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Earth's Changing Cli
Earth's Changing Climate
| Term | Definition |
|---|---|
| How much of Earth's surface do glaciers cover and where are they located? | over less than 10% of earth's land surface, most in Greenland and Antarctic ice sheets |
| if all of the ice melted what would happen? | the ocean would rise about 213 ft |
| what can be discovered through ocean sediment? | Distribution and type of organisms(shells) found indicate temp of the surface wate |
| what can be discovered by the oxygen-isotope ratio of the shells? | sequence of the glacier advances |
| Higher ratio of oxygen 18 than oxygen 16 means? | colder climate, lower ratio means warmer climate |
| what can be streamlined from vertical ice cores? - | ratio info for records of past temp trends - Sulfuric acid layers in the ice core indicate physical or biological climate change whether they are from acid snow (from volcanic eruption) or chemicals from human sources -dust shows whether the climate was |
| Dendrochronology | study of annual growth rings of trees |
| What indicates climate change in tree rings? - | Density of late growth tree rings and thickness of the rings -chemistry of the wood -frost rings(during cold period) |
| Other data used to reconstruct past climates - | Natural lake-bottom sediments -Soil deposits, sea sediments, pollen in deep ice caves -Geological evidence, change in water level of closed basins -Records of drought, floods, crop yields, rain, snow -Oxygen-isotope levels in coral -Calcium carbonate |
| Glacial periods (in millions of years ago) | occurred 700m.y.a. and 300m.y.a., most recent was the Ice Age (Pleistocene epoch) 2.5m.y.a. |
| Ice Age - | Appearance of continental glaciers marked the beginning -period when glaciers alternately advanced and retreated over North America -lasted for over 10,000 years |
| Interglacial periods | warmer periods bw glacial advances |
| conditions 22,000 yrs ago - | avg temp in Greenland was 18F lower than present -tropical avg temp 7F lower -sea level 395ft lower than present (bc more water in form of ice over land) -Bering Land Bridge was exposed allowing migration from Asia to N America |
| climate 14,000 y.a. | warm spell |
| conditions 12,700 y.a. | avg temp dropped, reverted back to glacial conditions -called Younger Dyras |
| conditions 11,700 y.a. | cold spell(aka Younger Dyras) ended abruptly, temps rapidly rose |
| conditions 6,000y.a. - | continental ice sheet over N America gone, warm spell called "mid-Holocene maximum" -plants developed (aka "climatic optimum") |
| conditions 5,000 y.a. | alpine glaciers returned, no continental glaciers |
| Medieval Climatic Optimum | 1000y.a., tranquil period of several hundred years over western Europe |
| 15th to 19th centuries in Western Europe | long winters, alpine glaciers formed, Viking colony in Greenland disappeared, cold period known as "Little Ice Age" |
| what happened in 1816? | "the year without a summer", cold summer followed by a bitterly cold winter (**occurred the year after huge volcanic eruption of Mt Tambora in Indonesia) |
| in the past 100 years when did the warming trend set in? - | in the 1970s that has lasted into the 21st century |
| what were the 2 warmest years over the past 1000 years? | 1998(major El Nino) and 2005(no El Nino) |
| where has the most warming occurred in the past 100 years? | Greatest warming in the arctic over mid-latitude continents winter/spring |
| Errors in temperature records - | recording stations have moved -measuring techniques varied -marine stations scarce -urbanization artificially raises temps of growing cities (urban heat island effect) |
| With errors taken into account what is the temp raise over the 20th century? | about 1F |
| Ove the past few decades what has the temp increase changed to? | change increases to 3.6F per century |
| Many scientists believe most of recent warming is due to what? | greenhouse effect, with increasing greenhouse gases, like CO2 levels |
| Three external causes to change in climate | change in incoming solar radiation, the composition of the atmosphere, and in earth's surface |
| Internal changes in climate | circulation patterns in the ocean/atmosphere(redistribute energy) |
| Water vapor-greenhouse feedback | during a warm spell, more water evaporating from the ocean, more water vapor absorbing infrared energy, greenhouse effect strengthened, cycle continues as air temp rises |
| what type of feedback mechanism is the Water vapor-greenhouse feedback? | positive because the increase in temp is reinforced by the other processes |
| Runaway greenhouse effect | if the processes were unchecked then the ocean would evaporate away |
| snow-albedo effect - | positive feedback mechanism -increase in global surface temp causes snow/ice to melt in polar altitudes -melting would reduce the albedo (reflectivity) of the surface, allowing more solar energy to reach surface further raising the temp |
| Snow-albedo effect on cooling planet - | lower temps allow for greater snow cover in middle/high latitudes, increasing the albedo of the surface which would reflect more sunlight back to space, reinforcing lower air temps and even more snow cover -still a positive feedback |
| Runaway ice age - | unchecked snow-albedo positive feedback in cooling period -highly unlikely bc of other mechanisms moderating the magnitude of cooling |
| Negative feedback mechanisms | weaken interactions among variables |
| Warming planet - | if more infrared radiation is emitted, the radiant energy from the surface would slow rising air temps and help stabilize the climate -this is the strongest type of negative feedback which lowers the possibility of a runaway greenhouse effect |
| Feedback mechanisms | earth's checks and balances that help counteract tendencies of climate change |
| Sunspots - | huge magnetic storms on the sun, seen as cooler/darker regions on it's surface -occur in cycles (max number and size occurs every 11 years) -During max sunspot periods sun emits more energy (.1% more) than minimum periods -bright areas (faculae) around |
| Maunder minimum (1645-1715) | period where there were few if any sunspots, same time as the "Little Ice Age", reduction in sun's energy output could be in part responsible for the cold spell |
| aerosols - | Microscopic liquid and solid particles -from human-induced or natural sources -can affect the climate -depends on particles' size, shape, color, chemical composition, vertical distribution |
| Sulfate aerosols - | when sulfur in the atmo combines with oxygen to form sulfur dioxide which converts into these aerosols -can be created by phytoplankton that release sulfur in the ocean which surfaces into the atmo -volcano eruptions also emit sulfur-rich aerosols -onl |
| what is the effect of sulfate aerosols? | cooling the surface by preventing the sun from reaching it |
| Volcanic eruptions - | fine particles of dust/ash can reach the stratosphere, eruptions with the greatest impact are those containing sulfur gases -The sulfur gases from the eruption combine with water vapor in the sunlight to produce tiny reflective sulfuric acid particles, w |
| effect of haze from volcanic eruptions on the atmosphere | Haze can last in stratosphere for years, absorbing and reflecting portion of sunlight back to space, which tends to cool earth's surface |
| What suggests volcanic eruptions may have played a part in cooling the atmo during the Little Ice Age? - | the greater the concentration of sulfuric acid particles in the atmo, the more acidic an ice layer -the Little Ice Age period corresponds to relatively acidic ice layers -suggesting volcanic eruptions may have played a role in cooling |
| human -induced aerosols | emissions from factories, autos, trucks, aircraft, power plants, home furnaces/fireplaces |
| what particles can cause a net cooling of surface air? | sulfates and nitrates, because they reflect incoming sunlight |
| what has more than doubled globally since pre-industrial years? | sulfate pollution, due to combustion of fossil fuels |
| how do sulfate aerosols affect clouds? - | serve as cloud condensation nuclei -have potential for altering the physical characteristics of a cloud -if these nuclei increase, then cloud droplets also increases -reflecting more sunlight/brightening the cloud/reducing sunlight that reaches the sur |
| Cooling effect from these particles (aerosols) could explain what 3 things? - | why regions of the N Hemi have warmed less than those of the S Hemi during the past decades -why the US has experienced less warming than rest of world -why up until last few decades most warming has occurred during night especially over polluted areas |
| The more CO2 in the atmosphere | the warmer the surface air |
| CO2 levels have been increasing mostly due to what? | human activity like burning fossil fuels, deforestation (through photosynthesis, leaves absorb the CO2 in the air, when a tree is cut down, that CO2 goes back out into the atmosphere) |
| clearing of forests will do what to the atmosphere? | lower evaporative cooling important to cooling of the atmosphere |
| Desertification - | reflectivity of that region would also change (like in overgrazing/excess cultivation of grasslands), causing an increase in desert conditions -Cause surface albedoes and dust swept into the air to increase |
| Annually millions of acres are reduced to uselessness through what? | overgrazing, overcultivation, poor irrigation practices, and deforestation |
| what does the newest global warming model take into consideration? - | interaction bw oceans and the atmo -cooling effect produced by sulfate aerosols in the lower atmo -processes by which CO2 is removed from the atmosphere |
| Radiative equilibrium | rate of incoming solar energy balances the outgoing rate of infrared energy |
| Radiative forcing agents | greenhouse gases disturbing this equilibrium |
| Radiative forcing - | increase/decrease in net radiant energy observed over an area at the tropopause -has increased by about 3 W^2/m^2 over past several hundred years with CO2 accounting for 60% of the increase |
| Natural events causing change | "solar irradiance" (changes in sun's energy output), and volcanic eruptions rich in sulfur |
| what kind of change came out of several major eruptions bw 1880-1920 and 1960-1991 and solar activity? | combined change in radiative forcing appeared to be negative, cooling earth's surface |
| noise | Natural climatic variations -in determining effect of human activity it is difficult to separate a signal from the noise -new model is better at filtering and taking into account the forcing agents that are both natural and human-induced |
| a model's projected temperature change closely matches observed temperature change when what factors are taken into account? | greenhouse gases, sulfate aerosols, and changes in solar radiation |
| What would happen if the amount of CO2 concentration was doubled? - | it would produce surface warming of about 3F -a surface increase of 2F would mean warming 3x greater than what was experienced in the 20th century |
| Alaskan tundra - | temps recently have exposed more melting soil -exposed decaying moss releases CO2 -tundra now acts as a producing source of CO2 |
| What greenhouse gas has been decreased since the 1990's? | CFCs or "halocarbons" |
| where is the majority of the ozone found? | stratosphere |
| What greenhouse gas has little effect on the greenhouse effect? | ozone, because of the fraction of concentration present near the surface, varies with photochemical smog |
| How climate responds to clouds depends on what factors of the cloud? | -type -height above the surface -physical properties (liquid water/ice content) -depth -droplet size distribution |
| what effect do high/thin/cirriform clouds (mostly ice) have on the climate? | warming effect bc they allow good amount of sunlight to pass through, bc they are cold they warm the atmo around them by absorbing more infrared radiation than they emit upward |
| what effect do low/stratified clouds (mostly water droplets) have on the climate? | cooling effect, reflect much of sun's incoming energy, tops are warm so they radiate to space much of which they absorb from earth |
| whose response to global warming will probably determine the global pattern and speed of climate change? | ocean temps, ocean circulations, and sea ice |
| when/where did the greatest surface warming period occur? | 2001-2006, occurred over landmasses in high-latitude N Hemi |
| As the world warms, what must increase to balance the increase of evaporation? | rainfall |
| what predictions are made about rainfall in the future? | increase in winter precip in high latitudes of the N Hemi, while overall decrease in precip in the subtropics |
| How high is the sea level supposed to rise in the next century? | an additional 12in or more this century, depending on how ice in Greenland and Antarctica melts |
| Where models predict precip to increase, what is also predicted? | more frequent/extreme flooding, with periods of little precip in between -less precip would mean more frequent/intense droughts |
| as the polar region warms, what would happen to the polar jet? | the temperature gradient would decrease, decreasing the strength of the polar jet, therefore decreasing diverging air above a storm -polar jet stream will move northward, and the mid-latitude cyclonic storms will also move north |
| As climate warms over continental US... - | conditions may become drier which would lead to fewer thunderstorms -Or, warmer conditions might initiate convection and maybe more storms |
| what are future expectations about hurricanes? | -warmer oceans, more water evaporation, more energy for hurricane development -more intense storms, stronger winds, heavier rainfall -longer hurricane season |
| Kyoto Protocol | 2005, 160 countries (not US) formal agreement to limit greenhouse gas emissions, mandatory targets to reduce gases by at least 5% in 5 yr period |
| Geoengineering | idea of reducing impact of climate change through global scale technological fixes, projects include: -fertilizing oceans with CO2 absorbing plants -putting reflective mirrors in space to reduce sunlight -changing reflective characteristics of clouds t |
| What would result from a reduction of air pollutants? | reduce acid rain, diminish haze, and slow production of photochemical smog |
Created by:
rudolph.beukes
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