AOS/IES 171 Short answers to go with the Study Guide for the 2nd Midterm (You will need the study guide from our course website for the questions.) 1. When forces balance. Negative feedbacks dominate. Positive feedbacks dominate. A new force that upsets equilibrium. Tends to restore the sytem back to where it was (friction, emission of infrared). Tends to amplify changes away from where the system was (ice albedo feedback). Cooler, more ice, more sunlight reflected, cooler, more ice ... Warmer, less ice, more sunlight absorbed, warmer, less ice ... Forests trap heat so they behave similarly to the ice albedo feedback. Warmer, more CO2 and CH4 come out of the ground and ocean, making it warmer ... Cooler, gases go into the ocean and ground, making it cooler ... There are several states of the climate system that are preferred states. The smallest uncertainty in initial conditions implies an inability to predict the weather a few weeks in advance. Chaos theory emphasizes nonlinear interactions of variables in a complex system, the state wanders around within limits. Determinism tells you the limits and explores cause and effect. 2. 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. 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 a deep sea core tells you about the temperature in the past. 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. 3. 130 kybp, 20 kybp, 13-12 kybp, 8-4 kybp, 1400-1900 AD. Axial tilt, ellipticity of orbit, precession of axis. Warm winters build up ice, cool summers don't melt ice. 5000 years. Starting in about 5000 years. Laurentide Ice sheet retreat, Lake Agassiz drained into north atlantic, affecting the gulf stream. Higher number of volcanic emissions, aided by a weak sun, and consistent with millenial variations associated with the thermohaline circulation see-saw between the North Atlantic and Antarctic. Millenial variations are stronger when the Laurentide Ice Sheet is large. 4. 1.2 K or 2 F Sea level up by 20 cm, cooler stratosphere by 1-3 K, coral bleaching, summertime heat wave events are worse. Reduced diurnal temperature range, diseases associated with warm water found 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 temperate 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 midlatitude westerlies. Arrhenius predicted that 2xCO2 from coal burning would lead to 5-6 K global surface temperature increase. Since we're putting 10 Gt/yr anthropogenic C into the atmosphere now, it looks like we're heading for 3-4x CO2, increasing sea level by 20-50 cm, and increasing temperatures of 5-6 K in the next 100 years. Melting of Greenland, release of boreal forest and tundra soil carbon, ocean acidification and reduction of coccolithophore ecosystems. Crop challenges and opportunities. As ozone hole restores to normal Antarctica proper may begin to melt more. 5. 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. 6. More ice, more sun reflected, cooler, more ice OR less ice, more sun absorbed, warmer, less ice (positive feedback either way). Thermal expansion and mountain glacier melt. Antarctica is so high and cold that global warming might lead to more snowfall there instead of melting. Meltwater at the base of coastal glaciers might help them flow off into the sea. 7. SO2 Sulfuric acid and water. These liberate Cl gas which can destroy ozone. Poleward and downward. -0.5 K for 1-3 years. Some massive eruptions may have cause 1-3 K cooling during the Holocene. 8. Oxygen and sunlight. Warms the stratosphere. Transport poleward and downward from the sunlight tropics. Continentality is greater in NH, so jet stream waggles north/south more, so more ozone is transported in NH. O+O2+M-->O3+M* Families that can catalytically destroy ozone. Methane, Nitrous Oxide, CFCs, Halons. 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 compounds to stop the ozone loss.) -5 to -10% ozone loss outside of south pole, caused by rise in anthropogenic chlorine (CFCs and others) Ozone should slowly recover, hindered by rise in ozone-destroying compounds besides CFCs. 9. June-September in the 12-24 km layer over Antarctica. Polar stratospheric clouds (PSCs) 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. 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. 10. N comes from N2 in the air, while S comes from the fuel. OH. Reduced visibility, daytime not as warm, acid rain on forests, lakes, and human structures. CO2 causes things to be warmer 24 hours - all day and night long. But sulfate reflects sunlight during the daytime, tending to reduce the daytime maximum, so the diurnal range in temperature would be smaller. 11. 7.0, 5.6, 2-5 Down to about 5 Limestone. Limestone bedrock scraped away. Lime. Ozone damages needles, acid rain leaches out chlorophyll, kills mycorrhizae, mobilizes toxic metals. 12. 10% vs 90% Damages eyes and lungs. Sunlight and commuting cause the big diurnal cycle in ozone and other pollutants in summer cities. Biomass burning in South America and Africa. 13. 25-29 C. Symbiotic algae hosted by the coral animals which give plant food, aid fixing CaCO3, and give color to reefs. 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. 14. 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 types of plants to survive!) 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. Collectively, life acts as a living organism that can respond to thermoregulate our planet, being enabled by the sheer complexity of the biosphere. 15. 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. If a reservoir amount exhibits a lot of natural variability, it will be hard to diagnose a trend. We are simplifying the biosphere by species reduction, raising the risk of reducing the resiliency of the biosphere-climate system. 16. Gt (10^12 kg) 800 Gt, increasing at 5 Gt/yr. fossil fuel=7500 Gt, land biosphere=2100, ocean=38,000 Gt Animal respiration puts CO2 into the atmosphere, while plant photosynthesis puts O2 into the atmosphere. Fossil fuel burning (most), cement making and deforestation put out 10 Gt/yr. 5 Gt/yr are going Into the oceans and land biosphere. Net fluxes between land-atmosphere and ocean-atmosphere. Plankton take up CO2, die, and sink, "pumping" C to the bottom of the ocean. Exceeds 300 years. 500-1200 ppmv. Some estimates are 2-5 times the known fossil fuel supply. Since a lot of CO2 is subducted in bottom water formation, this sink would be reduced, so atmospheric co2 would grow a lot. In addition, phytoplankton are declining in the world's oceans, so this will make it harde for the ocean to take up more CO2. 17. Temperature and rainfall. It does well in colder climates. 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. The range in GDD for boreal forest is 600-1300. As the climate warms, latitude bands of biomes shift poleward. Growth rate, stuff in the way, limited mechanisms of dispersal limit migration. The effects of Amazon deforestation are increased temperature, decreased rainfall, decreased evaporation. 18. High latitude northern biome that's cold but with moderate precipitation. Spruce. Some plants are more efficient at retaining water when there is more CO2 in the air. We need to know whether plants can make the transition that is happening. It might take 50 years for a spruce tree to have progeny. Soil microbes will access the large carbon reservoir as soils warm so that a lot of CO2 and CH4 will go into the air. 19. The DNA and food in a seed. He started the first seed bank in St. Petersburg, Russia over 100 years ago. Maintain genetic diversity for food and other crops. Irish potato famine. Not many coffee trees left in Ethiopia. 20. 1 meter of rain falls on average. A water molecule will spend about 5 days in the atmosphere and travel about 1000 km before raining out. Atmospheric winds import moisture from the ocean to over the continents, while river runoff returns it to the sea. Less rain. Drier. 21. ITCZ is where air comes together to rise in deep thunderstorms, tends to follow the sun across the seasons. Shrubland south of the Sahara desert. Less leaves, less evapotranspiration, less moisture in air, thunderstorms don't get so far north, less rain, less plants, etc. 22. 2500 m3 per year. Irrigation and power plant cooling. 2000 kCal, 100 W. About 3000 m2 (half a football field) About 3000 m2. Plant mass created through photosynthesis, minus what the plants used, per year. About 40% of land NPP used by humans already. Earth could support perhaps 2 times as many people, but with serious encroachment on ecosystems. 23. Russia, Middle East, Canada. Factor of 10. Taxes that support military protection of reserves, pollution and health costs, encourages usage of fossil fuel that leads to acid rain and global warming. Storage for 10,000 years is longer than the length of civilization, terrorists can obtain our stuff and threaten us with it. Solar, wind, waves, geothermal. Using sunlight to create electricity. 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. 24. Conservation of energy, momentum, mass, and individual constituents (chemicals, aerosols). Representing model variables (temperature, wind, moisture) at grid points, perhaps 100 km apart horizontally and 1 km vertically, misses a lot of processes, which must be parameterized, such as moisture flux linked to mean temperature and wind speed. The fluxes of moisture, heat, and momentum are crucial for getting atmosphere/ocean coupling right. The average of many forecasts (ensemble) does better than any single membe. Current climate models and observations are uncertain regarding current clouds, esp. tropical convection. They often have a cold bias of 2-5 K in the troposphere, yet departures from this may be regarded as reasonably represented. Convection is poorly represented in the atmosphere and ocean. The tropics get hotter and drier when vegetation is cut down. CO2 trends will increase in the atmosphere if NABW formation slows. 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).