Nội dung

Ch. 56 Warm-Up How does acid precipitation affect the environment? 2. Explain how the greenhouse effect can be both positive and negative. 3. Should humans be concerned about biological magnification? Explain. 1. Define Ch. 56 Terms:  Eutrophication  Biological magnification  Greenhouse effect  Global warming  Acid precipitation Chapter 56: Conservation Biology and Global Change What you need to know: The value of biodiversity, and the major human threats to it. How human activity is changing the earth Biodiversity Conservation biology is a goal-oriented science that seeks to counter the biodiversity crisis, the current rapid decrease in Earth’s variety of life. Extinction is a natural phenomenon that has been occurring since life evolved on earth. The current rate of extinction is what underlies the biodiversity crisis. A high rate of species extinction is being caused by humans. The three levels of biodiversity:  genetic diversity  species diversity  ecosystem diversity The four major threats to biodiversity: 1. Habitat loss Human alteration of habitat is the single greatest threat to biodiversity 2. Introduced species: invasive/nonnative/exotic species 3. Overexploitation: harvest wild plants/animals 4. Global change: alter climate, atmosphere, & ecological systems  reduce Earth’s capacity to sustain life Landscape conservation Movement corridors can promote dispersal if habitats are fragmented Biodiversity Hot Spots Eutrophication  Excess nitrogen from agriculture enters aquatic ecosystems  Algae and bacteria bloom/die  reduce oxygen  fish and invertebrates die Mississippi basin dead zone (red) Acid Precipitation  Rain, snow, or fog with a pH less than 5.6  Caused by burning of wood & fossil fuels  release sulfur oxides and nitrogen oxides  React with water in the atmosphere to produce sulfuric and nitric acids The effects of acid precipitation on a forest Acid rain damage to statuary, 1908 & 1968 Biological Magnification  Toxins become more concentrated in successive trophic levels of a food web  Toxins can’t be broken down & magnify in concentration up the food chain  Problem: mercury in fish Human activities are depleting the atmospheric ozone Life on earth is protected from the damaging affects of ultraviolet radiation (UV) by a layer of O3, or ozone. Chlorine-containing compounds erode the ozone layer Greenhouse Effect  Greenhouse Effect: absorption of heat the Earth experiences due to certain greenhouse gases  CO2 and water vapor absorb infrared radiation and re-reflect back toward Earth  The Earth needs this heat, but too much could be disastrous. Rising atmospheric CO2  Since the Industrial Revolution, the concentration of CO2 in the atmosphere has increased greatly as a result of burning fossil fuels. Global Climate Change (“Global Warming”)  Studies predict a doubling of CO2 in the atmosphere will cause a 3ºC increase in the average temperature of Earth.  Rising temperatures could cause polar ice cap melting, which could flood coastal areas.  Approach: stabilize use of fossil fuels and reduce deforestation Global Climate Change Snow and rainfall patterns shifting Floods, drought, intense rainfall, more frequent and severe heat waves NASA Video Clip: Daily Arctic Sea Ice C hanges