GLG 335

Which trees would be better for sources of climate variability?

Trees growing near the edge of their tolerance limits in terms of temperature and precipitation.

CO2 fertilization of tree growth during the time-frame of the instrumental record complicates efforts to extract climate information from tree rings because it mimics improved growth conditions that would otherwise be related to temperature and precipitation.

True

Changes in solar output (how much energy the Sun is putting out) constitute an external forcing of the climate system.

True

During an El Niño period the δ18O of eastern Pacific corals will decrease

True

Earth is a(n) nearly closed system.

True

One hypothesis for the megafaunal extinctions 15-10 ka is that the climate changes seen during deglaciation created conditions to which the animals could not adapt. One key criticism of this hypothesis is that no similar extinction events had been seen in any of the previous 40+ deglaciations over the last 2.75 Ma.

True

Positive feedbacks tend to destabilize a system.

True

Radiocarbon (14C) ages are generally younger than true, or calendar, ages.

True

Episodes of opening and closing of gateways between oceans provide an excellent explanation for the gradual cooling of Earth over the last 50 million years.

false

Humans are the only animals that use tools.

false

If you can accurately map the surface and bed elevation of an ice sheet, then you have an accurate measure of the mass of that ice sheet.

false

Millennial oscillations are truly cyclic, with a consistent, or regular, periodicity.

false

Modeling studies suggest that Earth's climate is less sensitive to changes in atmospheric greenhouse gas concentrations during colder (icehouse) times than during warmer (greenhouse) periods.

false

Periods when the Sun has fewer sunspots correspond to times of increased output of solar radiation.

false

Radiocarbon ages are generally older than true, or calendar ages.

false

Sea-level lowering causes glaciation.

false

The ability of the precession of the equinoxes to impact Earth's climate is increased if Earth's orbit is more circular (i.e., less elliptical).

false

The braincase size for modern humans (Homo sapiens) is the largest of all the species in the Homo genus.

false

The degree to which human evolution was influenced by climate change is well constrained by the combination of fossil human remains and proxy records of climate.

false

Times when the Sun has a large number of sunspots correspond to times of reduced solar energy output.

false

Water in ice sheets is relatively enriched in 18O when compared to that in the oceans.

false

What storm-related hazard is not addressed in the Hurricane Category system?

flooding from heavy rain and storm surge

Also from the fourth paragraph of the article, a spike in what material is found in lake-sediment layers dating to around 1950?

fly ash from the burning of coal

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

forcing

The Stefan-Boltzman law states that the energy emitted by a body is proportional to the ______ power of the body's temperature.

fourth

How might the source(s) of energy change for those folks shifting from a rural to urban lifestyle?

from wood and dung to mostly fossil fuels

Heinrich events are

periods of unusually rapid deposition of ice rafted debris in the N. Atlantic Ocean, separated by 7-12 kyrs.

Heinrich events are:

periods of unusually rapid deposition of ice rafted debris in the N. Atlantic Ocean, separated by 7-12 kyrs.

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

photosynthesis

What is a biotic climate proxy commonly found in lake sediments, which indicates how the vegetation surrounding a lake has varied through time?

pollen

Sarah-Jane Lock, of the European Centre for Medium-Range Weather Forecasts, that as the climate system warms, we

should expect to see stronger and likely more frequent storms.

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

From your reading of the James Kasting 2019 review article for homework 3, what does 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

As was the case in previous interglaciations, millennial climate variability over the last 8 kyrs has been _______ in amplitude when compared to the amplitude of millennial variability during glaciations.

smaller

Match the following alternative energy sources to their estimated potential energy production, in terawatts (TW).

solar - 173,000 wind - 1,220 biomass - 166 geothermal - 44 hydroelectricity - 1.9

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

solar luminosity & distance of the planet from the Sun

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

stabalize

A measure of the strength of a feedback is the feedback factor, f. If f is much smaller than one (i.e., f<<1) for a given feedback, that feedback is

strongly negative

Milankovitch theory proposes that higher latitude (polar) insolation changes, produced by orbital variations, drive the growth and decay of ice sheets. For which season are those insolation changes most important, according to the theory?

summer

The δ18O values of the shells of foraminifera found in ocean sediments primarily reflect changes in ice volume and ______?

temperature

What's the short-hand name for the hypothesis that variations in the rate of sea-floor spreading lead to variations in the amount of carbon dioxide in the atmosphere?

the BLAG hypothesis

What are the three key ingredients that produce both the Ekman spiral and Ekman transport? (Choose the correct three options below.)

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

The iron fertilization hypothesis suggests that increasing which process below will result in a reduction in atmospheric CO2 concentration?

the biological pump

The strength of the Coriolis force acting on a moving parcel of air or water depends all of the following except:

the heat capacity of the parcel

The main reason(s) that subsequent work to CLIMAP supports thinner North American ice coverage than the CLIMAP maximum scenario is (are)

the modeled thickness of ice that is required to produce the observed bedrock rebound history is thinner than the CLIMAP maximum scenario' that the southern portion of the Laurentide Ice Sheet was underlain by soft, easily deformable sediment that would allow faster flow than the CLIMAP scientists had considered

The wet adiabatic lapse rate of Γ=6.5 ºC/km means that tropical glaciers can exist above 5 km elevation today.Today tropical sea-level temperature Tss=30 ºCWhat would the temperature (Tg) be at z=5 km elevation?

-2.5 ºC

From the fifth paragraph of the article, what level did atmospheric CO2 exceed around 1950?

310 ppm

The albedo of Earth today is approximately

0.3 or 30%

The instrumental record of temperature (mostly from meteorological stations, and later satellite observations) indicates a global increase of approximately _____ ºC since the late nineteenth century. The temperature increase on land has been slightly less than double that.

0.8-1

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

1 kg of seawater

What's the ratio of the time it took to create the world's fossil fuels and the time over which we will have largely consumed them? In other words, how much more quickly are we consuming those resources than they are produced?

1,000,000

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

1-10 centimeters per year

What are the two key processes which cause deep water to form at higher latitudes today? (1-2 sentences, at most)

1. The cooling of seawater as it increases in latitude 2. Salt rejection during sea ice formation increases the salinity of the seawater

Describe two ways in which ice-core layers are dated (3 sentences at most)

1. the ice core annual layers (in their uppermost layers) can be counted 2. can be dated radiometrically

From approximately 900 kyr ago to the present, the dominant period of ice-volume variation is:

100 kyr

Approximately when did agriculture begin?

12 ka

How much damage, in monetary terms, did Hurricane Irma do to Cuba?

13 billion dollars

The approximate time frame for the Little Ice Age is

1400-1900 AD

Which of the following carbon isotopes is not stable?

14C

From the eighth paragraph of the article, what Anthropocene start date is Mark Maslin noted as favoring?

1610

The global sea-level rise from 1900-2000 AD was approximately:

17 cm

The formula to convert from temperature in ºF (call it Tf) to temperature in ºC (say Tc) is Tc = (Tf-32) x 5/9 What is the temperature in ºC if you know the temperature is 68ºF?

20

The pre-industrial and present-day atmospheric concentrations of carbon dioxide are approximately _____ and _____ ppm, respectively.

280 (pre-industrial) & 405 (present) ppm

The Stefan-Boltzman Law relates the temperature of a black body and the total amount of radiation that the body is emitting (per square meter of its surface area). More specifically, denoting the energy emitted per square meter as E, the Stefan-Boltzman constant as and the temperature as T, the law is E= T4 Knowing this, to increase the energy output of a black body by factor of 81, by what factor would you need to increase the temperature of that body?

3

If tropical glaciers, that today need Tg=-2.5 ºC to survive, were 600-1,000 m (0.6-1 km) lower at LGM, how much tropical cooling would that imply?Assume the wet adiabatic lapse rate applies.

3.9-6.5 ºC

According to the documentary, Harvey dropped over ____ inches of rain on southeast Texas.

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

Salinity is a measure of the mass of salt dissolved in a given mass of water, reported in permil, or ‰, or parts per thousand. 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

What is the projected number of people expected to move from China's rural areas to cities by 2030 AD? For perspective, the current (2020) US population is approximately 330 million.

350 million people

By what factor would global energy consumption increase if the global population adopted the per-capita consumption rate of North America?

4

What category (1,2, 3, 4, or 5) was Hurricane Harvey when it made landfall on the Texas coast?

4

What is the approximate global birth rate, in births per second?

4

According to the documentary, estimates of the Maria-related death toll in Puerto Rico, which includes people who died in the storm's aftermath, exceed:

4,000

Since satellite-based measurements of Arctic sea-ice extent began in the 1970s, sea-ice extent has declined by approximately _____%

40

The Stefan-Boltzmann law describes how the total energy radiated by a blackbody depends on the temperature of that body. Based on that law, if you know that one blackbody object has an absolute temperature of 1,200 K, and that this object emits 81 times as much energy as a second blackbody object, what is the absolute temperature of the second blackbody object? (One of these equations may be useful - 23=8, 161/4=2, 811/4=3, 34=81)

400K

The degree of tilt of the Earth's rotational axis relative to the plane of Earth's orbit around the Sun varies on what timescale?

41 kyr

The tilt (or obliquity) of the Earth's rotational axis relative to the plane of Earth's orbit around the Sun varies on what timescale?

41 kyr

Parts of Jacksonville experienced how many feet of flooding due to Irma?

5 feet

When is the next glaciation? Ignoring anthropogenic climate change, the timing should be guided by insolation changes, per Milankovitch Theory. In particular, a sensible idea is to examine calculations of future insolation at high norther latitudes. It so happens that high northern latitude (65ºN) insolation will not fall significantly below our present-day value until ___________ thousand years (kyrs) from now.

50

When is the next glaciation? Ignoring anthropogenic climate change, the timing should be guided by insolation changes, per Milankovitch Theory. In particular, a sensible idea is to examine calculations of future insolation at high norther latitudes. It so happens that high northern latitude (65ºN) insolation will not fall significantly below our present-day value until ____ years from now.

50,000

In approximately what amount of time did Tropical Storm Maria intensify into a category 5 hurricane?

54 hours

The three main reservoirs receiving the carbon dioxide released by anthropogenic activities are the atmosphere, the shallow ocean, and the biosphere. Over the last several decades, what fraction of the emitted carbon dioxide has ended up in each reservoir?

55% atmosphere, 25-30% surface ocean, 15-20% biosphere.

Continental crust has a density that is approximately 80% of the density of the mantle. Knowing this, and treating a block of crust as floating on the mantle: Approximately how much of a 30 km thick block of crust is above the top of the mantle? I.e., what is the so-called freeboard height of the crust? [Hint: think about a good tip at a restaurant.]

6 km

As of the 2011 production date of the documentary, how far had the Tasman glacier of New Zealand retreated since the early 1980's?

6 km (about 3.7 mi.)

The Stefan-Boltzmann law describes how the total energy radiated by a blackbody depends on the temperature of that body. Based on that law, if you know that one blackbody object has an absolute temperature of 1,200 K, and that this object emits 16 times as much energy as a second blackbody object, what is the absolute temperature of the second blackbody object? (One of these equations may be useful - 23=8, 161/4=2, 811/4=3, 34=81)

600 K

What is the approximate global human population today?

7.7 billion

Both accumulation and ablation depend, to some degree, on mean annual temperature, but __________ is much more sensitive to temperature than ____________.

Ablation & Accumulation

The modeling efforts of Dave Pollard and Rob DeConto suggest that in order for Antarctica to begin to glaciate the atmospheric carbon dioxide levels have to be below what specific threshold concentration?

750 ppm

According to the documentary, how much damage, in monetary terms, did Maria cause in Puerto Rico?

90 billion dollars

Why did proglacial lakes travel slowly northward, following the retreating ice sheets, during the last deglaciation?

A delayed uplift of the crust subsequent to the removal of ice, in combination with meltwater supplied by the ice sheets from the north, produced the dynamic (moving) water-filled depressions.

Which of the following is not a coupling illustrated in figure 2 below? tundra, albedo, temp, sun reflect

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

Evidence suggests tropical glaciers and vegetation limits extended some 0.6-1 km lower in elevation at LGM than today. If that elevation drop, relative to today, is purely due to cooler temperature at sea level, how much cooling does it represent? Let's assume that the appropriate lapse rate to apply for the tropics is the wet adiabatic lapse rate of 6.5 ºC/km. Use this lapse rate and the lower LGM glacier and vegetation limits to estimate how much cooler the LGM tropics were relative to today.

Approx. 4-6ºC

What are the two or three lines of evidence that fossil fuel use is behind the recent rise in atmospheric carbon-dioxide concentrations?

Carbon Isotopes: 12C is rising, 13C is not, and 14C is not (both 13C and 14C are declining relative to 12C); so the source is very old plant material (fossil fuels). Decline in oxygen: the decrease in oxygen in the atmosphere coincides with the rise in CO2, indicating that burning (oxidation) is producing the CO2. Book-keeping: anthropogenic emissions are 50-100 times larger than natural volcanic emissions.

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

Lithospheric, or tectonic, plates are made up of:

Crust and the outermost, coolest mantle

What is the primary, or main, reason we have seasons on Earth?

Earth's rotational axis is tilted relative 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 energy output 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 greenhouse gas concentration was ______ earlier in Earth's history than it is today.

Faint/weaker/higher

In the areas that were formerly covered by ice sheets during the last glacial maximum, local (or relative) sea level is now ______________.

Falling

A closed system is one that exchanges neither energy nor mass with its surroundings.

False

Millennial oscillations are truly cyclic, with a consistent periodicity.

False

Polaris has always been the Northern Hemisphere navigational star.

False

Positive feedbacks in Earth's climate system tend to stabilize the temperature, making the temperature variations smaller than they would otherwise be without those positive feedbacks.

False

The asteroid impact approx. 65 million years ago had a long-lasting impact on climate.

False

The opening and closing of gateways between oceans provide an excellent explanation for the gradual cooling of Earth over the last 50 million years.

False

The process of volcanic degassing of CO2 into Earth's atmosphere, by itself, acts as a thermostat which regulates climate.

False

Times when the Sun has a large number of sunspots correspond to times of reduced solar energy output.

False

Any process or disturbance that drives changes in climate is referred to as a

Forcing

Match the stated percentages with the appropriate energy sources used by over over seven billion people today.

Fossil Fuels - 78 Nuclear - 5 Hydropower - 6 Renewables - 1 Wood and Dung - 10

The polar position hypothesis posits that major glaciations occur when continents are found in 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.

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 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

While most scientists agree that the last deglaciation was driven by an increase in summer insolation, two important positive feedbacks played a role in amplifying that insolation signal. Those two feedbacks are...(choose two)

Ice - Albedo Feeback, wherein insolation changes drive ice-sheet response, which in turn changes the planetary albedo (reflectivity). In particular, as ice extent decreases, the planetary albedo is reduced, leading to more absorption of solar radiation, yielding warmer conditions. Greenhouse Gas - Ice Feedback, wherein insolation changes drive ice-sheet response, which in turn creates conditions that control the concentration of greenhouse gasses. In particular a reduction in ice volume and extent allows for higher greenhouse gas concentrations, leading to warmer conditions.

While most scientists agree that the last deglaciation was driven by an increase in northern hemisphere insolation, two important positive feedbacks played a role in amplifying that insolation signal. Choose both feedbacks below

Ice-Albedo Feedback, wherein changes insolation lead to changes in the amount of global ice coverage, leading to changes in the amount of energy absorbed by the planet. In particular, a decrease in insolation yields more ice coverage, leading to a reduction in absorbed energy, and thus cooler conditions. Greenhouse Gas - Ice Feedback, wherein insolation changes drive ice-sheet response, which in turncreates conditions that control the concentration of greenhouse gasses. In particular a reduction in ice volume and extent allows for higher greenhouse gas concentrations, leading to warmer conditions.

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.

A thin layer of sediment that is enriched in what rare element is found worldwide and dated to the time of the major extinction event approximately 65 Ma? (Hint: it may influence your answer to know that this element is rare on Earth, but much more common in some types of meteorites.)

Iridium

Why is Venus so hot in comparison to Earth?

It has a stronger greenhouse effect than Earth

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.

The channeled scablands of eastern Washington and western Idaho were produced by what deglacial process?

Massive deglacial floods from a large proglacial lake (in this case glacial Lake Missoula).

Who proposed the uplift-weathering hypothesis?

Maureen Raymo

Say the northern North Atlantic ocean is suddenly filled with a large number of melting icebergs. How might that impact deepwater formation in the North Atlantic?

It would decrease deepwater formation

Say a palynologist (pollen expert) examined a lake-sediment core from the upper midwest of the United States, and she found that LGM-aged sediments contained mostly spruce pollen, while the more recent (Holocene) sediment contained mostly prairie pollen. What can you say about the change in conditions near the lake from LGM to Holocene times?

LGM conditions were cooler and wetter than Holocene conditions, near that lake.

Say a sediment core was collected from a lake in the upper midwest, and that core was then examined by a palynologist (pollen expert). Further, say she found that LGM-aged lake sediments contained predominantly spruce pollen, and that more recent (Holocene) sediment contained mostly prairie (grasses and herbal) pollen. What can you say about the change in conditions near the lake from LGM to Holocene times?

LGM conditions were cooler and wetter than Holocene conditions, near that lake.

What two lines of evidence suggest the tropics at LGM may have been cooler than the CLIMAP project suggested? (choose the two correct answers)

LGM vegetation limits being 0.6-1 km lower in elevation terminal moraines dated to the LGM that are 0.6-1 km lower in elevation than modern glaciers

Are we in La Niña, El Niño, or neutral conditions?

La Nina

According to the CLIMAP project results, which ice sheet held the largest fraction of the excess ice volume at last glacial maximum?

Laurentide

As part of the CLIMAP reconstruction of the Last Glacial Maximum (LGM) world the "excess ice volume", or ice volume in excess of our present-day ice volume, was partitioned amongst the various ice sheets of that glacial world. Which ice sheet held the largest fraction of the excess ice volume at LGM?

Laurentide

According to the CLIMAP project, the largest contributor to the lower sea level during the last glacial maximum (LGM), relative to today's sea level, was which ice sheet?

Laurentide Ice Sheet

The coastlines along areas formerly covered by ice sheets during LGM are presently experiencing:

Local sea-level fall

The channeled scablands of eastern Washington and Oregon, along with western Idaho were produced by what deglacial process?

Massive deglacial floods from a large proglacial lake (in this case glacial Lake Missoula).

Which of the following conditions would be most favorable for generating the cool summers that Milankovitch suggested are conducive to growing ice in the Northern Hemisphere? (Choose the three correct conditions)

Norther Hemisphere summer coinciding with aphelion high eccentricity Low obliquity

If the rise in atmospheric CO2 concentration since the start of the industrial revolution is due to burning of organic material (wood and fossil fuels), what should we expect to see in terms of atmospheric O2 concentration?

O2 should decrease

Which one of the following types of records could provide climate information covering tens of millions of years at possibly ten thousand to one hundred thousand years of resolution?

Ocean sediments

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

decrease

Paleogeographic reconstructions indicate that most of today's widely separated continental landmasses were joined together 250 million years ago in one single super continent. What is the name of this super continent?

Pangea

All of the following are factors which contributed to higher sea levels 100-80 million years ago (Ma), relative to modern sea level, except:

Reduced deep-sea fan sedimentation 100-80 Ma, compared to today.

Which of the following is not a factor which contributed to higher sea levels 100-80 million years ago (Ma), relative to modern sea level?

Reduced deep-sea fan sedimentation 100-80 Ma, relative to today

The largest carbon reservoir within the global carbon cycle is:

Rocks and sediments

As deglaciation proceeded, sea level _______, meaning important connections between landmasses were _______.

Rose/lost

As was the case in previous interglaciations, millennial climate variability over the last 8 kyrs has been _________ in amplitude than during glaciations.

Smaller

The three main orbital characteristics, precession, obliquity, and eccentricity, do indeed change over time. Broadly speaking, on what time scale do these orbital characteristics vary?

Tens of thousands to hundreds of thousands of years

The main reason Venus is so much hotter than Earth is because

The concentration of greenhouse gases in Venus's atmosphere is much greater than is the case for Earth.

In order for a change in the strength of the greenhouse effect to explain the greater warmth 100-80 Ma relative to today, what must have happened to the concentration of greenhouse gasses between then and now?

The concentration of greenhouse gasses must have decreased.

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

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

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

The dip, or inclination, of the rock's magnetic minerals

Tectonic uplift (mountain building) increases rock fragmentation, and thus weathering, by: (Choose all that are correct.)

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

One of the factors that can change the δ18O of snow falling on a a glacier or ice sheet is the distance of the source, i.e., how far the water vapor had to travel before precipitating and falling. How does increasing source distance impact δ18O of the snow that's falling?

The farther away the source, the smaller, or more negative, the δ18O values

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.

Which one of the following is not a hypothesis for the unexpected strength of the 41 kyr response of ice sheets from 2.75-0.9 Ma?

The isostatic bedrock response to ice loading lags ice volume by several thousand years.

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.

Looking at initial graph of different populations vs. energy, how does the present-day per-capita (per person) energy consumption in North America and Europe compare to South America and Asia?

The per capita energy consumption is much higher in North American and Europe than in South America and Asia.

There are two main reasons that radiocarbon (14C based) age is offset from calendar (true) age. One is that the standard half life adopted is slightly shorter than the correct half life for 14C. What is the other main reason?

The rate of production of 14C has varied through time. The process involves 14N being converted to 14C through bombardment by cosmic radiation.

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 generate variations in climate, from warm (hothouse) to cool (icehouse).

The rate of seafloor spreading and thus volcanic degassing of carbon dioxide.

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

What is the primary cause of Earth's seasons?

The spin axis of Earth is tilted with respect to the plane of Earth's orbit around the Sun.

Say we analyze the carbon content of a chunk of wood found in a glacial moraine, and find that it appears to be 3 14C half lives old. Say I use the standard, but incorrect, 14C half life of 5,568 yrs/half-life, rather than the correct half life of 5,730 yrs/half-life. Will my standard 14C age be younger or older than the correct (calendar) age?

The standard 14C age will be younger than calendar

Describe the uplift-weathering hypothesis, proposed by Maureen Raymo and her colleagues.

The uplift-weathering hypothesis by Maureen Raymo proposes that tectonic uplift contributed to surface cooling. Specifically, she looked at the Himalayas and the Tibetan Plateau. She supported this by looking at how raining in the Himalayas eroded the mountains. This erosion caused carbon dioxide to be stripped from the air. Due to this lack of carbon dioxide, the atmosphere began to get cooler and cooler due to its role in the greenhouse effect.

Which of the following are critical steps in human evolution (you may select more than one)

The use of stone tools circa 2.5 million years ago. The branching of the prehuman line into the genus Homo and other forms by around 2 million years ago. The onset of bipedalism approximately 4 million years ago. The development of large brains in the Homo genus since around 2 million years ago. The initial branching off from primitive apes between 6 and 4 million years ago.

Climate is a broad composite of the time-averaged (over years or longer) condition of a region, measured by its temperature, amount of rain or snowfall, snow and ice cover, wind direction and strength, and other factors. Which one of the following scenarios does not represent a climate change?

The wind direction over Shideler Hall changes from north to east between 8 and 9 AM.

Say we suspect that the oceans warmed over some particular time period. If we were to look at oceanic sediments from that time period, and more specifically at the δ18O values of foraminifera shells found in those sediments, how should we expect those δ18O values to change as a result of the hypothesized warming?

The δδδ18O values will decrease (become more negative or less positive)

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 δ18O values of foraminifera shells found in those sediments, how should we expect those δ18O values to change as a result of the hypothesized cooling?

The δδδ18O values will increase (become less negative or more positive)

Describe at least one line of evidence (i.e., change in some type of climate proxy over time), besides changes in benthic foraminiferal δ18O, that implies a long-term cooling trend over the last 50 million years. (2-3 sentences at most) [Note: This question is not seeking a hypothesized mechanism for why the cooling occurred, but rather evidence pointing toward a cooling having occurred.]

There have been igneous rocks (pillow lava rocks) whose sediments were dated back to a time period in which they could only have formed in a marine environment. These sediments and their dating depict that greenhouse gas quantities and variations have changed over time.

Describe at least one line of evidence (i.e., change in some type of climate proxy over time), besides changes in benthic foraminiferal δ18O, that implies a long-term cooling trend over the last 50 million years. (2-3 sentences at most) [Note: This question is not seeking a hypothesized mechanism for why the cooling occurred, but rather evidence pointing toward a cooling having occurred.]

There have been rocks (such as igneous pillow lava rocks), and their sediment that was data back to the time period that could only have formed in a marine environment. This shows that greenhouse gas variations and quantities have changed over time.

The main reason(s) that the Last Glacial Maximum, at approximately 21,000 years ago, was colder than today is (are) (choose one or more answers)

There was extensive glaciation in the Northern Hemisphere, which cooled regional climate and increased Earth's albedo compared to today. Greenhouse gas concentrations were lower than today, weakening the greenhouse effect relative to its modern strength.

Which of the following is not a reason why the Last Glacial Maximum (LGM), at approximately 21,000 years ago, was colder than today?

There was significantly less high-latitude Northern Hemisphere insolation at that time than there is today.

There are three stable isotopes of oxygen.

True

When using trees to look for climate signals, it is generally better to core trees that are often stressed and living near the environmental limits of their species.

True

In addition to coral reef and benthic foram δ18O records, what other records indicate a dominant 100-kyr periodicity of climate change over the last 900 kyrs?

Vegetation changes recorded as pollen-assemblage variations in European lake sediments Dust in the ice-core record North Atlantic sea-surface temperature varations derived from planktonic foraminifera assemblage changes seen in marine sediment cores. Loess records from southern China

What is the primary, or main, reason that Venus is warmer than Earth?

Venus has a denser atmosphere which is composed almost entirely (96%) of CO2, in contrast to Earth's atmosphere, where CO2 is a trace gas.

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.

How quickly after deposition does freshly fragmented (broken up by physical weathering) debris undergo most chemical weathering? (Hint: remember the case-study outlined in the textbook about the rate of weathering of glacial moraines of different ages within the Wind River Range)

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

Say we were somehow able to magically stabilize the atmospheric concentrations of all greenhouse gases at today's levels, and kept them at those levels in perpetuity. What would happen to global temperature?

Warming would continue; thermal inertial (delay) in the Earth system, and in particular in the ocean, mean we have only seen a fraction of the total warming we should expect from the anthropogenic rise in greenhouse gas concentrations.

When the Southern Hemisphere is experiencing stronger seasonality due to precession, the Northern Hemisphere is experiencing:

Weaker seasonality

Why does the size of a growing or melting ice sheet lag well behind (i.e., by thousands of years) changes in insolation. (5 sentences at most)

When summer insolation declines from its peak, the surrounding ice begins to increase and accumulate together behind the wall.

Describe how and why proglacial lakes travel slowly across the landscape behind melting ice sheets? (5 sentences at most)

When the ice retreats, the depressions that they created in the land remain there, fill with water and create a lake. The slow-moving rebound of the crust causes the depression to move to follow the ice that was retreating.

The ice-volume variations are thought to be dominated by growth and decay of ice sheets in the Northern Hemisphere. Did the Southern Hemisphere climate respond to what was happening in the Northern Hemisphere?

Yes, S.H. climate largely tracked that in the N.H. on orbital time scales.

From ~2.75 Ma to 900 ka, ice volume varied at a 41 kyr period. Since 900 ka, the dominant period of ice-volume variation was 100 kyr. So the period changed circa 900 ka. Did the amplitude change as well?

Yes, the amplitude of ice-volume variation increased circa 900 ka.

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.

From the sixth paragraph of the article, why does Ruddiman argue against a recent (e.g., 1950) start to the Anthropocene epoch?

a recent start would miss significant earlier impacts that humans have been having on the planet

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

Some of the evidence for the cooling over the last 50 million years comes from changes in leaf morphology (shape). According to this leaf-morphology proxy, as conditions cooled, the fossil leaf record should generally show

a trend toward more jagged leaf margins through time

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

ablation

In order for the uplift-weathering hypothesis to be a candidate in explaining the gradual global cooling over the last 50 million years, what would need to happen?

an increase in silicate weathering in conjunction with an increase in continent-continent collision over the last 50 million years.

Methane production tends to occur in _________ environments such as swamps and other wetland areas. On orbital timescales, the production rate of methane is thought to have been __________ during times of lower insolation.

anoxic (low oxygen) & lower

Earth is farther from the Sun during perihelion, and closer to the Sun during aphelion.

false

Records from long ocean sediment cores reveal that millennial oscillations have occurred

as far back as the 41-kyr period glaciations, before 900 kyr, with the exception of interglacial times.

Lithospheric plates consist of

both the outer-most, coolest mantle and the crust

Changes in the δO18 values recorded in ice cores can be produced by

changes in air temperature over the ice sheet or glacier glacier or ice sheet. changes in the δ18O of the source waters. changes in the proximity to the source waters for precipitation landing as snow on the glacier or ice sheet changes in the elevation of the glacier or ice sheet

Changes in the δ18O values recorded in ice cores can be produced by(choose all correct options below)

changes in the proximity to the source waters for precipitation landing as snow on the glacier or ice sheet changes in air temperature over the ice sheet or glacier glacier or ice sheet. changes in the δ18O of the source waters for precipitation landing as snow on the glacier or ice sheet. changes in the elevation of the glacier or ice sheet

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

clockwise

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

clockwise

The Earth system is, to good approximation,

closed

Which of the following is least dense?

continental crust

During La Niña conditions the eastern side of the tropical Pacific Ocean will usually experience

cooler temperatures and less rainfall

An increase in the clustering of volcanic eruptions after 1200 AD may have contributed to a small ___________ in the northern hemisphere.

cooling

The Younger Dryas was a _______ event that primarily affected the ________ region.

cooling/North Atlantic

What is the name of the type of drone being developed to give forecasters a better sense of the conditions near the sea surface, at the base of a large storm or hurricane?

coyote

Identify the current primary downsides to solar energy production.

currently it is more expensive than fossil-fuel based energy production night and cloudy days shut down or slow the production of solar energy, meaning storage and alternative energy sources are required

Dansgaard-Oeschger oscillations were first identified in

d18O and dust changes in Greenland ice cores

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

decrease

The growth of ice sheets on land leads to a(n) increase in global (eustatic) sea level.

decrease

δ18O of coral skeletons responds similarly to δ18O from foraminifera. Thus a warming of waters around a coral reef will be seen as a(n) ________ in coral δ18O.

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

Which of the following would tend to decrease albedo?

decrease snow and ice cover

Peter Clark suggested that over the repeated glaciations of last 2.75 million years the ability of the North American ice sheet to slide over its bed has ______ due to weathering and erosion of that bed. The result is that the later versions of this ice sheet were _______ than the earlier versions.

decreased/thicker

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

decreases

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

distance of the planet from the Sun solar luminosity

Looking at the wind direction in the figure below, would the resulting Ekman transport be producing downwelling or upwelling along the coast of California?

downwelling

Dansgaard/Oeschger events were first identified as millennial-scale variations in what ice-core derived quantities? (choose the two correct answers)

dust δ18O

A measure of how elliptical, rather than circular, Earth's orbit is around the Sun is called , and it varies on an approximately 100 kyr (kyr=1,000 years) timescale, as well as on an approximately 400 kyr timescale.

eccentricity

The measure of how elliptical, rather than circular, the orbit of the planet is around the Sun is called _______, and it varies on an approximately 100 kyr (kyr=1,000 years) timescale, as well as on an approximately 400 kyr timescale.

eccentricity

Match the orbital characteristic with its respective period.

eccentricity 100 kyr precession 23 kyr obliquity 41 kyr

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

electromagnetic radiation arriving from the Sun

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

erratic

What product of urbanization is suggested to have exacerbated the flooding associated with Harvey in Harris County, Texas?

extensive land area covered by impermeable /impervious surfaces like concrete and asphault

A drop in global sea level is thought to cause glaciation.

false

As the period of ice volume transition from 41 kyr to 100 kyr around 900 kyrs ago, the amplitude (size) of ice volume variation remained unchanged.

false

Earth is closer to the Sun during Aphelion

false

In the Cretaceous the rate of carbonate deposition was higher and the temperature was higher , relative to the present day.

higher

Evidence for a cooler climate in areas surrounding the North Atlantic during the Little Ice Age includes

historical records of glacier advances in the Alps and the mountains of Norway the failure of crops in far norther regions of Europe that had previously been successful, due to a shorter growing season areas of dead lichen on Baffin Island which date to the Little Ice Age period more weeks per year of sea ice along the north and west coasts of Iceland

From the second paragraph of the article, what are the noted ways that humans have been impacting our planet over the last several thousand years?

hunting and burning planting crops such as corn and wheat over wide swaths of the landscape ranching and herding of various animals, including cows and chickens rice agriculture

From the first paragraph of the article, what is suggested as the main culprit behind the extinction of megafauna like woolly mammoths, giant ground sloths, and giant kangaroos?

hunting and landscape-burning by humans

Which of the following are noted as renewables?

hydropower geothermal wind solar

What is our best source of data for atmospheric greenhouse gas concentrations going back several hundred thousand years?

ice cores

The δ18O values of the shells of foraminifera found in ocean sediments primarily reflect changes in what two key variables? (Choose the two correct options below.)

ice volume ocean temperature

The δ18O values of the shells of foraminifera found in ocean sediments primarily reflect changes in which of the following two quantities?

ice volume ocean temperature

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

increase

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

increase

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

δ18O of coral skeletons responds similarly to δ18O from foraminifera. Thus a cooling of waters around a coral reef will be seen as a(n) ________ in coral δ18O.

increase

Which of the following would increase albedo?

increase cloud cover

The Snowball Earth hypothesis addresses cold periods that are thought to have involved extensive glaciation and sea-ice cover. As noted in class, and in the James Kasting 2019 review article associated with homework 3, evidence suggests that immediately after these cold "snowball" periods, marine carbonate deposition:

increased a lot

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

Select all of the ways in which tectonic uplift (mountain building) increases rock fragmentation, and thus weathering.

increased water flow b/c of orographic precipitation erosive power of mountain glaciers increased mass wasting due to steeper slopes

As the salinity of seawater decreases, its freezing temperature:

increases

Earth and the Sun have different peak wavelengths of electromagnetic radiation (EMR) emission. Those respective wavelengths fall into which bands of the EMR spectrum?

infrared (Earth) & visible (Sun)

Wien's law relates the temperature of an black body and the wavelength at which it emits its maximum amount of energy. In particular, the law says that the temperature and wavelength of maximum emission are ______________ related.

inversely related (if temperature increases, the wavelength of maximum emission decreases)

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? (Hint: it may impact your answer to know that this element is rare on Earth's surface, but much more common in some types of meteorites.)

iridium

As more and more CO2 dissolves into our oceans, what will happen to the pH of the ocean water?

it will decrease

If the planet's surface becomes ice covered and very cold, shutting down silicate weathering (or hydrolosis), what should happen to the atmospheric concentration of CO2?

it will rise

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

left & left

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

left , left

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

less

Which orbital configuration below is more likely to produce Northern Hemisphere ice-sheet growth, according to Milankovitch theory?

less obliquity, high eccentricity, N. Hemisphere summer solstice during aphelion

Which situation is more likely to produce ice-sheet growth, according to Milankovitch theory?

less tilt, high eccentricity, summer solstice during aphelion

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 lower temperature.

longer

A side-by-side comparison of the ice-core CO2 record, and the ice-volume record from ocean sediments, over the last few hundred-thousand years, reveals that when atmospheric CO2 concentration is high, ice volume is:

low

The higher the salinity of seawater, the _________ the freezing temperature of that water.

lower

The ratio of Magnesium (Mg) to Calcium (Ca) in foraminifer shells is used as a proxy for ocean temperature, and serves as one line of evidence of the decrease in temperature over the last several 10's of millions of years. In this Mg/Ca proxy, the cooler the water, the ______ the Mg/Ca ratio.

lower

If we incorrectly assume that LGM production of 14C is the same as today, when it was in fact higher, then we are in effect assuming that the starting amount of 14C in a LGM sample (an organism that died back then) is _____ than it should be, and thus our resulting age estimate for an LGM sample will be too ______.

lower and young

What physical property of rocks can serve as a proxy for the latitude at which the rock formed?

magnetic inclination

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

From your reading of the James Kasting 2019 review article for homework 3, what is the main criteria for defining the habitable zone around a star?

maintenance of liquid water on a planet's surface

As water, including seawater cools, it can hold more dissolved carbon dioxide (CO2).

more

The global average increase in surface temperature is 0.8-1ºC since 1900. That global average includes both land and ocean temperature changes. Given that the land surface is made of rock and soil, which have notably lower heat capacities than water, would you expect temperature on land to have risen more or less than what has been seen globally?

more

The Cretaceous period is generally associated with __________ carbonate sedimentation and _________ temperature, relative to today.

more & warmer

What do you think: is our climate system more sensitive to a change in atmospheric CO2 concentration during colder times or warmer periods? In other words, would a given increase in atmospheric CO2 concentration yield a larger warming during cooler or warmer times?

more sensitive during colder times

The higher heat capacity of water compared to rock or sediment means that for the same seasonal variation in insolation the land temperature will vary ___________ the ocean.

more than

The chemical weathering rate is ______________ for fresh material in comparison to very old material.

much higher

The atmospheric concentration of methane has increased markedly since the early nineteenth century (from 600 to over 1800 ppb). Several human activities have caused this increase, including

ncreased cultivation of rice increased numbers of cattle and other livestock leakage from natural gas pipelines, in addition to leakage from oil and gas extraction activities (e.g., wells and refineries)

Organic material (made mostly through photosynthesis) tends to have a lower ratio of 13C to 12C than inorganic material. The mean value of δ13C of inorganic carbon dissolved in ocean water is 0‰. Therefore, the δ13C value for organic material, is, by comparison:

negative

Sulfate aerosols produced by burning of coal as well as smelting (processing of metal ores) act as a _____ radiative forcing.

negative (cooling)

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

nuclear fusion

Which has absorbed more heat during the 20th-Century warming: the atmosphere or the ocean?

ocean

Millennial variations in d18O seen in Antarctic and Greenland ice cores are ______ phase with each other.

out of

Millennial variations in δ18O seen in Greenland and Antarctic ice cores are _____ phase with each other.

out of

As an ice sheet grows, its upper surface is moved higher into the atmosphere. The higher the ice sheet surface moves into the atmosphere, the cooler the mean annual air temperature experienced by the ice sheet surface. The cooler the mean annual air temperature, the less ablation experienced by the ice sheet. The smaller the amount of ablation, the more an ice sheet can grow. Together these facts constitute a __________ feedback on ice sheet growth.

positive

Together the facts below constitute a _______ feedback on ice-sheet growth. As an ice sheet grows, its upper surface is moved higher into the atmosphere. The higher the ice-sheet surface moves into the atmosphere, the cooler the mean-annual air temperature experienced by the ice sheet surface. The cooler the mean-annual air temperature, the less ablation experienced by the ice sheet. The smaller the amount of ablation, the more an ice sheet can grow.

positive

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

proxy

What is a proxy indicator of the delayed response of the crust to ice removal?

raised beaches in formerly glaciated areas

The bipolar seesaw involves:

redistribution of heat within the Atlantic ocean

The bipolar seesaw involves

redistribution of heat within the atlantic ocean

Times of major human population decline have been hypothesized to correspond to times of __________ atmospheric CO2 concentration.

reduced

The uplift-weathering hypothesis, proposed by Maureen Raymo and her colleagues, suggests that uplift produced by continental collisions increases weathering and thereby ________ the amount of carbon dioxide in the atmosphere, producing a ________ climate.

reduces/ cooler

From the fourth paragraph of the article, what human-related phenomena was occurring around the time of 1610, one of the proposed start dates for the Anthropocene epoch?

reforestation due to small-pox caused mass deaths in Africa and the Americas.

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

respiration

The growth in which type of agriculture would be a good candidate to explain an increase in atmospheric methane?

rice

The Coriolis force causes moving objects to be deflected to the __________ in the Northern Hemisphere.

right

The Coriolis force, produced by the rotation of our planet, tends to deflect moving objects to the ________ in the northern hemisphere.

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

The early anthropogenic hypothesis attempts to explain an anomalous ______ in greenhouse gas concentration over the last several thousand years as a consequence of early ________

rise, agriculture

The early anthropogenic hypothesis attempts to explain an anomalous ______ in greenhouse gas concentration over the last several thousand years as a consequence of early ________.

rise, agriculture

After removing local effects from tide gauge records, and including recent satellite-based measurement of sea level, it appears that sea level has ______ roughly _______ cm over the 20th century.

risen--- 17

The lapse rate (rate of decrease in temperature with altitude) is larger in magnitude for dry (unsaturated) air than for moist (saturated) air because

rising moist air gains warmth from the latent heat of condensation/vaporization for water

In order for the BLAG, or sea-floor spreading, hypothesis to be a candidate in explaining the gradual global cooling over the last 50 million years, what would need to happen?

sea-floor spreading would need to have decreased over the last 50 million years

Fossil coral reefs provide direct evidence for

sea-level changes, reflecting ice-sheet volume changes over orbital time scales

Fossil coral reefs provide direct evidence for:

sea-level changes, reflecting ice-sheet volume changes over orbital time scales

What phenomena, produced by global warming, is going to exacerbate flooding due to rain and storm surges during storms in coastal areas?

sea-level rise

The largest carbon reservoir within the carbon cycle is

sediments and rocks

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 higher temperature will have a ___________ peak wavelength of emission than a body with a lower temperature.

shorter

The strength of the Coriolis force acting on a moving parcel of air or water depends on which of the following three quantities? (Choose the correct three options below.)

the speed of the parcel rotation rate of the planet the latitude of the parcel

Earth's seasons are primarily produced by

the tilt of Earth's rotational axis relative to the plane of its orbit around the sun; this produces seasonal changes in the angle at which sunlight arrives on Earth's surface at a particular latitude.

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

thermohaline

Why is Forrest Masters measuring ground level windspeed in major storms?

to help in the design of more resilient buildings

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

As northern hemisphere insolation begins to increase just after reaching a minimum, northern hemisphere ice volume continues to increase until insolation becomes large enough to cause ablation to exceed accumulation

true

Both ablation and accumulation depend, to some extent, on mean annual temperature, but ablation is much more sensitive to temperature.

true

CO2 fertilization of tree growth during the time-frame of the instrumental record complicates efforts to extract climate information from tree rings because it mimics improved growth conditions that would otherwise be related to temperature and precipitation.

true

During an El Niño period the δ18O of eastern Pacific corals will decrease

true

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

It is at times when Earth's orbit is more elliptical (less circular) that precession of the equinoxes has the most impact on the planet's seasonality.

true

One hypothesis for the megafaunal extinctions 15-10 ka is that the climate changes seen during deglaciation created conditions to which the animals could not adapt. One key criticism of this hypothesis is that no similar extinction events had been seen in any of the previous 40+ deglaciations over the last 2.75 Ma.

true

When using trees to look for climate signals, it is generally better to core trees that are often stressed and living near the environmental limits of their species.

true

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

During an El Niño event, sea surface temperatures (SSTs) in the eastern tropical Pacific are _____ than normal?

warmer

The Cretaceous period is generally associated with _______ temperature and ______ carbonate sedimentation, relative to today.

warmer & more

During El Niño periods, the eastern Pacific tends to experience

warmer, wetter conditions

Say that your lake sediments show a shift from mostly spruce pollen to mostly grass and herb pollen as we go from the LGM to the mid—Holocene. What qualitative climate change can you infer from that change in pollen?

warming and drying

Say that your lake sediments show a shift from mostly spruce pollen to mostly grass and herb pollen as we go from the LGM to the mid—Holocene. What qualitative climate change does that indicate?

warming and drying

LGM conditions in the American southwest were

wetter than today, because of the southward displacement of the jet stream at LGM.

LGM conditions in the american southwest were

wetter than today, because of the southward displacement of the jet stream at LGM.

From the third paragraph of the article, what more recent actions by humans are added to the list of options for the start of the Anthropocene epoch?

widespread burning of coal detonation of the atomic bomb

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

young

The air trapped within a bubble in an ice core is _______ the ice surrounding the bubble.

younger than

What do you think: in our longest ice core record, going back 800,000 years, what's the highest atmospheric CO2 concentration measured prior to the industrial revolution?

~300 ppm

Dansgaard/Oeschger events were first identified as millennial-scale variations in what ice-core derived quantities?

δ18O dust

Dansgaard-Oeschger, or DO, oscillations were first identified in:

δ18O and dust changes in Greenland ice cores

What would happen to the δ18O signal seen in the Gulf of Mexico if the delivery of glacial meltwater were to suddenly stop? Presume nothing else changes.

δ18O would go up