Because pollutants such as CFCs (chlorofluorocarbons) can go up into the environment, and because their chlorine atoms take a really long time to break down, the Cl atom can bond with the single oxygen atoms and prevent them from reuniting with O2
This means that O3, which would have otherwise been formed by O and O2 reuniting, is no longer being formed
Therefore, the amount of ozone in the stratospheric ozone layer (where ozone is useful) is decreasing
Decreasing levels of ozone in the stratospheric layer mean that more UV rays can harm humans, such as by causing skin cancer
9.2 Reducing Ozone Depletion
Hydrofluorocarbons (HFCs)
Replacements for CFCs (chlorofluorocarbons) that don’t use the Cl atoms that would otherwise inhibit the production of ozone in the stratospheric ozone layer
While HFCs prevent some of the issues associated with CFC usage, HFCs do act as greenhouse gases, which can still cause negative environmental effects
Both CFCs and HFCs are used by humans as refrigerants for appliances
When heat from the sun enters the Earth’s atmosphere and then stays near Earth because gases in the atmosphere act like a blanket and trap the heat near the Earth
While the greenhouse effect can be good because it keeps the planet warm enough to support life, it can be bad if there are too many gases in the atmosphere that trap too much heat
Carbon dioxide, methane, water vapor, nitrous oxide, and CFCs can all act as greenhouse gases
Water vapor isn’t focused on as an issue because it doesn’t stay in the atmosphere for nearly as long
GWP (global warming potential)
A measuring unit to show how much each type of global warming substance could potentially increase global warming
As a baseline, CO2 (carbon dioxide) has a GWP of 1
A consequence of too many greenhouse gases being present in the environment
Because too much heat is being trapped near the Earth’s surface, temperatures around the globe are gradually rising
This can cause issues such as polar ice caps melting
When ice caps melt, water levels can also rise, which may cause issues near coastal areas
9.5 Global Climate Change
Climate change
Climate change has occurred in the past, which has resulted in periodic warming and cooling
Rising temperatures can lead to droughts and habitat losses
When permafrost (which is supposed to stay frozen for long periods of time) is melted, the methane and CO2 that was previously frozen within the permafrost is released into the environment
Islands that can regulate wind and waves to protect coastal communities
Global warming, which can cause rising sea levels, may cause these barrier islands to be submerged, causing more wind/wave damage to coastal areas
Thermohaline circulation
Global ocean currents, which carry/distribute heat around the world, can be slowed down or affected by changes in global climate, which can impact coastal regions
Species introduced to an environment that are not naturally native to that area
These species might be accidentally introduced to an area, such as organisms that end up on a boat that carries them from one continent to another
However, some invasive species are purposefully introduced to an area, but end up growing too much and disrupting the natural order
Generalist species
Species that can adapt to a wide variety of ecosystems
Invasive species are usually generalist species because they are able to adapt to an area despite not being native to it
Native species that are specifically adapted to their environments are referred to as specialist species (the opposite of generalist species)
Because generalist species can take full advantage of native species’ habitats, native species may be challenged or pushed out of their natural areas, which can cause them to struggle/die out
Although invasive species have the potential to be beneficial, they also often outcompete native species for resources
Invasive species can be controlled by humans, such as through inspection of incoming boats, introduction of predators to invasive species, and hunting/removal of invasive species members
9.9 Endangered Species
Endangered species
A species that is in serious danger of becoming extinct in the future
Human activities often contribute to a species’ endangerment
Poaching/illegal hunting of animals with low populations can further reduce their numbers, making it harder to repopulate/grow back
Industrial expansion into habitats that species cannot survive out of can cause species members to die off
Additionally, climate change can render habitats that used to be comfortable for species uninhabitable and unfriendly
Invasive species that are either purposefully or accidentally introduced by humans can outcompete native species for resources, causing the native species to dwindle
However, human activity can also protect endangered species
Laws that prevent people from hunting endangered species members can help the population grow back
The establishment of natural parks and wildlife preserves can protect endangered species’ habitats
When larger habitats are broken up into smaller pieces
For example, this can happen when humans construct things in the middle of a habitat
The pieces of habitat that are separated from one another as a result of the manmade obstacle therefore become habitat fragments
This can be bad for species/organisms that need a larger habitat range in order to have enough resources/food to survive
Domestication
The process by which some species become managed by humans for economic/other reasons
For example, honeybees and livestock have been domesticated for economic purposes
This can be bad for biodiversity if humans selectively breed organisms that have only the traits desired by humans
For example, if humans only breed honeybees that produce the most/best honey, then the members of the honeybee species will become less diverse and will instead all share the same “ideal” characteristics
This can cause future problems if a threat to the honeybee population presents itself because a lack of biodiversity means that the odds of some members of the population having the traits needed to fight off that threat will be lower
