Systems? Chapter 15 • What is a system? • Geologic phenomena are complex. Climate Systems • All processes are related to, and interact with, other processes. • So it is useful to think of geologic processes as systems or cycles. Earth Systems Earth Interior Systems • Earth Interior Systems • Rock Cycle – Mantle Convection and Plate Tectonics – Igneous-Weathering-Sedimentation- – Core Convection and Magnetic Field Metamorphism – Rock Cycle (weathering & metamorphism) • Mantle Cycle • Atmospheric/Biospheric Systems – Mantle Convection, Crust Formation, – Hydrologic Cycle and Subduction = Plate Tectonics – Ocean Cycles (Circulation and El Niño) – Water Cycling – Carbon Cycle (CO2 in atmosphere) • Core Convection – Oxygen Cycle – Magnetic Field - Ozone shield Atmospheric/Biospheric Hydrologic Cycle 3 Systems: Human Impact in 1000’s km /y • Hydrologic Cycle – Evaporation - Transport - Precipitation - Flow • Ocean Cycles – Global Circulation & El Niño • Carbon Cycle (Greenhouse Gas) – CO2 - Photosynthesis - Carbon - Carbonates • Oxygen Cycle – O2 in atmosphere is biogenic – Incompatible with methane (CH4) 1 Hydrologic Cycle: Hydrologic Cycle H and O isotopes in 1000’s km3/y • Heavier isotopes depleted in gas, enriched in liquid and solid. • Ice cores hold record of global temperatures • Heavy isotopes indicate warm periods, light isotopes cold Carbon Cycle: Natural Sources and Sinks Carbon cycle • Carbonate Cycle – Carbonate stored in oceans – Carbon (CO2) stored in atmosphere – Carbonate stored in limestone – ReducedCarbon stored in coal, oil, & gas • Complex feedbacks Carbon Cycle: Anthropogenic What is a greenhouse gas? • Gas molecules with 3 or more atoms CO2, CH4, H2O, etc. • These molecules absorb IR from Earth surface and convert to heat. • Traps heat in atmosphere • O2 and N2 do not do this. 2 Carbon Cycle CO2 Carbon Cycle CO2 Sun emits visible Earth emits IR Carbon Cycle CO2 Carbon Cycle CO2 Earth Surface Systems • Carbon Cycle – Carbonate stored in oceans – Carbon (CO2) stored in atmosphere – Carbonate stored in limestone – Reduced Carbon stored in coal, oil, & gas • Complex feedbacks 3 Carbon Cycle: Anthropogenic Carbon Cycle Carbon Cycle 4 Warming Warming: Vulnerable US Cities • Sea Level Rise • New Orleans • New York – Thermal Expansion of water • Houston • Boston – Melting Glaciers • Corpus Christi • Philadelphia • Mobile • Washington • Increased Storm Intensity • Orlando • Baltimore • Miami Climate Cycles: Climate Cycles: Tilt Eccentricity Continental Drift and Climate Cycles: Precession Ocean Circulation 5 Ocean Cycle: El Niño Continental Drift Past Climate History Atmospheric/Biospheric • 18O/16O Variation in Ice Cores Systems: Human Impact – Oxygen isotopes are fractionated by • Hydrologic Cycle evaporation and precipitation. – Evaporation - Transport - Precipitation - Flow – The vapor prefers the lighter isotope. • Ocean Cycles – Cold global temperatures deplete 18O in – Global Circulation & El Niño ice and enrich it in ocean water. • Carbon Cycle (Greenhouse Gas) – Isotope variation can be measured in ice – CO - Photosynthesis - Carbon - cores and in ocean sediments. 2 Carbonates • CO2 variation can be measured in gas • Oxygen Cycle bubbles in ice. – O2 in atmosphere is biogenic • Both methods provide evidence of – Incompatible with methane (CH4) large variation in global temperatures Climate Learning Goals Climate Learning Goals • Atmosphere is in equilibrium with surface • What is a greenhouse gas? • Cycles and Systems • How does it trap heat? • Hydrologic Cycle: Surface, shallow, deep • How much CO2 do we have now? • Ocean circulation: heat transport • What are main sources and sinks? • Carbon Cycle: Sources and sinks • Do we have a record of past CO2? • Oxygen Cycle: Where does it come from? • Rock Cycle: weathering, transport. • Do we have a record of Earth temperatures? 6 Next Chapter 16 Next Chapter 16 Weathering, Erosion, Weathering, Erosion, Mass Wasting Mass Wasting • Does weathering of rock remove or • Does weathering of rock remove or add CO2 to the atmosphere? add CO2 to the atmosphere? – A. Adds – A. Adds – B. Removes – B. Removes – C. No effect on CO2 – C. No effect on CO2 Earth Interior Systems: Earth Interior Systems: Deep Water Cycle Deep Water Cycle • Ocean crust hydrates on ocean • 0.2% H2O in subducting crust is bottom. sufficient to recycle the oceans once • Crust and lithosphere subduct. in 4 Gy. • >90% of water is returned at arc • Oceans (0.025% of Earth mass) are volcanoes maintained by a deep cycle of H in high pressure minerals. • 1 to 10% of this water goes deep. • H solubility in rock is responsible for • This water is returned at mid ocean the style of plate tectonics. ridges. 7.