GEL 10 Final Study Guide Quiz Questions PDF

Quiz Questions: What is the present concentration of CO2 in our atmosphere? 280 parts per thousand 360 parts per million 417 parts per thousand 423 parts per million 560 parts per million There is widespread agreement that to minimize the amount of catastrophic damage due to climate change t...

Quiz Questions: What is the present concentration of CO2 in our atmosphere? 280 parts per thousand 360 parts per million 417 parts per thousand 423 parts per million 560 parts per million There is widespread agreement that to minimize the amount of catastrophic damage due to climate change the total amount of warming of the Earth's surface since the onset of the Industrial Revolution must be kept to ≤1.5°C. Given current trends in fossil fuels burning and energy policies of industrialized countries, what is the more likely amount of total global warming that will occur in this century? between 1.5 and 2.0°C between 2.0 and 3.0°C between 3.0 and 4.0°C 4°C or higher as we are on the 'business as usual' emissions track This is a trick question --- we are in fact, on track to remain at or below 1.5°C of total warming as most countries are committed to reaching net zero Carbon emissions (Carbon neutrality) by 2045-2050. Which one of the following statements best describes how the present-day concentration of CO2 in the atmosphere compares to the past --- before the accelerated use of fossil-fuels? The CO2 concentration in today's atmosphere has stayed near constant over the time since humans evolved. The CO2 concentration in today's atmosphere is higher than the past few 100s of thousands of years but it is rising so slowly that it is negligibly impacting humans and other life on Earth. The CO2 concentration in today's atmosphere is higher than that of any time in the past 14 million years ago. The CO2 concentration in today's atmosphere has started to decline since the Paris Agreement was made in 2015 reflecting that industrial countries have successfully initiated efforts to develop and use more green energy. We don't know because it is not possible to reconstruct how atmospheric CO2 has varied in the very distant past. Extreme precipitation events have been increasing in both frequency and intensity over the past 3 decades. Which one of the following is not a reason why this is happening? A warmer atmosphere holds more moisture (water) and more energy. Deforestation and urban heat created by the loss of grasslands and trees is permitting the moisture in soils/land surface to be evaporated and accumulate as water in the atmosphere leading to more extreme precipitation. Water cycling through the atmosphere intensifies as the atmosphere warms. Atmospheric circulation patterns are shifted by global warming. The Earth's surface has warmed on average by 1.2°C since the onset of the Industrial Revolution. Which one of the following conditions has maintained the warming at this level and prevented a higher level of warming? That is, given the amount of CO2 that has been added to the atmosphere since the 1860s, higher temperatures would be expected. The land has absorbed half of the excess heat created by increasing CO2 concentrations in the atmosphere. Clouds have reflected back to space over half of the excess heat created by increasing CO2 concentrations in the atmosphere. GEL 10 Final Study Guide Fall Qtr 2024 7 Ice sheets and glaciers in the polar regions have absorbed much of the excess heat created by increasing CO2 concentrations in the atmosphere, but at the cost of melting ice and sea-level rise. The oceans have absorbed \~90% of the excess heat created by increasing CO2 concentrations in the atmosphere. Which one of the following best explains why climate change that is happening now appears to be unprecedented in Earth history when compared to past times of major climate change? Humans now dominate the Earth, whereas humans were not present during past times of climate change. There were many fewer (100s of 1000s and not billions) humans on Earth during past times of climate change so the impact was less. This statement is not true. Past periods of climate change that we will learn about in GEL 10 were far more extreme than what is happening presently thus modern climate change is not unprecedented. Modern climate change is unprecedented because the rate of change in environmental conditions is faster than ever previously experienced on Earth. Climate change has played a major role in the 5-fold increase in wildfire activity in CA and the western US over the past few decades. Which one of the following behaviors is not contributing to this increase in wildfire activity? More months of the year are warmer than normal as compared to several decades ago. Warmer temperatures are leading to greater evaporation of soil moisture, leading to dry soils and vegetation. Extreme rainfall events that are happening earlier in the fall than a few decades ago are encouraging the increased growth of vegetation that creates lots of additional fuel for fires. Record-breaking heat waves in the summers create lots of dry lightning (but often with little to no rain) Increasingly stronger winds during the warm months due to a warmer atmosphere allow fires to grow rapidly Energy and matter are constantly flowing through the different reservoirs of the Earth system. What do we call the atmosphere if more CO2, which is generated by fossil-fuel burning, flows into the atmosphere (and is stored) than flows out (into the ocean or into the biosphere for photosynthesis)? Pick the best answer. a source a sink a flux a feedback polluted Which one of the Earth system components has absorbed the most heat energy created by fossil-fuel burning and land-use changes over the past 100 years? the oceans (part of the hydrosphere) GEL 10 Final Study Guide Fall Qtr 2024 8 the land surface (soils and rocks; part of the geosphere). the atmosphere the biosphere the anthroposphere Are the greenhouse effect and global warming interchangeable terms? Which one of the following statements correctly speaks to this issue? The greenhouse effect and global warming are interchangeable terms. The natural greenhouse effect is primarily controlled by the amount of water vapor in the atmosphere (the primary greenhouse gas), which varies seasonally with changing temperature of the atmosphere, whereas global warming (enhanced greenhouse effect) is a consequence of fossil-fuel burning that is adding more CO2 to the atmosphere. The natural greenhouse effect provides 10°C of additional warming to Earth relative to if it didn't have an atmosphere with greenhouse gases, whereas global warming is a consequence of fossil-fuel burning that is creating an enhanced greenhouse effect. The natural greenhouse effect provides 33°C of additional warming to Earth relative to if it didn't have an atmosphere with greenhouse gases, whereas global warming is a consequence of fossil-fuel burning that is creating an enhanced greenhouse effect. Which one of the following sets of actions will lead to a negative feedback loop? Note, the actions listed below do not complete the feedback loop; you need to do that to answer the question. Set 1: Arctic air temperatures cool, ice expands, and the air above it cools. Set 2: Arctic air temperatures warm, ice melts, and deep dark ocean is exposed. Set 3: Air temperatures warm leading to increased evaporation of soil moisture and dying of vegetation. Drier soils and dry, dead vegetation promote the faster spread of fires, which in turn releases Carbon into the atmosphere. Set 4: Air temperatures warm, white ice and flowers, which cover most land on Earth, melt or wilt and die and expose dark brown soil. Set 5: Air temperatures warm, the number of photosynthesizing algae (coccoliths) in the ocean increases. These algae give off a sulfur-rich gas (di-methyl sulfide) that causes formation of sulfate aerosols in the atmosphere, which in turn act to nucleate low-lying clouds. And what is the effect of this negative feedback on the Earth's climate? It amplifies the original change. It stabilizes the system by returning conditions back towards where they started. It will lead to a climate threshold. It will lead to a tipping point. You work for an environmental advocacy group (thank you) and you have traveled to the Arctic with a White House representative to negotiate buying Greenland (yes, a previous administration did propose to GEL 10 Final Study Guide Fall Qtr 2024 9 do so). You board a private jet on Ellesmere Island, Canadian Arctic (83° North latitude and 77° West longitude) that will take you back to Washington D.C. (39° North latitude and 77°West longitude). This trip of 4600 km --- due south --- will take \~7 hours. As the plane descends, the pilot announces that he seems to have miscalculated the landing target (Washington, D.C.) by several 1000s of kilometers. This is because the flight path of the plane has been deflected in which one of the following directions? there is no actual deflection --- the plane got picked up by the Jet Stream and was taken off target. deflected to the east (left) --- you're gonna swim! deflected to the west (right) --- welcome to Missouri deflected southward by magnetic winds --- you're headed to Disney World, Florida The tropics is where atmospheric circulation is initiated. Which one of the following statements best describes why? Deflection of air masses by the Coriolis effect --- critical to initiating atmospheric circulation --- is maximized in the tropics given the Earth's maximum circumference in that region. The albedo in the tropics is higher than anywhere else on Earth because there is more ocean surface exposed to the atmosphere in that region than elsewhere and thus the air above the tropics is heated and rises vertically. The hottest point on Earth is the geographic equator (0°) causing warm air to rise precisely at that latitude. The intensity of Sun's heat energy delivered to Earth is greatest in the tropics (i.e., the ITCZ) leading to warming of the oceans, evaporation, and vertical rising of moisture-rich warm air masses. The Jet Stream is strongest in this region and can pull the air upwards to initiate atmospheric circulation. Which one of the following is the 'pump' (fuel) that keeps the flow of air moving through the atmospheric circulation cells and is an effective way to move water and heat energy from one area to another? the Coriolis effect density differences in the atmosphere's layers latent heat of evaporation & condensation thermohaline circulation the pull of the Earth's magnetic field, which is highest at the poles. The Jet Stream delivers winter storms brought from the northern Pacific Ocean to California, Oregon and Washington. Which one of the following correctly describes the Jet Stream? The warming arm of air in the subtropical high-pressure regions that picks up moisture as it descends. A local name in the Pacific Northwest for the westerly winds that bring winter storms to the west coast of the U.S. A river of fast-moving, wet air \~10 km high in the atmosphere that comes from the tropical Pacific when the ocean is warmer than usual. GEL 10 Final Study Guide Fall Qtr 2024 10 A low-pressure region centered over the tropical Pacific that permits moisture-laden air to flow like a river over the mid-latitudes (30 to 60°). A river of fast-moving air \~10 km high in the atmosphere that flows between the high- and low-pressure regions in the mid-latitudes. Which one of the following is causing the Jet Stream to weaken and develop 'kinks' that leads to extended heat waves or freezes? The loss of sea ice in the Arctic due to 4 times more rapid warming in the region than elsewhere on the planet is pushing the Jet Stream southward where there is less heat energy to 'energize' the air flow. The 4 times more rapid warming in the Arctic region than elsewhere on the planet is lessening the difference in temperatures between the Arctic and the tropics, causing the Jet Stream to weaken. The warming atmosphere is becoming thicker which makes it harder for air currents such as the Jet Stream to flow. The Coriolis influence on large-scale atmospheric winds, such as the Jet Stream, is weakening due to global warming, leading to the slowing of the winds. The loss of continental ice such as the Greenland Ice Sheet in the polar region is exposing warm ocean water that is evaporating and putting excess moisture in the atmosphere, making it more dense and slowing down the Jet Stream. Which of one of the following statements explains why O2 and N2, which make up 99% of the atmosphere, do not absorb Earth's heat energy, whereas gases such as CO2 and CH2, which are present in small quantities in Earth's atmosphere, are strong greenhouse gases? The bonds between atoms in dipolar molecules (greenhouse gases) can bend and stretch to accommodate the absorption of infrared radiation; diatomic molecules (charge balanced) cannot do this so heat energy passes right through them. O2 and N2 (diatomic molecules) have much stronger molecular bonds than do greenhouse gases preventing them from being able to absorb heat energy. Diatomic molecules lose their ability to absorb heat energy as the atmosphere warms, whereas CO2 and CH4 (dipolar molecules) do not. Gas molecules that are made up of atoms with balanced charges, such as O2 and N2, have longer life spans in the atmosphere, whereas greenhouse gas molecules are short-lived but powerful because they are strongly 'charged' (dipolar) molecules. Because diatomic molecules, such as O2 and N2, can only absorb the longest wavelength electromagnetic radiation which doesn't create much heat, whereas dipolar molecules can absorb the shorter wavelengths that are higher intensity and generate more heat energy. Some parts of the surface ocean are 'marine deserts' and others are teeming with photosynthesizing life (primary producers). Of the following places in the ocean, where are marine deserts found? in the Arctic region where ocean water descends deep & connects to the lower limb of the oceanic conveyer belt along the upwelling zones at the equator GEL 10 Final Study Guide Fall Qtr 2024 11 in the middle of gyres in the Intertropical Convergence Zone in the Southern Ocean around Antarctica Which one of the following reasons best explains why these regions are marine deserts? These regions are positioned under the atmospheric subtropical highs, thus there are minimal winds, there are no strong surface currents, and the surface water is evaporatively enriched. These regions are positioned under the atmospheric subtropical highs, thus there are very strong winds, very rapid surface currents, and the surface water is too rough to sustain life. These regions are positioned in the tropical Intertropical Convergence Zone, thus there are no winds, there are no strong surface currents, and the surface ocean water is too warm to support much life. The very strong oceanic upwelling in these regions bring up very cold water that is CO2-rich and thus acidic. These conditions are not suitable for life. Very high nutrient levels in these regions cause 'dead zones' where only toxic algal blooms thrive. The present-day decrease in formation of melting of the Greenland Ice Sheet and the loss of Arctic sea ice are major concerns given the impact on the climate system. Which one of the following statements best describes this impact? Melting of the Greenland ice sheet and less sea-ice formation will decrease the heat deficit in the polar regions and weaken the latitudinal temperature gradients, which in turn directly affect the rates of deep- water formation and circulation of the oceanic conveyer belt. Melting of the Greenland ice sheet and less sea-ice formation will increase the Earth's albedo in the polar region, which will lead to increased warming of the ocean and the overlying atmosphere. Melting of the Greenland ice sheet and less sea-ice formation will lead to a major shift in circulation patterns of the ocean gyres, which in turn decreases the ability of the surface ocean to redistribute heat. Melting of the Greenland ice sheet and less sea-ice formation will decrease the ability of the polar atmospheric circulation cell to efficiently transfer heat energy to lower latitudes. Melting of the Greenland ice sheet and less sea-ice formation will decrease the surface ocean salinity in the polar region making it less dense, decrease the rate of deep-water formation and lead to a slowing of the oceanic conveyer belt. The El Niño-Southern Oscillation (ENSO) has been disrupting climate in the western Americas for over 4 million years. Which one of the following statements best summarizes what is the ENSO system? An oceanic system in the tropical/subtropical Pacific that leads to short-term variability in weather patterns over the western Americas. An atmospheric system in the tropical/subtropical Pacific that leads to short-term variability in weather patterns over the western Americas. GEL 10 Final Study Guide Fall Qtr 2024 12 A linked oceanic-atmospheric system in the tropical/subtropical Pacific that creates drought conditions in the western Americas during El Niño events and wet conditions during La Niña events. A linked oceanic-atmospheric system in the tropical/subtropical Pacific that creates wet conditions in the western Americas during El Niño events and drought conditions during La Niña events. A linked oceanic-atmospheric system in the Pacific that influences the frequency and intensity of monsoonal climate over the western Americas. The transfer (cycling) of carbon through the different reservoirs of the Earth system influences surface conditions and is necessary for life. Which one of the following statements best explains why C cycling is so critical? C cycling through the Earth System reservoirs regulates the CO2 and CH4 contents in the atmosphere. C cycling through the Earth System reservoirs regulates the CO2 and O2 contents in the atmosphere. C cycling through the Earth System reservoirs is the primary control on the distribution of Earth's surface temperatures around the globe. C cycling through the Earth System reservoirs promotes biologic pumping in the ocean and on land, which is the main process regulating atmospheric CO2 levels. C cycling through the Earth System reservoirs is not balanced under natural conditions, thus permitting sufficiently high CO2 and O2 levels in the atmosphere to create a natural greenhouse effect --- necessary for life. Which one of the following is direct evidence that the Earth's carbon cycle is currently out of balance and that the atmosphere is acting more like a sink for CO2 than a source? The amount of Earth's electromagnetic radiation being sent to space through the atmosphere is less than the amount of Sun's radiation entering the atmosphere. The troposphere has been warming since the 1950s while the stratosphere has been cooling --- one argument against climate change being real. The Earth's surface temperature has increased by 1.2°C over the past century. CO2 levels in the atmosphere have increased by 35% over the past 70+ years and continue to rise by \~ 2 ppm/yr. The ozone content in the atmosphere has doubled over the past century. Rapid climate changes of the past teach us that certain natural processes in the Earth's climate system are capable of restoring atmospheric CO2 to 'background low levels' regardless of the magnitude of the climate change. Which one of the following processes is the uber-restorer of atmospheric CO2 levels --- that is, it is the only process that can completely return the Earth's CO2 to 'healthy' levels and stabilize its climate if given enough time? neutralization of atmospheric CO2 by the ocean's natural alka seltzer (the carbonate molecule CO32-) biologic pumping in the oceans and photosynthesis on land by trees and other vegetation GEL 10 Final Study Guide Fall Qtr 2024 13 the long-term cycle of weathering of silicate minerals exposed on land and formation of new carbonate minerals as shells in the ocean an increase in the rate of circulation of the oceanic conveyor belt, created by the initial climate change, leads to more organic carbon (thus CO2) burial in the ocean the migration of the continents (plate tectonics) changes atmospheric and oceanic circulation patterns leading to more sequestration of CO2 in the ocean and on land, thus cooling the climate The Earth has two main climate states --- which one of the following has been the far more common climate state throughout Earth history? Greenhouses Icehouses Glacials Interglacials Transient climates such as today Most of the world's oil formed during a greenhouse period 200 million years ago --- the time of the dinosaurs & giant reptiles. The oil- & gas stored in deeply buried rocks or pumped out are the geologic expression of which environmental condition that developed during this time of global warming? Very slow ocean circulation due to warming that led to little CO2 being brought to the deep ocean by the oceanic conveyor belt and thus the dead organic matter that sank to the seafloor could be preserved and buried to create oil and natural gas. Much loss of life in the ocean due to extensive ocean acidification and enhanced burial of the dead organic matter that turned into oil and natural gas. Rapidly rising sea level due to collapse of all ice sheets at this time of major global warming that led to burial of organic matter in coastal regions that were previously exposed to the atmosphere. Ocean anoxia (loss of oxygen) in the deep ocean due to an overall warmer ocean that led to much less decay of organic matter on the seafloor, and thus the organic matter could be preserved and buried into rocks. The ocean circulation was very different than today because the continents were combined as one supercontinent, thus permitting the preservation and burial of most dead organic matter in the deep ocean which was warmer and oxygen-poor in comparison to today. The PETM is our closest, but still imperfect, analogue for better understanding modern climate change. Which one of the following is the most important lesson learned from studying this past event in terms of better understanding modern climate change? It defines precisely what are the thresholds in the climate system that will control the level of CO2 concentrations in our atmosphere in the future and whether or when we will cross climate thresholds. That there are natural processes in the Earth System that can cause oceans to lose oxygen (anoxia) due to global warming and that our biggest threat in the future is not warming but rather is oceanic anoxia as most of the world's food comes from the oceans.GEL 10 Final Study Guide Fall Qtr 2024 13 the long-term cycle of weathering of silicate minerals exposed on land and formation of new carbonate minerals as shells in the ocean an increase in the rate of circulation of the oceanic conveyor belt, created by the initial climate change, leads to more organic carbon (thus CO2) burial in the ocean the migration of the continents (plate tectonics) changes atmospheric and oceanic circulation patterns leading to more sequestration of CO2 in the ocean and on land, thus cooling the climate The Earth has two main climate states --- which one of the following has been the far more common climate state throughout Earth history? Greenhouses Icehouses Glacials Interglacials Transient climates such as today Most of the world's oil formed during a greenhouse period 200 million years ago --- the time of the dinosaurs & giant reptiles. The oil- & gas stored in deeply buried rocks or pumped out are the geologic expression of which environmental condition that developed during this time of global warming? Very slow ocean circulation due to warming that led to little CO2 being brought to the deep ocean by the oceanic conveyor belt and thus the dead organic matter that sank to the seafloor could be preserved and buried to create oil and natural gas. Much loss of life in the ocean due to extensive ocean acidification and enhanced burial of the dead organic matter that turned into oil and natural gas. Rapidly rising sea level due to collapse of all ice sheets at this time of major global warming that led to burial of organic matter in coastal regions that were previously exposed to the atmosphere. Ocean anoxia (loss of oxygen) in the deep ocean due to an overall warmer ocean that led to much less decay of organic matter on the seafloor, and thus the organic matter could be preserved and buried into rocks. The ocean circulation was very different than today because the continents were combined as one supercontinent, thus permitting the preservation and burial of most dead organic matter in the deep ocean which was warmer and oxygen-poor in comparison to today. The PETM is our closest, but still imperfect, analogue for better understanding modern climate change. Which one of the following is the most important lesson learned from studying this past event in terms of better understanding modern climate change? It defines precisely what are the thresholds in the climate system that will control the level of CO2 concentrations in our atmosphere in the future and whether or when we will cross climate thresholds. That there are natural processes in the Earth System that can cause oceans to lose oxygen (anoxia) due to global warming and that our biggest threat in the future is not warming but rather is oceanic anoxia as most of the world's food comes from the oceans. GEL 10 Final Study Guide Fall Qtr 2024 14 That the Earth has experienced many past periods of natural release of greenhouse gases --- on the same time-scale as anthropogenic greenhouse gas emissions --- and the Earth has recovered from climate change, each time, through natural processes that are operating today. So it is likely that these processes will resolve present-day climate change within the next few decades. That the rate of C emissions to the atmosphere today is minimally an order of magnitude faster than any naturally driven climate change event in Earth's history. That rapid climate changes can lead to evolutionary innovation, which could be a welcome consequence of modern climate change. Today methane (CH4) ice clathrates are common in deep-water (100s of meters deep) sediments along most continental margins of Earth's continents. Which one of the following statements best describes why methane (CH4) clathrates are of scientific relevance to humans today? They are considered a safely mineable and cheap form of new natural gas (a fuel). Communities of unusual forms of marine life live around the vents on the sea floor where the ice clathrates form. Study of past climate change tells us they can melt if the deep ocean warms by a few degrees leading to anoxia (oxygen depletion) in the ocean as the CH4 oxidizes (a positive feedback). Study of past climate change tells us they can melt if the deep ocean warms by a few degrees leading to underwater landslides along the continental edges. Study of past climate change tells us they can melt if the deep ocean warms by a few degrees leading to intensified greenhouse-gas warming in the atmosphere (a positive feedback). Different reservoirs in the Earth System are capable of naturally sequestering a lot of CO2, but sometimes at an environmental cost. Which one of the following choices best indicates what natural method(s) on land or in the sea is/are currently being used to effectively alleviate these environmental costs while increasing CO2 sequestration? Adding ground minerals/rock to the Earth's oceans, rivers, and agricultural (working) lands to enhance silicate weathering that converts CO2 to inorganic carbon that is then buried. Adding organic matter to the Earth's oceans, rivers, and agricultural (working) lands to 'fertilize' primary producers and increase biological pumping, thus sequestering more CO2 in buried organic carbon. Adding ground minerals/rock to the Earth's oceans and rivers to increase alkalinity (decrease acidity and increase its ability to absorb CO2), and to agricultural (working) lands to enhance silicate weathering and provide nutrients to crops. Planting more trees in deforested areas, and urban and working lands to increase the storage of CO2 through more photosynthesis while minimizing land erosion. Capturing CO2 from the atmosphere or power plants and refineries, liquifying it, and then pumping it into the ocean and/or soils of working lands. The liquid CO2 promotes additional photosynthesis by primary producers (including crops), thus locking up more CO2 in organic matter while producing more food for the growing human population. GEL 10 Final Study Guide Fall Qtr 2024 15 Which one of the following lessons, relevant to our future climate, is demonstrated by the ice core records of the past 1 million years? Earth's surface temperature is overall higher now than it has been for the past 1 million years (minimally). Although atmospheric CO2 has been as high as today during the warmest of the past interglacials, the combination of high CO2, CH4 & NO2 concentrations that we measure in the atmosphere today is unprecedented over the past million years. Unlike today, periods of past warmings --- interglacials --- during the last million years were created primarily by the release of methane (CH4) from melting ocean clathrates. Increases in atmospheric CO2 levels in the past were not always linked to increases in surface temperature. Changes in CO2 concentrations and Earth surface temperatures were strongly linked over the past million years despite major changes in both over the past million years. The development of urban centers and society-states around the world over the past 6,000 years is not coincidental but rather reflects which one of the following? the gradual warming of the past 6000 years the overall climate stability of the past 6000 years the stability of coastlines 6000 years ago once ice-melting ended and the rate of sea-level rise slowed considerably the establishment of agriculture & domestication of animals \~6000 years ago the overall wetter conditions and more moderate temperatures of the past 6000 years relative to the 10s of 1000s of years before. The primary impact of climate change on Californians is/will be the availability of water. Which one of the following issues does not contribute to making this the case? California has a semi-arid (desert) climate with highly seasonal rainfall Water flows uphill to money in CA --- that is, water from different sources both internal and external to the State is transferred up and over mountains and around the state by 100s of miles of aquaducts, pipes and pumps. With warming there is more drought and thus less water, but still being shared by the same number of people. Water flows downhill to money in CA --- that is, water primarily comes from snowmelt in the high mountains, flows downhill to the valley rivers and delta, then is transferred around the state by 100s of miles of aquaducts, pipes and canals. With warming there is less snow and thus less water, but still being shared by the same number of people. Two-thirds of CA's water is used for agriculture. Rain falls in CA primarily where the population density is lowest, thus it is needed most where water is less plentiful (much less rain and snow). Which one of the following climate solutions is being used for addressing water shortages in regions like CA and anticipated with continued global warming? GEL 10 Final Study Guide Fall Qtr 2024 16 Manipulating clouds by seeding the atmosphere with tiny droplets of seawater that promotes the formation of more and brighter clouds, which in turn rainout more leading to more frequent rains. Recharging groundwater aquifers by directing flood waters into engineered bypasses and new aqueduct systems so that the water can be directed to urban regions and areas where agricultural water needs are greatest. Recharging groundwater aquifers by directing flood waters into farm fields, ranchlands, eco-conservation lands, etc. Injecting sulfur dust into the atmosphere to artificially increase the abundance of low-lying clouds that produce more rain than clouds higher in the atmosphere. Building high-efficiency dams on most major rivers that provide water to regions of anticipated water shortages. This will provide more reservoirs for storing the rain that comes from extreme precipitation events (preventing flooding) as well as the snow that melts earlier in the year than previously due to warming. Which of the following times is the current best estimate of when the world will reach peak global carbon emissions (not net zero emissions) to the atmosphere given off primarily by burning fossil-fuels? We have already reached peak emissions (\~2020) By 2030 Between 2030 and 2050 By 2075 It is unlikely that we will reach peak emissions in this century because the world relies too heavily on fossil fuels (coal, oil, gas) for electricity and transportation. Why is it so important to stay at ≤ 2°C of total warming since the onset of the Pre-Industrial era? Above 2°C of total warming, new positive feedbacks will activate leading to accelerated and worsening impacts of climate change. Life in marine ecosystems of the oceans cannot reproduce at 2°C or higher of warming, thus we would lose a critical food source. Paleoclimate studies of past warmings have documented with no uncertainty that methane clathrates (ice) in the deeper ocean will fully melt at 2°C or higher of warming. 2°C of total warming is the threshold for permanent loss of the Antarctic Ice Sheet. Humans cannot tolerate temperatures that are 2°C or higher over those under which they evolved. Successfully reaching peak fossil-fuel emissions (and limiting them afterwards) in the next couple of decades requires a rapid transition to alternative 'green' energies. But that will not be enough to reach net zero carbon emissions (carbon neutrality) and reduce the atmospheric CO2 content to the level of our climate mitigation goal. Which one of the following statements indicates why this is so? It is necessary to remove the methane in the atmosphere that comes from agricultural lands (farms and ranches) as it quickly becomes CO2 adding to the total CO2 levels in the atmosphere. GEL 10 Final Study Guide Fall Qtr 2024 17 It is necessary to remove the methane (CH4) emissions to the atmosphere that are anticipated in our future due to melting of methane ice (clathrates) that will occur with continued warming of the oceans. It is necessary to remove the methane (CH4) from the atmosphere that has built up over the past 100+ years due to fossil-fuel burning. It is necessary to remove the remaining legacy CO2 (15% of all CO2 in the atmosphere) that has built up over the past 100+ years. It is necessary to remove the remaining legacy CO2 (50% of all CO2 in the atmosphere) that has built up over the past 100+ years. We discussed several negative emission technologies over the past couple of weeks. Which one of the following is not a negative emission technology? Brightening of clouds over the oceans so that they reflect more of the Sun's heat energy Expanding coastal wetlands & managing their carbon Capturing CO2 directly from the air and liquifying it to inject it into the ground for storage & carbonate mineral formation Afforestation, reforestation, and regenerative agriculture practices, including soil amendments Boosting photosynthesis in the ocean by adding nutrients to seawater Removal of CO2 from the atmosphere through planting of new trees in existing forests (reforestation) and creating new forests (afforestation) is one approach we discussed for carbon removal and sequestration. Which one of the following statements best explains the potential of this negative emissions technology? This is not considered a viable approach given that trees die and decay soon after and thus the sequestration of the carbon is not long-lived (decades at most). This is considered an excellent approach as it is non-invasive, relatively inexpensive, and is capable of sequestering \~ 50% of all the CO2 in the atmosphere. This is a viable approach, but it is unlikely to sequester more than 10---20% of the CO2 needed to reach the climate mitigation goal. This is a viable approach as there is unlimited land on which to build forests and given the power of photosynthesis, this could be a major player in removing CO2 from the atmosphere. This is a viable approach because not only do trees sequester a lot of CO2 from the atmosphere through photosynthesis but they also create aerosols that help to nucleate clouds that in turn reflect more of the Sun's heat energy back to space, cooling us in the process. Direct air capture (DAC) of CO2 by machines is both a promising and contentious technology for climate mitigation. Which one of the following is not a reason that this technology is highly debated. Some believe that promoting this technology will distract us from shifting away from burning fossil fuels to onboarding alternative energy sources. There are local to possibly regional environmental and environmental justice impacts that must be considered. GEL 10 Final Study Guide Fall Qtr 2024 18 The cost per ton of CO2 removal by DAC is inexpensive but it requires a lot of land thus outweighing its moderate potential for removing CO2 from the atmosphere The potential for DAC to remove CO2 from the atmosphere is very high, but it requires a lot of land. DAC is a very energy intensive approach that typically requires the use of fossil fuels as energy leading to a high carbon footprint. Which one of the following fuel types, burned by humans for energy, puts out the most CO2 per kilowatt of energy and thus is the least fuel-efficient and biggest contributor to atmospheric CO2 concentrations? coal natural gas liquid petroleum propane biomass (wood) burning Enhanced mineral (rock) weathering is being used in multiple ways to sequester carbon from the atmosphere through silicate weathering and carbonate mineral formation, but at rates relevant to combatting climate change. Which one of the following is not an approach to sequestering carbon through enhanced mineral weathering? Injection of industrial CO2 that was created and captured at fossil-fuel powered electricity plants into the underground reservoirs from which the fossil fuels originally came. Application of ground rock as nutrients to open-ocean waters to fertilize photosynthesis and thus sequester carbon in the biomass. Enhancing the weathering of minerals in mine tailings by adding water and CO2. Direct air capture and geologic sequestration of the extracted and liquified CO2. Application of ground minerals as soil amendments in agricultural lands to sequester carbon.