Geo 102

Match the following paleoclimate proxy archives with the time span that their records can cover. ocean sediment cores: ice cores: instruments (e.g thermometers):

- 100 million years ago - 1 million years ago - 150 million years ago

NASA has the goal of sending humans to Mars in the next twenty years. Temperatures on Mars range from 130 to 300 K. What is the temperature range on Mars in °C and °F?

-143° to 27°C (-225° to 81°F)

Over the past 150 years, globally averaged air temperature has increased by __________

-1℃ (1.8℉)

For an Earth climate sensitivity of 0.8°C/W/m2, what radiative forcing would be required to cool the Earth's surface temperature by 2°C?

-2.5 W/m2

Calculate Earth's temperature (in degrees C) assuming albedo is 0.6 (i.e. 0.3 greater than today) and S is 1360 W/m2, and assuming a one-layer atmosphere that absorbs all infrared radiation emitted by Earth. Note: only enter the value without units. Canvas is just expecting a number, not text.

-9.82

What was the single largest contributor to human CO2 emissions 1) prior to 1900 and 2) after 2000?

1) Land-use change, 2) Coal

Looking at the state of warming from 1998 to present, as people like Ted Cruz sometimes do, is misleading because

1998 was an El Niño year and therefore anomalously wark compared to other years around that time

Place the following carbon reservoirs in the Earth system in order from the reservoir that has the LEAST carbon (1) to the reservoir that has the MOST carbon (4).

1= atmosphere ; 2= land ; 3= deep ocean ; 4=Sediment & rock

Pre-industrial atmospheric CO2 concentration was approximately __________. Charles David Keeling started his measurements of atmospheric CO2 in 1958. The CO2 concentration that he measured back then was approximately _________. Currently, the atmospheric CO2 concentration is approximately ____________.

280 ppm; 320 ppm; 410 ppm

The graph below shows how the 18O/16O ratio of the calcium carbonate shells of foraminifera changed from 65 million years ago to the present. Based on this record, when was Earth's climate the warmest? Note: look carefully at the y-axis!

50 million years ago, when the 18O/16O ratio was the lowest

Currently, atmospheric CO2 is about 415 ppm. How much carbon (in Pg) is currently stored in the atmosphere? How does the size of the current atmospheric CO2 reservoir compare with the preindustrial atmosphere?

830 Pg; 1.4 times the size

If the Earth's deserts disappeared and "greened" into forests, what would happen to Earth's albedo, and why?

Albedo would decrease, because forests have a lower albedo than deserts.

Sulfate aerosols indirectly affect the climate when their concentrations in the atmosphere increase by causing

An increase in cloudiness, because the sulfate aerosols lead to a greater number of water droplets

Which of the following chemical equations shows the process by which carbon is removed from the atmosphere and added to the land reservoir of organic carbon?

CO2+H2O-->CH2O+O2

The expected temperature change for a given climate forcing (e.g. from a change in carbon dioxide concentration) is determined by multiplying the radiative forcing by which variable?

Climate sensitivity

As discussed in class, clouds are particularly important in setting Earth's albedo. Which of the following best explains why they are so important?

Clouds have a particularly high albedo and are common in areas near the equator, where the intensity of sunlight is greatest.

Of the following, which two gases contribute the most to the absorption of the infrared radiation leaving the Earth surface at low latitudes? Choose two gases below.

Co2 & H20

The high topography of the Tibetan plateau resulted from which process?

Collision of continental lithosphere (India) with continental lithosphere (Asia)

Which of the following is not a line of evidence showing that the observed atmospheric CO2 rise is mostly due to fossil fuel burning?

Contemporaneous increase in atmospheric radiocarbon (14C) concentration

The oxygen isotopic composition (18O/16O ratio) of foraminifera ______ with increasing ocean temperature and _____ with increasing global ice volume.

Decreases; increases

Which of the following best explains why the temperature of the Earth's surface rises when the concentration of greenhouse gases increase?

Earth must emit more radiation in order to balance the energy received from the Sun, so Earth's temperature must rise

The average power intensity of Sunlight across Earth's surface is 1/4 the power intensity of Sunlight at the distance of Earth from the Sun. What best explains this?

Earth's surface is a rotating sphere, so different parts of Earth's surface receive different power intensity of Sunlight at different times of day.

The rise in China's per capita carbon dioxide emissions since ~2002, shown in the graph below, can be explained by population growth.

False

As noted in class, we can rule out heat transport and heat storage as the causes of rising air temperatures. Which of the following is the best explanation for why? Correct!

For both heat transport and heat storage to cause warming, there would need to be corresponding cooling somewhere in the Earth system. However, we do not observe such cooling.

Which of the following best describes Holocene climate conditions?

Generally stable climate, with weak cooling in the last 5,000 years

Which of the following indicates that Earth is warming because of changes to the atmosphere? Choose all that apply.

Glaciers and ice sheets are melting, contributing water to the oceans and thereby raising sea level; Boreholes in bedrock show that the ground has been warming from the surface downward; Ocean temperatures show that warming has occurred in all ocean basins, with the greatest warming near the ocean surface.

Which of the following are true of greenhouse gases? Choose all that apply.

Greenhouse gases absorb IR radiation; Greenhouse gases possess an asymmetric molecular structure

In the sequence of events associated with a Snowball Earth glaciation, an initial cooling set off two main feedback cycles: ice/albedo and CO2/weathering. Which one of the following best describes what happened?

Ice/albedo feedback was more rapid, causing complete glaciation. The CO2/weathering feedback slowly caught up and returned climate to its original state.

During the snowball earth scenario, an initial cooling set off two main feedbacks, ice/albedo and CO2/weathering. Which best describes what happened?

Ice/albedo feedback was more rapid, causing complete glaciation. The CO2/weathering feedback slowly caught up and returned the climate to its original state.

Which of the following was NOT a feature of Earth's climate at the peak of the last ice age?

Increased forest cover

The primary role of volcanoes in Earth's temperature on timescales of 1-10 years is

Increasing sulfate aerosols in the stratosphere, thereby causing temperatures to decrease.

N2 is not an important greenhouse gas because

It is a symmetric molecule

In lecture, you calculated Earth's temperature assuming an albedo of 0.3, S of 1360 W/m^2, and one layer of atmosphere that perfectly absorbs infrared energy radiated from Earth's surface. Which of the following is true about the result of the calculation

It is warmer than Earth's actual temperature because Earth's actual atmosphere does not absorb all outgoing infrared energy.

Climate records indicate that, compared to interglacial times, during the glacial periods that occurred over the last eight hundred thousand (800,000) years:- CO2 concentrations were _________ - the amount of global forest cover was __________ - northern hemisphere ice volume was ________ - and sea level was ____

Lower, lower, higher, lower

On a per-molecule basis, methane is a stronger greenhouse gas than CO2. Why are we more concerned about CO2 than we are with methane. Choose all that apply

Methane has a lower concentration in the atmosphere than CO2 & Methane has a shorter average lifetime in the atmosphere than CO2

Of the following, which two gases are the most abundant gases in the atmosphere? Choose two gases below.

N2 & O2

Over the next 50,000 years, the largest recipient of anthropogenic CO2 emissions will be the

Ocean

Which of the following components of the Earth system has taken up the greatest amount of energy since 1955?

Oceans

Select the appropriate reaction for the processes listed below: Photosynthesis: photosynthesis: Respiration: Fossil Fuel Burning: Metamorphism of limestone: Silicate rock weathering and limestone generation: Methanogenesis:

Photosynthesis: CO2 + H20 => O2 + CH2O Respiration: O2 + CH2O => CO2 + H2O Fossil Fuel Burning: O2 + CH2O => CO2 + H2O Metamorphism of limestone: CaCO3 + SiO2 => CaSiO3 + CO2 Silicate rock weathering and limestone generation: CaSiO3 + CO2 => CaCO3 + SiO2 Methanogenesis (Generation of methane): 2CH2O => CO2 +CH4

As we saw in class, the sun has been getting gradually brighter throughout Earth's history and will continue to get brighter in the future. What does this mean for Earth's temperature into the distant future?

The CO2/weathering feedback will stabilize earth's temperature until the atmosphere has nearly no CO2. Earth's temperature will then start to rise as S increases.

In which, if any, of the following climate change events in Earth's history is carbon dioxide NOT thought to have played an important role? Choose all that apply.

The Little Ice Age

Which one or more of the following feedbacks were explicitly part of the no-atmosphere and 1-layer atmosphere models we created in class

The Stefan-Boltzmann feedback (Temperature-IR radiation)

Which of the following statements best describes the energy emitted by the Sun, compared to energy emitted by Earth?

The Sun emits energy with a higher power intensity and at a shorter average wavelength compared to Earth

Of the following, which best describes the "Faint Young Sun Problem"?

The Sun was much fainter than today for much of Earth's history. If the ancient atmosphere were similar to today, we would expect that there would not have been liquid water until ~1.5 billion years ago because temperatures would have been too cold. Instead, we have evidence of liquid water for almost all of Earth's history.

Which of the following is true of carbon dioxide concentrations, as measured in the atmosphere since the 1960s? Choose all that apply.

The average carbon dioxide concentrations have been increasing year-to-year & Carbon dioxide varies seasonally, with highest values during the winter (as experienced by each hemisphere) and lowest values in the summer (again, as experienced by each hemisphere).

What is the likely cause of climate change since about 50 million years ago?

The collision of India with Asia created the Himalayan mountain range and Tibetan Plateau, increasing the "weatherability" of rocks in the region.

There were two multi-million year cold periods during the Phanerozoic (the last 540 million years of earth's history). What was the likely cause of those cold times?

The collision of continents near the equator at those times, leading to mountain building that increased the weatherability of rocks.

Below is an infrared image of a person's head, indicating varying temperatures from lowest temperature in blue and green to warmest temperatures in yellow and red. Which of the following statements are true? Choose all that apply.

The coolest areas, the nose and glasses, emit electromagnetic energy with a longer wavelength than the warmest areas. & The warmest areas, like the mouth, emit a greater intensity of electromagnetic energy than the coolest areas.

In lecture, we discussed the fact that ocean sediments are an important source of climate-proxy data, which are useful in reconstructing past climate. What makes ocean sediments so important?

The deep seafloor provides a quiet environment where sediments accumulate with few interruptions, preserving fossils and chemical traces of climate conditions.

Earth is continually receiving energy from the Sun, yet Earth's temperature is relatively stable. What does this imply about Earth's energy budget?

There must be a process by which Earth loses energy back to space at the same rate as energy is delivered by the Sun.

Ocean acidification is a lowering of ocean pH due to higher CO2 concentrations in the water. True/False: During the Paleocene-Eocene Thermal Maximum (PETM), a sudden increase in carbon dioxide in the atmosphere led to ocean acidification, making it much less likely for fossils of organisms that make their shells out of CaCO3 to be preserved in ocean sediments from that time.

True

As we saw in class, Venus is a surprisingly hot planet, even taking into account its closer orbit to the sun than Earth's orbit. Why is Venus so hot that it is uninhabitable while Earth remains habitable?

Venus has no water at its surface, so there is no CO2 weathering feedback to draw down greenhouse gases and decrease its temperature.

Which of the following contribute(s) to why Venus's average temperature is warmer than Earth's? Select all that apply.

Venus is closer to the Sun than Earth is & Venus has a higher concentration of greenhouse gases in its atmosphere than Earth has

Earth is currently absorbing more energy than is being radiated out to space from the Earth system. Where is most of that energy going?

Warming the ocean waters.

Go to the website http://climatemodels.uchicago.edu/geocarb/ (Links to an external site.) and use the GEOCARB model to determine how plants impact weathering, and hence climate. To do this, change the "Transition CO2 Spike" to 0 and change the "Plants" dropdown menu under the "Spinup" column to "no" (this will begin the model with no plants). See the image below for guidance.

Weathering increases with the addition of land plants, causing global climate to cool over hundreds of thousands of years.

The long-term rise in instrumental CO2 records is due to

all of the above: an excess of organic carbon oxidation relative to organic carbon production; land use changes ("deforestation"); burning of fossil fuels

Of the following, over the last 100 years, the largest recipient of anthropogenic CO2 emissions has been the

atmosphere

The image below shows a photograph of sediments from the Paleocene-Eocene Thermal Maximum (PETM). The y-axis shows depth below the seafloor (meters of core depth, mcd). The youngest sediments in the core image are located at the top of the y-axis, while the oldest sediments are at the bottom of the y-axis. The blue line on the right side shows the amount of calcium carbonate in the core sediments at each depth. The sediments deposited during the warmest times are between 335 mcd and 336 mcd . During that time period, there was a sharp increase in calcium carbonate burial. This change in calcium carbonate burial worked to lower atmospheric carbon dioxide, helping to return atmospheric carbon dioxide levels to their pre-PETM values.

between 335 mcd and 336 mcd / decrease/ lower

Earth's climate has largely _________ over the last 50 million years. This led to the growth of ice sheets in _________ around 35 million years ago, and the growth of cyclic ice sheets in ______________ around 3 million years ago.

cooled; Antartica; the Northern Hemisphere

During the Last glacial maximum (20,000 yrs ago) temperatures were _______ in the Northern Hemisphere and ______ in the Southern hemisphere relative to today's temps

cooler & cooler

Over long timescales, where does carbonate (in the form of limestone) accumulate in the ocean? Choose all that apply.

coral reefs; carbonate banks; deep sea sediments

As a result of the fact that water molecules containing 16O are more readily ____________ than water molecules containing 18O, the 18O/16O of ocean water during a glacial period is _____________ than the 18O/16O of ocean water during an interglacial period.

evaporated; higher

T/F: The modern rate of CO2 input to the atmosphere from volcanoes is 0.05 Pg C/year, while the rate of CO2 input from humans burning fossil fuels is twice that.

false

The intensity (W/m^2) of radiation emitted by a _____ object is greater than that emitted by a colder object. The hotter an object, the ______ the wavelength of the radiation that it emits

greater; shorter

A requirement for a molecule to function as a greenhouse gas is that it ________ .

has the ability to be asymmetric

Relative to the calculations that we have done in class, computer models that simulate climate through time probably yield a more accurate prediction of climate sensitivity because they (choose the best answer)

include climate feedbacks

An increase in earth's surface temperature results in an _____________ in the amount of water vapor in the atmosphere which results in an ____________ in the strength of the greenhouse effect. The change in the greenhouse effect results in an increase in Earth's surface temperature. The feedback loop described above had an overall _____________ effect.

increase; increase; amplifying

During the Paleocene-Eocene Thermal Maximum (PETM) temperature __________ abruptly because the atmospheric carbon dioxide concentration ___________ abruptly. The corresponding change in carbon dioxide concentration in the ocean caused the ___________ of calcium carbonate on the ocean floor because there was an increase in ocean acidity. The body sizes of mammals tended to _____________ during this time interval.

increased ; increased; dissolution; decrease

The primary role of volcanoes in Earth's temperature on timescales of 1-10 years is

increasing sulfate aerosols in the stratosphere, thereby causing temperatures to decrease.

The primary role of volcanoes in Earth's temperature on timescales of greater than 1 million years is

increasing the greenhouse gas concentration in the atmosphere through emitting carbon dioxide, thereby causing temperatures to increase

Which of the following Earth carbon reservoirs contain mainly organic carbon?

land

Over the last 100 years, the most rapid CO2 emissions have been from which two of the following (Choose 2)

land clearance; fossil fuel burning

Choose all that apply. The addition of sulfate aerosols to Earth's atmosphere:

leads to greater scattering of incoming solar radiation; sources from explosive volcanic eruptions and fossil fuel burning; increases Earth's albedo through direct and indirect effects

The processes of erosion and weathering mainly occur __________ , and sedimentation mainly occurs ____________ .

on land; in the ocean

Imagine that there are two stars. Both stars have the same temperature, but one star is much larger than the other. The electromagnetic radiation given off by the two stars have different power but the same power intensity .

power; power intensity

Earth receives energy from the Sun through ________.

radiation

Comparing ultraviolet (UV) radiation and infrared (IR), radiation, UV has a ______ wavelength and _______ energy per photon than IR.

shorter; more

Consider a hypothetical planet, Thear, that has no oceans but is otherwise experiencing similar climate forcing as our Ocean-rich Earth: The storage of heat to Earth's oceans is currently causing _____ warming of the atmosphere compared with Thear's atmosphere. If both planets were to reach a new energy balance in the future, Earth's atmospheric temperature would _____ the atmospheric temperature of The earth If both planets began to cool, Earth's oceans would cause _____ cooling of the atmosphere compared with The earth's atmosphere

slower; less than; slower

The clearing of tropical rainforests causes the tropical land biosphere to serve, in net, as a ________ of CO2 to/from the atmosphere. The growth or regrowth of temperate forests are, in net, _________ CO2 to/from the atmosphere.

source; taking up

Per capita emissions from China have risen dramatically since 2000 because its ________________ has risen. China's per capita rate is _____________ the US rate. The US rate has __________ since 2000.

standard of living ; below; fallen

During limestone metamorphism, limestone in ocean sediments is ______ by seafloor spreading, where the limestone breaks down to form _______, which is released to the atmosphere through volcanism.

subducted; carbon dioxide

An example of the dynamic in Question 3 (volcano question) from Earth's history is

the "Year Without a Summer," following the eruption of Mount Tambora in 1815.

An example of the dynamic in Question 1 from Earth's history is

the processes that allowed Earth to "escape" Snowball Earth conditions.

The calculation above is ________ than you would expect if Earth's actual albedo were 0.6 because _____

warmer; Earth's atmosphere does not absorb all outgoing infrared energy