Chapter 9: Global Change (copy)

9.1: Stratospheric Ozone Depletion

• Stratosphere: Contains approximately 97% of the ozone in the atmosphere, and most of it lies between 9 and 25 miles (15–40 km) above Earth’s surface.

• Formation of Stratospheric Ozone

  • Ultraviolet radiation (uv) strikes an oxygen molecule, creating atomic oxygen.

  • Atomic oxygen can combine with oxygen molecules to form ozone.

• Ultraviolet radiation is subdivided into three forms:

  • UVA: It is closest to blue light in the visible spectrum and is the form of ultraviolet radiation that usually causes skin tanning.

  • UVB: It causes blistering sunburns and is associated with skin cancer.

  • UVC: It is found only in the stratosphere and is largely responsible for the formation of ozone.

• Ozone Layer: A belt of naturally occurring ozone gas that sits between 9 and 19 miles (15–30 km) above Earth and serves as a shield from the harmful ultraviolet B radiation emitted by the sun.

• Ozone: A highly reactive molecule and is constantly being formed and broken down in the stratosphere.

  • There are no natural reservoirs of chlorofluorocarbons (CFCs) or halocarbons (halons), but %%their chemical stability allows them to reach the stratosphere and degrade the ozone layer.%%

  • Chlorofluorocarbons: These are nonflammable chemicals that contain atoms of carbon, chlorine, and fluorine.

  • Halocarbons (halons): These are organic chemical molecules that are composed of at least one carbon atom with one or more halogen atoms; the most common halogens are fluorine, chlorine, bromine, and iodine.

Effects of Ozone Depletion

• A reduction in crop production

• A reduction in the effectiveness of the human body’s immune system

• A reduction in the growth of phytoplankton and the cumulative effect on food webs

• Climatic changes

• Cooling of the stratosphere

• Deleterious effects on animals

• Increases in cataracts

• Increases in mutations, since UV radiation causes changes in the DNA structure

• Increases in skin cancer

• Increases in sunburns and damage to the skin

Reducing Ozone Depletion

• %%Support legislation%% that reduces ozone-destroying chemicals in medical inhalers, fire extinguishers, aerosol hairsprays, wasp and hornet sprays, refrigerator and air conditioner foam insulation, and pipe insulation.

• %%Introduce tariffs%% on products produced in countries that allow the use of chlorofluorocarbons (CFCs).

• %%Offer tax credits or rebates%% for turning in old refrigerators and air conditioners.

• Use helium, ammonia, propane, or butane as a %%coolant alternative%% to HCFCs (hydrochlorofluorocarbons) and CFCs.

Ozone (O3) naturally exists in the stratosphere.

Formation/destruction of ozone prevents UVC/UVB radiation from reaching the

Earth's surface.

Antarctic winters create stratospheric ice crystals that contribute to ozone degradation, thinning the ozone layer there.

Chlorofluorocarbons (CFCs) were used as refrigerants, coolants, propellants, components of some plastics.

CFCs can escape and enter the stratosphere.

UV light removes chlorine from CFCs.

Free chlorine catalyzes the conversion of O3 to O2.

Depressed photosynthesis

Impacted food chains/webs

Impacts on organisms sensitive to UV radiation

Skin cancer and cataracts rates increase in humans

Levels of Zones

1. Troposphere

2. Ozone layer

3. Stratosphere

4. mesosphere

5. thermosphere

6. exosphere

9.2: Reducing Ozone Depletion

• Strategies for reducing the use of ozone-depleting substances, such as HCFCs and CFCs, through international agreements like the Montreal Protocol.

Montreal Protocol:

• International treaty

• Reduction/phase out of CFCs

CFCs are persistent.

• It will take decades for CFCs currently in stratosphere to completely dissipate, allowing ozone layer to fully repair.

HFCs replaced CFCs:

• No chlorine to catalyze transformation of ozone into atmospheric oxygen

Powerful greenhouse gas

9.3: The Greenhouse Effect

• When sunlight strikes Earth’s surface, some of it is reflected back toward space as infrared radiation (heat).

• Greenhouse gases absorb this infrared radiation and trap the heat in the atmosphere.

  

  Greenhouse gases include carbon dioxide, methane, nitrous oxide, water vapor, tropospheric ozone, CFCs, HFCs.

  Most occur naturally, but concentrations are increased via anthropogenic means.

  CFCs and HFCs are manmade.

  Water vapor does not contribute significantly to the greenhouse effect, due to its short atmospheric residence time.

Carbon dioxide is a reference molecule for the greenhouse effect, so has a global warming potential (GWP) of 1.

GWPs of various greenhouse gases: CFCs/HFCs > ozone > nitrous oxide >

methane > carbon dioxide

Carbon dioxide has the greatest overall impact on the greenhouse effect because of its concentration in the atmosphere.

Human activities influence the concentration of various greenhouse gases in the atmosphere.

9.4: Increases in Greenhouse Gases

Greenhouse Gases by Source

• Agriculture: Mostly comes from the management of agricultural soils.

• Commercial and residential buildings: On-site energy generation and burning fuels for heat in buildings or cooking in homes

• Energy supply: The burning of coal, natural gas, and oil for electricity and heat is the largest single source of global greenhouse gas emissions.

• Industry: Primarily involves fossil fuels burned on-site at facilities for energy; cement manufacturing also contributes significant amounts of CO2 gas

• Land use and forestry: It includes deforestation of old-growth forests (carbon sinks), land clearing for agriculture, strip-mining, fires, and the decay of peat soils

• Transportation: It involves fossil fuels that are burned for road, rail, air, and marine transportation.

• Waste and wastewater: Landfill and wastewater methane (CH4), and incineration as a method of waste management.

  Greenhouse gases that produce the greenhouse effect include carbon dioxide, methane, nitrous oxide, ozone, CFCs,

  HFCs and water vapor.

  Concentrations of many greenhouse gases have steadily increased in the atmosphere as a result of human activity.

  Increased greenhouse gases have led to climate change.

Sea level rise:

• Terrestrial ice melts into ocean

• Thermal expansion of ocean water increased range for disease vectors impacts on ecological populations

impacts on human populations, especially those already vulnerable to changes

Environmental impacts:

• Changes in ocean salinity and temperature affect marine organisms at every trophic level
  in many ways.

• Changes in temperatures affect terrestrial organisms at every trophic level in many ways.

Impacts on humans:

• Impacts include responses to temperature changes, access to food, access to fresh water, and changing land availability.

Anthropogenic activities produce the additional greenhouse gases that drive climate change:

• Many activities - individual actions, agriculture, industry - produce greenhouse gases.

Greenhouse Gas Emissions by Gas

• Carbon dioxide (CO2): It is an important heat-trapping (greenhouse) gas, and is released through human activities such as deforestation and burning fossil fuels, as well as natural processes such as respiration and volcanic eruptions.

• Agricultural activities, waste management, and energy use all contribute to methane emissions.

• Fertilizer use is the primary source of nitrous oxide emissions.

• Fluorinated gases: Industrial processes, refrigeration, and the use of a variety of consumer products all contribute to this gases, which include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).

• Black carbon (soot): It is a solid particle or aerosol, not a gas, but it also contributes to the warming of the atmosphere.

9.5: Global Climate Change

• The world’s oceans contain more carbon dioxide than the atmosphere.

• Atmospheric temperatures, cloud cover, surface albedo, and water vapor cause pole-wide warming.

  • %%The north and south poles are warming faster because of energy in the atmosphere that is carried to the poles through large weather systems%%.

• Ocean currents carry heat around the Earth.

  • As the oceans absorb more heat from the atmosphere, sea surface temperatures rise and ocean circulation patterns change.

  • As the oceans store a large amount of heat, even small changes in these currents can have a large and lasting effect on the global climate.

• Air temperatures today average 5°F to 9°F (3°C to 5°C) warmer than they were before the Industrial Revolution.

  • Higher average air temperatures may increase the frequency or severity of storms, surface water/groundwater inputs, sedimentation in bodies of water, flooding and associated water runoff, and aquifer recharge.

• %%Global warming could completely change estuaries and coastal wetlands.%%

  • Sea-level rise threatens to inundate many coastal wetlands, threatening biota that cannot move inland due to coastal development.

• The UN estimates that 150 million people will need to be relocated worldwide by 2050 due to coastal flooding, shoreline erosion, and agricultural disruption.

• The total surface area of glaciers worldwide has %%decreased 50% since the end of the 19th century%%.

• The main ice-covered landmass is Antarctica at the South Pole, with about 90% of the world’s ice and 70% of its freshwater.

  • %%If all of the Antarctic ice melted, sea levels around the world would rise about 200 feet (60 m)%%.

• Greenhouse gases trap solar radiation in the Earth’s atmosphere, making the climate warmer.

• Due to global warming, mosquitoes have more places to breed, which increases malaria, dengue fever, Zika virus, and yellow fever rates.

  • Warmer water may spread amoebic dysentery, cholera, and giardia because it increases bacterial activity.

• %%Higher air temperatures have been proven to result in higher incidences of heat-related deaths%% caused by cardiovascular disease, heat exhaustion, heat stroke, hyperthermia, and diabetes.

• Arctic fauna will be the most affected. The food webs of polar bears that depend on ice floes, birds, and marine mammals will be drastically affected.

• The movement of tectonic plates causes volcanoes and mountains to form, which can also contribute to changes in the climate

• Volcanic gases that reach the stratosphere have a long-term effect on climate.

• %%The fluctuations in the solar cycle impact Earth’s global temperature by ~0.1°, slightly hotter during solar maximums and slightly cooler during solar minimums.%%

• As rivers and streams warm, warm-water fish are expanding into areas previously inhabited by cold-water species.

• The Arctic region is a large natural source of methane.

  • Arctic methane release, caused by melting glaciers, creates a positive feedback loop because methane is a greenhouse gas.

• %%Sea levels have risen 400 feet (120 m) since the peak of the last ice age approximately 18,000 years ago.%%

  • From about 13,000 years ago to the start of the Industrial Revolution, sea levels rose 0.1 to 0.2 mm per year. Since 1900, sea levels have risen about 3 mm per year.

• The amount of energy absorbed and stored by the oceans has an important role in the rise of sea levels due to thermal expansion.

• Ocean acidification: It occurs when atmospheric carbon dioxide reacts with seawater to form carbonic acid,

• Kyoto Protocol (2005): A plan created by the United Nations to reduce the effects of climate change, which results in a reduction in the pH of ocean water over an extended period of time.

• Montreal Protocol (1987): An international treaty designed to phase out the production of substances that are responsible for ozone depletion.

• Paris Agreement (2016): It deals with greenhouse gas emissions and mitigation.

  • The goal is to keep global temperature rise below 2°C above pre-industrial levels while each country determines its own plans to mitigate global warming.

Historical data has shown that the Earth has gone through periods of warming and cooling.

• Ice cores are an important source of that data.

Current data shows that the Earth is warming, which is correlated with an increase in the concentration of greenhouse gases in the atmosphere.

Climate change may change global wind patterns, affect soil quality.

Effects of climate change include rising temperatures, rising sea levels, and displacement of coastal populations.

Melting polar ice reveals darker soil and water

(lower albedo than ice), which drives a positive feedback warming loop.

Melting permafrost releases methane gas, which drives a positive feedback warming loop.

Melting sea ice affects species that depend on the ice for habitat and food, such as polar bears and seals.

Climate change leads to sea level rise.

• Benefit - new marine habitat created

• Drawback — increasing depth of ocean impacts organisms that will no longer be in the photic zone

Climate change can alter ocean currents

• Salinity and temperature changes impact water density, which can impact the ocean conveyer belt

• Altered ocean currents can impact terrestrial climate, especially in coastal areas.

9.6: Ocean Warming

Image Courtesy of Wikimedia

As global air temperatures increase from excess greenhouse gasses, ocean temperature increases as well.

A lot of marine species are highly dependent on the temperature of the water to regulate the temperature of their bodies. Ectotherms, including fish, amphibians, reptiles, and invertebrates, depend on external sources of heat for their body temperature, meaning the body temperature of an aquatic ectotherm is usually very close to the temperature of the surrounding water. As the temperature of the ocean increases, organisms are subject to extreme metabolic stress and may lose the ability to metabolize their food or reproduce!

Increasing GHG emissions are the cause of ocean warming.

Marine and coastal species are often negatively affected by ocean warming and subsequent sea level rise.

Effects can include loss of habitat, metabolic changes and reproductive harm.

Warmer ocean temperature stress corals, which then expel their symbiotic algae. When this happens, the corals "bleach", which may cause them to die.

Impact on Coral

Image courtesy of Wikimedia

If the temperature becomes hotter than species can handle, they must be able to adapt or move.  For sedentary (non-mobile) species like coral, the increase in temperature is often fatal. 

Corals are complex animals that are made up of a colony of tiny polyps. Each polyp resembles a tiny sea anemone and is capable of catching small organisms out of the seawater. Although the coral catches food and is able to share nutrients from one polyp to the next, tropical water is often nutrient-poor and will not provide enough to sustain the coral. 

Coral has developed a symbiotic relationship with algae called zooxanthellae. The algae are provided with a stable place to live and nutrients and, in turn, provide the coral with sugar.  

However, the algae living inside corals are very temperature sensitive and cannot live in warmer water.  When the algae die and are expelled, the coral turns white or bleaches. Bleaching events occur with heat waves that drive the temperature of the ocean up.  Most corals are not able to recover from these events and will die. 

There have been over sixty major global coral bleaching events since 1980, with the most devastating occurring from a strong El Niño event from 2014-2017. In just this event, over 70% of the world's coral reefs were damaged. 

Image courtesy of Wikimedia

Ice Caps

The polar regions have already warmed by one to four degrees celsius. This increase caused over 3,000 trillion pounds of ice to melt into the ocean between 2000 and 2008.  With the predicted increase of four more degrees, there will be a catastrophic impact on sea ice levels. The melting of sea ice not only destroys polar habitats but changes habitats globally with sea-level rise and changes to currents.

9.7: Ocean Acidification

Acid Formation

Dissolving CO2 in seawater increases the hydrogen ion (H+) concentration in the ocean and thus decreases ocean pH, as follows:

Ocean acidification is caused by the absorption of excess atmospheric CO2 into the ocean. As more CO2 is released into the atmosphere, the oceans will continue to become more acidic. Humans are inadvertently causing ocean acidification by increasing atmospheric CO2 with the burning of fossil fuels and deforestation. Over the last 200 years of global industrialization, ocean pH levels have dropped by 0.1 pH units. The pH scale is logarithmic, meaning that a change of 0.1 would translate to a 30% increase in ocean acidity levels. 

Impacts of Changing pH

Calcium Carbonate

As CO2 dissolves in seawater, it forms carbonic acid, which, in turn, reduces the pH of the water. This process can have a number of negative effects on marine life, including making it more difficult for organisms like corals, snails, clams, and shellfish to build and maintain their skeletons and shells. 🐚

Carbonic acid reduces available calcium carbonate in the ocean. Calcium carbonate is important for marine organisms because it provides a strong and durable material for building skeletons and shells. These structures are essential for protecting the organisms from predators and for maintaining their shape and buoyancy. Additionally, calcium carbonate is also used by many organisms to control their internal pH and regulate the number of calcium ions in their bodies.

Fish Physiology

Additionally, acidification can also alter the behavior and physiology of fish. Many fish use their sense of smell to locate food, find mates, and avoid predators. Acidification can disrupt the ability of fish to detect certain odors, making it more difficult for them to interact with stimuli in their external environment. 🐠

Aquatic Plants

In contrast, ocean plants like seagrass and algae tend to thrive in a CO2-rich environment. These conditions, lack of adequate herbivores, and exploding plant growth could create hypoxic, eutrophicated environments. 

Scientists are predicting that at current CO2 production, ocean acidity could increase by over 100% in the next 100 years. This change would present a significant challenge to marine organisms and impact human populations that rely on them. 

Pteropods

Image courtesy of Wikimedia

One organism of concern is the pteropod. These tiny pelagic snails make up the basis of the food chain for a wide variety of animals. Scientists have studied these organisms in ocean waters that simulate predicted acidity levels, and their shells completely dissolve in less than 50 days! The collapse of this species would have a domino effect on the organisms that rely on it for food. Whales, salmon, and other pelagic organisms would most likely not survive the total collapse of pteropods 🌀

Increasing levels of atmospheric CO, are the cause of ocean acidification. Excess CO, is absorbed by the oceans, lowering their pH through a series of chemical reactions.

Humans increase CO, concentrations by burning fossil fuels, driving vehicles, and deforestation

Organisms that use CaCO, to build their shells and skeletons are damaged by ocean acidification because it reduces the amount of free CO, ions available for them to use, and may even lead to loss of CaCOz in existing structures

9.8: Biodiversity and Invasive Species

• Plants are initially more susceptible to habitat loss than animals. This occurs for several reasons, as follows:

  • Plants cannot migrate.

  • Plants cannot seek nutrients or water.

  • Seedlings must survive, and they are grown in degraded conditions.

  • The dispersal rates of seeds are slow events

• Animals can cope with habitat destruction by migration, adaptation, and/or acclimatization. Migration depends upon:

  • access routes or corridors;

  • the magnitude and rate of degradation;

  • the organism’s ability to migrate; and

  • the proximity and availability of suitable new habitats.

• Adaptation: The ability to survive in changing environmental conditions.

  • Adaptation depends upon:

  • birth rate;

  • gene flow between populations as a function of variation;

  • genetic variability;

  • population size;

  • the length of generation; and

  • the magnitude and rate of degradation.

• Acclimatization: The process by which an individual organism adjusts to a gradual change in its environment allowing it to maintain performance across a range of environmental conditions.

  • Acclimatization depends upon:

  • physiological and behavioral limitations of the species; and

  • the magnitude and rate of degradation.

Invasive Species

• Invasive species: These are animals and plants that are transported to any area where they do not naturally live.

• Characteristics of Invasive Species

  • Abundant in native range

  • Broad diet

  • High dispersal rates

  • High genetic variability

  • High rates of reproduction

  • Living in close association with humans

  • Long-lived

  • Pioneer species

  • Short generation times

  • Tolerant of a wide range of environmental conditions

  • Vegetative or clonal reproduction

• Examples of Invasive Species

  • Dutch elm disease is transmitted to elm trees by elm bark beetles — killing over half of them elm trees in the northern US.

  • European green crabs found their way into the San Francisco Bay area in 1989 threatening commercial fisheries.

  • Water hyacinth is an aquatic plant, introduced to the United States from South America.

  • It forms dense mats, reducing sunlight for submerged plants and aquatic organisms, crowding out native aquatic plants, and clogging waterways and intake pipes.

  • Zebra mussels can attach to almost any hard surface—clogging water intake and discharge pipes, attaching themselves to boat hulls and docks, and even attaching to native mussels and crayfish.

Invasive species are non-native species accidentally or purposefully introduced into an ecosystem that threaten or harm native populations

They are often r-selected, generalist species that can survive in a wide range of abiotic conditions and habitats

Invasives often out-compete native species

Invasive species can be spread in a variety of ways

Invasive species and the damage they cause can be controlled through a variety of human interventions

9.9: Endangered Species

• Endangered Species: A species considered to be facing a very high risk of extinction in the wild.

• Factors are taken into account for being labeled “endangered:”

  • Breeding success rate

  • Known threats

  • The net increase/decrease in the population over time

  • The number of animals remaining in the species

• Arguments for protecting endangered species

  • Maintaining genetic diversity

  • Maintaining keystone species

  • Maintaining indicator species

  • Preserving the endangered species’ aesthetic, ecological, educational, historical, recreational, and scientific value

  • Preserving the yet-to-be-discovered value of certain endangered species

• Characteristics That Have Contributed to Endangerment

  • Compete for food with humans

  • African penguins

  • High infant mortality

  • Leatherback turtles

  • Highly sensitive to changes in environmental conditions

  • Cotton-top tamarins

  • Hunting for sport

  • Passenger pigeons, blue whales, Bengal tigers

  • Introduction of nonnative invasive species

  • Bandicoots threatened by cats that were introduced by Europeans

  • Limited environmental tolerance ranges

  • Frogs, whose eggs are sensitive to water pollution, temperature changes, and the destruction of wetlands

  • Limited geographic range

  • Pandas

  • Long or fixed migration routes

  • Salmon in the Pacific Northwest that have been driven to extinction because of dam construction, logging, and water diversion

  • Loss of habitat

  • Red wolves. Whooping cranes

  • Low reproductive rates

  • Whales, elephants, and orangutans.

  • Move slowly

  • Desert tortoises

  • No natural predators, which makes them vulnerable as they lack natural defensive behaviors and mechanisms

  • Dodo birds, Steller’s sea cows, sea otters

  • Not able to adapt quickly

  • Polar bears

  • Possess characteristics sought after for commercial purposes

  • Sharks, elephants, rhinoceros’ horns. gorillas

  • Require large amounts of territory

  • Tigers

  • Small numbers of the species, which limits genetic diversity

  • Tigers

  • Specialized feeding behaviors and/or diet

  • Pandas (Bamboo)

  • Spread of disease by humans or livestock

  • African wild dogs

  • Superstitions

  • Aye ayes—some people native to Madagascar believe that aye ayes bring bad luck, and therefore kill them.

Maintaining Biodiversity

• Creating and expanding wildlife sanctuaries

• Establishing breeding programs for endangered or threatened species

• Managing habitats and monitoring land use

• Properly designing and updating laws that legally protect endangered and threatened species.

• Protecting the habitats of endangered species through private and/or governmental land trusts

• Reintroducing species into suitable habitats

• Restoring compromised ecosystems

• Reducing nonnative and invasive species

9.10: Human Impacts on Biodiversity

HIPPCO

The major factors causing a decrease in biodiversity can be abbreviated as HIPPCO:

H - Habitat destruction

I - Invasive species

P - Population growth (human)

P - Pollution

C - Climate change

O - Over exploitation

Summarizes the main factors leading to biodiversity decreased

Habitat destruction

Habitat destruction refers to the destruction, fragmentation, or degradation of natural habitats, which can make it difficult for species to survive. This can be caused by human activities such as urban development, agriculture, and logging.

An example of habitat destruction is the destruction of tropical rainforests. Tropical rainforests are home to an estimated 50% of all plant and animal species on Earth, but these forests are being destroyed at an alarming rate. The main cause of destruction is the conversion of forests to agricultural land for crops such as soybeans, palm oil, and beef. The destruction of tropical rainforests can lead to the extinction of many plant and animal species that are found nowhere else on Earth, and it also releases large amounts of carbon into the atmosphere, contributing to global warming. Additionally, deforestation can lead to soil erosion, loss of biodiversity, and destruction of indigenous peoples' ways of life.

Invasive species

Invasive species are non-native species that have been introduced to an ecosystem and are causing harm to native species. They can outcompete native species for resources and spread diseases.

An example of an invasive species is the Burmese python in the Florida Everglades. Burmese pythons are native to Southeast Asia, but they have been introduced to the Florida Everglades as a result of pet owners releasing them into the wild. These snakes have no natural predators in the Everglades and they have been able to thrive and reproduce, leading to a population explosion. As a result, they are now considered a major ecological threat to the Everglades. They are known to eat native animals such as raccoons, opossums, and even alligators, which can have a significant impact on the food chain and ecosystem. This invasive species have been causing the decline of native animals population and the disruption of the ecological balance of the region.

Population growth

Population growth can lead to an increase in human activities that can harm wildlife and their habitats, such as urbanization and resource extraction.

An example of population growth impacting the environment is the overpopulation of cities. As population grows and urban areas expand, more land is developed for housing and infrastructure. This leads to the destruction of natural habitats and the fragmentation of ecosystems. As a result, many species of plants and animals are losing the areas they need to survive. Additionally, as cities grow and demand for resources increases, pollution and waste also increase, leading to a degradation of air and water quality. Furthermore, overpopulation can put a strain on local resources and services such as water and sanitation systems, transportation, and housing, making it difficult for cities to sustain the growing population. This can lead to increased poverty and social issues.

Pollution

Pollution can have a variety of negative impacts on species, including the release of toxic chemicals, plastic debris, and other pollutants that can harm or kill animals and plants.

An example of pollution is the Great Pacific Garbage Patch. The Great Pacific Garbage Patch is a massive collection of plastic debris in the Pacific Ocean. It is estimated to be twice the size of Texas and is made up of millions of pieces of plastic, including bottles, bags, and microplastics. These plastics can be harmful to marine life, as they can be mistaken for food and ingested, leading to suffocation, starvation, and entanglement. Marine mammals, sea turtles, and fish are among the species most affected by plastic pollution. The plastic debris can also have a negative impact on commercial and subsistence fishing, as well as tourism, recreation and other activities. Plastic pollution can also have a serious impact on human health, as some of the chemicals in plastics can leach into the food we eat and the water we drink, causing negative health effects.

Climate change

Climate change can lead to changes in temperature, precipitation, and other weather patterns that can make it difficult for species to survive. Changes in temperature can also affect migration patterns, reproduction, and other aspects of animal behavior.

An example of climate change is the melting of Arctic sea ice. Arctic sea ice plays a critical role in regulating global temperatures and weather patterns, and it also provides important habitat for polar bears, walruses, and other Arctic species. In recent decades, the Arctic sea ice has been shrinking at an alarming rate. The sea ice has been declining at a rate of roughly 13% per decade, and the amount of older, thicker ice has been declining even faster. This is caused by the warming of the earth's atmosphere and the oceans which is due to the increasing levels of greenhouse gases. This loss of sea ice is having a ripple effect throughout the Arctic ecosystem, disrupting the food web and making it harder for animals to find food, leading to population decline. Additionally, the loss of sea ice can also have far-reaching effects on weather patterns and coastal communities worldwide, as the ice helps to reflect sunlight back into space, and as the ice melts, it reveals darker ocean waters that absorb more heat, leading to a feedback loop of warming.

Overexploitation

Overexploitation refers to the overuse of natural resources, including the overharvesting of wild animals and plants, which can lead to population declines and endangerment.

An example of over exploitation is the overfishing of cod in the North Atlantic. Cod is one of the most important commercial fish species in the North Atlantic, and it has been fished for hundreds of years. However, in the 20th century, fishing technology advanced rapidly, allowing boats to catch more fish faster. This, combined with increased demand for fish, led to overfishing of cod. As a result, cod populations declined dramatically, and by the 1990s, many cod stocks were considered to be overfished. This has not only had a negative impact on the cod population, but also on the entire ecosystem of the North Atlantic, as cod is a key species that plays an important role in the ocean's food web. This overfishing has led to the collapse of the cod fishing industry, and has had serious economic and social consequences for coastal communities that rely on fishing for their livelihoods. Many countries and international organizations have implemented management measures such as quotas, fishing bans, and marine protected areas to help rebuild cod populations, but it is a slow process and many stocks still have not fully recovered.

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