2Past climates Global cooling and warming occur in cycles Glacial and interglacial periodsGlacial periods last about 100,000 years.Interglacial last about 10,000-12,500 years.Our current interglacial age has lasted about 12,000 years…
3Glacial and Interglacial Periods Average temperature over past 900,000 years17161514Average surface temperature (°C)131211109900800700600500400300200100PresentThousands of years agoGlacial and Interglacial Periods
4Temperature change over past 22,000 years Agriculture established1Average temperature over past10,000 years = 15°C (59°F)-1End oflast iceageTemperature change (°C)-2-3-4-520,00010,0002,0001,000200100NowYears agoPast 22,000 years
5Temperature change over past 1,000 years Temperature change (°C) 1.00.50.0Temperature change (°C)-0.5-1.0100011001200130014001500160017001800190020002101YearPast 1,000 years
6Past 130 years Average temperature over past 130 years 15.0 14.8 14.6 14.4Average surface temperature (°C)14.214.013.813.6186018801900192019401960198020002020YearPast 130 years
7Ice can tell us WHAT?Past climate information is found through ice cores from Antarctica and Greenland.The ice core (see fig 21.3) can tell us:Greenhouse gas concentrationsSolar activitySnowfallForest fires (layers of soot)Core samples from lakes/ponds bottom tell us:PollenFossilsPlant lifeGrowth trends
8Too much information!! What we do with all that information: IPCC: Intergovernmental Panel on Climate Change2,000 experts from 70 nationsIPCC uses probability to describe trends:Virtually certain: more than 99% probabilityVery likely: 90-99% probabilityLikely: 66-90% probabilityOur current interglacial age is likely to last another 15,000 years
9Pink vs. BlueVarious regions of the world all show warming trends over the past 100 years. These graphs compare the observed changes in temperature (black lines) with model results that include only natural climate forcings like volcanic eruptions and changes in solar energy (blue) and model results that use both natural and human caused climate forcings (pink).
11What’s happening here?More greenhouse gases in the air, prevents heat moving out of the atmosphere. Added greenhouse gases absorb the heat.
12Greenhouse EffectHeat is “trapped” inside the atmosphere much like heat is trapped in a greenhouse.What causes the “trapping”?Carbon DioxideMethaneNOxCFC’sHCFC’sHalonsWater vapor (hasn’t changed – closed system)CF4This animation shows how a carbon dioxide molecule vibrates when it absorbs heat.
13Greenhouse EffectHeat is “trapped” inside the atmosphere much like heat is trapped in a greenhouse.What causes the “trapping”Carbon DioxideMethaneNOxCFC’sHCFC’s view clipHalonsWater vapor (hasn’t changed – closed system)CF4
14Effects to think about Increased death from heat, malnutrition Very likely (90-99%) that tree deaths from disease and pests will increaseVery likely that wildfires will increaseLoss of animals and plants that can’t migrate quickly enoughIncrease in pest (high tolerance) animals and insectsTree species would move toward polar regions (5 miles per decade now)Increased hurricanes (over warmer water)
15CO2 effects 380 360 340 320 300 Concentration of carbon dioxide in the atmosphere (ppm)280Carbon dioxide260240+2.5220200Variation of temperature (˚C)from current level180–2.5–5.0–7.5TemperaturechangeEnd oflast ice age–10.01601208040Thousands of years before present
16Where’s all this gas from? Burning of fossil fuels (CO2 )Deforestation (CO2)Clearing and burning grasslands (CO2)Larger cattle herds (CH4)Rice paddies/fertilizers (Nox and CH4 )Automobiles (1 gallon of gas = 20 lbs. of CO2 ; one tank of gas = 360 lbs. of CO2)
17Dirty, Rotten Americans! #1 producer of CO2 emissions (24% of world’s emissions)CO2 emissions from our cars is more than the emissions of everything that powers Japan!Each American produces more CO2 than any other nations individuals (per capita). 500 tons of CO2 in your lifetime!Huge amounts of methane from landfills and livestock.
19Carbon dioxide (CO2) 410 360 Parts per million 310 260 1800 1900 2000 2100YearCarbon dioxide (CO2)
20Methane (CH4) 2.4 1.8 Parts per million 1.2 0.6 1800 1900 2000 2100 YearMethane (CH4)
21Nitrous oxide (N2O) 320 310 Parts per million 300 290 260 1800 1900 20002100YearNitrous oxide (N2O)
22Global Warming vs Climate Change Global warming: trend towards increasing temperatures. 10 warmest years on record have occurred since 1990.Global climate change: changes in precipitation, temperatures, storm intensity. Global warming can lead to global climate change.
24“Proof” of Global Warming 20th century was hottest on recordSince 1861, average global temperature has risen between 1o- 1.4o F (most of that has been since 1980)16 hottest years on record have been since 1980, 10 hottest have been since 1990.Glaciers and sea ice are shrinking.Sea level rising (4 to 8 inches)
26Factors Affecting Earth’s Temperature Oceans can store heat and CO2, but no one knows how much.Cloud cover: can warm by trapping and releasing heat or cool by reflecting heat back to space (albedo effect)!
27Albedo is measured on a scale from 0-1(or sometimes as a %). Very dark colors have an albedo close to 0 (or close to 0%).Very light colors have an albedo close to 1 (or close to 100%).
28Albedo is measured on a scale from 0-1(or sometimes as a %). Forests have low albedo, near 0.15.Snow and ice, have very high albedo, as high as 0.8 or 0.9, and reflect most of the solar energy that gets to them, absorbing very little
29Factors Affecting Earth’s Temperature Oceans can store heat and CO2, but no one knows how much.Cloud cover: can warm by trapping and releasing heat or cool by reflecting heat back to space (albedo effect)!Outdoor air pollution: aerosols can either warm or cool the atmosphere (much like clouds)Stimulate photosynthesis: more CO2 can temporarily cause higher photosynthesis. Temporary because plants will “level off” and die, releasing their CO2Methane trapped under ice is released when the ice melts.
30SolutionsGlobal WarmingPreventionCleanupCut fossil fuel use (especially coal)Remove CO2 from smokestackand vehicle emissionsShift from coal to natural gasStore (sequester) CO2 by planting treesImprove energy efficiencyShift to renewable energy resourcesSequester CO2 deep undergroundTransfer energy efficiency and renewable energy technologies to developing countriesReduce deforestationSequester CO2 in the deep oceanUse more sustainable agricultureRepair leaky natural gas pipelines and facilitiesSlow population growthUse feeds that reduce CH4 emissions by belching cows
31What are things would you be willing to do around your house?
32What Can You Do?Reducing CO2 EmissionsDrive a fuel-efficient car, walk, bike, carpool,and use mass transitUse energy-efficient windowsUse energy-efficient appliances and lightsHeavily insulate your house and seal all draftsReduce garbage by recycling and reuseInsulate hot water heaterUse compact fluorescent bulbsPlant trees to shade your house during summerSet water heater no higher than 49°C (120°F)Wash laundry in warm or cold waterUse low-flow shower head
34Ozone Depletion The culprits: The “hole”: CFC’s: used as coolants (Freon). Are now being phased out.Halons: in fire extinguishersHydrobromofluorocarbonsThe “hole”:More of a thinning.August-November (late winter/spring) over AntarcticaWhy: wind patterns bring pollutants up and polar vortex keeps them there.
35Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breakingoff a chlorine atom and leavingCFCl2.SunClClCOnce free, the chlorine atom is offto attack another ozone moleculeand begin the cycle again.ClFUV radiationClClOOA free oxygen atom pullsthe oxygen atom offthe chlorine monoxidemolecule to form O2.The chlorine atom attacksan ozone (O3) molecule, pulling an oxygen atomoff it and leavingan oxygenmolecule (O2).ClClOOOOOThe chlorineatom and theoxygen atom jointo form a chlorinemonoxide molecule (ClO).ClOSummary of ReactionsCCl3F + UV Cl + CCl2FCl + O3 ClO + O2Cl + O Cl + O2Repeatedmany timesOO
37Ozone Depletion Solar Backscatter Ultraviolet (SBUV) Total Ozone Mapping Spectrometer (TOMS) instruments
38Natural Capital Degradation Effects of Ozone Depletion Human HealthWorse sunburnMore eye cataractsMore skin cancersImmune system suppressionFood and ForestsReduced yields for some cropsReduced seafood supplies from reduced phytoplanktonDecreased forest productivity for UV-sensitive tree speciesWildlifeIncreased eye cataracts in some speciesDecreased population of aquatic species sensitive to UV radiationReduced population of surface phytoplanktonDisrupted aquatic food webs from reduced phytoplanktonAir Pollution and MaterialsIncreased acid depositionIncreased photochemical smogDegradation of outdoor paints and plasticsGlobal WarmingAccelerated warming because of decreased ocean uptake of CO2 from atmosphere by phytoplankton and CFCs acting as greenhouse gases
40ProtocolsKyoto Protocol: 1997; Reduce greenhouse gases. (concern is global warming)Montreal Protocol: 1987; Reduce use of CFC’s (concern is ozone depletion)Copenhagen Protocol: 1992; Reduce ozone depleting chemicals (concern is ozone depletion)
41Kyoto Protocol International agreement 1997 161 nations Directs 39 countries to take steps to decrease greenhouse gas emissions.Developing countries were not held to the same standards as developed ones.2001: G.W. Bush withdrew the US from the agreement because of expense and the fact that developing countries like China and India weren’t held accountable.