chapter 19 global change 1. o global change- any chemical, biological or physical property change of...
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Chapter 19Global Change
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o Global change- any chemical, biological or physical property change of the planet.
o Global climate change- changes in the climate of the Earth.
o Global warming- the warming of the oceans, land masses and atmosphere of the Earth.
Global Change
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The Sun-Earth Heating System
The Greenhouse Effect1. Incoming solar energy = 100% - Radiation is absorbed by the clouds and the
surface of Earth thus becoming warmer.2. I/3 of all solar energy is reflected.3. Most of the infrared radiation from Earth is absorbed
by greenhouse gases in the atmosphere.- The rest is emitted back into space.- Known as the greenhouse effect.
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o Water vaporo Absorbs and
releases energy
o Carbon dioxide
o Methaneo Nitrous oxideo Ozoneo CFCs
Greenhouse Gases
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Greenhouse warming potential—ratio of how much a molecule of a compound can contribute to global warming over 100 years compared to 1 molecule of CO2
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1. Volcanic eruptionso CO2—long term effectso Particulate Matter — (ash) shorter term
o Ash reflects incoming solar radiation back to space, causes Earth’s temperature to decrease.
4 Natural Greenhouse Gases
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2. Methane – is created when there is not enough oxygen available to produce carbon dioxide during decomposition.
o Occurs at the bottom of wetlands – largest natural source of methane (anaerobic decomposition)
o Organism digestion, gut of a termite, no oxygen is present methane given off. Second largest source.
4 Natural Greenhouse Gases
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3. Nitrous oxideo Produced during denitrification
o NO3- N2O
o Occurs in a low oxygen environment such as soils at the bottom of wetlands, lakes, and oceans.
4 Natural Greenhouse Gases
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4. Water vaporo Most abundanto Greatest contributor
4 Natural Greenhouse Gases
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5 Anthropogenic Sources of Greenhouse Gases
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1. Burning of fossil fuelso Trapped reserves of CO2 plants don’t take in as
much as we are contributing during burning.o Coal v. Petroleum v. Natural gaso Particulate Matter
5 Anthropogenic Sources of Greenhouse Gases
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2. Agricultural practiceso Anaerobic conditions (CH4 and N2O)
o Irrigation and flooding for cultivating crops create low oxygen environments for bacteria.
o Fertilizerso Excess Nitrates are added denitrification = N2O
o Livestock o Digestion – sheep and cows rely on gut bacteria to
break down cellulose which produces a lot of CH4
o Manure lagoons – not aerated, decompose and release CH4
5 Anthropogenic Sources of Greenhouse Gases
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3. Deforestation…without replacemento Plants remove CO2
o Slash-and-burn method (shifting agriculture)releases CO2, CH4, and N2O
5 Anthropogenic Sources of Greenhouse Gases
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4. Landfillso Anaerobic methane generation from low oxygen
due to poor aeration.
5 Anthropogenic Sources of Greenhouse Gases
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5. Industrial productiono CFCs replaced by HCFCs
5 Anthropogenic Sources of Greenhouse Gases
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o David Keeling began measuring CO 2 in 1958.
Increasing CO2 Concentrations
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Emissions from the Developed and Developing
World
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o Indirect measurements—lack of recordso Changes in species compositions
o Foraminiferao Chemical analyses of ice
Temperatures and Greenhouse Gas Concentrations in Past
400,000 Years
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Historic CO2 Concentrations
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Historic CO2 Concentrations
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- We know that an increase in CO2 in the atmosphere causes a greater capacity for warming through the greenhouse effect.
- When the Earth experiences higher temperatures, the oceans warm and cannot contain as much CO2 gas and, as a result, they release CO2 into the atmosphere.
Putting It Together
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Evidence of Global Climate Change1. Global sea level rose about 17 centimeters (6.7 inches) in
the last century. The rate in the last decade, however, is nearly double that of the last century.
2. Average Arctic temperatures increased at almost twice the global average rate in the past 100 years. Shrinking glaciers and ice caps.
3. Most of this warming has occurred since the 1970s, with the 20 warmest years having occurred since 1981 and with all 10 of the warmest years occurring in the past 12 years.
4. Seasonal events starting earlier and ending later5. The top 700 meters (about 2,300 feet) of ocean showing
warming of 0.302 degrees Fahrenheit since 19696. The number of record high temperature events in the
United States has been increasing, while the number of record low temperature events has been decreasing, since 1950. The U.S. has also witnessed increasing numbers of intense rainfall events.
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Feedbacks
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Feedbacks
POSITIVE High C in soil High temperatures decomposition CO2 in
atmosphere
Tundra warms Anaerobic
decomposition CH4
NEGATIVE High CO2
plant growth Removes CO2
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1. Melting of polar ice caps, Greenland and Antarctica2. Melting of many glaciers around the world3. Melting of permafrost4. Rising of sea levels due to the melting of glaciers and ice sheets and as water warms it expands5. Heat waves6. Cold spells7. Change in precipitation patterns8. Increase in storm intensity9. Shift in ocean currents
Consequences to the Environment From Global
Warming
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North Pole is currently 39% smaller than it was in 1979
The Melting Polar Ice Cap
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1.Thermal expansion2.Additions of water from melting ice
Rising Sea Levels
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o Wild plants and animals can be affected. The growing season for plants has changed and animals have the potential to be harmed if they can’t move to better climates.
o Humans may have to relocate, some diseases like those carried by mosquitoes could increase and there could be economic consequences.
Consequences to Living Organisms
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Consequences to Living Organisms
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o The fundamental basis of climate change- that greenhouse gas concentrations are increasing and that this will lead to global warming is not in dispute among the vast majority of scientists.
o What is unclear is how much world temperatures will increase for a given change in greenhouse gases, because that depends on the different feedback loops.
The Controversy of Climate Change
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o 1997, Japan--discuss how best to control emissions contributing to global warming.
o Green house gas emissions from all industrialized countries will be reduced to 5.2% below their 1990 levels by 2012.
o Developing nations did not have emission limits imposed by the protocol.
The Kyoto Protocol