Atmosphere, Oceans & Earth’s ClimateQuestions to ponderPowerPoint PresentationSlide 4Slide 5AlbedoSlide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Atmosphere, Oceans &Earth’s ClimateLecture 26Questions to ponder•What is the evidence of climate change•What are the interactions between earth, biosphere and climate•How does disruption of the Carbon cycle affect climateAtmospheric Basics: review•The greenhouse effect •Radiant energy that is absorbed heats Earth and eventually is reradiated skyward.–Radiation is in the form of longwave infrared radiation.–Atmospheric gases, primarily H2O and CO2, are more efficient absorbers of longwave radiation.–This selective absorption, called the greenhouse effect, results in warming of the atmosphere.AlbedoGlobal Climate Change•Human impact on climate change–Changes in atmospheric composition•CFCs and ozone depletion•Rate of change of greenhouse gas concentrations–Rate of human impact vs. response of Earth’s systems is not well understoodGreenhouse gases•Carbon dioxide•Methane•Nitrous oxide•CFCs•Water vapor - actually one of the more effective greenhouse gases. Why don’t we consider this?•Residence times a prime factorHow Is Climate Change Detected? •Techniques for analyzing Earth’s climate history •Seafloor sediments—Numbers and types of organic remains are indicative of past sea-surface temperatures.•Oxygen isotope analysis—The ratio of 18O/ 16O in shells of microorganisms reflect past temperatures.How Is Climate Change Detected?•Techniques for analyzing Earth’s climate history •Other sources of data for studying past climates include:–Growth of tree rings–Drill cores in glacial ice–Pollen contained in sediment and coral reefs–Information found in historical documentsClimate ChangeBoth regional and Global climate change can be recognized in man’s recent past by looking at changes in:(1) ice volume (and sea level)Climate ChangeBoth regional and Global climate change can be recognized in man’s recent past by looking at changes in: Isotopic record of temperature changeOxygen two isotopes:16O and 18OThese isotopes are “stable”, which means that they don’t undergo radiometric decay“heavies” versus “lights” distribution follows physical controls such as TemperatureTree Rings Are Useful Recorders of Past ClimatesAlso record Oxygen Isotope dataClimate ChangeBoth regional and Global climate change can be recognized in man’s recent past by looking at changes in: Atmospheric compositionGlobal Climate Change•Sea level Increases•Change in the size of global climate zones–Expansion and contraction of tropical, temperate and polar zones–T is critical component–Factors that change T are most importantPlus: Sea floor (MOR) spreading ratesW. Antarctic Ice Sheet CollapseW. Antarctic Ice Sheet CollapseLarge-scale Ice Sheet CollapseCauses of Climate Change(Short term)Most change is driven by natural geologic processes and internal feedbacksChanges in atmospheric compositionParticulate MatterSulfur CompoundsCarbon DioxideEffect of Volcanic Activity on Solar RadiationWhy focus on Carbon?Gas content of a magma:Water vaporCarbon dioxideCarbon monoxideNitrogenSulfur dioxideHydrogen sulfideChlorineCO2 Concentrations Over the Past 400,000 YearsWhy focus on Carbon?Humans release about 26GT of carbon each year;Volcanoes release about .3 GTChemical and Physical Laws•Ideal Gas LawPV = nRT•P = Pressure•V = Volume occupied•N = Avagadro’s number (constant)•R = Ideal gas constant•T = Temperature•If P increases, what MUST happen?Why focus on Carbon?Carbon is a very reactive elementReduced C4-Oxidized C4+Carbon•Carbon can form various ions•C4+ Oxidized carbon (inorganic)Ex) C4+ + 2O2- = CO2•C4- Reduced Carbon (Organic)C4- + 4H+ = CH4Photosynthesis:Takes Oxidized Carbon and Reduces itReduced Carbon has more electrons, thus more potential energyEarly earth – a reducing atmosphere•Methane rich•Little Free O2•An aside: oxygen is toxic to cellsPhotosynthesis - cyanobacteriaFossils from 3.5 bya:StromatolitesPhysical evidence from sedimentIron •Fe 2+ (reduced)•Fe 3+ (oxidized)•Oxidized Iron is Red•Reduced Iron is DarkBanded Iron FormationsAfter ~ 2.0 bya, Banded Iron deposition ceasesOnly Red Beds remainGlaciationHelps understandFaint Young SunCoalThe CarboniferousBiota and atmosphere from 65 mya to