Climate Systems

Chapter 15

Clicker Question • What is the approximate CO2 content of the

atmosphere?

–A. 0.004% (40 ppm)–B. 0.04% (400 ppm)–C. 0.4% (4000 ppm)–D. 4% (40,000 ppm)–E. 40% (400,000 ppm)

Clicker Question • What is the approximate CO2 content of the

atmosphere?

–A. 0.004% (40 ppm)–B. 0.04% (400 ppm)–C. 0.4% (4000 ppm)–D. 4% (40,000 ppm)–E. 40% (400,000 ppm)

Clicker Question • The CO2 content of the atmosphere has

increased by more than 20% in the past 50 years.

–A. True –B. False

Clicker Question • The CO2 content of the atmosphere has

increased by 19% in the past 50 years.

–A. True –B. False

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 (CO2 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

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.

Earth Interior Systems:Deep Water Cycle

• 0.2% H2O in subducting crust is sufficient to recycle the oceans once in 4 Gy.

• Oceans (0.025% of Earth mass) is maintained by a deep cycle of H in high pressure minerals.

• H solubility in rock is responsible for the style of plate tectonics.

Atmospheric/Biospheric Systems: Human Impact

• 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)

Hydrologic Cyclein 1000’s km3/y

Carbon Cycle: Natural Sources and Sinks

Carbon Cycle: Anthropogenic

Carbon Cycle CO2

Carbon Cycle

Carbon Cycle

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

Climate Cycles:Eccentricity

Climate Cycles: Tilt

Climate Cycles: Precession

Continental Drift and Ocean Circulation

Ocean Cycle: El Niño

Continental Drift

Past Climate History• 18O/16O Variation in Ice Cores

– Oxygen isotopes are fractionated by evaporation and precipitation.

– The vapor prefers the lighter isotope.– Cold global temperatures deplete 18O in ice

and enrich it in ocean water.– Isotope variation can be measured in ice cores

and in ocean sediments.

• CO2 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)– CO2 - Photosynthesis - Carbon - Carbonates

• Oxygen Cycle– O2 in atmosphere is biogenic

– Incompatible with methane (CH4)

Earth Systems Terms

• Carbon Cycle• Rock Cycle• Mantle Cycle• Greenhouse Gas• El Niño• La Niña

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 CO2 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?

Next Chapter 16Weathering, Erosion,

Mass Wasting• Does weathering of rock remove or add

CO2 to the atmosphere? – A. Adds– B. Removes – C. No effect on CO2

Next Chapter 16Weathering, Erosion,

Mass Wasting• Does weathering of rock remove or add

CO2 to the atmosphere? – A. Adds– B. Removes – C. No effect on CO2