AL

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.

9.2: 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.

9.3: 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 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.

9.4: 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.

9.5: 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.

9.5: 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