2 Climate and Climate Change Climate- long term prevailing weather conditions in a particular placeFactors that influence climateLatitudeAtmospheric circulation patternsOceanic circulation patternsLocal geographySolar activityVolcanic activity
3 Climate and climate change Latitude- distance north or south of the equatorLow latitudes- 12 hours of sun light, high temperatures year around, no seasonsHigh latitudes- sun light varies between summer and winter months, lower temperature than areas near the equator
4 Climate and Climate Change Atmospheric circulation-Cold air sinksWarm air risesWarm air holds more moisture than cold airSun light shines on the ground and warms the air above it. The warm air rises and cooler air moves in to fill its place. This causes wind.The uneven heating of the earth’s surface and the spin of the earth causes prevailing winds.
6 Climate and Climate Change Oceanic circulation patternsSurface currents are mainly affected by prevailing windsEl Nino- short term (6-18 months), warm water is pushed east, causes increased rainfall in the southern US and central America, causes drought in Indonesia and AustraliaLa Nina- cooler than normal water- opposite effects to El Nino
7 Climate and Climate Change Ocean Circulation PatternsPacific Decadal Oscillation- long term (20-30 year cycle), affects climate over North America, affects surface water temperatures, air temperatures, and precipitation patterns.
8 Climate and Climate Change Topography-Elevation- temperature drops 6 C for every 1000 ftMountains can affect precipitationSunSolar maximum- increased amounts of UV radiation can increase stratospheric temperatures as well as lower atmospheric temperature.Volcanic eruptionsSulfur dioxide emitted from a volcano can reach the upper atmosphere and react with water vapor and dust to form a bright haze. This haze reflects sunlight back into space cooling the earth.
13 The Ozone ShieldOzone layer- an area of the stratosphere where ozone is highly concentratedOzone = a molecule made of 3 oxygen atomsAbsorbs most of the UV light that reaches the earth from the sun
14 The Ozone Shield Ozone depletion- Chlorofluorocarbons (CFC’s)- a class of human-made chemicals that might damage ozoneNonpoisonous, nonflammable, non-corrosiveUsed as..coolant in refrigeratorsTo make foamSpray propellantChemically stable at earth’s surfaceOver a year period CFC’s make there way to the upper atmosphere.
16 The Ozone ShieldScientist have estimated that a single chlorine atom can destroy 100,000 ozone molecules.
17 The Ozone ShieldThinning of the ozone layer was reported in 1985 (50-98%) around Antarctica.Polar stratospheric clouds form causing CFC’s to breakdown to Cl. The Cl reacts with the ozone in the presence of UV light.UV light kills living cells
19 The Ozone Shield1987 Montreal Protocol- a group of nations agreed to decrease the production of CFC’s1992- developed nations agreed to ban the use and production of CFC’s
20 Global WarmingGreenhouse effect- process of heat absorption by gasses in the earths atmosphereGreenhouse gasesWater vaporCarbon dioxideCFC’sMethaneNitrous oxide
21 Global WarmingMost scientist think that increased levels of greenhouse gases will cause increases in global atmospheric temperature, but not all scientist agree.Global CO2 levels fluctuate throughout the year (high in winter and low in summer)
23 Global WarmingSome scientist believe that the warming trend that started at the beginning of the 20th century will continue. Other believe that the warming trend is part of a natural occurrence of fluctuating temperatures that appear throughout time.
24 Global Warming The Consequences Melting ice and rising sea level Weather pattern changesStronger hurricanes and typhoonsChange in precipitation patternsHuman health problemsHeat related deathsIncrease in ground level ozone causing reparatory diseaseIncrease in disease carrying insects
25 Global Warming Consequences- con’t Agriculture DroughtsDiseased crop yields may increaseEffects on plants and animalsAlter habitat rangesAlter available food sources (zooplankton)
26 Global Warming Recent findings- IPCC Third Assessment Report Average global temperature increased 0.6 C during 20th centurySnow cover and ice extent decreasedGlobal sea level has risenIncrease in greenhouse gases due to human activities
27 Global Warming Reducing Risk Kyoto Protocol (1997) 55% of nations ratifyDeveloped nations decrease emissions by 5% below their 1990 levels by 2012