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129 Cards in this Set
- Front
- Back
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Observations indicate an increase in average
global surface temperature over the last century. By how much (in degrees Kelvin and in degrees Fahrenheit)? |
1.2 K or 2 F
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What are some changes that have already occurred associated with this warming?
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Sea level up 20cm, cooler stratosphere by 1-3 K, coral bleaching, summertime heat wave events worse. Reduced diurnal termperature range, diseases associated with warm water farther from tropics, change in rainfall patterns for crops. Warming/drying in the US west, melting of mountain glaciers, periphery of Greenland, and Palmer Peninsular of Antarctica. Reduced temperature lake freeze duration. Earlier snowpack runoff. Cloud particles over land are much more numerous, with longer-lived clouds and reduced precipitation. Reduced precipitation in tropical rainforests. Reduced arctic sea ice thickness and extent in summer and fall. Destabilization of tundra permafrost. Higher, colder tropical tropopause, spreading of tropics, poleward shift and strengthening of mid-altitude westerlines.
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It is anticipated that with some regulation of fossil fuel emission we will probably reach about 800 ppmv CO_2 by the end of the century. This is a tripling of CO_2 since 1900 (about 280 ppmv). What did Svante Arrhenius predict around 1900?
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Arrhenius predicted that 2xCO2 from coal burning would lead to 5-6K global surface temperature increase.
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What is the current flux of anthropogenic carbon into the atmosphere?
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Since we're putting 8.5 Gt/yr anthro C into atm., we're heading for 3-4x CO2.
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Most climate forecast models predict a surface warming of 3-6 K by the year 2100. What are some likely consequences of this?
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Melting of Greenland, release of boreal forest and tundra soil carbon, ocean acidification, reduction of coccolithophore ecosystems. Crop challenges and opportunities. As ozone hole restores to normal, Antarctica proper may begin to melt more.
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The role of clouds in an enhanced greenhouse gas scenario is uncertain. What would an increase in high clouds do to the average temperature?
What would an increase in low clouds do? |
High clouds let in sunlight but emit only a little infrared from their cold surfaces to space, so more high clouds will warm the planet.
Low clouds reflect a lot of sunlight and don't trap as much infrared, so more low clouds will cool the planet. |
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What is the ice-albedo feedback?
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More ice, more sun reflected, cooloer, more ice, OR: less ice, more sun absorbed, warmer, less ice (positive feedback both ways).
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If the globe were to warm, what two main factors would contribute toward a rise in sea level?
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Thermal expansion and mountain glacier melt.
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What aspect of Antarctica might actually contribute to a drop in sea level?
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Antarctica is so high and cold that global warming might lead to more snowfall there instead of melting.
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What aspect of Antarctica might lead to a rise in sea level?
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Meltwater at the base of coastal glaciers might help them flow off into the sea.
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What ingredients are need to make stratospheric ozone?
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Oxygen and sunlight.
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Ozone protects life by absorbing ultraviolet radiation.
What is another primary result of absorbing uv? |
Warms the stratosphere.
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Why does column ozone tend to be largest at higher latitudes?
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Transport poleward and downward from the sunlit tropics.
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Why is there usually less ozone over the south pole than over the north pole?
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Continentality is greater in NH, so jet stream waggles north/south more, so more ozone ins transported in NH.
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What reaction creates ozone?
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O + O2 + M --> O3+M*
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What are HO_x, NO_x, ClO_x, and BrO_x?
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Families that can catalytically destroy ozone.
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What are the primary surface source gases that supply these families in the stratosphere?
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Methane, Nitrous oxide, CFCs, Halons.
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What is a catalytic destruction cycle?
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O3 + Cl --> O2 + ClO
ClO + O --> O2+ Cl Cl can wipe out billions of ozone molecules in this loss cycle before reacting with N or H to stop the loss. |
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What is the observed trend in ozone outside of the polar regions over the past two decades? What probably caused it?
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-5 to -10% ozone loss outside of south pole, caused by rise in anthropogenic chlorine (CFCs and others).
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What do scientists think will happen to stratospheric ozone over the next 50 years?
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Ozone should slowly recover, hindered by rise in ozone-destroying compounds besides CFCs.
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Where and when do little crystals form in the stratosphere?
What are the resulting clouds called? |
June-September in Polar Stratospheric Clouds (PSCs)
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In the dark, ``heterogeneous" reactions near the surfaces of the ice crystals create Cl_2. What happens when the sun comes up in the springtime?
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Cl2 gas is broken apart and catalytic destruction of ozone begins. Then PSC crystals evaporate, with N and H binding the Cl to stop the ozone loss.
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How did the eruption of Mt. Pinatubo in July 1991 lead to
one of the biggest ozone holes ever (300 --> 90 Dobson Units) in October 1993? |
Volcanic aerosol constitute surface area for chemical reactions. When this material reaches the south polar region during winter a lot of PSCs can form, with enhanced ozone loss.
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What gas in large volcanic eruptions leads to the stratospheric aerosol layer?
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SO2
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What is this aerosol layer made of?
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Sulfuric acid and water.
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How can these aerosols affect stratospheric ozone?
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These liberate Cl gas which can destroy ozone.
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In which directions does the Brewer-Dobson circulation transport the aerosol and ozone?
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Poleward and downward.
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After a major volcanic eruption, low long and by how much will the planet's temperature be affected?
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-0.5 K for 1-3 years. Some massive eruptions may have caused 1-3 K cooling during the Holocene.
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Where does the N and S come from that make NO_2 and SO_2 during burning?
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N comes from N2 in the air, while S comes from the fuel,
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What is the ``tropospheric cleanser" that converts these to nitric and sulfuric acid?
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OH.
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List three effects of sulfuric acid in the troposphere.
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Reduced visibility, daytime not as warm, acid rain on forests, lakes, and human structures,
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Burning fossil fuels lead to both an increase in both CO_2 and SO_2. How could this cause a reduction in the diurnal temperature range?
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CO2 causes warmer 24 hours, but sulfate reflects sunlight, causing daytime to be about the same, but nighttime is warmer.
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What are the pHs of pure water, natural rain water, and ``acid rain"?
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7.0, 5.6, 2-5
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What is the range of pH that freshwater fish and amphibians can tolerate?
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Down to about 5
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What kind of bedrock makes ecosystems less sensitive to acid rain?
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Limestone. Limestone bedrock scraped away. Lime.
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How can ancient glaciers affect the sensitivity to acid rain?
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Ozone damages needles, acid rain leeches out chlorophyl,l kills mycorrhizae, mobilizes toxic metals
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Compare the relative amounts of ozone in the troposphere and stratosphere.
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10% vs. 90%
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Why is tropospheric ozone a problem?
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Damages eyes and lungs.
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One needs strong sunlight, hydrocarbons, and odd nitrogen compounds
to make tropospheric ozone. Why is there a diurnal cycle in ozone concentration in big cities in the summertime? |
Sunlight and commuting cause the big diurnal cycle in ozone and other pollutants in summer cities.
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What causes high ozone concentrations over the South Atlantic ocean in September?
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Biomass burning in South America and Africa.
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Coral bleaching. What is the temperature range for healthy coral growth?
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25-29 C
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What are zooxanthellae and how do they help coral?
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Symbiotic algae hosted by the coral animals which give plant food, aid fixing CaCO3, and give color to reefs.
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What is coral bleaching and what can cause it?
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Bleaching can be caused by too warm or too cold, too silted, too much UV, oil, pollution, cyanide and bomb fishing, anchors, windborne disease organisms.
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What is Daisy World and what are its competetive and cooperative aspects?
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White daisy reflects sunlight and grows best when hot, black absorbs sunlight and grows best when cold. Their competition ensures one will dominate to return planet to hospitable temperature (a cooperation that allows both plants to survive!)
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How might phytoplankton regulate the amount of tropical clouds?
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Phytoplankton produce dimethylsulfide (DMS) which can nucleate clouds. The interplay among phytoplankton, clouds and DMS production provides for a potential negative feedback system of checks and balances which keeps our planet in a good temperature zone for life.
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What is the Gaia hypothesis?
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Collectively, life acts as a living organism that can respond to thermoregulate our planet, being enabled by the sheer complexity of the biosphere.
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Geophysical budgets. What are a reservoir, source, sink, and flux? What leads to a trend?
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Reservoir = an amount of stuff. Sink is loss of stuff per unit time, source is gain of stuff per unit time. Flux is from one reservoir to another (in stuff per unit time). If sources and sinks don't balance then there will be a trend.
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What might make it difficult to diagnose a trend?
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If a reservoir amount exhibits a lot of natural variability, it will be hard to diagnose a trend.
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For earth system cycles, each component is interdependent, with many feedbacks. What
are some of the ways that we are reducing the complexity of this feedback system? How might this affect the stability of the system? |
We are simplifying the biosphere by species reduction, raising the risk of reducing the resiliency of the biosphere-climate system.
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List a unit commonly used to describe the global carbon budget.
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Gt (10^12 kg)
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What is the current reservoir of atmospheric carbon and its current rate of increase?
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800 Gt, increasing at 3 Gt/yr
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How big is the fossil fuel reservoir compared to the atmosphere, land biosphere, and ocean reservoirs?
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fossil fuel = 7500 Gt, land biosphere = 2100, ocean = 38,000 Gt
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What are the main natural sources and sinks for atmospheric CO_2?
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Animal respiration puts CO2 into the atmosphere, while plant photosynthesis puts O2 into the atmosphere.
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What are the main anthropogenic sources of atmospheric CO_2?
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Fossil fuels burning (most), cement making, and deforestation.
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What is the ``missing sink" problem and where might it be?
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Into the oceans and land biosphere.
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What are some of the uncertainties in the carbon budget?
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Net fluxes between land-atmosphere and ocean-atmosphere.
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What is the ``biological pump"?
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Plankton take up CO2, die, and sink, "pumping" C to the bottom of the ocean.
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What is the residence time of carbon dioxide in the deep ocean?
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Exceeds 300 years.
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In the IPCC scenarios, what is the range of CO2 concentration expected in the year 2100?
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500-1200 ppmv.
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How much carbon is stored in the high latitude continental shelf below the ocean in the form of methane relative to the known fossil fuel supply?
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Some estimates are 2-5 times the known fossil fuel supply.
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What will happen to the ability of the ocean to take up CO2 as surface temperatures rise?
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Since a lot of CO2 is subducted in bottom water formation, this sink would be reduced, so atmospheric CO2 would grow a lot.
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List 5 of the major plant biomes.
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Tundra, Taiga, Deciduous Forest, Rainforest, Savanna
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What main factors influence the ability of plants to grow?
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Temperature and rainfall.
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What is a cold-adapted plant?
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It does well in colder climates.
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What is a growing degree day?
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Each plant has a threshold temperature above which it will photosynthesize. If the daily average temperature exceeds this then it is added to the growing degree days, which accumulate across the growing season.
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Briefly describe what physical processes account for the upper and lower GDD limits.
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The range in GDD for boreal forest is 600-1300.
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How is this related to
latitudinal extent of a plant species? |
As the climate warms, latitude bands of biomes shift poleward.
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What processes might help
or hinder plant migration when climate changes? |
Growth rate, stuff in the way, limited mechanisms of dispersal limit migration.
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What are the effects of deforestation in the Amazon on temperature, evaporation, and precipitation?
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The effects of Amazon deforestation are increased temperature, decreases rainfall, decreased evaporation.
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15. What is the boreal forest and what is the primary species in it?
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High latitude northern biome that's cold but with moderate rainfall. Spruce.
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What is ``CO_2 fertilization"?
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Some plants are more efficient at retaining water when there is more CO2 in the air.
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Why is the rate of plant migration
important to global change? |
We need to know whether plants can make the transition that is happening.
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How long does it take a spruce tree to mature?
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It might take 50 years for a spruce tree to have progeny.
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What would likely happen to atmospheric carbon dioxide concentrations from warming high latitude soils?
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Soil microbes will access the large carbon reservoir as soils warm so that a lot of CO2 and CH4 will go into the air.
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Diversity. What is germ plasm?
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The DNA and food in a seed.
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Who was Nikolai Vavilov?
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He started the first seed bank in St. Petersburg, Russia, over a hundred years ago.
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Why would we care about
maintaining seed banks? |
Maintain genetic diversity for food and other crops.
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Give two examples illustrating
the importance of genetic diversity. |
Irish potato famine. Not many coffee trees left in Ethiopia.
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Water cycle. About how much rain falls over the globe each year?
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1 meter of rain falls on average.
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How long does a water vapor molecule typically reside in the atmosphere?
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A water molecule will live about 5 days in the atmosphere before raining out.
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Over continents, rainfall exceeds evaporation. What maintains an
equilibrium? |
Atmospheric winds import moisture from the oceans to over the continents, while river runoff returns it to the sea.
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What might happen to continental rainfall if plant cover were reduced?
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Less rain.
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What might happen if a river were diverted?
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Drier.
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Desertification. What is the ITCZ?
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ITCZ is where air comes together to rise in deep thunderstorms, tends to follow the sun across seasons.
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What is the Sahel?
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Shrubland south of the Sahara desert.
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How could overgrazing lead to an expansion of the Saharan desert?
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Less leaves, less evapotranspiration, less moisture in air, thunderstorms don't get as far north, less rain, less plants, etc.
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In the U.S., how much water does each of us use each year?
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2500 m3 per year.
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What is most of it used for?
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Irrigation and power plant cooling.
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How many food calories does the average person need? How much heat do we emit?
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2000 kCal, 100W
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How much land is required to grow a year's worth of food for a vegetarian, compared to a person who gets most of their calories from meat?
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3000 m2 vs. 21,000 m2
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How much agricultural land per person is available on earth right now?
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3000 m2
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What is net primary productivity?
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Plant mass created through photosynthesis, minus what the plants used, per year.
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About what percentage of the earth's net primary productivity is used by humans?
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About 40% of land NPP used by humans already.
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Given ``business as usual", how many more people could the earth support?
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Earth could support perhaps 2 times as many people, but with serious encroachment on ecosystems.
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Energy. Where are most of the world's oil and gas reserves?
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Russia, Middle East, Canada.
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By what factor does the per capita emission of CO2 in the US exceed that of the
average person in the world? |
Factor of 10.
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What kinds of "hidden costs" might there be associated with low U.S. gas prices?
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Taxes that support military protection of reserves, pollution and health costs, encourages use of fossil fuel that leads to acid rain and global warming.
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What problems are there with nuclear power?
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Storage for 10,000 years is longer than the length of civilization, terrorists can obtain our stuff and threaten us with it.
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What are a few alternative energy sources besides fossil fuels?
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Solar, wind, waves, geothermal.
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What is the most promising energy pathway that we can develop which can save us lots of money and greatly alleviate the threats of pollution and global warming?
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Using sunlight to create electricity.
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What is the Kyoto Protocol and what is the current United States
policy regarding global warming? |
International treaty to regulate greenhouse gas emissions to avoid global warming. Current U.S. policy is to deny the threat and not sign any treaties.
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What is equilibrium? What is
a stable system? What is an unstable system? |
When forces balance. Negative feedbacks dominate. Positive feedbacks dominate.
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What is a perturbation?
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A new force that upsets equilibrium.
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What is a negative feedback?
What is a positive feedback? |
Tends to restore the system to back to where it was (friction, emission of infrared).
Tends to amplify changes away from where the system was (ice albedo feedback). |
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How does the ice albedo feedback work?
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Cooler, more ice, more sunlight reflected, cooler, more ice...
Warmer, less ice, more sunlight absorbed, warmer, less ice... |
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What is the boreal forest feedback?
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Forests trap heat so they behave similarly to the ice albedo feedback. Warmer, more CO2 and CH4 come out of the ground, making it warmer...
Cooler, gases go into the ocean and ground, making it cooler... |
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Describe how greenhouse gases and the ocean can enhance either a cooling or
warming tendency. What is the idea of multiple equilibria? |
There are several states of the climate system that are preferred states.
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What is the butterfly effect?
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The smallest uncertainty in initial conditions implies an inability to predict the weather a few weeks in advance.
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Briefly contrast Chaos theory and determinism.
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Chaos theory emphasizes nonlinear interacts of variables in a complex system, the state wanders around within limits. Determinism tells you the limits and explores cause and effect.
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What is an isotope? What is deuterium?
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Some elements have the same number of protons but a different number of neutrons. Deuterium has one proton and one neutron, so is twice as heavy as normal hydrogen.
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What are O^16 and O^18 and how are they useful?
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O^16 has 8 neutrons, while O^18 has 10 neutrons, so water with O^18 in it is heavier. This implies fractionation upon evaporation, so that when it is cold it is less likely for such heavier water to evaporate, get incorporated in a snowflake. and fall on a glacier. Hence, measuring O^18 in an ice core or deep sea core tells you about the temperature in the past.
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Why is H_2O^18 enhanced relative to H_2O^16 in deep ocean sediments when the surface waters are colder?
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Since there is a fixed amount of O^18, if less is in the ice core at some time, then there is more left in the ocean to get incorporated in a deep sea core.
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When were the Eemian Interglacial, Wisconsin Glacial, Younger Dryas event, Holocene maximum, and the Little Ice Age?
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130 kybp, 20kybp, 11kybp, 8kybp, 1400-1900AD
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What are the three Milankovich orbital parameters?
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Axial tilt, ellipticity of orbit, precession of axis.
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How could a weak axial tilt favor growth of continental ice sheets?
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Warm winters build up ice, cool summers don't melt ice.
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How long might it take to build an ice sheet 1000 m thick?
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5,000 years.
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When might we expect to have our next glacial period?
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About 5,000 years from now.
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What might have caused the Younger Dryas oscillations?
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Laurentide Ice sheet retreat, Lake Agassiz drained into north atlantic, affecting the gulf stream.
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What might have caused
the Little Ice Age? |
Higher number of volcanic emissions, aided by a weak sun, and consistent with milennial variations associated with the THC see-saw between the North Atlantic and Antarctic.
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Climate forecast models. What conservation laws are used?
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Conservation of energy, momentum, mass, and individual constituents (chemicals, aerosols).
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What is the relationship between grid spacing and parameterization?
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Representing model variables (temperature, wind, moisture) at grid points, perhaps 100km apart horizontally and 1km vertically, misses a lot of processes, which must be parameterized, such as moisture flux linked to mean temperature and wind speed.
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Give two examples of fluxes between parts of the earth system that need to be accurately represented.
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The fluxes of moisture, heat, and momentum are crucial for getting atmosphere/ocean coupling right.
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What is an ensemble forecast?
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The average of many forecasts (ensemble) does better than any single member.
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How accurately do climate models represent the current distribution and type of clouds?
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Current climate models and observations are uncertain regarding current clouds, esp. tropical convection.
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How accurate are their surface temperatures? How accurately is tropical convection represented?
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They often have a cold bias of 2-5 K in the troposphere , yet departures from this may be regarded as reasonably represented.
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How accurately is deep water formation represented?
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Convection is poorly represented in the atmosphere and ocean.
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What happens to tropical rainfall and temperatures if the tropical rainforest is cut down?
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The tropics get hotter and drier when vegetation is cut down.
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What happens to atmospheric CO2 trends if NABW formation is turned off.
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CO2 trends will increase in the atmosphere if NABW formation slows.
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What happens to global temperature?
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This would cause temperatures to increase globally but actually cool in the region where bottom water formation is slowing (reduced heat flux out of the ocean).
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