GLG335 Exam 2

Which atmospheric layer is the one we (mostly) live within, containing the bulk of the weight of the atmosphere and where most weather occurs?

Troposphere

(T/F) Episodes of opening and closing of gateways between oceans are not considered a viable explanation for the gradual cooling of Earth over the last 50 million years.

True

(T/F) Water in ice sheets is relatively enriched in 16O when compared to that in the oceans.

True

From your reading of the James Kasting 2019 review article for homework 2, what does James Kasting suggest happened at the beginning of the Phanerozoic, around 542 million years ago, that put an end to the earlier climate stability hypothetically provided by so-called "reverse weathering"?

silica-precipitating organisms evolved, such as sponges, radiolarians, and diatoms, thereby reducing the amount of silica dissolved in ocean water

The Stefan-Boltzmann law describes how the total energy radiated by a blackbody depends on the temperature of that body. Say you know that one blackbody object has an absolute temperature of 1,200 K, and a second blackbody object has a temperature of 6,000 K. Based on the Stefan-Boltzmann law, how much more energy is the first object emitting in comparison to the second object?

sixteen (16) times as much

What are the three key ingredients that produce both the Ekman spiral and Ekman transport?

the Coriolis force friction within the water winds blowing on the sea surface

What two factors below govern the magnitude (size) of the so-called solar constant of a planet?

- solar luminosity - distance of the planet from the Sun

Tectonic uplift (mountain building) increases rock fragmentation, and thus weathering, by:

-The erosive power of mountain glaciers -Increased mass wasting due to steeper slopes -Increased water flow because of orographic precipitation

The strength of the Coriolis force acting on a moving parcel of air or water depends on which of the following three quantities?

-The latitude of the parcel -Rotation rate of the planet -The speed of the parcel

Given the same amount of solar heating, which object will exhibit the least increase in temperature, based on its heat capacity?

1 kg seawater

The speed of plate tectonic motion usually falls in what range?

1-10 cm per year

Say an igneous rock sample initially formed with 800 radioactive parent atoms, and no daughter atoms. After three half lives, how many parent and how many daughter atoms are present? Assume the sample is closed, i.e., does not exchange either daughter or parent atoms with its surroundings.

100 parent 700 daughter

Earth's present-day albedo is approximately:

30%

Salinity is a measure of the mass of salt dissolved in a given mass of water, reported in permil, or ‰, or parts per thousand. For example, the average salinity of seawater is approximately 35‰. Given that, how many grams (g) of dissolved salt are in a 1 kilogram (kg) parcel of seawater if that parcel of seawater has a salinity of 35 ‰? (Hint: Remember that a kilogram (or kg) is equal to 1,000 grams (or g))

35

The lapse rate is the rate of decrease in temperature with altitude in the lower layer of the atmosphere. The approximate wet and dry lapse rates are, respectively:

6.5 & 9.8 ºC/km

The abundance of free oxygen O2 in our atmosphere today is a result of

A build up of O2 over billions of years as a byproduct of photosynthesis.

____ is the combined set of processes that result in the removal of ice from a glacier or ice sheet.

Ablation

Which of the following is not a coupling illustrated in figure 2 below?

An increase in the amount of sunlight reflected will increase the planet's temperature

What is the name for a rock fragment, typically large, that is transported and deposited by a glacier?

Erratic

Ocean-continent collision involves an ocean-crust capped lithospheric plate colliding with a continental-crust capped lithospheric plate. Continent-continent collision, on the other hand, involves two continental-crust capped lithospheric plates colliding. Which of those two types of collision does not typically result in volcanic activity?

Continent-continent collision

Which of the following is least dense?

Continental crust

At midlatitudes, in both the Northern and Southern hemispheres, the trade and westerly wind belts meet. In the Southern hemisphere the trade winds are, on average, moving air from the southeast to the northwest, while the westerly winds are, on average, moving air from the northwest to the southeast. The result of these two wind belts blowing over midlatitude oceans is a so-called gyre circulation. In the Southern hemisphere, what direction does the gyre spin?

Counter-Clockwise

Lithospheric, or tectonic, plates are made up of:

Crust and outermost, coolest mantle

Which of the following would decrease albedo?

Decrease cloud cover

What is the primary cause of Earth's seasons?

Earth's rotation axis tilts with respect to the plane of its orbit around the Sun.

The _____ Young Sun paradox comes from the fact that early in our solar system's history the Sun's luminosity was notably ______ than it is today, yet geological evidence suggests that Earth's overall temperature was not significantly different from today's. The presumed solution to the paradox is that the present-day greenhouse gas concentration is _____ than it was earlier in Earth's history.

Faint/ Dimmer/ Lower

(T/F) A drop in global sea level is thought to cause glaciation.

False

(T/F) The process of volcanic degassing of CO2 into Earth's atmosphere, by itself, acts as a thermostat which regulates climate.

False

Does the uplift process invoked in the uplift-weathering hypothesis serve as a climatic forcing or feedback?

Forcing

The polar position hypothesis posits that major glaciations occur when continents are found within the arctic or antarctic circles. Why is the hypothesis not the accepted explanation for the timing of major glaciations over the last 500 million years?

Glaciations do not always occur when continents are in a polar position.

Which of the following are thought to be factors which contributed to the mid-Cretaceous sea level being so much higher than modern sea level?

Higher mid-Cretaceous ocean ridge volume than modern mid-ocean ridge volume Reduced deep-sea fan sedimentation 100-80 Ma, compared to today.

Which type of weathering serves as a sink (loss process) of atmospheric carbon dioxide that, over millions of years, roughly balances the rate of input from volcanic degassing?

Hydrolysis of silicate rocks

The main reason that Earth is cooler than Venus is:

In Earth's atmosphere CO2 is a trace gas, while Venus has a denser atmosphere that is composed almost entirely (96%) CO2.

The greenhouse effect of Earth's atmosphere causes our surface temperature to be warmer because:

Incoming shortwave radiation is transmitted by the atmosphere but outgoing longwave radiation is partially absorbed by gases in the atmosphere.

If the globally averaged rate of photosynthesis were to exceed the globally averaged rate of respiration for a few months, what should we expect the globally averaged atmospheric oxygen (O2) concentration to do over that time period?

Increase

Thinking back to the planetary energy balance exercise you worked on for the very first homework assignment, to represent a decrease in the greenhouse effect due to decreasing concentrations of greenhouse gases in the atmosphere, you would need to

Increase emissivity

The freezing temperature of saltwater __________ as the salinity of the water decreases.

Increases

Where did most of the extra CO2 from Earth's early atmosphere go?

It is stored as limestone and other carbon-containing rocks in the geosphere.

Which one of the following does not qualify as internal forcing of Earth's climate system?

Large volcanic eruptions injecting reflective aerosols high into the atmosphere

Wein's law relates the temperature of a black body and the wavelength at which that body emits its maximum (or peak) amount of electromagnetic radiation. Based on that law, a body with a lower temperature will have a ___________ peak wavelength of emission than a body with a higher temperature.

Longer

All other things being unchanged, the rate of chemical weathering tends to ____________ with decreasing temperature and moisture.

decrease

Consider evaporation of water (H2O) from the surface of the ocean into the atmosphere. A water molecule whose oxygen atom is 16O will evaporate _________ readily than a water molecule whose oxygen atom is 18O.

More

By what process is the energy emitted by the Sun is produced?

Nuclear fusion

The 𝛿δ18O values of the shells of foraminifera found in ocean sediments primarily reflect changes in what two key variables?

Ocean temperature Ice volume

What is the term commonly used to describe the following biochemical reaction: CO2 + H2O + sunlight → CH2O (i.e., sugar) + O2

Photosynthesis

The whole feedback illustrated in figure 2 below is:

Positive

Periods of time when sea-level was lower are referred to as ____________, while those periods when sea-level was higher are called ________.

Regressions & Transgressions

What is the term commonly used to describe the following biochemical reaction? CH2O (i.e., sugar) + O2 --> CO2 + H2O + energy

Respiration

In the Northern hemisphere: the Coriolis force deflects moving objects to the ______, and Ekman transport moves ocean water to the ______ of the wind blowing above it.

Right/ Right

The Snowball Earth hypothesis addresses cold periods that are thought to have involved extensive glaciation and sea-ice cover. These "snowball" periods, when Earth was much colder than present, correspond to times when atmospheric CO2 concentration would be expected to

Rise (These are extremely cold periods, with much of Earth's surface covered by ice. That means silicate weathering, the key removal process of CO2 on tectonic timescales, essentially stops, while volcanic degassing of CO2 to the atmosphere will continue)

The largest carbon reservoir within the global carbon cycle is:

Rocks and Sediment

Negative feedbacks in Earth's climate system tend to _______ its temperature

Stabilize

Sun and the Earth have different peak wavelengths of electromagnetic radiation (EMR) emission. Indicate the band of the EMR spectrum in which each body's peak wavelength of a emission resides

Sun: visible earth: infrared

What aspect of the paleomagnetism (fossil magnetic character) of igneous rocks provides an indication of the latitude of the rock when it solidified?

The inclination, or dip, of the rock's magnetic field.

Say you could magically and instantaneously remove the Antarctic ice sheet, resulting in a roughly 3 km lower surface elevation of that continent. Considering only the lapse rate in the lowest layer of the atmosphere, how would that 3 km lowering in elevation effect the surface temperature

The new surface temperature would be warmer.

In order for BLAG hypothesis to explain the gradual global cooling over the last 50 million years, what should have happened over this time period?

The rate of sea-floor spreading should have decreased.

The BLAG hypothesis relies on gradual variations in ________ over time to drive variations in climate, from warm (hothouse) to cool (icehouse).

The rate of seafloor spreading, and thus, volcanic degassing of carbon dioxide to the atmosphere

Say we suspect that the oceans cooled over some particular time period. If we were to look at oceanic sediments from that time period, and more specifically at the 𝛿δ18O values of foraminifera shells found in those sediments, how should we expect those 𝛿δ18O values to change as a result of the hypothesized cooling?

The 𝛿δ18O values will increase (become less negative or more positive)

At the equator the northern and southern trade wind belts meet. The southern trade winds are, on average, flowing from the southeast to the northwest. The northern trade winds are, on average, blowing air from the northeast to the southwest. What type of ocean circulation should we expect at the equator, on average, as a result of these wind belts meeting at the equator? (Hint: Ekman transport is involved)

Upwelling

Would coastal upwelling or downwelling result from the North wind blowing off the western coast of the Iberian Peninsula, as shown in figure 3 below? (Hints: this is in the Northern hemisphere, and Ekman transport is involved)

Upwelling

How soon after deposition does freshly fragmented rock debris undergo most chemical weathering?

Very quickly, because easily weathered minerals are exposed; over time the rate slows down, as only the more chemically resistant minerals remain.

Ocean basins are _____________ relative to the age of most continental crust.

Young

According to the leaf-morphology (shape) proxy, as conditions cool, the fossil leaf record should generally show

a trend toward more jagged leaf margins through time

The present-day temperature is _______, with _______ carbonate deposition, when compared to conditions experienced during the Cretaceous Period.

cooler & less

Keeping all other things the same, if atmospheric CO2 concentration were to decrease, the average temperature of Earth would:

decrease

How would the chemical-weathering thermostat respond to a decrease in atmospheric CO2 concentration due to a temporary decrease in volcanic degassing of CO2 to the atmosphere?

decrease silicate weathering

Earth's climate system is driven primarily by what energy source?

electromagnetic radiation arriving from the Sun

The Monterey hypothesis suggests that the rapid cooling seen approximately 13 million years ago was produced by a temporary increase in the burial of organic carbon in the shallow continental margins of the Pacific Ocean.

increase

he shrinkage of ice sheets on land leads to a(n) _____ in global (eustatic) sea level.

increase

The Snowball Earth hypothesis addresses cold periods that are thought to have involved extensive glaciation and sea-ice cover. As noted in lecture, and in the James Kasting 2019 review article associated with homework 2, evidence suggests that immediately after these cold "snowball" periods, marine carbonate deposition:

increased a lot

A thin layer of sediment that is enriched in what rare element is found worldwide and dated to the time of a major extinction event approximately 65 Ma?

iridium, Ir

From your reading of the James Kasting 2019 review article for homework 2, what is the main criteria for defining the habitable zone around a star?

maintenance of liquid water on a planet's surface

Earth is a(n) _____ system

nearly closed

The term for any indirect indicator of climate change in a climate archive is a(n) _________ indicator.

proxy

The circulation of water in the deep ocean is referred to as _________ circulation.

thermohaline