MET 112 Global Climate Change -A Big Argument on Climate ChangePaleoclimateSlide 4Slide 5Slide 6Determining Past ClimatesSlide 8Slide 9Slide 10Slide 11Climate Through the AgesSlide 13Slide 14Slide 15Climate During the Past 1000 YearsSlide 17Slide 18Slide 19Temperature Trend During the Past 100-plus YearsSlide 21Slide 22Causes of Climate ChangeNatural Climate ChangeExternal ForcingSOLAR ACTIVITYTHE SOLAR CYCLEClimate Change and Variations in Solar OutputTHE MAUNDER MINIMUMSlide 30Slide 31Slide 32Slide 33Slide 34Slide 35The Year Without SummerSlide 37Climate Change and Atmospheric ParticlesSlide 39Slide 40Orbital changesClimate Change and Variations in the Earth’s OrbitSlide 44Slide 45Slide 46Slide 48Slide 49Slide 50ActivitySlide 52Slide 53If the earth’s tilt was to decrease, how would the summer temperature change at our latitudeA: How would climate changeB: How would glaciers change?Internal ForcingSlide 58Climate Change, Plate Tectonics, and Mountain-buildingSlide 60Slide 611 MET 112 Global Climate ChangeMET 112 Global Climate ChangeMET 112 Global Climate Change -Natural Climate Forcing2 MET 112 Global Climate ChangeMET 112 Global Climate ChangeA Big Argument on Climate ChangeIs the current warming a natural variation caused by natural forcing or a human-induced change related to greenhouse gases?3 MET 112 Global Climate ChangeMET 112 Global Climate ChangePaleoclimateA lead to4 MET 112 Global Climate ChangeMET 112 Global Climate ChangeEarth geological time scalePaleo : Greek root means “ancient”Modern age, ice age, last 2 million yearsAge of dinosaursFrom the formation of earth to the evolution of macroscopic hard-shelled animalsAnimal explosion of diversity5 MET 112 Global Climate ChangeMET 112 Global Climate ChangeSurface Temperature is not uniform in Earth historyChange of Surface Temp. relative to present6 MET 112 Global Climate ChangeMET 112 Global Climate ChangeTemperature: the last 400,000 yearsFrom the Vostok ice core (Antarctica)7 MET 112 Global Climate ChangeMET 112 Global Climate ChangeDetermining Past ClimatesHow do we know what past climates were like?Fossil evidenceFossil evidenceFossils of tundra plants in New England suggest Fossils of tundra plants in New England suggest a colder climatea colder climateOcean sediment coresOcean sediment coresCertain animals must have lived in a range of Certain animals must have lived in a range of ocean temperaturesocean temperaturesOxygen isotope ratiosOxygen isotope ratiosDiffering isotope counts mean differing Differing isotope counts mean differing temperaturestemperatures8 MET 112 Global Climate ChangeMET 112 Global Climate ChangeDetermining Past Climates Ice coresIce coresSulfuric acid in ice coresSulfuric acid in ice coresOxygen isotopes (cold the air, more isotopes)Oxygen isotopes (cold the air, more isotopes)Bubbles in the ice contain trapped composition Bubbles in the ice contain trapped composition of the past atmospheresof the past atmospheresDendrochronologyDendrochronologyExamining tree rings to see growth patternsExamining tree rings to see growth patterns9 MET 112 Global Climate ChangeMET 112 Global Climate ChangeClimate record resolution1 ,000,000 100,000 10,000 1000 100 10 1 1mon 1day(years)1 ,000,000 100,000 10,000 1000 100 10 1 1mon 1daySatellite, in-situ observationHistorical dataTree ringsLake core, pollenIce coreGlacial featuresOcean sediment, isotopesFossils, sedimentary rocks10 MET 112 Global Climate ChangeMET 112 Global Climate ChangeClimate record distribution from 1000 to 1750AR4 6.1111 MET 112 Global Climate ChangeMET 112 Global Climate ChangeCosmic rays produce C14C14 has half-life of 5730 years and constitutes about one percent of the carbon in an organism.When an organism dies, its C14 continues to decay.The older the organism, the less C14C14 and O18 proxyO18 is heavier, harder to evaporate. As temperature decreases (in an ice age), snow deposits contains less O18 while ocean water and marine organisms (CaCO3) contain more O18 The O18/ O16 ratio or δO18 in ice and marine deposits constitutes a proxy thermometer that indicates ice ages and interglacials.Low O18 in ice indicates it was deposited during cold conditions worldwide, while low O18 in marine deposits indicates warmth C14 dating proxyO18 temperature proxy12 MET 112 Global Climate ChangeMET 112 Global Climate ChangeClimate Through the AgesSome of Earth’s history was warmer than today by as much as 15°CIce age–Most recently 2.5 m.y.a.–Beginning marked by glaciers in North America–Interglacial periods (between glacial advances)–When glaciers were at their max (18,000 – 22,000 years ago) sea level 395 feet lower than today–This is when the sea bridge was exposed•20,000 years ago the sea level was so low that the20,000 years ago the sea level was so low that theEnglish Channel didn’t even exist.English Channel didn’t even exist.13 MET 112 Global Climate ChangeMET 112 Global Climate ChangeClimate Through the Ages14 MET 112 Global Climate ChangeMET 112 Global Climate ChangeClimate Through the AgesTemps began to rise 14,000 years agoThen temps sank again 12,700 years ago–This is known as the Younger-Dryas15 MET 112 Global Climate ChangeMET 112 Global Climate ChangeClimate Through the AgesTemps rose again to about 5,000 years ago (Holocene Maximum). Good for plants16 MET 112 Global Climate ChangeMET 112 Global Climate ChangeClimate During the Past 1000 YearsAt 1000, Europe was relatively warm. Vineyards flourished and Vikings settled Iceland and Greenland17 MET 112 Global Climate ChangeMET 112 Global Climate ChangeClimate During the Past 1000 YearsFrom 1000-1300Huge famines due to large variations in weather. Crops suffered.Floods and great droughts18 MET 112 Global Climate ChangeMET 112 Global Climate ChangeClimate During the Past 1000 YearsFrom 1400-1800Slight cooling causes glaciers to expandLong winters, short summers. Vikings diedKnown as the Little Ice Age19 MET 112 Global Climate ChangeMET 112 Global Climate ChangeClimate During the Past 1000 YearsLittle Ice Age1816 – “Year Without A summer”Very cold summer followed by extremely cold winter20 MET 112 Global Climate ChangeMET 112 Global Climate ChangeTemperature Trend During the Past 100-plus YearsWarming