Unit 9– Global Change

Module 55– Stratospheric Ozone Depletion and its reduction

• Stratospheric ozone is beneficial to the health and survival of life on earth

  • Formation of stratospheric ozone: radiation breaks down oxygen molecules, creating O_3

  • Benefits of stratospheric ozone: filters out harmful ultraviolet radiation (UV-A, UV-B, and UV-C increasing in energy)— and reduces skin cancer

• Humans have depleted the ozone layer through the use of CFCs

  • Chlorofluorocarbons (used to cool fridges/ air conditioner), releasing chlorine which forms chlorine monoxide and breaks down ozone

  • Ozone depletion has occurred, which means UV-B radiation reaches the earth causing skin cancer

• Nations around the world have agreed to reduce CFC production to reduce ozone depletion

  • Montreal protocol: reduces CFC production

Module 56– The greenhouse effect

• Global change includes global climate change and global warming

  • Global change: rising sea levels, more contamination, overexploitation

  • Global climate change: more storm intensity, altered patterns of ocean circulation

  • Global warming: heat waves, no cold spells

• Solar radiation and greenhouse gases make our planet warm

  • Infrared radiation passes through greenhouse gases and warms them (greenhouse effect)

  • Gases that cause this: water vapor, methane, nitrous oxide, and ozone

  • Greenhouse warming potential: how much a molecule can contribute to global warming over a period of 100 years relative to a molecule of carbon dioxide

• Sources of greenhouse gases are both natural and anthropogenic:

  • Natural: volcanoes, decomposition/ digestion, denitrification, evaporation/ evapotranspiration

  • Anthropogenic: burning fossil fuels, agricultural practices, deforestation, landfills, industrial production of new greenhouse chemicals

Module 57– Increases in greenhouse gases and global climate change

• CO2 concentrations have increased for the past 7 decades

  • Seasonal variation because trees, measured in ppm

  • Among nations: china/ US emit the most, Canada is highest per capita

• Global temperatures and greenhouse gases have dramatically increased over the past two centuries

  • Climate models predict things getting very hot

• Global climate change is causing ice to melt and sea levels to rise

  • Melting polar ice caps in arctic/ Greenland, melting glaciers

  • More water= thermohaline circulation can be shut off because the saltwater can be diluted from the melting ice caps

  • Warming soils/ permafrost: changing biomes, more methane released= more warmth

  • Rising sea levels affects cities and land

• Global climate change is affecting the timing and performance of plants and animals

  • Can harm organisms

  • Negative feedback loops

  • Arctic seals, polar bears, fox

Module 58– Ocean warming and acidification

• Ocean warming is affecting a variety of marine species

  • Impacts: many fish migrate to cooler areas from different locations

  • Coral bleaching occurs

• Increased carbon dioxide concentrations are causing ocean acidification

  • CO2 reacts with water and forms carbonic acid, resulting in ocean acidification

  • Bad for organisms who build shells out of calcium because it dissolves, makes them less capable to detecting predators

  • This also affects humans

• International agreements include the Kyoto protocol (sets limits for global emissions) and Paris agreement (sets limits to keep global warming under 2 degrees Celsius)

Module 59– Invasive species, endangered species, and human impacts on biodiversity

• Invasive species can negatively impact native species, ecosystems, and human activities (r-selected, generalists)

  • Kudzu vine prevents other plants from growing

  • Controlling invasive species: hard to control, mainly killing them or inspecting goods

• Plants and animals are becoming endangered because of human activities

  • 50k species

  • Causes: habitat destruction, global warming, invasive species

• Human activities are causing declines in genetic biodiversity

  • Population bottlenecks because of humans= low genetic diversity= less of a chance of developing traits resistant to things

  • Genetic diversity also declines in livestock b/c selective breeding

  • Irish potato famine= result of low genetic diversity

• Declining biodiversity has a variety of causes

  • Habitat destruction= loss of species

  • Coral bleaching= loss of species

  • Negative feedback loops

  • Invasive species and human population growth threaten biodiversity

  • Pollution kills animals, oil spills, etc

  • Climate change

  • Overexploitation (dodos)

• To conserve biodiversity, we need to reduce the threats

  • Single species conservation (one at a time)

  • Lacey Act for illegal plant/animal trade

  • Marine Mammal protection Act (killing of marine animals)

  • Endangered species act

  • Convention on International Trade in Endangered Species of Wild Fauna and Flora

  • Conserving entire ecosystems

  • Configuring protected areas

  • Biosphere reserves (protected areas that don’t undergo human impact)

  • Restoration of habitats (Everglades and Chesapeake bay)