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Global warming
This document discusses global warming and its potential causes and consequences. It begins with an introduction that asks whether the world is getting warmer, if human actions are responsible, and what can be done about it. It then covers the history of Earth's climate over billions of years, influenced by factors like the sun's energy output, lifeforms, and orbital variations. Recent temperature changes are examined, showing a general warming trend over the last century. Potential consequences of further warming discussed include rising sea levels, stronger hurricanes, effects on wildlife and humans. The document considers a range of perspectives on both natural and human influences on the climate.
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Global warming
- 1. Global Warming Will Human-InducedClimate Change Destroy the World? By Rich Deem www.GodAndScience.org Note: This slideshow is NOT meant to be printed. View in slideshow mode only because of extensive builds and animations. Go to the website for a printable copy. Requires PowerPoint 2003 or PowerPoint Viewer 2003.
- 2. Introduction • Is theworld getting warmer? • If so, are the actions of mankind to blame for earth’s temperature increases? • What can/should be done about these issues? • Are the potential resolutions worth the cost to implement them?
- 3. History of Earth’sClimate • Earth formed ~4.6 billion years ago • Originally very hot • Sun’s energy output only 70% of present • Liquid water present ~4.3 billion years ago (zircon dating) • Much of earth’s early history erased during late heavy bombardment (~3.9 billion years ago)
- 4. History of Earth’sClimate • Life appeared ~3.8 billion years ago • Photosynthesis began 3.5-2.5 billion years ago Produced oxygen and removed carbon dioxide and methane (greenhouse gases) Earth went through periods of cooling (“Snowball Earth”) and warming • Earth began cycles of glacial and interglacial periods ~3 million years ago
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- 10. Earth’s Atmospheric Gases Nitrogen(N2) Oxygen (O2) Water (H2O) Carbon Dioxide (CO2) 99% Methane (CH4) 1% Non- Greenhouse Gases Greenhouse Gases
- 11. Sun Runaway GreenhouseEffect • 97% carbon dioxide • 3% nitrogen • Water & sulfuric acid clouds • Temperature: 860°F Venus
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- 13. 170 220 270 320 370 420 200000400000600000 Time (YBP) CO2(ppm) Vostok IceCoreDome Concordia Carbon Dioxide Levels 0 Muana Loa Readings CO2 Levels Since 1958 310 330 350 370 10203040 CO2(ppm) 0
- 14. Worldwide Carbon EmissionsCarbon(109 metrictons) 0 1 2 3 4 5 6 7 8 17501800 1850 1900 1950 2000 Year Liquid fuel Total Gas fuel Solid fuel
- 15. Annual Carbon Emissions Annualcarbon emissions Atmospheric CO2 Atmospheric CO2 average 1955 1965 1975 1985 1995 2005 0 4 6 8 2 Year Carbon(109 metrictons)
- 16. Future Carbon DioxideLevels • Increasing CO2 emissions, especially in China and developing countries • Likely to double within 150 years: Increased coal usage Increased natural gas usage Decreased petroleum usage (increased cost and decreasing supply)
- 17. Kyoto Protocol • Adoptedin 1997 • Cut CO2 emissions by 5% from 1990 levels for 2008-2012 • Symbolic only, since cuts will not significantly impact global warming
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- 19. -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1880 1900 19201940 1960 1980 2000 Year ∆MeanTemperature(°C) Recorded Worldwide Temperatures Flat Decreasing
- 20. Winter Temperatures 10 11 12 13 14 15 16 17 1880 19001920 1940 1960 1980 2000 Year Summer Temperatures 18 19 20 21 22 23 24 25 1880 1900 1920 1940 1960 1980 2000 Year Annual Temperatures 15 16 17 18 19 20 21 22 1880 1900 1920 1940 1960 1980 2000 Year Temperature(°C) Historic Los Angeles Temperatures
- 21. -3 -2.5 -1.5-1 -.5 -.1 .1 .5 1 1.5 2.5 3.4 2007 Temperature Changes Compared to 1951-1980
- 22. Past Temperatures Measurement •Proxy – a method that approximates a particular measurement (e.g., temperature) Ice cores Pollen records Plant macrofossils Sr/Ca isotope data Oxygen isotopes from speleothem calcite (stalactites and stalagmites)
- 23. Temperature History ofthe Earth • Little ice age (1400-1840) – 1°C cooler • Medieval warm period (800-1300) – 1°C warmer than today • Cool/warm cycles occur ~1,500 years • Affect mostly Northeastern U.S. and North Atlantic • Mostly due to changes in thermohaline circulation → • Dramatic shutdown of thermohaline circulation occurred 8,200 years ago as a large lake in Canada flooded the North Atlantic
- 24. Main Ocean Currents Adaptedfrom IPCC SYR Figure 4-2
- 25. Temperature History ofthe Earth • For the past 3 million years, the earth has been experiencing ~100,000 year long cycles of glaciation followed by ~10,000 year long interglacial periods • These climate periods are largely the result of cycles in the earth’s orbit – precession, obliquity, and eccentricity
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- 28. Orbital Parameters: Eccentricity PerihelionApehelionApehelion Minimum:0.005 Maximum: 0.061 Not to scale!To Scale!
- 29. Orbital Parameters &Earth’s Climate Age (kya) 1000900 800 700 600 500 400 300 200 100 0 Eccentricity (100 ky) Temperature Obliquity (41 ky) Precession (22 ky)
- 30. Temperature History ofthe Earth • For the past 3 million years, the earth has been experiencing ~100,000 year long cycles of glaciation followed by ~10,000 year long interglacial periods • Last ice age began to thaw 15,000 years ago, but was interrupted by the “Younger Dryas” event 12,900 years ago
- 31. Younger Dryas Younger Dryas Event -55 -50 -45 -40 -35 -30 -25 05101520 Age(kya) Temperature(°C) 0.05 0.10 0.15 0.20 0.25 0.30 0.35 SnowAccumulation(m/yr) Little Ice Age Ice Age Medieval Warm
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- 33. Temperature History ofthe Earth Middle Pliocene (3.15 to 2.85 million ya) • Temperatures: 2°C higher than today. 20°C higher at high latitudes 1°C higher at the Equator • Sea levels were 100 ft higher • Causes CO2 levels that were 100 ppm higher Increased thermohaline circulation
- 34. Temperature History ofthe Earth Eocene (41 million years ago) • Opening of the Drake Passage (between South America and Antarctica). • Increased ocean current exchange Strong global cooling First permanent glaciation of Antarctica ~34 million years ago
- 35. Temperature History ofthe Earth Paleocene Thermal Maximum (55 mya) • Sea surface temperatures rose 5-8°C • Causes Increased volcanism Rapid release of methane from the oceans
- 36. Temperature History ofthe Earth Mid-Cretaceous (120-90 mya) • Much warmer • Breadfruit trees grew in Greenland • Causes Different ocean currents (continental arrangement) higher CO2 levels (at least 2 to 4 times higher than today, up to 1200 ppm)
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- 38. “Hockey Stick” Controversey 10001200 1400 1600 1800 2000 -0.8 Year -0.6 -0.4 -0.2 0 0.2 0.4 0.6 TemperatureChange(°C) Direct temperature measurements Mann et al. 1999
- 39. Mann et al.1999 Esper et al. 2002 800 1000 1200 1400 1600 1800 -2 -1 0 1 2 TemperatureChange(°C) 2000 Year Is the Hockey Stick Correct?
- 40. Is the HockeyStick Correct? -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0 400 800 1200 1600 2000 Year TemperatureChange(°C) Mann et al. 1999 Esper et al. 2002 Moberg et al. 2005 Mann et al. 2008
- 41. U.S. National Academyof Sciences: June 2006 1000 1200 1400 1600 1800 2000 -0.8 Year -0.6 -0.4 -0.2 0 0.2 0.4 0.6 TemperatureChange(°C) “high level of confidence”“2:1 chance of being right”
- 42. -1.0 -0.5 0.0 0.5 1.0 1.5 1980 1990 2000 Year -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 19801990 2000 Year TemperatureCgange(°C) Atmospheric Temperatures Troposphere Stratosphere
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- 45. Global Warming PrimarilyImpacts the Northern Hemisphere -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1920 1960 2000 Year TemperatureChange(°C) 1920 1960 2000 Year Northern vs. Southern Latitude Land vs. Ocean Northern Hemisphere Southern Hemisphere Land Ocean
- 46. 2007 Temperature Changes Comparedto 1951-1980 -3 -2.5 -1.5 -1 -.5 -.1 .1 .5 1 1.5 2.5 3.4
- 47. Ice Sheets Melting? •GRACE (gravity measured by satellite) found melting of Antarctica equivalent to sea level rise of 0.4 mm/year (2 in/century) • Zwally, 2005 (satellite radar altimetry) confirmed Antarctica melting Greenland ice melting on exterior, accumulating inland (higher precipitation)
- 48. Melting Glaciers –Mt. Kilimanjaro
- 49. 1000 800 600 400 200 0 -200 -400 -600 2003 2004 2005 IceMass(km3 ) Year Changesin Antarctica Ice Mass
- 50. Rise in SeaLevels? • Present rate is 1.8 ± 0.3 mm/yr (7.4 in/century) • Accelerating at a rate of 0.013 ± 0.006 mm/yr2 • If acceleration continues, could result in 12 in/century sea level rise • Scenarios claiming 1 meter or more rise are unrealistic
- 51. Changing Sea Levels 17001750 1800 1850 1900 1950 2000 -20 -10 0 10 20 RelativeSeaLevel(cm) Adapted from IPCC SYR Figure 2-5 Amsterdam, Netherlands Brest, France Swinoujscie, Poland GlobalTemperatureChange
- 52. Time (KYBP) SeaLevel(m) 20 0 -20 -40 -60 -80 -100 -120 Sea Levelsfor 450,000 Years 450 400 350 300 250 200 150 100 50 0 25 26 27 28 29 30 31 SST(°C)TropicalPacific
- 53. Increase in Hurricanes? •Two studies showed the total number of hurricanes has not changed • However, the intensity of hurricanes has increased (more category 4 and 5 hurricanes and cyclones) • Probably due to higher sea surface temperatures (more energy) • Difficult to know if this trend will continue 1860 1880 1900 1920 1940 1960 1980 2000 2020 0 5 10 15 Data Unreliable Scaled August-October Sea-Surface Temperature Adjusted Atlantic Storm Power Dissipation Index SST/SPDI(meters3 /sec2 )
- 54. How Much Temperature Increase? •Some models propose up to 9°C increase this century • Two studies put the minimum at 1.5°C and maximum at 4.5°C or 6.2°C • Another study puts the minimum at 2.5°C
- 55. Wildlife Effects • PolarBears Require pack ice to live Might eventually go extinct in the wild • Sea turtles Breed on the same islands as their birth Could go extinct on some islands as beaches are flooded • Other species may go extinct as rainfall patterns change throughout the world
- 56. Effect on Humans •Fewer deaths from cold, more from heat • Decreased thermohaline circulation Cooler temperatures in North Atlantic • CO2 fertilization effect • Precipitation changes Droughts and famine (some areas) Expanded arable land in Canada, Soviet Union
- 57. Potential Worldwide Precipitation Changes -50-20 -10 -5 5 10 20 50
- 58. Drought in Africa LakeFaguibine Lake Chad
- 59. Cost to StabilizeCO2 Concentrations 450 550 650 750 1800 1600 1400 1200 1000 800 600 400 200 0 Carbon Dioxide (ppm) Cost(TrillonsU.S.Dollars)
- 60. Possible Solutions to GlobalWarming
- 61. Mitigation of GlobalWarming • Conservation Reduce energy needs Recycling • Alternate energy sources Nuclear Wind Geothermal Hydroelectric Solar Fusion?
- 62. Storage of CO2in Geological Formations 1. Depleted oil and gas reservoirs 2. CO2 in enhanced oil and gas recovery 3. Deep saline formations – (a) offshore (b) onshore 4. CO2 in enhanced coal bed methane recovery Adapted from IPCC SRCCS Figure TS-7 3a3a 22 3b3b 11 44
- 63. Conclusions • Global warmingis happening • Most warming is probably the result of human activities • There will be positive and negative (mostly) repercussions from global warming • The costs to mitigate global warming will be high – better spent elsewhere?
Editor's Notes
- #2 This slideshow present an overview of global warming issues, last updated 8/11/2006. A more detailed analysis of global warming issues is available at http://www.godandscience.org/apologetics/global_warming.html, including a printable PDF version.
- #3 In examining global warming, we will be looking at questions such as Is the world getting warmer? If so, are the actions of mankind to blame for earth’s temperature increases? What can or should be done about global warming? Are the potential resolutions to global warming worth the cost to implement them?
- #4 This is a big picture examination of the earth’s climate The Earth was formed around 4.6 billion years ago And was originally very hot However, the Sun’s energy output was only 70% of what it is presently Liquid water was present on the surface around 4.3 billion years ago, according to zircon dating However, much of earth’s early history was erased during late heavy bombardment, which took place around 3.9 billion years ago
- #5 The first life forms appeared ~3.8 billion years ago Photosynthesis began 3.5-2.5 billion years ago, which produced oxygen and removed carbon dioxide and methane, which are greenhouse gases, from the atmosphere As a result, the Earth went through periods of cooling, commonly referred to as “Snowball Earth” and subsequent warming Earth began its current cycles of glacial and interglacial periods around 3 million years ago
- #6 The temperature of the earth is directly related to the energy input from the Sun. Some of the Sun’s energy is reflected by clouds. Other is reflected by ice. The remainder is absorbed by the earth.
- #7 If amount of solar energy absorbed by the earth is equal to the amount radiated back into space, the earth remains at a constant temperature.
- #8 However, if the amount of solar energy is greater than the amount radiated, then the earth heats up.
- #9 If the amount of solar energy is less than the amount radiated, then the earth cools down.
- #10 To a certain degree, the earth acts like a greenhouse. Energy from the Sun penetrates the glass of a greenhouse and warms the air and objects within the greenhouse. The same glass slows the heat from escaping, resulting in much higher temperatures within the greenhouse than outside it.
- #11 Likewise, the earth’s atmospheric gases affect the ability of the earth to radiate the Sun’s energy back into space. Nitrogen and Oxygen make up 99% of the earth’s atmospheric gases and are non-greenhouse gases. Water, Carbon Dioxide, and Methane make up 1% of the earth’s atmosphere, but are greenhouse gases, since they cause the earth to retain heat.
- #12 A dramatic example of the Greenhouse effect can be seen with the planet Venus. Venus’s atmosphere consists of 97% carbon dioxide and 3% nitrogen. In addition, the surface is covered by dense clouds of water and sulfuric acid. The combination of greenhouse gases results in a surface temperature of 860°F – even hotter than the planet Mercury, which is nearest the Sun.
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- #14 This graph shows the amount of carbon dioxide in the atmosphere for the last 650,000 years, as determined through Antarctic ice cores. You will notice the large spike at the end of the graph, which can be seen in the inset as a dramatic increase in atmospheric carbon dioxide over the last 45 years.
- #15 This spike is due to the exponential increase in the use of fossil fuels over the last 150 years. Shown here are emissions of carbon from gas, solid, liquid fuels, and the total carbon emissions.
- #16 Despite this rapid increase in carbon emissions, only about half the carbon can be detected in the atmosphere. The remainder of the carbon dioxide is being dissolved in the oceans or incorporated into trees.
- #17 Future Carbon Emissions will probably increase, especially in China and developing countries This will result in a likely doubling of carbon dioxide levels within 150 years, due to Increased coal usage And increased natural gas usage, although petroleum usage is likely to decrease due to increased cost and decreasing supply
- #18 In an effort to reduce carbon emissions, the Kyoto protocol was adopted in 1997. It proposed to cut CO2 emissions by 5% from 1990 levels for period of 2008-2012 However, such minor cuts would be symbolic only, since such cuts would not significantly impact global warming
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- #20 This is a graph of the change in worldwide temperatures over the last 120+ years. Although the trend is decidedly upward, there are periods when temperatures are flat or even slightly decreasing, suggesting that increasing temperatures may not be entirely due to increased carbon dioxide levels.
- #21 The previous graph does not tell the entire story, since temperature changes have not occurred to the same extent during different seasons. For example, in Los Angeles, temperatures have risen pretty dramatically over the last 120+ years. However, summer temperatures have not risen as quickly. In fact, summer temperatures in the 1880’s were about the same as summer temperatures in the 2000’s. In contrast, winter temperatures have risen much more consistently and dramatically. Global warming models have predicted that warming will be greater during the winter than the summer.
- #22 This is a map of global temperature changes for the year 2005 compared to a base period of 1951-1980. The colors in the reds and oranges represent temperature increases, whereas areas colored with blue represent temperature decreases. As can be seen here there are few areas of temperature decreases, and nearly all of the dramatic temperature increases have occurred in the far northern latitudes.
- #23 Past temperatures changes beyond 120 years ago are approximated through what are called proxies. Common proxies include ice cores, pollen records, plant macrofossils, Sr/Ca isotope data, and oxygen isotopes from stalactites and stalagmites.
- #24 Now let’s examine the temperature history of the earth based upon these proxies. Most recently, the earth was up to 1° C cooler than today, during what has been called the “Little Ice Age”. Preceding this period was the “Medieval warm period” during which time temperatures were up to 1° C warmer than today. These periods of modest temperature changes occur at ~1,500 year intervals, affecting mostly Northern Europe and the North Atlantic. These temperature changes are largely the result of changes in what is called the thermohaline circulation. In this model, cold water in the North Atlantic sinks and flows south through deep currents. Warm water from the south flows north, moderating the climate of Europe and Eastern North America. A dramatic shutdown of thermohaline circulation occurred 8,200 years ago as a large lake in Canada flooded the North Atlantic, resulting in much cooler temperatures in Europe.
- #25 In fact, ocean currents are extremely important in determining the climate of the world’s continents. This model shows the major ocean currents, with orange representing warm surface currents and blue representing cold deep currents. The light circles represent areas where heat is release into the atmosphere.
- #26 For the past 3 million years, the earth has been experiencing ~100,000 year long cycles of glaciation followed by ~10,000 year long interglacial periods These climate periods are largely the result of cycles in the earth’s orbit – precession, obliquity, and eccentricity
- #27 Precession is the wobble of the earth’s tilt in relation to the seasons. Right now, the earth is farthest to the Sun during northern hemisphere’s summer and nearest during northern hemisphere’s winter. However, in another 20,000 years, the earth will be reversed with the earth closest to the Sun during northern hemisphere’s summer and farthest during northern hemisphere’s winter.
- #28 The second orbital parameter is obliquity or tilt. The earth’s tilt goes from a minimum of 22.5° to a maximum of 24.5°. The current tilt is 23.5°.
- #29 The third orbital parameter is eccentricity, which is a measure of the elliptical nature of the earth’s orbit. The maximum eccentricity is 0.061 and the minimum eccentricity is 0.005. You should note that these drawings are not to scale. The maximum eccentricity of the earth’s orbit drawn to scale looks like this!
- #30 So how do these orbital variations play out over time? Precession cycles over a period of ~22 ky. Obliquity cycles every 41 ky. And eccentricity cycles every 100 ky. The bottom curve represents the earth’s temperature over this same period of time. As can be seen, the cycles of glaciation closely match the earth’s cycles of eccentricity.
- #31 The last ice age began to thaw 15,000 years ago, but was interrupted by the “Younger Dryas” event 12,900 years ago.
- #32 This graph shows temperatures and snow accumulation in Greenland for the last 20 ky. The last ice age began to thaw 15 kya, but was interrupted by a period of cooling, leading to the Younger Dryas Event. At 12,900 ya there was a period of rapid warming leading into our current interglacial period. This period has been characterized by ~1,500 year periods of warming and cooling, with the last warm period being known as the Medieval warm period and the last cool period being known as the “Little Ice Age”.
- #33 The Younger Dryas event was not restricted to Greenland, but can also be seen in proxy records from China, shown here in blue. This data shows that it was a worldwide phenomenon.
- #34 During the Middle Pliocene (from 3.15 to 2.85 million ya) temperatures were an average of 2°C higher than today, but up to 20°C higher at high latitudes, and only 1°C higher at the Equator. In addition, sea levels were 100 ft higher. The warmer climate of this era most likely resulted from carbon dioxide levels that were 100 ppm higher than today, and increased thermohaline circulation
- #35 Cooler temperatures were present during the Eocene period (about 41 million years ago) The opening of the Drake Passage (between South America and Antarctica) Led to in increased ocean current exchange Resulting in strong global cooling And the first permanent glaciation of Antarctica ~34 million years ago
- #36 During the Paleocene Thermal Maximum (about 55 mya), sea surface temperatures rose between 5 and 8°C. This warming was probably caused by increased volcanism and a rapid release of methane from the oceans
- #37 During the Mid-Cretaceous period (about 120-90 mya) Temperatures were much warmer than today and Breadfruit trees grew as far north as Greenland This period was much warmer due to different ocean currents, because of the arrangement of continents and higher CO2 levels, which were at least 2 to 4 times higher than today, up to 1200 ppm.
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- #39 In 1998 and 1999, Michael Mann et al. published a study detailing his proxy reconstruction of global temperatures for the last 1,000 years. The graph is basically flat, other than the rapid increase of temperatures during the 20th century. The study received wide acclaim, especially after publication by the IPCC (Intergovernmental Panel on Climate Change) and is now referred to as the “Hockey Stick Graph”. The curve in pink represents actual temperatures measured over the last 120+ years.
- #40 A number of studies were published after the Mann study. In 2002 Esper et al. published a study covering the same period of time, but with much higher variations of temperature over time. So, although the ups and downs are roughly in the same place, the magnitudes of those ups and downs are vastly different.
- #41 Again, the 1999 Mann study is shown in green. Another study, by Moberg et al., using different proxy measures found higher magnitude differences in temperatures. Here the results of Esper et al. are shown on the same scale. Several other studies have been published that fall between the extremes of these three studies. Mann added multiple proxy data to his analysis in 2008, which showed higher variation than the 1999 study. However, all the studies show a rapid increase in temperature in the 20th century that is unmatched by any previous temperature changes over the last millennium.
- #42 In June, 2006, the U.S. National Academy of Sciences weighed in on the question of the Mann study. They put a “high level of confidence” in the last 400 years of proxy results, but only a 2:1 chance of being right for the first 600 years of data.
- #43 Satellite temperature measurements of the lower and upper atmosphere have been carried out since 1980. Temperatures of the troposphere show gradually increasing temperatures (although not as high as would be predicted), and decreasing temperatures in the stratosphere, which would be expected under global warming models.
- #44 Is there a correlation between carbon dioxide levels and temperatures? If we compare carbon dioxide measurements from Antarctica with sea surface temperatures from the tropical Pacific, we find that there is a high coincidence of carbon dioxide levels and temperatures in the past.
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- #46 If we examine global warming from the perspective of the two hemispheres, we find that temperatures in the northern hemisphere have increased much more than temperatures in the southern hemisphere. In a similar fashion, temperatures over land masses have increased much more than temperatures over the oceans. This is because the oceans tend to moderate temperature changes. So, since two thirds of the earth’s land mass is in the northern hemisphere, we would expect global warming to have its largest impact there.
- #47 Hence we see reason for the temperature changes seen in this graph.
- #48 With these temperature increases, one main question is whether the ice sheets of Antarctica and Greenland are melting.
- #49 Mount Kilimanjaro is the poster child of the global warming movement, since most of the glacier has disappeared over the last 30 years. However experts agree that the shrinking of the Mount Kilimanjaro glacier is more the result of deforestation of the surrounding area than changes due to global warming.
- #50 These are the result of the GRACE study, which show decreasing ice mass in Antarctica from 2002 to 2005.
- #51 Are sea levels rising? The present measured rate is 1.8 mm/yr, which is equivalent to 7.4 in/century Another study indicates that this rate is accelerating at 13 thousandths of a mm per year per year If this acceleration continues, this could result in a 12 inch sea level rise in this century Scenarios claiming a 1 meter or more rise in sea levels are unrealistic.
- #52 Measurement of sea levels have been carried out for three European ports over the last few hundred years. The results can be seen for a port in the Netherlands, one in France, and one in Poland. When the sea level is compared to recorded temperatures over this period of time, the correlation is quite good.
- #53 This graph shows sea levels of the Red Sea over the last 450,000 years. If we overlay sea surface temperatures, we can see a direct correlation between sea levels and temperature. In fact, some of the rise in sea levels is due to the expansion of water at higher temperatures, and not solely due to the melting of ice.
- #54 The year 2005 was marked by a number of destructive hurricanes. What this just an unusual year or a trend that has resulted from climate change? Two studies showed the total number of hurricanes has not changed However, the intensity of hurricanes has increased (more category 4 and 5 hurricanes and cyclones) This increase in intensity is probably due to higher sea surface temperatures, which provide more energy to the storms. However, it is difficult to know if this trend will continue.
- #55 How much will temperatures increase in the future? Some models propose up to 9°C increase this century Two studies put the minimum at 1.5°C and maximum at 4.5°C or 6.2°C Another study puts the minimum at 2.5°C
- #56 Some species of wildlife could be greatly affected by global warming For example, polar bears require pack ice in order to hunt and live. If all pack ice disappears, they might eventually go extinct in the wild. Sea turtles breed on the same islands as they are born on. They could go extinct on some islands as beaches are flooded before new beaches are produced. Other species may go extinct as rainfall patterns change throughout the world.
- #57 Global warming will affect peoples throughout the world. For example, Fewer deaths will result from cold weather, but more deaths will result from heat waves Initially, decreased thermohaline circulation will result in cooler temperatures in North Atlantic. The CO2 fertilization effect will increase crop yields by up to 30% Precipitation changes will result in droughts and famine in some areas and expanded arable land in Canada, Soviet Union
- #58 This map represents possible changes in worldwide precipitation as a result of global warming. Some areas (primarily in the northern latitudes) will experience increased precipitation, whereas other areas will experience decreased precipitation.
- #59 Africa's drought troubles began well before greenhouse gases increased to any appreciable degree. The inhabitants of Northern Africa have systematically cut down trees for firewood for thousands of years. The result has been that transpiration has decreased, decreasing rainfall and expanding the Sahara Desert. Similar deforestation is now occurring over much of Africa. The result is that the deserts of North, South and East Africa are expanding, leading to drought. Coupled with global warming induced changes in precipitation, it is likely that the peoples of much of Africa will be suffering from drought and starvation in the coming decades.
- #60 Depending upon the scenario, the cost to stabilize carbon dioxide concentrations will be expensive (from 200 times the U.S. annual budget) to very expensive (up to 900 times the U.S. annual budget).
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- #62 Methods of mitigating global warming include Conservation Reduce energy needs, such as electrical usage, petroleum usage, reduced packaging Recycling, which uses less energy to produce products compared to Another way to reduce carbon emissions is to use alternate energy sources, such as Nuclear Wind Geothermal Hydroelectric Solar Fusion?
- #63 Another promising way to reduce global warming is to store carbon dioxide underground. Carbon dioxide can be pumped into depleted oil and gas reservoirs. In addition, carbon dioxide can be pumped into existing oil and gas deposits to enhance recovery. Another method is to pump carbon dioxide into deep saline formations both offshore and onshore. Carbon dioxide can also be used to enhance methane recovery from coal beds.
- #64 In conclusion, Global warming is happening Most of the warming is probably the result of human activities There will be positive but mostly negative repercussions from global warming The costs to mitigate global warming will be high – better spent elsewhere?