GreeNHouse GaSes : “ Thickening the Earth’s Blanket”. Climate Alteration & Global Warming. What are Greenhouse gases?. Greenhouse gases are gases that trap heat in the atmosphere. Main Greenhouse Gases Carbon Dioxide, CO 2 Methane, CH 4 Nitrous Oxide, N 2 O Fluorinated Gases.
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GreeNHouseGaSes:“Thickening the Earth’s Blanket” Climate Alteration & Global Warming
What are Greenhouse gases? • Greenhouse gases are gases that trap heat in the atmosphere. • Main Greenhouse Gases • Carbon Dioxide, CO2 • Methane, CH4 • Nitrous Oxide, N2O • Fluorinated Gases
Carbon Dioxide • How can carbon dioxide enter the atmosphere? • Burning fossil fuels coal, natural gas and oil • Burning solid waste, trees and wood products • As a result of certain chemical reactions • For example: manufacture of cement • How is carbon dioxide removed (sequestered) from the atmosphere? • When absorbed by plants • Part of the biological carbon cycle
Methane • How can methane enter the atmosphere? • During production of coal, natural gas, and oil • During transport of coal, natural gas, and oil • Result from livestock and other agricultural practices • Decay of organic waste in municipal solid waste landfills • How is methane removed from the atmosphere? • See Hand-out
Nitrous Oxide & Fluorinated Gases • How can nitrous oxide enter the atmosphere? • During agricultural activities • During industrial activities • During combustion of fossil fuels and solid waste • What are fluorinated gases? • Synthetic, potent, powerful greenhouse gases that are emitted from a variety of industrial processes • Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride • Sometimes used as substitutes for stratospheric ozone-depleting substances • Emitted in small quantities, as they are categorized “High Global Warming Potential gases”
What 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 trillion • One part per million : one drop of a substance diluted into about 13 gallons of another substance • How long do they remain in the atmosphere? • Range: a few years to 1000s of years • Long enough to become well mixed • Amount measured of a particular gas in the atmosphere is the same all over the globe • Regardless of source of emmisions • What is their impact on global temperatures? • Gases that absorb more energy per pound contribute more to global warming http://www.epa.gov/climatechange/ghgemissions/gases.html
The Sun-Earth Heating System What makes our planet warm?
- Heating System 1. The Sun • The Sun radiates energy • Visible radiation aka Visible light high energy • Ultraviolet radiation aka UV light • The Sun’s energy strikes the Earth • Result: The planet warms 2. The Earth • The planet radiates energy • Infrared radiation aka Infrared light lower energy • Radiation you can’t see, but can feel • For example: the heat you feel being radiated from the hot asphalt • This radiation of lower energy is radiated because Earth is not as hot as the Sun.
How 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 radiation • Infrared radiation is ABSORBED by greenhouse gases • This warms the greenhouse gases • The greenhouse gases emit infrared radiation • Some of this emitted infrared radiation goes into space and the rest goes back toward Earth *The Greenhouse Effect
Greenhouse 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 Earth • Greenhouse 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, ozone • Without any greenhouse gases the average temperature would be 0°F • So what’s the problem?
The 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
Consequences of Global Warming To the Environment & ORganisms Chapter 14 continued
How is global warming expected to affect the environment? • Effects already happening to the Environment due to warming temperatures • Melting of polar ice caps • Melting of glaciers • Melting of permafrost • Rising sea levels • Effects predicted to occur in the future • An increased frequency of heat waves • Reduced cold spells • Altered precipitation patterns and storm intensity • Shifting ocean currents
How 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 Hemisphere • Many of species of plants flower earlier • Birds arrive at their breeding grounds earlier • Insects emerge earlier in the Northern Hemisphere • Corals are sensitive to global warming their range of temperature tolerance is very small • Causes of coral bleaching are warming oceans, pollution, and sedimentation • More coral bleaching is expected from global warming even if the climate changes are kept small
Consequences to Humans • Global warming could affect humans in the following ways… • Habitation • Some 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 ground • Will face severe consequences from flooding and saltwater intrusion if they can’t relocate financial difficulty? • Water availability might limit an areas habitability • The alternative: some areas might become more hospitable if they become warmer • Health • Tourism
Examining the feedback cycles: the way they influence temperatures on Earth Climate Alteration & Global Warming
The 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.
Examples of Feedback Loops • Positive Feedback Loop • Example: warmer soils increasing their rates of decomposition and thereby increasing their emission of carbon dioxide • Negative Feedback Loop • Example: plants being able to increase their growth under elevated carbon dioxide environments, thereby reducing some of the carbon dioxide in the atmosphere
Positive Feedbacks • 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 atmosphere • More Carbon dioxide in the atmosphere means temperature change will be amplified more • A 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 warming • Methane is a stronger greenhouse gas than carbon dioxide
Negative 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
Feedbacks can be limited by features of the systems in which they take place. • Carbon-soil feedback limited by amount of carbon in soils • Eventually soil stocks will become low • Enhanced 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
Global change needs to be addressed at the international level. Climate Alteration and Global Warming
Global 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
Kyoto Protocol • The 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 2012 • As 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
Kyoto Protocol cont. • Who?: Representatives of the nations of the world • What?: Addressing Climate Change Internationally • Meeting was to discuss how best to control the emissions contributing to global warming • An agreement that global emissions of greenhouse gases from all industrialized countries would be reduced by 2012 • Developing 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, Japan • When?: 1997
Kyoto 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 emisions • Or removing gases from the atmosphere
Kyoto 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 dioxide • How can we removing gases from the atmosphere? • Carbon sequestration • Involves taking carbon dioxide out of the atmosphere • Methods 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 ocean • We don’t know yet how this exactly effects the environment
What 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.