earth, environment, society exam 2

Nuclear energy is referred to as a "clean energy", why? What are some of the challenges and concerns associated with the large-scale use of nuclear power?

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What is "Carbon Capture & Storage" and what is its objective. Briefly describe the processes involved in implementing it.

"Carbon Capture and Storage" is ____. It's objective is to____.

Besides O3, urban air pollution can include fine particulate matter (PM), classified by particle size in microns. What does it mean to say that PM can be produced directly vs indirectly? What are two sources of direct and two sources of indirect PM? What are the effects of elevated fine particles (PM10 and PM2.5) on human health?

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Briefly describe the general patterns associated with Thermohaline circulation in the global oceans today (a.k.a., MOC), including how and where different water bodies move vertically and laterally. What is the timescale of this circulation?

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Climate change can be driven by both natural and anthropogenic causes. How do we use climate models to attribute the current changes in our climate to human fossil fuel combustion? How do the model runs shown in this figure help us attribute climate change to human behavior?

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Consider the same chain reaction as above, central to the production of O3-rich photochemical smog. These reactions can sometimes lead to an increase in O3, or a decrease in O3. Consider each of these scenarios and explain how O3 concentrations will change: a. It is a very hot, sunny day and it is late in the afternoon. b. Something else (like volatile organic compounds from auto emissions) converts NO to NO2.

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Consider this chain reaction that is central to the production of O3-rich photochemical smog. These reactions can sometimes lead to an increase in O3, or a decrease in O3. Consider each of these scenarios and explain how O3 concentrations will change: a. It is night time and there is no light (hv) to drive the first reaction. b. The sun rises.

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Continental coastlines change over time. Describe three processes that can cause changes in the positions and geometries of continental coastlines, including at least one that occurs rapidly and one that occurs over thousands of years. Detail how the coasts change due to these phenomena, and the factors that drive these changes.

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Hypsometric curves of land and seafloor elevations reveal two modes in elevation, i.e., large areas that lie within narrow ranges of elevation. At what elevations/depths do these two modes occur, and how do we explain them in terms of lithospheric properties.

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In your homework assignment working with the EnROADS climate solutions simulator, how many changes did you need to make to bring the expected temperature rise down to less than 2°C? What surprised you about the process of constructing climate solutions?

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Photochemical smog (urban smog) is characterized by high levels of O3 in the atmosphere, but there are no sources that emit O3: instead, it is a product of chemical reactions in the atmosphere. What are the two essential chemical precursors for the formation of elevated tropospheric O3? Where does each of these precursors come from? What are some of the health consequences of high levels of tropospheric O3?

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The atmosphere's temperature profile is complex, dropping with altitude until the tropopause, and then rising to a peak in the middle of the stratosphere (see figure below). What causes the peak in atmospheric temperature in the stratosphere? Write out and explain any relevant chemistry

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What are three lines of evidence that our climate is changing? Discuss each. Be as explicit and complete in your responses as you can.

1. 2. 3.

The Gulf of Mexico has experienced repeated "dead zones" in recent years. What is a "dead zone", what are their characteristics, and what causes them?

A "dead zone" entails lakes and oceans that have low-oxygen, known to be hypoxic. Dead zones occur because of a process called eutrophication, which happens when a body of water gets too many nutrients, such as phosphorus and nitrogen. Hypoxic water supports fewer organisms and has been linked to massive fish kills in the Black Sea and Gulf of Mexico. Eutrophic events have increased because of the rapid rise in intensive agricultural practices, industrial activities, and population growth. These three processes emit large amounts of nitrogen and phosphorous. These nutrients enter our air, soil, and water. Human activities have emitted nearly twice as much nitrogen and three times as much phosphorus as natural emissions. Most organisms need oxygen to live, few organisms can survive in hypoxic conditions. That is why these areas are called dead zones.

The morphology of continental margins depends on tectonic setting. Describe the morphologies of a passive margin (e.g., the Gulf of Mexico) and an active subduction margin (e.g., Cascadia margin in Oregon and Washington), and explain the reasons for their differences.

A passive continental margin occurs where the transition from land to sea is not associated with a plate boundary. Passive margins, as described above, have wide shelves, gentle slopes, and a well-developed rise. Since passive margins are not plate boundaries, they experience long periods of relative stability. An active continental margin is found on the leading edge of the continent where it is crashing into an oceanic plate. Active margins are commonly the sites of tectonic activity: earthquakes, volcanoes, mountain building, and the formation of new igneous rock. Because of the mountainous terrain, most of the rivers are fairly short, and the continental shelf is narrow to non-existent, dropping off quickly into the depths of the subduction trench. Passive continental margins are found along the remaining coastlines. Because there is no collision or subduction taking place, tectonic activity is minimal and the earth's weathering and erosional processes are winning. This leads to lots of low-relief (flat) land extending both directions from the beach, long river systems, and the accumulation of thick piles of sedimentary debris on the relatively wide continental shelves.

Describe (or sketch) the configurations of (a) a cold front and (b) a warm front? How do they differ? What happens in each case, and what kinds of weather conditions are likely to develop when each one passes?

A warm front occurs on the boundary of a warm air mass moving into a colder region, while a cold front occurs on the boundary of a cold air mass moving into a warmer region. A warm front is typically associated with a high-pressure system, while a cold front is associated with a low-pressure system. Cold fronts are generally associated with heavy precipitation and stormy atmospheric conditions. Extreme weather conditions such as hail and lightning. A warm front takes longer to build up and usually produces more gentle precipitation for more sustained periods. Warm fronts are associated with uniform low-lying stratus clouds, while cold fonts are accompanied by storm clouds with a significant vertical buildup like cumulonimbus clouds.

The modern atmosphere is composed of major gases and greenhouse gases. What are the three most important gases in the atmosphere by mass? What are the top three greenhouse gases? The Earth's atmospheric composition has changed significantly over geologic time, and in particular the level of O2 in the atmosphere has changed. Describe the changes in the Earth's O2 concentration, including when major changes occurred. How did these changes feed back to alter the Earth's greenhouse as well as its ozone layer?

A. Three most important gases in atmosphere by mass: - nitrogen, oxygen, and argon. - (Water vapor accounts for roughly 0.25% of the atmosphere by mass.) B. Three top greenhouse gases? - carbon dioxide, methane, nitrous oxide C. Changes in the Earth's O2 concentration is __.

The main sources of acid rain in the US are which two ions? For each ion, what are its major anthropogenic sources? Discuss three consequences of acid rain on ecosystem and/or human health.

Acid rain results when sulfur dioxide (SO2) and nitrogen oxides (NOx) are emitted into the atmosphere and transported by wind and air currents. The primary anthropogenic source of sulfur dioxide gas is fuel combustion from power generation and industrial processes. The nitrogen oxides are emitted from any combustion process. Coal- and gas-fired power plants and vehicles constitute the major anthropogenic (human-produced) sources. Consequences of acid rain: 1. Acid rain falling directly on trees and crops can harm them. Runoff from acid rain leaches minerals such as aluminum from soil, thereby decreasing its pH and making the soil acidic. Acidic soil is detrimental for the growth of crops and results in damaged harvests. 2. When the acidic runoff flows into lakes, rivers and seas, it disturbs the balance of these aquatic ecosystems and causes injury or even death of aquatic organisms. Imbalance in aquatic ecosystems has an adverse effect on fishing industry. 3. Sulfur dioxide particles in the air can encourage chronic lung problems, like asthma and bronchitis. Nitrogen oxides that create acid rain promote the formation of ground-level ozone. While ozone high above the Earth helps block ultraviolet radiation, ground-level ozone promotes severe lung problems like chronic pneumonia and emphysema.

What is Ekman flow? How is it related to surface winds, and what are some of the consequences of Ekman flow?

As wind blows across the ocean, it moves water because of friction at the ocean surface. Because the Earth rotates, surface water moves to the right of the wind direction in the Northern Hemisphere and to the left of the wind direction in the Southern Hemisphere due to the Coriolis effect. The impact of the Ekman Spiral is enhanced where geographic features create barriers to the movement of water. The speed and direction of the moving water changes with depth. Ocean water at the surface moves at an angle to the wind, and the water under the surface water turns a bit more, and the water below that turns even more. This makes a spiral of moving water 100 to 150 meters deep called an Ekman spiral. The average direction of all this turning water is about a right angle from the wind direction. This average is Ekman transport

What are the two major drivers of ocean circulation, and how and why do they work?

Ocean currents circulate the climate. The two major drivers of ocean circulation are surface currents and deep ocean currents. Surface currents are driven by global wind systems that are fueled by energy from the sun. These currents bring heat from the tropics to the polar regions; the Gulf Stream, for instance, brings warm water along the eastern coast of the US up to Northern Europe. Deep currents, also known as thermohaline circulation, result from differences in water density. These currents occur when cold, dense water at the poles sinks. Surface water flows to replace sinking water. Deep currents are driven by temperature and water density/salinity. Deep ocean currents impact surface ocean currents, which carry warm water to the poles. Surface currents are also driven by global wind systems fueled by energy from the sun. Factors like wind direction and the Coriolis effect play a role.

How and why does ocean water surface salinity vary with latitude, and what controls this variation?

Ocean water surface salinity is the concentration in dissolved salts. Salinity varies with latitude because of the changes in saltwater density and temperature. What controls the variations of ocean water surface salinity are freshwater sources, precipitation of rain and snow, and ice melting. High concentrations are found in the center of the ocean basins away from the mouths of rivers (freshwater). High concentrations are also in sub-tropical regions due to high rates of evaporation (clear skies, little rain) and in landlocked seas in arid regions. At high latitudes, salinity is low. This can be attributed to lower evaporation rates and the melting of ice that dilutes seawater. Salinity is low where precipitation is greater than evaporation, mainly in coastal or equatorial regions.

Briefly summarize the processes by which oil and gas will form in the Earth. What conditions determine which hydrocarbon will form where? Give examples.

Oil and gas, known as fossil fuels, are mixtures of hydrocarbons that formed from the remains of diatoms that lived millions of years ago in a marine environment before the existence of dinosaurs. Over millions of years, the remains of these animals and plants were covered by layers of sand, silt, and rock. Heat and pressure from these layers turned the remains into oil and gas. Crude oil and other hydrocarbons exist in liquid or gaseous form in tiny spaces within sedimentary rocks, and near the earth's surface in tar (or oil) sands. Different geological conditions determine which hydrocarbon will form where.

How do we use paleoclimate records to show that climate models are accurate? Give and explain at least three examples.

Paleoclimatology is the study of past climates. Since it is not possible to go back in time to see what climates were like, scientists use imprints created during past climate, known as proxies, to interpret paleoclimate. Organisms, such as diatoms, forams, and coral serve as useful climate proxies. Other proxies include ice cores, tree rings, and sediment cores - ice cores- analyzed for trapped gas, stable isotope ratios, and pollen trapped within the layers to infer past climate. - tree rings- counted to determine age. The thickness of each ring can be used to infer fluctuations in temperature and precipitation, since optimal conditions for the particular species will result in more growth, and thus thicker rings for a given year. Scars and burn marks can indicate past natural events such as fire. - sediment cores- analyzed in many ways. Sediment laminations, or layers, can indicate sedimentation rate through time. Charcoal trapped in sediments can indicate past fire events. Remains of organisms such as diatoms, foraminifera, microbiota, and pollen within sediment can indicate changes in past climate, since each species has a limited range of habitable conditions. When these organisms and pollen sink to the bottom of a lake or ocean, they can become buried within the sediment. Thus, climate change can be inferred by species composition within the sediment.

What is meant by "renewable energy"? Describe three types of renewable energy, and how they are captured and used.

Renewable energy comes from natural sources or processes that are constantly replenished. Three types of renewable energy include: 1. Solar Energy - Solar or PV cells are made from silicon or other materials that transform sunlight directly into electricity. Solar farms can generate power for thousands of homes, using mirrors to concentrate sunlight across acres of solar cells. 2. Wind Energy - Wind energy turns a turbine's blades, which feeds an electric generator and produces electricity. 3. Hydroelectric Power - the largest renewable energy source for electricity in the US, it relies on water—typically fast-moving water in a large river or rapidly descending water from a high point—and converts the force of that water into electricity by spinning a generator's turbine blades.

Why is the ocean so effective in storing heat? When does the ocean take up heat, and when and where is it released?

The ocean absorbs some of this energy from the sunlight and will store it as heat. The heat is absorbed at the surface, but some goes to deeper waters. Currents also move this heat around the world. Water has a much higher heat capacity than air, meaning the oceans can absorb larger amounts of heat energy with only a slight increase in temperature. The ocean takes up heat when sunlight reaches its surface. It can also take up heat through emissions from clouds, water vapor, and greenhouse gases. Heat absorbed by the ocean is moved from one place to another, but it doesn't disappear. The heat energy eventually re-enters the rest of the Earth system by melting ice shelves, evaporating water, or directly reheating the atmosphere.

Scientists use the ratio of 18O/16O in ice preserved in glaciers to estimate how big glaciers have been in the past. Why do oxygen isotope ratios in glacial water record the past volumes of ice sheets?

The ratio of these two oxygen isotopes has changed over the ages and these changes are a proxy to changing climate that have been used in both ice cores from glaciers and ice caps and cores of deep sea sediments. Many ice cores and sediment cores have been drilled in Greenland, Antarctica and around the world's oceans. These cores are actively studied for information on variations in Earth's climate. Measurement of the isotopic ratio of 18O in ice cores can be directly related to climate. Ice cores from Greenland or Antarctica are often layered, and the layers can be counted to determine age. The heavy oxygen ratio can then be used as a thermometer of ancient climates.

How and where does a "Cyclone" (a.k.a., Typhoon, Hurricane) typically develop? What is a "Cyclone Bomb" and how does it differ from a typical Cyclone?

Tropical cyclones form only over warm ocean waters near the equator. Warm, moist air over the ocean rises upward from near the surface. As this air moves up and away from the ocean surface, it leaves is less air near the surface. As the warm air rises, it causes an area of lower air pressure below. Air from surrounding areas with higher air pressure pushes in to the low pressure area. A "Cyclone Bomb" is when a midlatitude cyclone becomes more intense very quickly, usually over a 24-hour period. This intensity builds due to rapidly dropping atmospheric pressure. The drop in pressure can cause cold and warm air to collide, for example when a mass of strong, cold wind collides with the air over warm ocean water. A midlatitude bomb cyclone can cause many weather events, such as storms and heavy rain. Bomb cyclones can play out like a normal storm, and don't result in the strong winds of a hurricane. A tropical cyclone, on the other hand, which is also known as a hurricane, mainly produces heavy winds.

Describe the typical differences between western boundary currents and eastern boundary currents that define ocean gyres, and the reasons for these differences.

Typical differences between the western boundary currents and the eastern boundary currents are the intensity and volume. The same volume of water must pass through both the east and west sides of the gyre. In the western gyre currents, that volume is passing through a narrower area, so the current must travel faster in order to transport the same amount of water in the same amount of time. On the eastern side of the gyre the current is much wider, so the flow is slower. Western boundary currents are faster and deeper than eastern boundary currents, as they move the same volume through a narrower space. The currents making up the western side of the gyre are much more intense than the currents on the eastern side, known as western intensification.

Give two examples of "unconventional hydrocarbons", and where and how they are being exploited today. What environmental issues are associated with their production?

Unconventional hydrocarbons are sources of oil and gas which require methods for extraction which are not normally necessary in the conventional extraction of hydrocarbons. Examples include Coal bed Methane and shale gas/oil. They are being exploited today in India and other countries where there are coal reserves or where there are large shale deposits. These "unconventional hydrocarbons" are exploited through fracking and drilling wells. Shale gas exploitation issues: The massive amount of water used in the fracking process has led to water shortages in some drilling areas, extensive deforestation and flooding of the nearby area, groundwater contamination from carcinogenic chemicals. Coal Bed Methane exploitation issues: There is a possibility of damage of gas wells resulting in explosive atmosphere in coal mines during simultaneous extraction of coal and CBM.

Plate tectonics, orbital parameters, and human behavior have each changed climate over the course of the Earth's history. a. Give an example of how plate tectonics have impacted climate, providing explanation of the mechanisms involved. b. Give an example of how orbital parameters have impacted climate, providing an explanation of the mechanisms involved. c. Give an example of how human behavior has impacted climate, providing an explanation of the mechanisms involved.

a. b. c.