geol 300i final

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  1. 1. Biosphere
    • a. What are some key aspects of the biosphere in the Earth System?
    • Moderates climate (changing albedo, how the surface interacts with the atmosphere), biogeochemical cycles (carbon, water and nitrogen), weathering, and consciousness.
  2. b. Gaia hypothesis
    • 1) Life has altered the environment at a global scale throughout life history on Earth and continues to do so.
    • 2) Life tends to stabilize the environment by reducing the variability of the physical and chemical aspects
    • 3) These alterations benefit life because they increase the probability of the persistence of life.
    • • coherent system of life, self regulating, self changing, a sort of immense organism.
  3. c. Three possible Origins of life
    • 1) Primordial Soup- products of chemosynthesis from inorganic compounds collected as organic molecules in the surface waters on early Earth. Miller- Urey experiments (methane ammonia and hydrogen)
    • 2) black smoker- organic molecules formed around hot springs and hydrothermal vents in the ocean, reaction occurred similar to metabolism led to organic molecule formation.
    • 3) Panspermia- organic molecules are synthesized outside or earth and carried to earth (Earth isn’t a closed system) Carbonaceous chrondrites carry a variety of organic molecules (these may have been the starting molecules of life) Potentially extends the origins of life to before the formation of the solar system.
  4. d. What type of life was first?
    Organic compounds concentrate and clump, more complex structures form as amino acids are heated and proteins from. Eventually structures enclose. Life began on Earth 3.5 Billion years ago, simple life forms (prokaryotes = no nucleus) were only life forms on Earth for 2 billion years.
  5. e. Half the Earth history to go from molecules to bacteria; 12% of Earth history to go from sea-creatures to humans
    1.4 billion years ago eukaryotes (with nucleus) developed and eventually began aerobic respiration (more efficient) larger membrane bound organelles started to from three-dimensional structures.
  6. f. Cambrian radiation 542 million years ago
    Rapid diversification of life in the sea was due to sexual reproduction, oxygen, development of skeletons and stratospheric ozone. 500 million years ago life left oceans to develop on land because they now had structural support, ability to transfer water within the organism to keep from dehydrating, ability to exchange gases with air instead of water, moist environment for reproductive system.
  7. g. Mass extinctions – no details
    99% of earths species have come and gone. Losses are balanced by speciation (change number of species = speciation – extinction. 5 times in the past 540 million years extinct. Impacts, volcanism, sea level changes, marine anoxia, climate change, food webs (Ordovician, Devonian, Permian, Triassic, Cretaceous)
  8. 2. Leaf Physiology: Water movement from the soil to plant to atmosphere
  9. a. Water moves from the soil to the plant to the leaves to the atmosphere driven by a gradient in water potential
    • Cohesion- pulls water up the plant through the roots and through the leaf. Two types of water transport: molecular diffusion- molecules more due to thermal motions , net movement causes mol to move from high to low concentrations, slow over long distances.
    • Bulk flow movement of mol together driven by a pressure gradient.
  10. b. Soil texture: what types of soil will hold more water? Why?
    Percentage of sand, silt and clay. Sand and clay have high porosity but clay has low permeability – I think this is correct - Fine textured soils hold more water.

    • c. What is water potential?
    • Total energy state of soil water- pure water under no pressure are the soil surface = 0 Pa
    • Potential energy/ volume = J/m^3= Pa
  11. c. What is water potential?
    Total energy state of soil water- pure water under no pressure are the soil surface = 0 Pa Potential energy/ volume = J/m^3= Pa
  12. d. What drives water movement?
    • Water moves along a potential gradient from high to low. J= L( delta Psi/ length)
    • J= rate of water flow, L= hydraulic conductivity ( 1/resistance), delta psi/ length = water potential gradient
    • Hydraulic conductivity depends on the soil properties like texture and the size of the aggregates L declines in dry soils.
  13. e. What is conductance?
    • Pulling water through the plants cohesion vs adhesion
    • I’m not sure which one he needs but hydraulic conductivity was mentioned (the ease at which water moves through the plants or through soil) and also stomatal conductance (rate at which CO2 enters the leaf and water exits) more in next question.
  14. f. Stomata? Why do we care about stomata? What might cause low stomatal conductance? Physical and biochemical processes co-limit carbon fixation
    Stomata control water loss from the leaf cuticle. Plants can adjust stomata to reduce stomatal conductance when the air is dry, during drought, poor/low light, and based on internal CO2 concentrations
  15. g. Where does a plant get CO2 from? How does CO2 enter a plant leaf?
    CO2 enters through the stomata.
  16. h. Compare the Exchange of H2O with CO2 through stomata
    500 molecules of water for 1 molecule of CO2, difference in concentration gradients, bigger co2 diffuses more slowly than water and co2 must get to the chloroplasts (not xylem)
  17. i. Controls on photosynthetic rates
    • rate is limited by physical properties, mediated by enzymes and the regeneration of intermediary molecules – often limited at RuBP step,
    • Environmental control- plats adjust components of photosynthesis, physical and biochemical processes co-limit carbon fixation ( uptake),
    • Low CO2- leaf has more photosynthetic machinery than it can use, CO2 limited
    • High CO2- leaf needs more photosynthetic machinery, can not regenerate RuBP, Insufficient light
  18. j. CO2 is converted to sugars for plant use
  19. 3. Ecosystems
  20. a. Plants allocate sugars to maintenance and growth
  21. b. Plant growth is allocated to minimize resource limitations
    i. What are some examples of plant strategies (grow roots, grow leaves, etc)?
  22. c. gross primary production (GPP)
    • Gross Primary Production, amount of photosynthesis that occurs.
    • i. What are possible units
    • gC/m^2/yr
  23. d. controls on GPP
    • i. How much leaf area
    • ii. How much photosynthesis per leaf area
  24. e. Leaf Area Index
    Leaf Area/ Ground Area (m^2 of leaf/ m^2 of ground)
  25. f. controls on photosynthesis per leaf area
    • Leaf shape, amount of foliage,
    • i. Growing season length
    • Environmental controls, weather and day light, variations in temp and moisture.
    • ii. Photosynthetic capacity
    • light, CO2, temp, water availability, nutrients
  26. g. What is plant respiration?
    Sugars are turned into CO2, supplies energy needed to live energy for growth, maintenance and ion uptake
  27. h. Net Primary Production = GPP – Plant Respiration
    net carbon gained by vegetation
  28. i. What are the type of units
  29. 4. Ecosystems to carbon balance
  30. a. What is Terrestrial Decomposition?
    • i. What is doing the decomposition?
    • Microbes- bacteria and other microorganisms
  31. b. Rate of decomposition is determined by:
    • i. Number of microbes per amount of matter to decompose
    • ii. Activity of the individual microbes
    • Temperature (enzyme activity) , amount and quality of substrate, amount of oxygen and water
  32. c. What do microbes require to grow rapidly?
    • i. Substrate quality, quantity
    • ii. Oxygen
    • iii. Temperature
    • iv. Moisture
  33. d. An example of decomposition - quantitative
    • i. Pool Size
    • The amount of carbon in the pool (gC/m2)
    • ii. Input
    • The amount of input of carbon to the pool (gC/m2/yr)
    • iii. Relative decomposition rate
    • aka the decomposition rate constant or K: the fraction of carbon lost from the pool each year ( units are per year and can be any positive number, zero means that none of the pool decomposes each year, 0.5 means that 50% is decomposed a year, 2.0 means it would take half a year for all of the carbon to decompose.
    • iv. Absolute decomposition rate
    • The absolute rate of decomposition (gC/m2/yr) the absolute rate of decay = the pool size multiplied by the relative decomp rate.
    • v. Steady state
    • Inputs and outputs are equal,
    • vi. Steady state pool size computation
    • 1. Steady state pool size = (Input) / (relative decay rate)
  34. e. Net Ecosystem Production
    whether the ecosystem is gaining or loosing C if gaining the carbon dioxide (1) uptake is greater than carbon dioxide loos during respiration and decomposition (2) one of the pools is increasing in size
  35. f. Understand this figure:
  36. 5. Carbon Cycle
  37. a. How does terrestrial ecosystem ecology fit into the carbon cycle?
    • i. What time scales? Why are we interested in the carbon cycle of terrestrial ecosystems?
    • Carbon cycle is the key in other biogeochemical cycles, eg. Carbon and Oxygen cycles are linked, we eed to know the carbon cycle for Earths radiative balance (greenhouse gases/ global warming/ albedo effect/ ocean acidification)
    • Time scales span from millions of years, thousands to hundreds of thousands and the last century.
  38. b. What are the relative sizes of the major carbon pools we discussed?
    • Pools:
    • Fluxes (sources and sinks)- different scales of sources and sinks
  39. c. What processes cycle carbon on annual time scales, 10s to 100s of years, thousands of years and longer
    • • Annually : photosynthesis (seasons), Burning forests, dissolution in surface ocean
    • • Decade to century: cycling of carbon in deep ocean, cycling of carbon in soils, land use/vegetation type changes.
    • • Centuries or more: cycling of carbon in deep ocean, chemical weathering and erosion, formation of sediments and rock e.g. limestone., formation of fossil fuels.
    • Slide 8 in Carbon lecture.
  40. d. What controls CO2 concentrations on long time scales
    • i. According to BLAG hypothesis
    • Berner, Lasage and Garrels hypothesis, aka spreading rate hypothesis, volcanic CO2 emission and CO2 outgassing link the carbon exchange between the Earths interior and the surface, Spreading rate controls the rate of CO2 delivery to the atmosphere.
    • ii. According to Uplift weathering hypothesis
    • weathering rates are affected by the amount of fresh rock surfaces
  41. e. What are 2 ways to move carbon into the deep ocean?
    • Driven by both physical and biological processes,
    • Deep water formation and photosynthesis (respiration)
    • Ocean mixing – Deep waters, isolated from the surface for thousands of years, dissolve carbonate and organic matter that fall from the surface. Upwelling waters high in CO2 Biology – organisms in surface turn CO2 and N,P into organic compounds, which either are eaten or fall into deep water. Respiration/decomposition of organic components enriches deep waters in CO2 and N,P. What is not consumed accumulates in sediments
  42. f. Where does the CO2 that we emit during fossil fuel burning go?
    Increase in atmospheric CO2 and CO2 is absorbed by the oceans the rest is taken up by the ecosystems on land.
  43. 6. Disturbances
  44. a. Terrestrial disturbances impact mass and energy fluxes between the ground and atmosphere
    I think this is just a statement? No extra info? This disturbs the carbon cycle.
  45. b. Disturbance regime properties:
    • i. Severity
    • ii. Frequency
    • iii. Type
    • iv. Size/pattern
    • v. Timing
  46. c. Steady State examples
    Inputs equal outputs. Live biomass = soil carbon
  47. d. Primary vs. secondary disturbance
    • Primary- removes or covers the soil and forces things to start from scratch- only parent material ( sand/lava/rock) remains no seeds or living plants.
    • Secondary- kills many but not necessarily all of the plants. Leaves the soil relatively undisturbed.
  48. e. Fire as a disturbance
    Fires link the atmosphere, biosphere and hydrosphere, as the forest recover from the fire, vegetation grows and biomass increases and the biomass increases the amount of carbon that can be stored, senescence (death of vegetation) means that carbon enters the soil.
  49. f. Fire in the Boreal Forest example (this does not apply to all forests on the Earth – just the boreal forest)
    • i. Changes energy balance
    • ii. Impacts carbon cycle (consumes biomass) removes carbon from biosphere and puts it into the atmospheric pool as CO2 and CH4- long lived greenhouse gasses (these will increase warming)
    • iii. Aerosols (absorb and reflect radiation) change the reflectivity of the earth’s surface. They can cool or warm depending on the aerosol and what is underneath it ( think greenhouse gases trapped) ,
  50. g. Radiative forcing
    • Radiative forcing is a measure of influence a factor has in altering the balance of incoming and outgoing energy in the Earth-atmosphere system and is an index of the importance of the factor as a potential climate change mechanism
    • Forcing is not in a steady state
    • If greenhouse gas concentrations increase, would the radiative forcing increase or decrease? - increase???
    • If albedo increased, would the radiative forcing increase or decrease? – increase???
  51. [focus reading: see Chapin link on Beachboard Chapter 12 pg 1;5-10]
    7. Biogeochemical cycles
  52. a. What are biogeochemical cycles?
    Bio- involves life Geo- involves solid earth and Chemical- involved chemical elements. Earth is nearly a closed system, elements are continually recycled.
  53. b. Chemical cycles are linked on Earth
  54. c. Big 6 CHNOPS
    macronutrients- Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur – 95% of the biosphere carbohydrates- CHO and proteins CHONS, nitrogen is needed for enzymes, phosphorus is needed in DNA and ATP
  55. d. Bioaccumulation
    • Bioconcentration- Active uptake of nutrients.
    • organisms are selective in their uptake of elements and can concentrate elements in their cells to make it easier to build molecules out of them. This requires energy, but through this mechanism, life affects the distribution of elements on Earth such as in sediments.
    • Bioaccumulation- occurs when uptake is more rapid than loss- organisms can also accumulate undesirable or toxic substances – leads to biomagnification
  56. e. A broad view of the Nitrogen cycle, the following things:
    • i. Is N2 in the atmosphere available to plants?- not available to most organisms, it is converted into forms that are available to plants. Nitrogen cycles through the biosphere. Decomposition of dead plant matter releases nitrogen, nitrogen compounds are eventually chemically converted to N2 and returned to the atmosphere. Many of the processes in the N cycle are mediated by microbes, they use the energy released from transformations of N to maintain life processes.
    • NH4 (ammonium) and NO3 (nitrate)- available to plants, N2- least reactive, not available to most organism atmosphere is 78% N2
    • ii. Nitrogen fixation –conversion of N2 to ammonium NH4+, nitrogen enters the ecosystem in two ways:
    • 1. Lightening
    • 2. bacteria – biological nitrogen fixation- free-living soil microbes, symbiotic associations with plants, metabolic cost ( not free: carbon for nitrogen) most of the fixation is done by biological processes.
    • iii. Denitrification – What is it? –Returns N2 to the atmosphere from the biosphere, some bacteria use NO3 for energy production ( under low oxygen), other losses of N from the biosphere: burial in sediments, and some volatile emissions but because it often limits growth, the loss is very small.
    • iv. Productivity (and, therefore, the carbon cycle) of many unmanaged ecosystems is limited by available nitrogen
    • internal cycling is high in comparison to fluxes in and out
    • v. What are 2 ways that people increase the nitrogen available to crops?
    • Rotate crops with nitrogen fixing crops (legumes) and they add fertilizers
    • vi. Human impact on the Nitrogen cycle
    • Haber- Bosch process: N2(g) + 3 H2 (g) -> NH3 (g)
    • Requires elevated temperature (400-50 deg C) and high pressure
    • Fossil Fuel Combustion: releases fixed nitrogen into the atmosphere as NOx and it is later deposited in precipitation over land and enters the biosphere.
    • vii. Eutrophication
    • nitrogen is transported to natural systems, increase growth. Organisms die and decompose. The decomposers require oxygen to perform the decomp and this creates hypoxic conditions which change ecosystems ( either species die or they move) eg. Gulf of Mexico
  57. 8. Time Scales
  58. a. Time scales of changes in the Earth System
    Not sure if he means the following graph.??
  59. b. Relative vs. absolute
    • Relative relies on our ability to order a sequence of events
    • Absolute relies on processes that happen at a known rate.
  60. c. Relative time
    • i. Law of superposition- younger sediments overly older ones
    • ii. Faunal succession – the chronologic sequence of life forms through geologic time, similar assemblages of fossil fauna or flora indicate similar geologic ages for rocks in which they are embedded, the fossils succeed one another in a definite recognizable order.
    • iii. Crosscutting relationships –a rock or fault is younger than any rock it transects ( lava cuts through existing rocks
  61. d. Absolute
    i. Radioactive clocks – radioactive decay occurs because some atomic nuclei are unstable, decay is spontaneous ( requires no outside energy to go, decay is predictable- it depends on the amount of radioactive material present. ( HALF – LIFE: amount of time it takes for half of the radioactive isotope to decay.
  62. e. What is a climate proxy?
    Climate Proxy records are records of natural events that are controlled by and closely mimic the climate. Not just dating but you also have to understand some facet of the past climate too.
  63. f. What are used to construct a climate proxy record? (eg. tree cores, ice cores…)
    • Ice layers- gasses and dust trapped in ice as well as chemical composition of ice (isotopes)
    • Tree rings/ cores
    • Sediment layers ( varves) of deep lakes
    • Coral (chemical and isotopic composition) – important because it is basically the only thing have to look at past tropical climate.
  64. 9. Oxygen Isotopes and Ice
  65. a. What is an isotope?
    Stable isotopes are different from radioactive, Isotopes of an element have slightly different chemical and physical properties because of their mass differences, isotopes are separated during physical, chemical and biological processes called FRACTIONATION
  66. b. Isotopes as a tool: Stable isotopes are used to reconstruct the transfer of chemicals between reservoirs/pools
    • Fractionation changes the relative proportion of isotopes in different pools, the differences indicate the processes that formed the pool and the source of the isotopes to the pool.
    • Heavier isotopes are less reactive and have stronger bonds and will stay in solids/liquids.
    • The ratio of isotopes depends on temperature, generally increased temp reduces the difference between compositions of isotopes at equilibrium.
  67. c. What are 2 processes that influence the ratio of heavy and light oxygen in the oceans? How do these processes influence the concentration of isotopes in the ocean/polar ice masses?
    Evaporation and condensation, Evaporated water will tend to contain less H2(18O)
  68. d. 2 things that control the isotopic concentration of foraminifera shells
    • Shells made of CaCO3; oxygen in the CaCO3 was obtained from ocean water.
    • The two controls were the ice volume and local ocean temperature.
  69. e. Oxygen isotopes used to construct past ice ages
    Seafloor sediment-core biota (warm vs cold) oxygen isotope ratios can be used.
  70. f. What is the “pacemaker” of ice ages?
    • The pacemaker of ice sheet formation is thought to be the amount of radiation arriving on Earth from the Sun so we need to consider the Earth’s orbit.
    • i. Milankovitch cycle- small changes in the earths orbit around the sun, wobble and tilt change how much radiation arrives at Earth.
    • 1. Eccentricity
    • how elliptical vs circular the earths orbit around the sun is. High eccentricity means it is more elliptical, low means the orbit is more circular. 100,000 year cycle
    • 2. Obliquity/tilt –
    • how tilted the earths axis is, without tilt we would have no seasons. 41,000 year cycle
    • 3. Precession
    • the position of the equinoxes over time ( Northern Hemisphere winter the earth is tilted away from the sun but we are closer to the sun during the orbit, Northern Hem summer we are tilted towards but are farther from the sun. 23,000
  71. g. What drives ice sheet growth?
    Using the three cycles of eccentricity, obliquity and precession we can create isolation curves for the different latitudes, to grow and ice sheet we need cold summers, to melt and ice sheet we need warm summers. Ice sheets grow at high latitudes were winter is always cold, a cool summer allows snow and ice to persist and grow a glacier. Earths orbital tilt is small and summer solstice occurs when earths northern hem is farthest from the sun.
  72. h. To make an ice-age, need feedbacks to amplify the pacemaker…eg Ice-albedo feedback
    need positive feedbacks to amplify temperature changes, ice albedo feedback and atmospheric carbon feedback : warmer oceans contain less carbon, sea ice retreat allows for the release of carbon from deeper ocean, melting permafrost releases carbon.
  73. 10. Scales of Climate Change
  74. a. What is the difference between average climate, climate variability, and climate change
    • climate variability- the way climatic variable (such as temp and precipitation) depart from some average state,
    • Climate – the steady/ long-term average
    • Climate change- a trend in one or more climatic variables characterized by a change in the average value during the period or record.
  75. b. Weather is what you get and climate is what you expect
  76. c. What are the three broad ways to change the energy balance on Earth (eg. changing albedo, etc…)
    • Changes in the amount of solar energy arriving at Earth
    • Changes in the amount retained (Greenhouse effect)
    • Changes in the amount reflected (albedo)
  77. d. What are some specific examples of how climate can change (eg. variation in solar output, changes in aerosols, etc)
    • Variations in solar output
    • Changes in Earth’s orbit (Milankovitch cycles)
    • Changes in greenhouse gas concentrations
    • Aerosols (affect transmission and absorption of solar and infrared radiation)
    • Distribution of continents, mountains and oceans
    • Surface characteristics - albedo
    • Feedback processes: positive = amplifying, negative = stabilizing
  78. e. Long time scales - What are some of the ranges of climate conditions that are thought to have occurred on Earth?
    Snowball earth and warm middle cretaceous earth where coral reefs grew much closer to the poles and dinosaurs ranged north of the artic circle
  79. f. What are some ways that climate has changed how people live in the past hundreds of years
    • i. medieval warm period? – unusually warm period in history lasting from 10th century to 14th century. Warming may have been regional (insufficient data) Vikings took advantage of ice free seas to colonize Greenland and other areas far north
    • ii. Little Ice Age?- cooler winters in Europe, alpine glacier advance, greater N. Atlantic sea-ice extent, winter temps cooled as much as 2-4 degrees F altered agriculture, froze rives and changed the economy of 1300-1850AD, life expectancy in England fell by 10 years
  80. g. El Nino and the Southern Oscillation (ENSO) drives major changes on 4-7 year periods What is El Nino? What is going on here (wind pattern, thermocline, upwelling, etc.)? What are the processes that link atmospheric and ocean circulation?
    • Disruption of ocean and atmosphere circulation in the pacific ocean, effects are global and arrives about every 4-7 years and can last months or years.
    • Normal- strong trade winds and upwelling cool in east side of Pacific and warm in the west pacific, high rain in the west.
    • El Nino- weak or reversed trade winds, warmth shifts from west to east, high rain in mid and east pacific.
    • Atmospheric pressure changes and theromohaline circulation shifts
  81. h. What is an example of abrupt or rapid climate change in the Earth’s history?
    Shift in climate patterns/variability, ENSO, monsoons and droughts in western US
  82. 11. Humans and Earth System 1 and 2
  83. a. The Earth is nearly a closed system. What are 3 implications?
    • Resources are finite
    • Can’t through things away
    • Changes in ne part of a closed system will eventually affect the other parts
  84. b. Where do humans fit into the Earth System?
    We drastically alter the earth system especially through our energy consumption
  85. c. Why is energy production so important to people?
    We have built our economy and lives around it, food production, material production for goods, housing- heating, movement of goods, services, and recreation. 3 main categories (transportations, home/commerce and industry )
  86. d. Where did most energy come from before fossil fuels?
    dead organic matter and the sun
  87. e. What is the ultimate source of fossil fuel energy?
    Dead organic matter and ultimately the Sun
  88. f. Where do most human energy resources come from: fossil fuels, nuclear, wind, etc…
    Fossil Fuels, Hydrocarbons- coal, oil, natural gas, peat
  89. g. When was the last time in the past 450,000 years that atmospheric CO2 concentrations were as high as today?
  90. h. What are 2 main human sources of CO2 to the atmosphere?
    Fossil Fuel combustion & _____??? Deforestation? Agriculture? Idk…
  91. i. How is the Earth System helping us out with our CO2 emission problem?
    • Climate forcing- an energy imbalance imposed on climate system either eternally or by human activity,
    • Radiative forcing (review)- a measure of the influence a factor has in altering the balance of incoming and outgoing energy in the Earth-atmosphere system and is an index od the importance of the factor as a potential climate change mechanism.
  92. j. What is radiative forcing?
    • i. Increased radiative forcing = increased energy added to the Earth System increased warming
    • ii. Radiative forcing is related to temperature
  93. k. What are 3 broad ways to change the Earth’s energy balance?
    • Changing in the amount of solar energy arriving at Earth
    • Changes in the amount retained (change the greenhouse effect)
    • Changes in the amount reflected (albedo)
  94. l. What are the relative contributions of human influence to radiative forcing? What is the overall/net radiative forcing due to human impacts?
    • Human based : Changes in greenhouse gas concentrations, aerosols, and surface characteristics (albedo)
    • The others (not based on humans)- variations in solar output, changes in the earths orbit (milankovitch cycles), distribution of continents, feedback processes: positive = amplify, negative = stabilizing
  95. 12. Climate Change
  96. a. Global Climate Change/Global warming
  97. b. Does Greenhouse Effect = Global Warming
  98. c. What is the IPCC
    Intergovernmental Panel on Climate Change (IPCC) 1988 UN Environmental Program and the World Meteorological Organization, summarizes thousands of studies, documents observed trends in climate and predicts future changes.
  99. d. What is a Global Climate Model (GCM)
  100. e. What are three reasons that should give us confidence in global climate model predictions?
    Based on sound physical principles, provide reliable spatial patterns that agree with observations, provide temporal patterns that agree with observations.
  101. f. There are greater errors in GCMs at smaller spatial scales
    larger errors happen when sharp elevation changes occur, outside the polar regions large errors are evident in the eastern parts of the tropical ocean basins a symptom of problems in the simulation of low clouds, there is also a tendency for a slight cold bias.
  102. g. What people are going to do over the next 100 years remains uncertain. How did the IPCC account for different possible futures?
    • Some scenarios describe possible future development.
    • 1) evaluating climatic and environmental consequences of alternative future GHG emissions in the absence of specifics
    • 2) cases with specific alternative policy interventions to reduce GHG emissions and enhance sinks
    • 3) assessing mitigation and adaptation possibilities ( costs, regions and economic sectors)
    • 4) negotiations of possible agreements to reduce GHG emissions
    • Four important human choices to consider on determining the future trajectory of future greenhouse gas emissions- demographic, socio-economic development, technology and institutional change.
  103. h. General GCM outputs, what do they say?
    • Emissions will continue to increase in the majority of the outputs some will increase more than others and global warming continues to happen in the majority of the outputs as well.
    • Poles warm the most, heat waves will be more intense and more frequent and longer lasting. Precipitation over land increases by 5% and over oceans increases 4% most increase occurs at high latitudes. , soil moisture generally decreases,
    • i. Climate change may include changing mean climate and also changes in climate variability
  104. 13. Climate Change in California
  105. a. Downscaling (global climate models) – what is it? Why downscale GCM outputs
    • Replicating key features of observed climatology, and providing daily level output. Downscaling is to increase the resolution of coarse GCM grid cells to smaller scales.
    • Regression methods- establishing a statistical relationship between a site within the grid cell to a model grid scale predictor variable. (modeled average monthly maximum temperature against the measured max temperature at a weather station of interest.
    • Limited- area climate models- use the focus regions GCM grid-cell predictions for regional climate change- drive a higher resolution climate model embedded in the GCM.
  106. b. What is the approximate amount of temperature increase in CA by 2100?
    Greater warming inland, 6 degrees C greatest warming in the summer.
  107. c. How may precipitation change over the coming century?
    Less precipitation inland more in other places ( over all trend of no change)
  108. d. What might happen to the Sierra Nevada spring snowpack?
    Less snow pack means less water 60% loss in the april 1st snow water equivalent
  109. e. Why is the Sierra Nevada snowpack important to California?
    It is a major source of fresh water
  110. f. What are 3 possible changes to precipitation arriving as snow over the coming century?
    More rain- less snow, reduction in the snow water content, earlier snowmelt.
  111. g. California agricultural
    top Us producer for more than 60 years. 50% of nation fruit and veggies, demand for water.
  112. 14. Alternatives
  113. a. What are some of the outstanding questions that we need to address as a global society to tackle climate change? Why is it so difficult?
    What are the costs? Who pays and when?
  114. b. What makes making a choice between adaptation and mitigation so difficult?
    We don’t know if we will be able to adapt and we don’t know if we can mitigate at this point. Also, who decides and who takes the responsibility of the consequences of the decision?
  115. c. Can humanity already solve the CO2 problem?
    • Yes we can solve the carbon and climate problem from the next 50 years, we have the science and technology/ industry know how we just need to implement it.
    • i. Wedges
    • Strategy to reduce carbon emissions that grows in 50 years from zero gigatons of carbon/year to 1 GtC/y
    • ii. Does reducing emissions to a constant resolve the CO2 problem? Think about a box model under steady state conditions. Where will carbon go
    • oceans absorb a lot of the earths carbon emissions and creates other problems, natural sinks like tropical forest, creation of urban forests, conservation tillage on crop land, using different forms of electricity like solar, wind, increase efficiency- electricity, transport and heat.

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geol 300i final
2013-05-16 02:07:59
geol 300i final

earth systems and global change
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