Chapter 19 Flashcards
Why do we use the term Earth System to describe the components of processes operating on this planet?
Processes on the earth are determined by interactions, everything works together. Operates as a system not as parts.
How have the Earth’s crust and atmosphere changed since they first formed?
Crust: o Core formed from differentiation
o Rocky mantle formed over it
o Earth’s mantle is molten after collision with Mars sized object, surface was a sea of magma
o Surface cooled and crust formed. Plate tectonics began operating. Subduction caused first continents. Ocean basins were formed and there were many levels to Earth.
Atmosphere: o Gases arose from melting of surface and magma
o Comets brought new gases into the atmosphere
o Early in history gases were CO2 and H2O, then nitrogen was very small.
o Once the surface cooled, water condensed and fell as rain to form oceans, CO2 dissolved into the oceans and was absorbed by chemical-weathering reactions on land
o O2 came into the picture in the early part of the Proterozoic
What processes control the rise and fall of sea level on Earth?
The moons position, the Earth’s rotational axis, and the temperature that determines how many glaciers there are.
How does carbon cycle through the various Earth systems?
o Started through volcanoes as CO2
o Dissolves in seawater or absorbed by photosynthetic organisms and converted into sugar.
o Some returns back to the atmosphere during respiration of animals again as CO2 or by flatulence as methan CH4 or by the decay of dead organisms
o Burning of fossil fuels also releases CO2
How do paleoclimatologists study ancient climate change?
-record of sedimentary rocks
-fossils provide environmental clues
-Oxygen isotope ratios in ice and carbonate sediments provide a proxy for
average temperatures
- Ancient air bubbles
-Variations in growth rings and recorded
human history
Contrast icehouse and greenhouse conditions.
Greenhouse climate is warmer than that of today’s (especially at the poles), and is
characterized by high atmospheric concentration of carbon dioxide and relatively high sea
level, with no continental glaciers at the poles. In contrast, icehouse conditions are colder,
with permanent ice present at the poles and relatively low levels of atmospheric carbon
dioxide and low sea level
What are the possible causes of long-term climatic change?
- sizes and positions of the continents
-Volcanoes emit carbon dioxide, which adds to the greenhouse effect
-Uplifted areas are sites of intense weathering
-Limestone, coal, organic-rich shale, and oil contain carbon, so when produced in
vast quantities and buried, they keep carbon from reaching the atmosphere as carbon
dioxide. Carbon burial is a check on the greenhouse effect
-appearance or extinction of certain life
What factors explain short-term climatic change?
-abundance of sunspots (cool spots on the surface of the Sun, which may
represent magnetic storms)
-Earth’s orbital shape, magnitude of tilt, and direction of tilt vary over Milankovitch
cycles with periods in the tens of thousands of years
-Earth’s albedo can be increased by an increase in aerosols (such as volcanic ash), cloud
cover, surface ice, or the spread of deserts and grasslands over land that was once forested.
-Ocean currents may change course
-Abrupt changes in concentrations of greenhouse gases
Give some examples of events that cause catastrophic change.
Comet or asteroid impact, mass extinctions, explosive or hyperactive volcanism, and
sudden episodes of global warming or cooling
Give some examples of how humans have changed the Earth.
Extraction of rock and groundwater, overhunting and overfishing, destruction of forests
and grasslands, and pollution of the air, streams, and oceans have led to subsidence, an
increase in mass wasting, famine, high rates of biotic extinction, acid rain, smog, a hole in
the ozone layer, and so on.
What is the ozone hole, and how does it affect
The ozone hole is a large opening in the stratospheric ozone layer over Antarctica (a
smaller hole sits atop the Arctic) caused by the reaction of ozone with anthropogenic
chlorofluorocarbons.
Describe how CO2-induced global warming takes place, and how humans may be responsible. What effects might global warming have on the Earth System?
Carbon dioxide is called a greenhouse gas because, much like the glass of a
greenhouse, it allows solar radiation to reach the Earth, but traps the infrared radiation that
the Earth emits to outer space. Because of its relative abundance, carbon dioxide is the most
significant of the greenhouse gases in the atmosphere. Humans are likely responsible for
increased atmospheric carbon dioxide (and resultant greenhouse warming); human burning
of fossil fuels emits carbon dioxide to the atmosphere, and the increase in atmospheric
carbon dioxide over the past two centuries is too rapid to have been caused by geologic
processes. Effects of global warming on the Earth System include sea-level rise, the breakup
of polar ice shelves, the melting of glaciers, a reduction in sea ice formation, shifts in
patterns of precipitation and climate belts, changes in the range distributions of animals,
imperilment of polar wildlife, stronger storms (including hurricanes), and disruption of
oceanic currents (which may bring further climatic change, including the cooling of high
latitudes).
What are some likely scenarios for the long-term future of the Earth?
Unless destroyed by impact, Earth will be consumed by the red giant stage of our Sun’s
evolution, approximately 5 billion years from now.
albedo
Amount of sunlight that is reflected by the surface of a planet or a satellite, such as the Moon.
