Presentation on theme: "GreeNHouse GaSes: “Thickening the Earth’s Blanket”"— Presentation transcript:
1GreeNHouse GaSes: “Thickening the Earth’s Blanket” Climate Alteration & Global Warming
2What are Greenhouse gases? Greenhouse gases are gases that trap heat in the atmosphere.Main Greenhouse GasesCarbon Dioxide, CO2Methane, CH4Nitrous Oxide, N2OFluorinated Gases
3Carbon Dioxide How can carbon dioxide enter the atmosphere? Burning fossil fuels coal, natural gas and oilBurning solid waste, trees and wood productsAs a result of certain chemical reactionsFor example: manufacture of cementHow is carbon dioxide removed (sequestered) from the atmosphere?When absorbed by plantsPart of the biological carbon cycle
4Methane How can methane enter the atmosphere? During production of coal, natural gas, and oilDuring transport of coal, natural gas, and oilResult from livestock and other agricultural practicesDecay of organic waste in municipal solid waste landfillsHow is methane removed from the atmosphere?See Hand-out
5Nitrous Oxide & Fluorinated Gases How can nitrous oxide enter the atmosphere?During agricultural activitiesDuring industrial activitiesDuring combustion of fossil fuels and solid wasteWhat are fluorinated gases?Synthetic, potent, powerful greenhouse gases that are emitted from a variety of industrial processesHydrofluorocarbons, perfluorocarbons, sulfur hexafluorideSometimes used as substitutes for stratospheric ozone-depleting substancesEmitted in small quantities, as they are categorized “High Global Warming Potential gases”
6What factors determine each gases effect on climate change? How much of each is present in the atmosphere?Concentrations measured in parts per million, billion, or trillionOne part per million : one drop of a substance diluted into about 13 gallons of another substanceHow long do they remain in the atmosphere?Range: a few years to 1000s of yearsLong enough to become well mixedAmount measured of a particular gas in the atmosphere is the same all over the globeRegardless of source of emmisionsWhat is their impact on global temperatures?Gases that absorb more energy per pound contribute more to global warming
7The Sun-Earth Heating System What makes our planet warm?
8- Heating System 1. The Sun 2. The Earth The Sun radiates energy Visible radiation aka Visible light high energyUltraviolet radiation aka UV lightThe Sun’s energy strikes the EarthResult: The planet warms2. The EarthThe planet radiates energyInfrared radiation aka Infrared light lower energyRadiation you can’t see, but can feelFor example: the heat you feel being radiated from the hot asphaltThis radiation of lower energy is radiated because Earth is not as hot as the Sun.
9How does infrared radiation have an effect on the planet’s warmth? Note: Infrared radiation doesn’t pass through the atmosphere as easily as UV and visible radiationInfrared radiation is ABSORBED by greenhouse gasesThis warms the greenhouse gasesThe greenhouse gases emit infrared radiationSome of this emitted infrared radiation goes into space and the rest goes back toward Earth*The Greenhouse Effect
10Greenhouse Gases, continued Review: Greenhouse gases are gases that trap heat in the atmosphere.Gases N2 and O2 compromise 99% of the atmosphere; they don’t absorb infrared radiation; they are not greenhouse gases, therefore they don’t contribute to the warming of the EarthGreenhouse gases make up a small fraction of the atmosphere.Most common greenhouse gas is water vapor (H2O)Water vapor absorbs more infrared radiation from Earth than any other compound.Water vapor does not persist as long as other greenhouse gases.Certain greenhouse gases have been apart of the atmosphere for millions of years, and have kept Earth warm enough so that it could remain inhabitable.Water vapor, carbon dioxide, methane, nitrous oxide, ozoneWithout any greenhouse gases the average temperature would be 0°FSo what’s the problem?
11The Danger of Greenhouse Gases There is a growing concern that an increase in concentration of these gases may cause the planet to warm even more.Example: CFCs don’t exist naturally and occur in the atmosphere due to synthesis by humans.Each gas has a greenhouse warming potential.Estimates how much a molecule of any compound can contribute to global warming over 100 years relative to 1 molecule of CO2
12Consequences of Global Warming To the Environment & ORganisms Chapter 14 continued
13How is global warming expected to affect the environment? Effects already happening to the Environment due to warming temperaturesMelting of polar ice capsMelting of glaciersMelting of permafrostRising sea levelsEffects predicted to occur in the futureAn increased frequency of heat wavesReduced cold spellsAltered precipitation patterns and storm intensityShifting ocean currents
14How is global warming expected to affect the organisms living on Earth? Global warming affects wild plants and animals.Intergovernmental Panel on Climate Change, IPCC, reviewed 2,500 scientific papers on the effects of warmer temperatures of plants and animals.Growing season for plants lengthened in Northern HemisphereMany of species of plants flower earlierBirds arrive at their breeding grounds earlierInsects emerge earlier in the Northern HemisphereCorals are sensitive to global warming their range of temperature tolerance is very smallCauses of coral bleaching are warming oceans, pollution, and sedimentationMore coral bleaching is expected from global warming even if the climate changes are kept small
15Consequences to Humans Global warming could affect humans in the following ways…HabitationSome people will have to relocate from such vulnerable areas as coastal communities and some ocean islands.Rebuild communities close to or along coastlines on higher groundWill face severe consequences from flooding and saltwater intrusion if they can’t relocate financial difficulty?Water availability might limit an areas habitabilityThe alternative: some areas might become more hospitable if they become warmerHealthTourism
16Climate Alteration & Global Warming Examining the feedback cycles: the way they influence temperatures on EarthClimate Alteration & Global Warming
17The Complexity in Predicting Global Warming & Climate Change Positive and Negative feedback loops make predicting global warming and climate change complex.What is a feedback?A feedback is an adjustment in input or output rates caused by changes to a system.They are diagrammed as loops/cycles.What are positive and negative feedback loops?A positive feedback loop is a feedback loop in which change in a system is amplified.A negative feedback loop is a feedback loop in which a system responds to a change by returning to its original state, or by decreasing the rate at which the change is occurring.
18Examples of Feedback Loops Positive Feedback LoopExample: warmer soils increasing their rates of decomposition and thereby increasing their emission of carbon dioxideNegative Feedback LoopExample: plants being able to increase their growth under elevated carbon dioxide environments, thereby reducing some of the carbon dioxide in the atmosphere
19Positive Feedbacks A More Troubling Example: A rise in temperature could create a positive feedback.Higher temperatures are expected to biological activity of decomposers in soils rich in carbon dioxide; decomposition leads to the release of additional carbon dioxide from soil to atmosphereMore Carbon dioxide in the atmosphere means temperature change will be amplified moreA More Troubling Example:In Tundra biomes containing permafrost- as carbon dioxide concentrations from anthropogenic sources, the region warms and the frozen tundra thaws; areas of standing water with little oxygen beneath the water develop; organic layers decompose (anerobic decomposition) which produces methane leading to even more global warmingMethane is a stronger greenhouse gas than carbon dioxide
20Negative Feedback Loops A rise in temperature could create a negative feedback.An increase in carbon dioxide can stimulate plant growth (Review: Carbon dioxide is needed for plant growth.) More plants = more carbon dioxide removed from the atmosphere; carbon dioxide and temperature increases are smaller than they would have been.This feedback may be one important reason why only ½ of carbon dioxide emissions from anthropogenic sources have remained in the atmosphere
21Feedbacks can be limited by features of the systems in which they take place. Carbon-soil feedback limited by amount of carbon in soilsEventually soil stocks will become lowEnhanced carbon dioxide uptake by plants is limited because only some plants benefit from carbon dioxide fertilization; also enhancement happens only until another factor becomes limiting- water and nutrient limiting
22Global change needs to be addressed at the international level. Climate Alteration and Global Warming
23Global change needs to be addressed at the international level. Why? The scale of impact is very large, and people and ecosystems affected can be distant from the cause.Review: What is global change? Change that occurs in the chemical, biological, physical properties of the planet
24Kyoto ProtocolThe nations of the world must work together to address the problem of global warming.The Kyoto Protocol – an international agreement to reduce global emissions of greenhouse gases from all industrialized countries to 5.2 percent or below their 1990 levels by 2012As of 2010, 190 countries had ratified (sign or give formal consent to) the Kyoto Protocol – The U.S. is the ONLY developed country that has not yet ratified the agreement
25Kyoto Protocol cont. Who?: Representatives of the nations of the world What?: Addressing Climate Change InternationallyMeeting was to discuss how best to control the emissions contributing to global warmingAn agreement that global emissions of greenhouse gases from all industrialized countries would be reduced by 2012Developing nations didn’t have emission limits imposed by the protocol –i.e. India, China.Why?Developing countries are unfairly exposed to consequences of global warming that mostly come from developed nations –i.e. U.S. (7% reduction), countries of the European Union (8% reduction).Having countries who emit the most emissions pay most of the cost of reducing emissions seemed fair.Where?: Kyoto, JapanWhen?: 1997
26Kyoto Protocol cont.Why?: There is sufficient evidence to suggest human activities are altering the global climate.Therefore, there is a need to stabilize greenhouse gases by…Reducing emisionsOr removing gases from the atmosphere
27Kyoto Protocol cont. How?: How can we reducing emmisions? Increase fuel efficiency or switch from coal and oil to energy sources (natural gas, solar energy, wind-powered energy, nuclear energy) that emit less or no carbon dioxideHow can we removing gases from the atmosphere?Carbon sequestrationInvolves taking carbon dioxide out of the atmosphereMethods to do this include storing carbon n soils, retiring agriculture land by allowing it to become pasture or forest (storage in plant biomass or soil carbon)New science: capturing carbon dioxide from air, compressing it, and pumping it into oil wells or the deep oceanWe don’t know yet how this exactly effects the environment
28What has the U.S. done?The U.S. Supreme Court required that the EPA had to regulate emissions of greenhouse gases as part of the CLEAN AIR ACT.EPA proposed increase in fuel efficiency requirements for cars (would bring a 30% reduction in carbon dioxide and other gases by 2016, and REDUCE U.S. CONSUMPTION OF FOSSIL FUELS).But has still not ratified the Kyoto Protocol.