2 Global Environmental Issues Global Warming – Greenhouse EffectWater PollutionEutrophicationAcid RainDeforestationHabitat lossOver exploitationBioaccumulation
3 Global Warming – Greenhouse Effect Greenhouse gases help to maintain the earth’s temperature at a level suitable to support lifeHuman activities are increasing the amount of greenhouse gases in the atmposphere, which cause more heat to be trappedPredicted effects of global warming include:Higher sea levelsHigher temperaturesVariable climatic conditionsThese changes are expected to cause a significant impact on agriculture and ecosystems.
4 PollutionWater pollution - A change in water quality that impacts on living organismsTypes and effects of water pollution include:Nutrients and eutrophicationToxic materials, through miningOrganic chemicalsSediments can disrupt aquatic ecosystemsAtmospheric Pollution:-CFC’s chlorofluorocarbons, can reach the stratosphere and destroy ozone gas.- Gas emissions – leads to Acid Rain
5 Eutrophicationan excessive amount of nutrients in a body of water, usually caused by runoff of nutrients (mainly phosphorous in freshwater and nitrogen in saltwater) from the land, which causes a dense growth of plant life, leading to a decrease in oxygen supply, which causes the death of animals.
6 Acid RainThe burning of fossil fuels leads to atmospheric emissions of NOx and SO2These gases react with water and oxygen to make sulfuric and nitric acids. Sunlight increases the rate of these reactionsRain, snow and fog can be polluted with these acidic compounds, which is then deposited at the earths surfaceThe effects of acid rain can:Damage forests and soilsCauses acidification of lakes and other water bodiesDisturb wildlifeCause the decay of building and other structuresImpact on human health
7 DeforestationThe deforestation of tropical rainforests is a major global problem-each year millions of hectares are lostDeforestation rates in some countries continue to increase despite worldwide pressuresRainforests are destroyed for wood products, and to make way for agricultural activities, mining and damsThe impacts of deforestation include:Loss of livelihood for local inhabitantsVariable environmental conditions (susceptability to flood, aggravated droughts, soil erosion etc)Loss of biodiversity and disturbance to ecosystemsLoss of carbon sink
8 Habitat lossdue to destruction, fragmentation or degradation of habitat—is the primary threat to the survival of wildlife in the United States.Habitat fragmentation: terrestrial wildlife habitat has been cut up into fragments by roads and development; Aquatic species’ habitat has been fragmented by dams and water diversions.Habitat destruction: A bulldozer pushing down trees is the iconic image of habitat destruction. Other ways that people are directly destroying habitat, include filling in wetlands, dredging rivers, mowing fields, and cutting down trees.Habitat degradation: Pollution, invasive species and disruption of ecosystem processes so the habitats become degraded that they no longer support native wildlife
9 Introduced SpeciesAny organism that was brought to an ecosystem as the result of human actionsCan pose a threat to the stability of an ecosystem if they prey on or crowd out the native speciesPurple loosestrifeBurmese python
10 OverexploitationOverexploitation of species affects the loss of genetic diversity and the loss in the relative species abundance of both individual and/or groups of interacting species.Overexploitation may include over fishing and over harvesting.Removing ground cover and degrading fertile land initiates desertificationWater washes away nutrients, the land becomes inhospitableThe process is accelerated by expanding populations and the need to overuse fragile areas of land
11 Bioaccumulation (biomagnification) Bioaccumulation is defined as the increase in concentration of a substance(s) in an organismBiomagnification is simply the increase in concentration of a substance in a food chain, not an organism.DDT, PCBs