV rays, famous for the ozone hole caused by: (CFCS)
Chlorofluorocarbons and other fluorinated gases (CFCs) such as hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride, which are all synthetic (man-made), and are emitted from a variety of industrial sources, and despite being emitted in very small concentrations, are extremely powerful, much more than the other gases, which are all natural;
Carbon dioxide (CO2), the greenhouse gas so notorious that you think of it immediately when you think of greenhouse gases, although it is a natural part of the carbon cycle (See Chapter 3), it is being emitted at higher concentrations than natural from burning of fossil fuels.
This climate change has many adverse effects:
Increasing the global temperature, which contributes to
Drought
Fires
Rising sea levels and flooding, which can submerge low lying land
Increase in abnormal weather activity such as powerful storms and other natural disasters
Melting ice caps will harm land dwelling species in polar regions, such as polar bears
Higher levels of UV radiation being retained will harm many species living above ground and close to the water surface .
Many more adverse impacts.
Due to this rapid rate of change in the natural environment, many species will not be able to adapt and they may even become extinct. It is worth noting that we are already in the sixth mass extinction, the only one caused by humans, the Holocene/Anthropocene Mass Extinction Event, one of the greatest reductions in biodiversity of all time.
Further Reading:
Definition: The industrial cycle that results in the mass creation of typically single-use goods which are created, consumed, then disposed of in a highly resource intensive and polluting linear system, not a cycle.
These three processes are very intensive and harmful to the environment: First of all, manufacturing the goods is a very resource intensive process, which requires much mining (adverse effects described in Creation of Roads, Buildings and Other Infrastructure). Manufacturing, transportation, and disposal (of all kinds, including recycling), is very energy intensive, and in many cases releases much pollution and carbon emissions. the harvesting of resources causes deforestation and habitat loss in many cases.
Note: transportation of goods is a particularly carbon intensive/emitting process, which is often not acknowledged.
In addition, due to marketing and business concepts such as planned obsolescence (objects being made to fail at some point) and perceived obsolescence (making customers have an obsessive need to buy the newest products, increased demand for the latest trendy goods which are often not much better than their predecessors), manufacturing (and by extension transportation and consumption) are "needed" to be increased to unsustainable levels, and also when the usable lifespan of goods is reduced, the number of goods disposed of is increased. This is an unsustainable practice.
Further Information:
Definition: The unsustainable and often unethical use of a natural resource (biotic or abiotic) to the point where it becomes completely depleted.
This can apply to our unsustainable use of fossil fuels (which contribute to the greenhouse effect), certain minerals, or the rapidly accelerating unsustainable use of resources that the vast majority of other organisms also need, such as land, water, and trees (lumber). It can also apply to our use of animals for food, and our use of animal parts for food/goods. For example overfishing using methods such as trolling, or the unethical (and now mostly illegal) use of animal parts for food ( shark fin soup), goods (ivory), and some traditional Eastern medicines (tiger paw). There are now much more ethical and often artificial counterparts to these items, and they are being used more.
Definition: The accidental or deliberate introduction of a non-native species to a new environment.
Sometimes species are deliberately introduced to a new region to control a pest population, this is called a biological control. An example would be the parasitoid fly brought over to control the European Gypsy moth (also an invasive species).
Other times, new species are accidentally and unknowingly introduced to new areas, often as stowaways on transportation vehicles (the international transportation network that humanity has built enables global reach. This is a bad thing for the environment because invasive species can land anywhere). An example would be the brown tree snake stowing away on warplanes and cargo planes during WWII, and landing in Guam.
Regardless of how the species is introduced, it can cause devastating damage to the environment. Invasive species are often far more efficient than their native counterparts, allowing the invasive species to easily outcompete native species occupying that niche, and in many cases the native species run out of resources (as the invasive species takes most of them), and are driven to endangerment, or even extirpation/extinction. For example, the purple loosestrife is an invasive weed introduced to North America, which successfully outcompetes many of its native counterparts and drastically reduces plant biodiversity.
Invasive species can also, with a high degree of efficiency, prey on native species (some of which have no natural predators), which have no natural adaptations to resist/avoid predation from the invasive species, and in many cases the prey species are driven to endangerment/extirpation. For example, the brown tree snake, when accidentally brought to Guam, it preyed on the local bird populations (including the Guam Rail), which had no natural predators, and thus no adaptations to resist predation: many of the birds didn't even recognize nearby snakes as threats. Many bird species were thus driven to extinction or extirpation.
Invasive species introduced for pest control also have mixed results. Sometimes they do not succeed in eliminating the pest, and in many cases, they also prey on non-threatening species as well. In general, invasive species are a serious threat to biodiversity.
Further Activity:
Documentary about Invasive Species (Note: Click Episode 4: Alien Invasion)
Entirely sourced from: Synerge - Grade 9 Science - 6 Main Threats to Biodiversity: https://sites.google.com/view/synerge/educational-resources/grade-9/grade-9-science/unit-1-ecology/chapter-1-biodiversity-and-how-humans-threaten-it
(Synerge is a component of the HelpWeb for Students, therefore this is not plagiarism)