 And how to fix them… Chapter 55

 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 o Practice slash-and-burn agriculture: tropical soils are infertile and cannot be used to grow crops for more than one season o Provide range land for cattle: overgrazing can cause desertification

 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

 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

 Rise of sea level  Changes in precipitation patterns  Changes in the range of organisms  Impact on human health  Impact on agriculture

 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

 More UV radiation will reach surface  Human health: o Skin cancer, cataracts  Photosynthesis impacts