Chapter 15 Climate Systems Systems? What is a system? Geologic phenomena are complex. 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 Mantle Convection and Plate Tectonics Core Convection and Magnetic Field Rock Cycle (weathering & metamorphism) Atmospheric/Biospheric Systems Hydrologic Cycle Ocean Cycles (Circulation and El Niño) Carbon Cycle (CO 2 in atmosphere) Oxygen Cycle Earth Interior Systems Rock Cycle Igneous-Weathering-Sedimentation- Metamorphism Mantle Cycle Mantle Convection, Crust Formation, and Subduction = Plate Tectonics Water Cycling Core Convection Magnetic Field - Ozone shield Atmospheric/Biospheric Systems: Human Impact Hydrologic Cycle Evaporation - Transport - Precipitation - Flow Ocean Cycles Global Circulation & El Niño Carbon Cycle (Greenhouse Gas) CO 2 - Photosynthesis - Carbon - Carbonates Oxygen Cycle O 2 in atmosphere is biogenic Incompatible with methane (CH 4 ) Hydrologic Cycle in 1000 s km 3 /y 1
Hydrologic Cycle: H and O isotopes Heavier isotopes depleted in gas, enriched in liquid and solid. Hydrologic Cycle in 1000 s km 3 /y Ice cores hold record of global temperatures Heavy isotopes indicate warm periods, light isotopes cold Carbon cycle Carbon Cycle: Natural Sources and Sinks 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 CO 2 Carbon Cycle CO 2 Sun emits visible Earth emits IR Carbon Cycle CO 2 Carbon Cycle CO 2 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 Sea Level Rise Thermal Expansion of water Melting Glaciers Increased Storm Intensity Warming: Vulnerable US Cities New Orleans Houston Corpus Christi Mobile Orlando Miami New York Boston Philadelphia Washington Baltimore Climate Cycles: Eccentricity Climate Cycles: Tilt Climate Cycles: Precession Continental Drift and Ocean Circulation 5
Ocean Cycle: El Niño Continental Drift Past Climate History 18 O/ 16 O Variation in Ice Cores Oxygen isotopes are fractionated by evaporation and precipitation. The vapor prefers the lighter isotope. Cold global temperatures deplete 18 O in ice and enrich it in ocean water. Isotope variation can be measured in ice cores and in ocean sediments. CO 2 variation can be measured in gas bubbles in ice. Both methods provide evidence of large variation in global temperatures Atmospheric/Biospheric Systems: Human Impact Hydrologic Cycle Evaporation - Transport - Precipitation - Flow Ocean Cycles Global Circulation & El Niño Carbon Cycle (Greenhouse Gas) CO 2 - Photosynthesis - Carbon - Carbonates Oxygen Cycle O 2 in atmosphere is biogenic Incompatible with methane (CH 4 ) Climate Learning Goals Atmosphere is in equilibrium with surface Cycles and Systems Hydrologic Cycle: Surface, shallow, deep Ocean circulation: heat transport Carbon Cycle: Sources and sinks Oxygen Cycle: Where does it come from? Rock Cycle: weathering, transport. Climate Learning Goals What is a greenhouse gas? How does it trap heat? How much CO 2 do we have now? What are main sources and sinks? Do we have a record of past CO2? Do we have a record of Earth temperatures? 6
Next Chapter 16 Weathering, Erosion, Mass Wasting Does weathering of rock remove or add CO 2 to the atmosphere? A. Adds B. Removes C. No effect on CO2 Next Chapter 16 Weathering, Erosion, Mass Wasting Does weathering of rock remove or add CO 2 to the atmosphere? A. Adds B. Removes C. No effect on CO2 Earth Interior Systems: Deep Water Cycle 0.2% H 2 O in subducting crust is sufficient to recycle the oceans once in 4 Gy. Oceans (0.025% of Earth mass) are maintained by a deep cycle of H in high pressure minerals. H solubility in rock is responsible for the style of plate tectonics. Earth Interior Systems: Deep Water Cycle Ocean crust hydrates on ocean bottom. Crust and lithosphere subduct. >90% of water is returned at arc volcanoes 1 to 10% of this water goes deep. This water is returned at mid ocean ridges. 7