Chapter 19: Global Change in the Earth System Flashcards
Why does the Earth change constantly?
- A plastic asthenosphere permits tectonic plate motion.
- A star is close enough to warm Earth and its atmosphere.
- Liquid water is possible; thus, weathering and erosion.
- Biotic evolution continually modifies the biosphere.
Life on Earth is due to interactions among the:
- Lithosphere
- Atmosphere
- Hydrosphere
- Biosphere
What is the “Earth System” composed of?
The “Earth System” is composed of these physical components interacting with the biosphere.
What are the types of changes?
- Gradual change
- Catastrophic change
- Unidirectional change
- Cyclic change
Unidirectional changes include:
- Evolution of the solid Earth
- Formation of the Moon
- Evolution of the atmosphere and oceans
- Evolution of Life
Explain how evolution of the solid Earth is a unidirectional change
- Planetesimal accretion
- Melting and differentiation
Explain how formation of the Moon is a unidirectional change
- Mars-sized protoplanet collides
- Mantle blasted into space
- Debris coalesced to form the Moon
Explain how evolution of the atmosphere and oceans is a unidirectional change
- Volcanic gases created an early atmosphere.
- CO2, H2O, N2
- Liquid water condensed to form the oceans.
- Photosynthetic organisms appeared.
- O2 becomes a significant component of the atmosphere.
Explain how evolution of life is a unidirectional change
- Life appeared on Earth about 3.8 Ga.
- Multicellular organisms appeared in Late Proterozoic and early Phanerozoic.
- Life inhabits all regions, within a few km of Earth’s surface.
Give examples to physical cycles
- the supercontinent cycle
- the rock cycle
Explain the supercontinent cycle
- Plate tectonics drives continental movement.
- Ocean basins open and close.
- Continental landmasses collide and rift apart.
- Supercontinents (like Pangaea) have formed several times.
Explain the rock cycle
there are three types of rock:
- Igneous—cooled from a melt.
- Sedimentary—made of weathered and eroded materials
- Metamorphic—rocks altered by heat and pressure
One rock type may transform into any other type.
The atoms in rocks are constantly being rearranged.
How do climate studies reveal our past and suggest our future?
- Distinguish kinds of climate changes
- Establish rates at which these changes occur
- Determine the effects on Earth and its inhabitants
What are the methods of climate studies?
- Paleoclimates—investigations of past climatic variation
- Computer simulations—modeling past and future changes
What is the greenhouse effect?
- H2O, CO2, and CH4 in Earth’s atmosphere absorb thermal energy and reradiate it, warming the lower atmosphere.
- This is called the greenhouse effect.
What are paleoclimates? Give an example
Past climates are interpreted by datable Earth materials that are climate-sensitive.
E.g. Stratigraphic records—sequences of rock strata
- Depositional environments are often climate-sensitive.
- Glacial tills—cold and continental
- Coral reef— tropical marine
How do oxygen isotopes determine paleoclimates?
- Oxygen isotopes—two isotopes: 16O and 18O
- 16O water evaporates faster than 18O water.
- 18O/16O in ice cores reveal the temperature in which snow formed.
- Oxygen isotope ratios are preserved in carbonate shells of organisms.
- The oxygen in CaCO3 shells mirrors oceanic 18O/16O.
- Sea-floor sediments preserve ocean chemistry and temperature changes.
here have been at least _____ major icehouse periods in Earth’s geologic history.
five
What causes long-term climate changes?
- Complex interactions across the Earth System
- Plate tectonics modifies the position of continents.
- Uplift of land surfaces influences atmospheric circulation.
- Formation of coal and oil removes carbon from atmosphere.
- Evolution of life affected atmospheric composition.
Short-term climate changes regulated by several factors:
- Fluctuations in solar radiation and cosmic rays
- Changes in Earth’s orbit and tilt
- Changes in volcanic emissions
- Changes in ocean currents
- Changes in surface albedo
- Abrupt changes in concentrations of greenhouse gases
How did humans impacted the Earth’s System?
- Prehistoric humans were few, having a small impact. Today, humans are a huge force of planetary change.
-Exponential population growth aided by advancements in:
Industry, agriculture, technology, and medicine; fueled by a suitable supply of natural resources - Human demands often rival or exceed some natural processes.
-Landscape modifications - Ecosystem modification—balances are destabilized. Destroys habitats
- Pollution—materials that harm life forms and resources
- Modern human society generates contaminants.
- ## Recent global warming—human greenhouse gas additions alter climate.
How do landscape modifications affect the Earth’s System?
Human-induced erosion may exceed natural processes.
How do ecosystem modifications affect the Earth’s System?
- Human-caused changes occur faster than indigenous organisms can adapt.
- Rainforest decline is largely the result of human activity.
- Deforestation
- Overgrazing
- Agriculture
- Urbanization
How does pollution affects the Earth’s System?
materials that harm life forms and resources
How do contaminants affect the Earth’s System?
- Contaminating materials are numerous and diverse.
- They are produced so fast that the natural environmental systems can’t absorb or modify/neutralize them.
Explain how human greenhouse gas additions alter climate
- O2 in the atmosphere has steadily climbed since the industrial revolution began.
- Ice core data show atmospheric CO2 in 1750 was ~ 280 ppm.
- In 1958, CO2 was ~315 ppm; in 2010, CO2 was ~390 ppm
- Human additions of CO2 and CH4 exceed natural removals.
- Fossil fuel combustion (CO2)
- Rice-paddy decay (CH4)
- Cow flatulence (CH4)
Thousands of observations worldwide have documented effects of recent global warming such as:
- Large ice shelves, like the Larsen B along the Antarctic Peninsula, are breaking up.
- The summer melt line indicates that melting of the Greenland ice sheet is accelerating.
- Valley glaciers worldwide are retreating.
- Arctic Ocean sea-ice is reduced.
The predicted effects of global warming are:
- Stonger storms due to a more vigorous hydrologic cycle: - Higher sea-surface temperatures
- Greater evaporation
- Greater differential pressures
- 2005 set a number of storm records
- A rise in sea level
- Warming will accelerate this trend by:
- Thermal expansion of seawater
- Melting ice
Many scientists think that global warming could lead to:
- Interruption of the oceanic heat conveyor system.
- Polar ice meltwater is freshwater.
- Would dilute surface ocean water near the poles.
- This freshwater won’t sink and move southward.
- Thermohaline circulation would stop preventing warm water from flowing northward.
What is going to happen to Earth’s System in millions of years?
- Earth’s surface will be different.
- Plate tectonics will reshuffle continents.
- Erosion will reshape the landscape.
- Seas will invade or expose land.
- Homo sapiens may no longer be present.
- A new species of hominids might have evolved by then.
What will happen to the Sun in 5 billion years?
In about 5 billion years, the Sun will run out of fuel and become a red giant.
- Earth will dry out.
- It will become vaporized.
