MSC 220 Exam 1 Study Guide
Describe the feedback mechanism from what you learnt in class.
All in all, the El Niño Southern Oscillation ENSO is a feedback or oscillation between the Equatorial Pacific Ocean and the atmosphere above it: El Niño occurs when the ocean is warmer than average and La Niña occurs when the ocean is cooler than average.
science vs politics normative
Concerns the way things should be right/wrong, wise/foolish, good/bad Involve value judgements and underlying morals or principles right/wrong can be a matter of culture/ideology Deeply contested, less amenable to resolution
Where does the most precipitation occur during El Niño and why?
During El Niño, the most precipitation occurs in the Central and Eastern Pacific because the sea surface temperature increases the most there, warming the atmosphere in which moist air then rises and develops into rain clouds, leading to increased precipitation.
If carbon emissions were reduced to zero tomorrow, how long would it take for atmospheric levels to reduce back to pre-industrial levels? Why?
If carbon emissions were reduced to zero tomorrow, it would take thousands of years for the carbon dioxide in the atmosphere to return to rocks to reenter the carbon cycle and reduce the atmospheric levels of CO2 back to pre-industrial levels. Chemical weathering and rock formation (how CO2 is typically removed from atmosphere, in addition to photosynthesis/respiration) are not processes that occur rapidly, thus carbon dioxide remains in the atmosphere for long periods of time, resulting in a significantly long period of time, approximately thousands of years, for atmospheric levels of carbon dioxide to reduce back to pre-industrial levels.
With a little research, quantify the effect on global sea level (in m) if the ice sheets were to totally melt!
If the Greenland ice sheet melted, scientists estimate that sea level would rise about 6.096 m. If the Antarctic ice sheet melted, scientists estimate that sea level would rise by about 60.96 m.
How has the concentration of this gas changed over the course of earth's 4.5 billion year history?
Over the course of Earth's 4.5 billion year history, the concentration of water vapor in the atmosphere has increased.
Explain the difference between the natural carbon cycle (carbon neutral) and the modern carbon cycle.
The difference between the natural carbon cycle and the modern carbon cycle is that the modern carbon cycle has additional levels of carbon entering the atmosphere from the burning of fossil fuels in industrialization.
Scientific model of global warming ozone model
The leading cause of global warming is an increase in carbon dioxide in the atmosphere,resulting from the burning of fossil fuels
how will the melting sea ice affect the properties and sea level of the ocean?
The melting of sea ice will release freshwater into the ocean, reducing the ocean's salinity, but it will not increase the sea level of the ocean.
What is the most abundant variable gas in the atmosphere? Give its name and chemical formula
The most abundant variable gas in the atmosphere is water vapor, or H2O, at a percentage of approximately 1-4%.
Where did it come from (sources) and (succinctly) what was it used for?
This carbon dioxide has come from the burning of fossil fuels for industrialization purposes.
Venus is about the same distance from the sun as Earth, so why is it so much hotter?
Venus is so much hotter than Earth because Venus is surrounded by a very thick atmosphere approximately 100 times more massive than the atmosphere on Earth, meaning there are significantly higher amounts of greenhouse gases present in the atmosphere on Venus than present in the atmosphere on Earth, which can warm Venus to a temperature significantly higher than Earth.
Describe a moulin and explain how it affects the stability of an ice sheet.
A moulin is a vertical or nearly vertical shaft in a glacier, formed by surface water percolating through a crack in the ice. Moulins tend to decrease the stability of ice sheets. Moulins decrease the stability of ice sheets by lubricating the movement of ice over land, allowing ice sheets to form ice shelves, which then can break into icebergs. Also, moulins decrease the stability of ice sheets by penetrating the ground, accelerating movement and melting of the ice.
"Millenial Oscillations", or abrupt climate changes, occur on time scales of thou- sands of years. Which events are thought to precede cooling? And which rep- resent abrupt warming? How are they marked in the climate record? Explain the possible cause(s) of these climate oscillations? Why are the oscillations stronger in the Northern Hemisphere?
An event that is thought to precede cooling of Earth's climate is the slowing or stopping of Earth's thermohaline circulation. An event that represents abrupt warming of the Earth would be the sudden influx of glacial meltwater and freshwater into the ocean. These events are marked in the climate record with layers of large amounts of coarse-grained sediments derived from land and layers with normal pelagic sediments. These events are also marked in the climate record with sudden decreases or increases in temperature on relatively short time scales. Possible causes of these climate oscillations include the diversion of meltwater flow from the Gulf of Mexico to the St. Lawrence estuary, melting of icebergs, release of methane hydrates, and the slowing or stopping of THC. The oscillations are stronger in the northern hemisphere because of the significant amount of land present when compared to the southern hemisphere and because the start/end of THC is in the North Atlantic.
Describe an example of climate change on a time scale of about a hundred thousand years. What forcing is believed to have set the pace of this change? Explain how changes in ice cover and in the ocean's biological pump are thought to have amplified the forcing.
An example of climate change on a time scale of approximately one hundred thousand years would be the cooling of the Earth. The forcing believed to have set the pace of this change would be the ice-albedo feedback process. In this process, as the amount of ice increases on Earth, less energy is absorbed and more energy is reflected. If Earth was not absorbing as much heat, the temperature of Earth would decrease, leading to continued cooling and and an increased ice cover. This increase in ice cover, in turn, would have amplified the forcing because the more ice cover, the more energy is reflected, allowing Earth's temperature to cool even more. Additionally, the ocean's biological pump may have amplified the cooling of Earth. If the biological pump would have increased, the amount of CO2 drawn down into the ocean would also have increased, taking GHGs out of atmospheric circulation and sequestering them into deep sea sediments, contributing to the cooling of Earth's temperature as well.
Describe an example of climate change that occurred over tens of millions of years. Explain the forcings, feedbacks, and/or processes that are believed to have driven changes on these slow time scales in the past? How was Earth's climate and atmospheric composition different before and after these changes?
An example of climate change that occurred over tens of millions of years would be the warming of the Earth. One forcing that may have driven this change would be volcanism. As volcanoes erupt, they release CO2 and other greenhouse gases into the atmosphere, which may have increased Earth's temperature over time. Emitted ash from volcanoes can also cause the blackening of ice and snow, reducing Earth's albedo and allowing Earth to absorb more heat, which may have also increased Earth's temperature over time. Another forcing that may have driven this change would be the regulation of methane hydrates. Methane is a much more volatile and dangerous GHG compared to CO2, and some methane is held within methane hydrates at the bottom of the ocean. If this methane was released, the methane would have gone into the atmosphere, which may have increased Earth's temperature over time. Finally, a forcing that may have driven this change would be a potential stop of the biological pump. The biological pump works to take CO2 out of the atmosphere and sequester it into deep ocean sediments. If the biological pump were to stop, CO2 would accumulate in the atmosphere, leading to the increase in Earth's temperature over time. Before these changes, Earth's climate was mild and relatively cool, with few GHGs present in the atmosphere. After these changes, Earth's climate was warm and wet, with many GHGs present in the atmosphere.
(3) How is it that anthropogenic climate change might be described as going "Back to the Jurassic"?
Anthropogenic climate change might be described as going "Back to the Jurassic" because the climate of the Jurassic period is similar to where our climate is heading today. In addition, the last time CO2 levels were this high in the atmosphere, it was the middle of the Jurassic period. This is why climate scientists are interested in studying the dynamics of climate during the Jurassic Period because what happened during that time (climate-wise) is relevant to today.
science vs politics positive
Concerns the way things are Scientific claims and questions are all positive Well posed positive questions have correct and incorrect answers Evidence can resolve positive arguments Does not have to be simple or easy to verify
Cultural models of global warming.
Contributing to perceived uncertainty is public confusion over the causes of global warming - i.e what climate is and how the greenhouse effect works
Convection (vertical motion/uplift) occurs in the troposphere but not in the stratosphere, why?
Convection does not occur in the stratosphere because the air temperature in the stratosphere increases with altitude (which does not allow convection to occur), versus the opposite in the troposphere, in which the air temperature decreases with altitude (which allows convection to occur)
Explain how the Earth's crust can uptake carbon dioxide over a time scale of tens of millions of years.
Earth's crust can take up carbon dioxide over a time scale of tens of millions of years through the movement of tectonic plates and the weathering of sedimentary rock, as seen in the following equations: CO2 + H2O → H2CO3, H2CO3 + CaCO3 → Ca(HCO3)2 (weathered rock).
Cultural models of global warming Ozone model
Global warming is linked to,or results from the ozone hole A main cause is spray cans and refrigerants Using the ozone model leads to incorrect inferences about the causes of global warming
What is ice sheet calving and why is it difficult for scientists to predict?
Ice sheet calving is the breaking of ice chunks from the edge of an ice sheet or glacier. Ice sheet calving is hard for scientists to predict because ice sheet dynamics are complex and involve non-linear thermodynamics and mechanics.
Scientific model of global warming pollution model
In fact, greenhouse gases Are naturally occurring Non-toxic (also invisible and odorless) Anthropogenic sources are industrial and automotive but there are natural sources Cannot be filtered out of the air - why?
Cultural models of global warming pollution model
Many people perceive greenhouse gases as pollution (the pollution model) Pollution consists of artificial chemicals Chemicals are toxic Sources are industrial and automotive Pollution can be fixed by filtering Using the pollution model leads to incorrect inferences about the causes, health effects, and solutions for global warming
How will melting ice sheets affect the properties of the ocean and sea level?
Melting ice sheets will increase the sea level and reduce the salinity of the ocean.
What kind of feedback tends to stabilize the climate? Give an example.
Negative feedback tends to stabilize the climate. An example of negative feedback would be radiative feedback, in which increased temperatures lead to increased heat loss.
(1) Explain, briefly yet clearly, what is oil and how and when was it formed?
Oil is a thick black liquid composed primarily of hydrogen and carbon, a fossil fuel. Oil is formed through a process that takes place on a time span of millions of years. The process begins when plankton die. When plankton die, they fall to the bottom of the ocean, where they get trapped under many layers of sand and mud. Over time, typically millions of years, the dead plankton get buried deeper and deeper, and increasing heat and pressure gradually turn the sediments into rock and the dead plankton into oil. The majority of oil used today was formed during the Jurassic period; however, oil is still being formed today in deep sediments around the globe.
List three other proxies for past climate change, together with where the proxies come from (ice, ocean sediment, historical etc), what climate parameter they represent (time, temperature, sea level.. etc), and roughly how long their records are (hundreds of years, thousands... etc).
One proxy for past climate change would be a deep ocean basin proxy. The proxy comes from ocean sediment, represents the time and temperature climate parameters, and its record is approximately 100 million years long. Another proxy for past climate change would be ice cores. The proxy comes from ice, represents time, sea level and temperature climate parameters, and its record is approximately 1 million years old in Antarctica and 120,000 years old in Greenland. A final proxy for past climate change would be tree rings. The proxy comes from trees, represents the time and temperature climate parameters, and its record is approximately 1000 years.
Oxygen isotope ratios found in the shells of marine organisms, such as foraminifera, are related to the volume of ice on Earth and also to sea level! Carefully explain how this is the case.
Oxygen isotope ratios found in the shells of marine organisms are related to the volume of ice on Earth and also to sea level because oxygen isotope ratios can help us infer what the climate was like on Earth at a particular point in time, which can be used to determine the volume of ice on Earth and sea level. The isotopic composition of oxygen is typically reported as ?18O, the ratio of 18O to 16O. 18O is only found in the ocean, whereas 16O is found both in the ocean and in ice sheets. Depending on the size of the ratio of ?18O, we can determine how much 16O was present in the ocean at a particular point in time, using that information to determine the volume of ice and sea level. When the ratio of ?18O is high, this means that the amount of 16O in the ocean is low, and thus a significant amount of 16O is present in ice sheets, demonstrating that the volume of ice on Earth is high and sea level is low. When the ratio of ?18O is low, this means that the amount of 16O in the ocean is high, and thus very little 16O is present in ice sheets, demonstrating that the volume of ice on Earth is low and the sea level is high.
(2) What is meant by "peak oil"? Do you think it remains a valid concept?
Peak oil refers to the hypothetical point at which global crude oil production will hit its maximum rate, after which production will start to decline. I do believe that peak oil remains a valid concept. It is known that the US oil reserves reached its peak in 1970, but world oil production has yet to reach its peak. There was a consensus between industry leaders and analysts that world oil production would peak between 2010 and 2030, with a significant chance of occurring before 2020; however, it is currently 2020 and world oil production has yet to reach its peak. Therefore, I do believe peak oil remains a valid concept because there is a strong chance that world oil production will reach its peak in the next 5 to 10 years.
Cultural models of global warming Photosynthesis and respiration
Plants absorb CO2 and produce O2 - deforestation will lead ota lack of oxygen for people to breathe Population growth - all those people breathing will increase CO2 and global warming Using an over-simplified photosynthesis - respiration model can lead to alarming inferences
Over simplified respiration model
Population growth - all those people breathing will increase CO2 and global warming
By what percentage have carbon dioxide levels increased since the beginning of the Industrial revolution?
Since the industrial revolution, the concentration of carbon dioxide levels has risen by approximately 43%.
with global warming, the Arctic Ocean is warming the quickest. Using concepts of albedo explain why
The Arctic ocean is warming the quickest due to the ice-albedo feedback. In the Arctic, melting ice is uncovering darker land/ocean underneath, which since it is dark, absorbs more sunlight and has a lower albedo, contributing to a faster rate of warming compared to the rest of the world (which does not have this same problem of ice covering dark ground/water underneath), which is why the Arctic is warming the quickest.
what is the albedo of snow covered sea ice? of open ocean?
The albedo for fresh snow (and thus snow covered sea ice) is 90%, the albedo for bare ice is 50% and the albedo for open ocean is 6%.
Does it occur preferentially in a warm, wet climate or a cold, dry climate?
The carbon cycle occurs preferentially in a warm, wet climate - uptake of CO2 through the weathering of calcium-silicate rocks increases with increased precipitation and temperature.
in a warming climate, what is the potential significance of this difference in albedo if more sea ice melts and its spatial extent decreases?
The difference in albedo between snow covered sea ice and the open ocean is quite significant. If more sea ice melts and its spatial extent decreases, there will be more open ocean and the albedo will change from approximately 90% to 6%, which will contribute to global warming as the newly created open ocean will absorb the majority of the heat and radiation from the sun that makes it through Earth's atmosphere instead of reflecting it back out into space as it had before when it was sea ice, resulting in an increase in Earth's overall temperature.
Carefully describe three ways in which the movement of Earth's crustal plates (plate tectonics) can affect climate.
The movement of Earth's crustal plates can affect climate in a few different ways. First, plate tectonics can affect climate by exposing silicate rock to weathering, thus removing huge quantities of carbon dioxide from the atmosphere, cooling the Earth's temperature. Second, plate tectonics can affect climate through volcanism, which can pump carbon dioxide into the atmosphere, warming the Earth's temperature. Finally, through uplift of plateaus, tectonic plates can cause land to become more arid, leading to the creation of deserts and making Earth's climate more sensitive to the cycle of Earth's orbit.
How many parts per million by volume (ppm) of carbon dioxide is currently in the atmosphere?
The ppm of carbon dioxide currently in the atmosphere is approximately 400 ppm and was approximately 280 ppm during pre-industrial times.
Venus is said to have undergone a "runaway greenhouse effect" to become as hot as it is today. Research this and explain it using concepts of positive feedbacks and the greenhouse effect.
The runaway greenhouse effect occurs when a planet absorbs more energy from the sun than it can radiate back into space. It is a positive feedback cycle on Venus, because the hotter the surface temperature of Venus gets from absorbing solar radiation, the faster Venus warms up. The faster Venus warms up, the more outgoing thermal radiation there is, and since Venus' atmosphere has significant amounts of greenhouse gases present, more radiation is absorbed by greenhouse gases and more back radiation occurs (greenhouse effect), resulting in the temperature of Venus rising even more to become as hot as it is today.
Why does it contain most of the mass of the atmosphere?
The troposphere contains most of the mass of the atmosphere because the other layers of the atmosphere are closer to space, which acts as a vacuum in which gas molecules are sucked into space instead of remaining in the atmosphere - thus, the layers of the atmosphere closest to space have much less gas molecules and consequently a lower mass than the layers closest to the surface of the Earth, such as the troposphere, which do not feel the effects of space as significantly, allowing those layers to have a higher mass?
Where is the troposphere?
The troposphere is the layer of the atmosphere closest to the surface of Earth
Name the world's two ice sheets.
The two ice sheets are the Antarctica and Greenland Ice sheets.
How large and thick are they and how much freshwater do they hold?
These ice sheets are 2-4 km thick, cover approximately 660,200 mi2 and 14 million km2 (Greenland and Antarctica, respectively), and hold approximately 99% of the world's freshwater (90% in Antarctica, 9% in Greenland).
How many GigaTonnes of carbon is this?
This is an increase of approximately 255.6 GtC in the atmosphere (400 ppm - 280 ppm = 120 ppm increase x 2.13 GtC = 255.6 GtC).
What is this process called?
This process is called the carbon cycle, with the mechanism referenced above being the weathering of sedimentary rock.
How does upwelling in the eastern Pacific affect fisheries?
Typically, under normal conditions, there is strong upwelling in the Eastern Pacific as the sea surface temperature is colder and the thermocline is shallow, resulting in increased nutrient flow to the surface from the depths of the ocean, allowing fisheries to prosper. However, when El Niño occurs, the sea surface temperature is warmer and the thermocline is deep, resulting in decreased nutrient flow to the surface from the depths of the ocean, resulting in declining fishery populations. Essentially, strong upwelling allows fisheries to prosper due to the increase of nutrients brought up from the depths whereas weak upwelling results in fishery decline due to the decrease of nutrients brought up from the depths of the ocean.
What happens to the atmospheric winds during El Niño events?
Under normal conditions in the Pacific, atmospheric winds drive the warm-cold gradient in sea surface temperature, which helps to maintain and drive the winds in response. However, during El Niño, the atmospheric winds weaken and the Eastern Pacific Ocean sea surface temperature warms, thus weakening the winds more (positive feedback). But, during La Niña, the atmospheric winds strengthen and the Eastern Pacific Ocean cools, strengthening the warm-cold gradient in sea surface temperature and strengthening the winds more (positive feedback).
Where is all the water?
Venus did have liquid water at one point in time, but because the surface of Venus is so hot, water cannot exist in liquid form, and thus can only exist in gaseous form (water vapor). However, there isn't any water vapor in Venus' atmosphere because Venus' atmosphere breaks up the water vapor into its constituent elements of hydrogen and oxygen, which then are removed from Venus' atmosphere by electric winds, pulling the elements out into space.
Cultural models of global warming Significance of temperature variation
Winter-simmer temperature swings are 100 degrees F, daily can be 20 F A long term rise of 2 F per century does not seem harmful Perception of warming on a personal level - like an uncomfortably hot summer Environmental consequences of warming not considered Global trend equated to local change
Scientific model of global warming Significance of temperature variation
Winter-summer and daily temperature swings are seasons and weather A long term rise of 2 degrees C per century globally is a significant climate change Personal conception of climate is deceiving; the change is too small and too slow to perceive Data and documentation is needed
Explain what is meant by albedo?
albedo is the reflectance of earth's surface
why are changes to the THC important for climate?
changes to thermohaline circulation are important for climate because thermohaline circulation helps to balance climate as part of the thermohaline circulation process, warm water from the tropical atlantic moves poleward near the surface where it gives off some of its heat to the atmosphere, partially moderating the cold temperatures and climate at higher latitudes
Why has the climate change debate been so prolonged?
cognitive bias ideologically charged perceived uncertainty
what is the global thermohaline circulation THC?
global thermohaline circulation is the large scale ocean circulation that is driven by density gradients created by surface heat and freshwater fluxes
how does the ocean circulate around an area of high pressure (sea surface high) in the northern hemisphere?
it rotates clockwise around an area of high pressure
perceived uncertainty
the media favor "balanced" reporting also, politicians and industry groups, particularly fossil fuel producers and car manufacturers, promote skepticism and uncertainty even while 97% of climate scientists agree
Is the troposphere stable or unstable, why?
the troposphere is unstable because the warm air near the surface of the earth rises and cool air higher in the troposphere sinks, resulting in a significant amount of mixing, leading to instability
Is there horizontal convergence or divergence at the high pressure?
there is horizontal convergence at the high pressure
how is thermohaline circulation set in motion?
thermohaline circulation is set in motion by the sinking of the warm salty waters that flow northward in the atlantic and are cooled by the arctic/sub arctic oceans once these waters cool, they become dense and sink to the bottom where they travel with currents (surface and deep depending on location) throughout the ocean, setting the global thermohaline circulation in motion
ideologically charged
those in favor of "small government" tend to dismiss global warming (for fuel "debate"), since it calls for collective/governmental policy and regulation
Carefully explain the role of water in convection
water plays a significant role in convection in order for convection to occur, water has to evaporate from the earth's surface and be transported around the globe by the wind as this water vapor rises as it is carried around the globe, it expands and then cools, after which it then condenses and falls back down to earth, aiding in convection in the atmosphere as one can see, without water vapor evaporating and condensing simultaneously in the atmosphere, convection would not be able to occur when there is deep enough moisture, deep convection can happen
why is this gas called a "greenhouse" gas?
water vapor is called a "greenhouse" gas because it absorbs long wave radiation and radiates it back to the surface of Earth, contributing to warming of the planet (essentially traps radiant heat)
cognitive bias
we make decisions about tomorrow, next week, or maybe next few years, but not about the next 50 to 100 years
