Environmental ProblemsAnd how to fix them… Chapter 55

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 itselfo 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

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

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

Global Warming - Predictions

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

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

Why is this ‘hole’ a problem?

More UV radiation will reach surface

Human health:oSkin cancer, cataracts

Photosynthesis impacts