Chapter 14: Atmosphere Resources and Climate Change
Chapter 14: Atmosphere Resources and Climate Change GEOL 1005
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Date Created: 10/19/15
GEOL 1005 Chapter 14 Atmosphere Resources and Climate Change 14 What Atmosphere Resources Are Nitrogen 7808 oxygen 2096 and argon 093 Cryogenic distillation distillation at very low temperatures at which gases become liquids and boil it is used to separate individual gases such as nitrogen from the atmosphere 142 Air Pollution Pollutants any substance that make air unsafe or dirty Common air pollutants Volatile organic compounds Nitrogen oxides Sulfur dioxide Carbon monoxide Carbon dioxide not considered a common air pollutant by the EPA but the Supreme Court ruled to monitor emissions Common greenhouse gases Water vapor Methane Carbon dioxide Nitrous oxide VOCs are an air pollution concern because in the presence of sunlight they participate in chemical reactions that lead to smog Nitrogen Oxides NOX ratio of nitrogen to oxygen atoms varies from compound to compound At high combustion temperatures nitrogen and oxygen in the air and in fuel combine to form NOX that is emitted as part of the exhaust gas NOX is the key ingredient in the formation of smog Sulfur dioxide S02 during combustion sulfur combines with oxygen to form sulfur dioxide which becomes part of exhaust emissions sulfur is a common ingredient in oil and coal Carbon monoxide CO colorless odorless tasteless and dangerous gas produced by incomplete combustion of fossil fuels Carbon dioxide C02 causes climate change and global warming coal is a key source of air pollution smog dense hazy air pollution that obscures visibility produced by the photochemical reaction of sunlight with hydrocarbons and nitrogen oxides released into the atmosphere especially by automotive emissions CO NOX and VOC emissions from vehicles cause most of today s smog problems VOCs and NOX are highly reactive in sunlight Photochemical smog brownish haze that settles over cities especially on warm sunny days NOx and 802 can react with water in the atmosphere to form droplets of acid Acid rain must have a pH of less than 56 Acid rain will damage plant leaves and degrade soil by dissolving nutrients and harming soil life The ozone layer in the atmosphere absorbs shorterwavelength ultraviolet radiation in sunlight that would otherwise by lethal to surface life CFCs are hydrocarbon compounds that contain uorine and chlorine When released into the atmosphere CFCs can persist unchanged for a long time some 50 to 200 years They don t dissolve in rain and get thoroughly mixed in the troposphere Some make it to the stratosphere and destroy ozone Ozone hole appearing Montreal Protocol bans certain chemicals and amount introduced into atmosphere 143 The Atmosphere and Climate Change The components of the atmosphere that in uence climate are water vapor carbon dioxide methane nitrogen oxide and air pollutants These are all greenhouse gases Solar radiation drives atmosphere and hydrosphere circulation the circulation then shifts air masses water and the energy around the world Over the next 2 billion years the average global temperate could rise by 10 degrees Celsius Sunspot cycle energy emitted by the sun varies a small amount over 11year periods Sunspots areas of intense magnetic activity visible on the Sun s surface as relatively dark areas Luminosity axis tilt orbital eccentricity precession and Milankovitch cycles all affect Earth s climate Earth s orbit varies over time from being perfectly circular to slightly elliptical Eccentricity the degree to which the orbit varies from a perfect circle Precession the Earth wobbles as it orbits the Sun Glacial maximums periods when ice sheets reached their maximum extent Interglacial periods periods of warmer climate Milutin Milankovitch proposed that cyclic changes in axis tilt orbital eccentricity and precession cycles led to cycles of colder climate and warmer climate Continent size and distribution mountain ranges and volcanoes also affect climate Silicate weathering is more extensive under the following conditions If plate tectonics splits continents into smaller fragments surrounded by oceans creating wetter conditions If the continental pieces are preferentially located at lower latitudes creating warmer conditions In mountain belts from here and there increasing crustal exposure and erosion 144 History of Climate Change Paleoclimatologists scientists who study past climate Tillite rock formed from an unstructured mix of mud and rock fragments Plants are very adaptive to climate change and distinctive plant fossils can be used to indicate past climates in a region Sedimentary rocks fossils oxygen isotopes atmosphere samples from ice cores and sea level history can be used to determine past climates Changes caused by movement to tectonic plates Seaways that allowed equatorial ow and global distribution of warm waters were blocked by converging continents Seaways were opened around Antarctica that led to circumpolar ocean currents and isolation of this continent from ows of warm equatorial water Convergent plate boundaries created mountain belts Mountain formation led to the increased removal of atmospheric carbon dioxide by silicate weathering process 145 People and Climate Change About 7000 years ago carbon dioxide concentrations started to rise instead of decline along the expected trend Methane concentrations began increasing instead of decrease about 5000 years ago Decreasing atmospheric carbon dioxide leads to global cooling Increasing atmospheric carbon dioxide concentration has started surface and ocean temperature rising Global climate models GCMS quantitative simulation that represents the interaction of the major components of the climate systems solar radiation atmosphere oceans land and ice Feedback mechanisms response to a change in the climate system that either amplifies the change or diminishes the change Positive feedback mechanism amplifies the change Negative feedback mechanism diminishes the change Examples of negative and positive feedback mechanisms page 455 The global climate system is dynamic and changes in response to its changes Global warming causes seal level to rise in two ways the oceans expand as they warm and they receive water from melting ice sheets Causes and effects of ongoing climate change Widespread melting of snow and ice and rising average sea level Increase in greenhouse gas emissions Increase in global average temperatures 146 Dealing with climate change Kyoto protocol imposes national caps on greenhouse gas emissions at a level 5 below their 1990 levels Carbon sequestration capturing and storing of carbon dioxide emitted by hydrocarbon burning Geosequestration storage of carbon in underground reservoirs