1. Environmental Problems And how to fix them… Chapter 55

2. Deforestation – where and why? • In the past – deciduous forests have been impacted • Today, it is more a problem in the tropics • Subsistence agriculture – a family produces just enough food to feed itself • Practice slash-and-burn agriculture: tropical soils are infertile and cannot be used to grow crops for more than one season • Provide range land for cattle: overgrazing can cause desertification

3. Deforestation – why is it a problem? • Increases soil erosion  decreases fertility, increases sedimentation of waterways • Loss of biodiversity – for both native species and migratory ones • Increases risk of flooding in low lying areas • Reduces transpiration  impacts hydrological cycle • Reduces photosynthesis  impacts global warming

4. Global Warming – How and why? • Greenhouse gases: CO2, methane, surface ozone… • Greenhouse effect: Solar energy passes through, heat energy cannot pass out; this is necessary for life on Earth • Enhanced greenhouse effect: additional warming due to addition of greenhouse gases to the atmosphere

5. Global Warming - Predictions • Rise of sea level • Changes in precipitation patterns • Changes in the range of organisms • Impact on human health • Impact on agriculture

6. The ‘Hole’ in the Ozone Layer • The ozone layer helps protect Earth from much of the sun’s UV radiation • There has been a thinning of this layer due to the use of certain chemicals • CFCs = chlorofluorocarbons and other industrial chemicals which destroy ozone

7. Why is this ‘hole’ a problem? • More UV radiation will reach surface • Human health: • Skin cancer, cataracts • Photosynthesis impacts