Final Flashcards
The solid Earth is differentiated into layers. The density of oceanic crust is
greater than that of continental crust
The Hawaiian islands have been formed by a volcanic phenomenon known as a
stationary hotspot
What tectonic changes occurred in the LAST 50 MILLION YEARS?
Australia and South America both drifted away from Antarctica
What is true about the ITCZ?
- In ITCZ, converging air rises and forms clouds
- trade winds flow out of tropical regions converging into ITCZ
- ITCZ is area of permanently low pressure
The primary reason the surface of Venus is much hotter than that of Earth is b/c Venus:
has much greater levels of CO2 in atmosphere than Earth does
largest reservoir of carbon in Earth’s system today
Earth’s crust
Which changes occur in a descending (sinking) parcel of air?
Air warms up adiabatically, no condensation occurs and no clouds form
What evidence did Alfred Wegener present to support his hypothesis of the continental drift in 1915?
similar shapes of widely separated continental margins
Why has Earth remained habitable throughout its history?
Chemical weathering of continental rocks both responds to and modifies level of CO2 and other greenhouse gases in atmosphere over geologic time scales
Many island arcs like the Aleutian Islands were formed when two tectonic plates interacted. Along what type of plate boundary do island arcs usually form?
oceanic-oceanic convergent plate boundary
Which type of tectonic plate boundary is likely to result in formation of deep ocean trench?
convergent with one oceanic and one continental plate colliding
As the temperature in a parcel of air goes up, its ability to hold water vapor:
increases exponentially
Negative Earth climate system feedbacks:
always suppress climate changes initially caused by external forcing
Why does chemical weathering occur faster in the Andes than in the Amazon Valley?
The Andes have more fresh rock exposed than do the Amazon lowlands
appropriate data archive for reconstructing what climate was like 100 MILLION YEARS AGO?
ocean sediment cores
What does the existence of ice sheets at tropical latitudes on all continents between 950 and 650 million years ago suggest?
Atmospheric CO2 concentrations were very low
fractionation
enrichment of oxygen heavier isotope O18 in ocean water as lighter oxygen isotope O16 is preferentially stored in snow and ice
Model simulations of climate on Pangaea indicate that the climate was likely one with:
very dry conditions in the tropical continental interior
What evidence is there for asteroid impact 66 million years ago?
Sediments containing grains of quartz w/ shock-produced texture (shock lamellae)
Gateway Hypothesis
suggests that separation of Antarctica from Australia and South America allowed ice sheets form on Antarctica
About how much would global sea level rise if all ice stored in Antarctic and Greenland ice sheets were returned to ocean?
65 meters
long-term effects (over millions of years) of the Chicxulub asteroid impact on climate include atmospheric:
There were no significant long-term effects on climate
The tectonic uplift of the Tibetan Plateau and the Himalayas:
resulted in increased rate of chemical weathering
What does climate modeling tell us about atmospheric CO2 concentrations above 1,000 ppm?
Large ice sheets cannot exist when CO2 concentrations are above 1,000 ppm
What may cause relative global sea level to rise?
thermal expansion of ocean water
The Himalayan Mountains were formed 55-45 million years ago b/c of a continental-continental
convergent plate boundary
formation of Isthmus of Panama 7-4 million years ago was the result of the Cocos Plate
subduction under the Caribbean Plate
The Arabian Plate and the African Plate have been
diverging for tens of millions of years which resulted in formation of Red Sea
What kind of feedback does chemical weathering provide to the initial climate forcing?
negative
What kind of feedback does albedo provide to the initial climate warming or cooling?
positive
Summer monsoon is caused by
uneven heating of ocean vs. continental landmasses
In summer monsoon, area of ____ pressure forms over ocean and area of ____ pressure forms of continent.
This results in high amount of rainfall in South Asia during the ____
high, low
winter
CaSiO3 + H2O + CO2 ->
CaCo3 + SiO2 + H2O
When is Earth closest to the Sun in its present orbit?
during the Northern Hemisphere’s winter
precession of the equinoxes
- causes solstices and equinoxes to move around Earth’s orbit.
- has an average period of 23,000 years.
- results from a wobble of Earth’s axis and a slow shift in the orbital ellipse axes.
The orbital monsoon hypothesis predicts that
greater summer insolation intensifies the wet summer monsoon.
Which isotopic transfer occurs during inter-glaciations?
O16-enriched water is transferred from the land to the ocean
Why is there a phase lag between changes in insolation and changes in ice volume?
The response time of the ice sheet is about one quarter of the orbital cycle wavelength.
Why do strongest monsoons occur in Northern Hemisphere rather than Southern Hemisphere today?
Landmasses are larger in the Northern Hemisphere.
What is the correlation between the CO2 oscillations and changes in ice volume, as recorded in the
Antarctica Dome C ice cores over the last 800 thousand years?
CO2 is low when ice volume is high.
According to Milankovitch theory, what season of insolation is most important in controlling the growth
and melting of ice sheets?
summer
How are CH4 (methane) variations over the last 800,000 years as measured in ice cores linked to orbital changes in summer insolation?
They are linked to changes in the strength of the summer monsoons in tropical and subtropical regions.
changes in the strength of the summer monsoons in tropical and subtropical regions.
20,000 years ago
Where was C12-enriched organic matter ultimately transferred to during the Last Glacial Maximum?
the deep ocean
Millennial oscillations of climate
may be the product of random behavior.
How did the Tibetan plateau uplift affect the monsoons of South Asia over the last 30-40 million years?
Monsoon intensity in East and Southeast Asia increased since the Tibetan uplift.
Younger Dryas
- The cause of the Younger Dryas remains unexplained.
- cold episode that interrupted the general interglacial warming.
- named after an Alpine flowering plant.
- occurred between 12,900 and 11,600 years ago.
What conditions characterized the LGM?
The global sea level was 120 meters (360 feet) lower than today.
δO18 changes over the last 2.75 million years show
a general cooling trend interrupted by interglacials.
According to the geologic data, during which of the following times were North African lakes at their
highest levels? (* think of the North African monsoon)
11,500-7,500 years ago
Approximately 11,500 years from today, the June 21 solstice position near perihelion will (increase
or decrease) __________________ Northern Hemisphere’s summer radiation
increase
If the Earth’s axis was ______________________ (tilted, horizontal, vertical,
perpendicular, parallel, circular) in respect to the orbital plane, the length of every day would be the
same everywhere on Earth
perpendicular
The orbital monsoon theory suggests that monsoonal strength is modified by a(an) _______ (41-thousand -year obliquity cycle, 100-thousand-year
eccentricity cycle, 23-thousand-year precessional cycle, seasonal change, rotation on Earth’s axis,
equatorial bulge, carbon dioxide concentration) due to the strong relationship between the monsoonal
circulation and _______ (decreased seasonal amplitude, increased
seasonal amplitude, cloud cover, volcanism, continental collisions).
- 23-thousand-year precessional cycle
- increased seasonal amplitude
What was the general climate trend during the early time of human evolution?
a general shift to dryer climates in Africa
What is hypothesized to have occurred ~ 5,000 years ago that could turn the tropospheric CH4 (methane) trend toward a gradual increase?
the spread of rice irrigation in Asia
What is the problem with the climatic explanation of the megafaunal extinction 12,500 years ago?
No comparable pulse of extinction occurred in any of the fifty earlier deglaciations.
With present insolation and natural interglacial greenhouse gas (GHG) levels, what would be the state of glaciation in the Northern Hemisphere today?
year-round snow cover in northern parts of North America and Eurasia
For about what fraction of Earth’s history have our species Homo Sapiens been present?
1/22,500 of Earth’s age
The Little Ice Age:
occurred from about 1400 to 1900 CE.
Which of the following characterizes average (non-El Nino) conditions in the Pacific Ocean?
strong trade winds pull surface water away from the shore causing upwelling at the American coast
How do explosive volcanic eruptions affect climate?
They may result in a short-term cooling of the climate.
The Medieval Warm Period (the Medieval Climatic Anomaly):
was marked by a significant drying of climate in North, Central, and South America
About 10% of the warming observed since the end of the Little Ice Age can be explained by this natural factor
increase in solar irradiance after the Maunder Minimum
What is happening today to Earth’s crust in areas that were underneath the ice sheets during the Last Glacial Maximum?
Bedrock is rising leading to rapid drop in relative sea level
How much did sea level rise during the 20th century?
0.17 meters
What accounts for the sea level rise in the 20th century?
- melting of land-based ice
- thermal expansion of sea water
The water extracted from the ocean and locked in glaciers during the Last Glacial Maximum:
was equivalent to the layer of ocean water of about 125meters thick.
Why does coal, primarily used for electricity production,still remain attractive for many local communities despite its well-known adverse environmental effects?
Local coal is much cheaper for power production than petroleum or gas.
What is a major disadvantage of geothermal power?
It is highly localized and most often can be produced only in the zones of active volcanism.
What region has the greatest potential to harvest solar power based on the amount of incoming solar radiation?
Sub-Saharan Africa
Which does not necessarily indicate that the climate has been warming?
Air temperature in downtowns of major cities is 3° to 4°C higher than in the surrounding farmlands.
The areas south of the former ice sheets(New England, Northern Germany, France) have been recording an unusually rapid sea level rise because of
sinking due to the peripheral forebulge collapse
