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Global Warming 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 including a printable PDF version.
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Introduction Is the world 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? 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?
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History of Earth’s Climate
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) 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
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History of Earth’s Climate
Life appeared ~3.8 billion years ago Photosynthesis began 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 The first life forms appeared ~3.8 billion years ago Photosynthesis began 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
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Earth’s Temperature Solar Energy Solar Energy Sun
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.
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Earth’s Temperature Solar Energy Radiative Cooling Sun
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.
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Solar Energy Earth’s Temperature Sun Radiative Cooling
However, if the amount of solar energy is greater than the amount radiated, then the earth heats up.
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Radiative Cooling Earth’s Temperature Sun Solar Energy
If the amount of solar energy is less than the amount radiated, then the earth cools down.
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Sun Greenhouse Effect 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.
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Earth’s Atmospheric Gases
Nitrogen (N2) Non- Greenhouse Gases Oxygen (O2) >99% Argon (Ar) Water (H2O) Likewise, the earth’s atmospheric gases affect the ability of the earth to radiate the Sun’s energy back into space. Nitrogen, Oxygen and Argon 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. Carbon Dioxide (CO2) Greenhouse Gases <1% Methane (CH4)
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Runaway Greenhouse Effect
Sun Runaway Greenhouse Effect Venus 97% carbon dioxide 3% nitrogen Water & sulfuric acid clouds Temperature: 860°F 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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Carbon Dioxide
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Carbon Dioxide Levels 420 370 320 CO2 (ppm) 270 220 170 600000 400000
Muana Loa Readings CO2 Levels Since 1958 310 330 350 370 10 20 30 40 CO2 (ppm) 370 320 CO2 (ppm) 270 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. 220 Dome Concordia Vostok Ice Core 170 600000 400000 200000 Time (YBP)
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Worldwide Carbon Emissions
8 Liquid fuel Total Gas fuel Solid fuel 7 6 5 Carbon (109 metric tons) 4 3 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. 2 1 1750 1800 1850 1900 1950 2000 Year
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Annual Carbon Emissions
8 Annual carbon emissions Atmospheric CO2 Atmospheric CO2 average 6 Carbon (109 metric tons) 4 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. 2 1955 1965 1975 1985 1995 2005 Year
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Future Carbon Dioxide Levels
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) 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
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Kyoto Protocol Adopted in 1997
Cut CO2 emissions by 5% from 1990 levels for Symbolic only, since cuts will not significantly impact global warming In an effort to reduce carbon emissions, the Kyoto protocol was adopted in It proposed to cut CO2 emissions by 5% from 1990 levels for period of However, such minor cuts would be symbolic only, since such cuts would not significantly impact global warming
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Past Temperatures
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Recorded Worldwide Temperatures
Flat 0.8 0.6 0.4 Decreasing Flat 0.2 D Mean Temperature (°C) 0.0 This is a graph of the change in worldwide temperatures over the last 130 years. Although the trend is decidedly upward, there are periods when temperatures are flat or even slightly decreasing and then flat again recently, suggesting that increasing temperatures may not be entirely due to increasing carbon dioxide levels. -0.2 -0.4 -0.6 1880 1900 1920 1940 1960 1980 2000 Year
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Historic Los Angeles Temperatures
Annual Temperatures 15 16 17 18 19 20 21 22 1880 1900 1920 1940 1960 1980 2000 Year Temperature (°C) Summer Temperatures 18 19 20 21 22 23 24 25 1880 1900 1920 1940 1960 1980 2000 Year Winter Temperatures 10 11 12 13 14 15 16 17 1880 1900 1920 1940 1960 1980 2000 Year 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 130 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. From a human perspective, one cannot say that higher temperatures during the winter are necessarily a bad thing.
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2009 Temperature Changes Compared to 1951-1980
This is a map of global temperature changes for the year 2009 compared to a base period of 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. 2009 Temperature Changes Compared to -4.1 -4 -2 -1 -.5 -.2 .2 .5 1 2 4 4.1
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Past Temperatures Measurement
Proxy – a method that approximates a particular measurement (e.g., temperature) Tree rings Ice cores Pollen records Plant macrofossils Sr/Ca isotope data Oxygen isotopes from speleothem calcite (stalactites and stalagmites) Now, we need to talk about proxies and how they are used in climate science. Past temperatures changes beyond 120 years ago are approximated through what are called proxies. Common proxies include tree rings, ice cores, pollen records, plant macrofossils, Sr/Ca isotope data, and oxygen isotopes from stalactites and stalagmites.
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Temperature History of the Earth
Little ice age ( ) – 1°C cooler Medieval warm period ( ) – 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 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.
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Main Ocean Currents 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. Adapted from IPCC SYR Figure 4-2
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Temperature History of the 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 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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Orbital Parameters: Precession
Apehelion Perihelion 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.
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Orbital Parameters: Obliquity
24.5° 22.5° 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°.
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Orbital Parameters: Eccentricity
Maximum: 0.061 Perihelion Apehelion Minimum: 0.005 Apehelion The third orbital parameter is eccentricity, which is a measure of the elliptical nature of the earth’s orbit. The maximum eccentricity is and the minimum eccentricity is You should note that these drawings are not to scale. The maximum eccentricity of the earth’s orbit drawn to scale looks like this! Not to scale! To Scale!
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Orbital Parameters & Earth’s Climate
Precession (22 ky) Obliquity (41 ky) Eccentricity (100 ky) Temperature 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. 1000 900 800 700 600 500 400 300 200 100 Age (kya)
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Temperature History of the 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 The last ice age began to thaw 15,000 years ago, but was interrupted by the “Younger Dryas” event 12,900 years ago.
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Younger Dryas Event -25 0.35 Younger Dryas -30 0.30 Medieval Warm
Little Ice Age -35 0.25 Ice Age Temperature (°C) -40 Snow Accumulation (m/yr) 0.20 -45 0.15 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”. -50 0.10 -55 0.05 20 15 10 5 Age (kya)
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Younger Dryas Event -8.0 -34 Younger Dryas -35 -7.5 -36 -7.0 -37 -6.5
-38 d18O (China) -6.0 d18O (Greenland) -39 -40 -5.5 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. -41 -5.0 -42 -4.5 -43 -4.0 -44 16 15 14 13 12 11 10 Age (kya)
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Temperature History of the 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 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
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Temperature History of the 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 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
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Temperature History of the Earth
Paleocene Thermal Maximum (55 mya) Sea surface temperatures rose 5-8°C Causes Increased volcanism Rapid release of methane from the oceans 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
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Temperature History of the Earth
Mid-Cretaceous ( 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) During the Mid-Cretaceous period (about 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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A Compilation of Phanerozoic Atmospheric CO2 Records
6000 5000 4000 Concentration (ppmV) Atmospheric CO2 3000 2000 1000 30 This is a plot of carbon dioxide levels in the atmosphere over the last 450 million years estimated using different proxies. The data shows that, in the past carbon dioxide levels have been up to 10 times higher than they are today. During those times, there were no continental glaciers present on earth. 60 Continental Glaciation (Paleolatitude) 90 S D Carb P Tr J K Pg Ng Paleozoic Mesozoic Cenozoic 400 300 200 100 Breecker D O et al. PNAS 2010;107:
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Recent Temperature Changes
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“Hockey Stick” Controversy
0.6 Direct temperature measurements Mann et al. 1999 0.4 0.2 Temperature Change (°C) -0.2 -0.4 In 1998 and 1999, Michael Mann et al. published studies 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. -0.6 -0.8 1000 1200 1400 1600 1800 2000 Year
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The Problem with Tree Rings
0.3 Jones et al. 1998 Briffa et al. 1999 Mann et al. 1999 0.2 0.1 -0.1 Temperature Change (°C) -0.2 -0.3 However, the problem with the graphs is that tree ring data from 1960 on does not match the instrument readings of temperature So, we can see a large divergence in the Jones study the Briffa study and the Mann study. Since tree ring proxies underestimate actual temperatures after 1960, one must ask if they also underestimate the Medieval warm period temperatures. Here we see the actual proxy records, which look more like a baseball bat than a hockey stick. -0.4 -0.5 -0.6 1000 1200 1400 1600 1800 2000 Year
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What Influences Tree Rings?
Temperature Rainfall Carbon dioxide concentration Although temperature increases the width of tree rings, rainfall, and to a lesser extent carbon dioxide, through a “fertilization effect” also increase the width of tree rings. So, the idea that tree rings are always an accurate representation of past temperatures is not always true. In other words, trees do not always make good thermometers.
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Is the Hockey Stick Correct?
2 Mann et al. 1999 Esper et al. 2002 1 Temperature Change (°C) 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. -1 -2 800 1000 1200 1400 1600 1800 2000 Year
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Is the Hockey Stick Correct?
0.4 Medieval Warm Period 0.2 0.0 -0.2 -0.4 Temperature Change (°C) -0.6 Mann et al. 1999 Esper et al. 2002 Moberg et al. 2005 Mann et al. 2008 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. So, some of these data suggest that the Medieval Warm Period was as warm or warmer than today’s temperatures. -0.8 -1.0 -1.2 400 800 1200 1600 2000 Year
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U.S. National Academy of Sciences: June 2006
0.6 “2:1 chance of being right” “high level of confidence” 0.4 0.2 Temperature Change (°C) -0.2 -0.4 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. -0.6 -0.8 1000 1200 1400 1600 1800 2000 Year
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Atmospheric Temperatures
Troposphere Stratosphere 0.8 1.5 0.6 1.0 0.4 0.5 0.2 Temperature Cgange (°C) 0.0 0.0 Satellite temperature measurements of the lower and upper atmosphere have been carried out since 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. -0.2 -0.5 -0.4 -0.6 -1.0 1980 1990 2000 1980 1990 2000 Year Year
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CO2 Concentration Vs. Temperature
370 320 31 30 CO2 (ppm) Antarctica SST (°C) Tropical Pacific 270 29 28 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. 220 27 26 170 25 600000 400000 200000 Time (YBP)
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Consequences of Global Warming
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Global Warming Primarily Impacts the Northern Hemisphere
Northern vs. Southern Latitude Land vs. Ocean 1.0 Northern Hemisphere Southern Hemisphere Land Ocean 0.8 0.6 0.4 Temperature Change (°C) 0.2 0.0 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. -0.2 -0.4 -0.6 1920 1960 2000 1920 1960 2000 Year Year
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2009 Temperature Changes Compared to 1951-1980
Hence we see reason for the temperature changes seen in this graph. -4.1 -4 -2 -1 -.5 -.2 .2 .5 1 2 4 4.1
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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) With these temperature increases, one main question is whether the ice sheets of Antarctica and Greenland are melting.
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Melting Glaciers – Mt. Kilimanjaro
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.
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Changes in Antarctica Ice Mass
1000 800 600 400 Ice Mass (km3) 200 These are the result of the GRACE study, which show decreasing ice mass in Antarctica from 2002 to -200 -400 -600 2003 2004 2005 Year
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Rise in Sea Levels? Present rate is 1.8 ± 0.3 mm/yr (7.4 in/century)
Accelerating at a rate of ± mm/yr2 If acceleration continues, could result in 12 in/century sea level rise Scenarios claiming 1 meter or more rise are unrealistic 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.
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Global Temperature Change
Changing Sea Levels 20 Global Temperature Change 10 Relative Sea Level (cm) 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. -10 Amsterdam, Netherlands Brest, France Swinoujscie, Poland -20 1700 1750 1800 1850 1900 1950 2000 Adapted from IPCC SYR Figure 2-5
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SST (°C) Tropical Pacific
Sea Levels for 450,000 Years 20 31 30 -20 29 -40 Sea Level (m) 28 SST (°C) Tropical Pacific -60 27 -80 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. 26 -100 -120 25 450 400 350 300 250 200 150 100 50 Time (KYBP)
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Increase in Hurricanes?
1860 1880 1900 1920 1940 1960 1980 2000 2020 5 10 15 Data Unreliable Scaled August-October Sea-Surface Temperature Adjusted Atlantic Storm Power Dissipation Index SST/SPDI (meters3/sec2) 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 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.
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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 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
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Wildlife Effects Polar Bears Sea turtles
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 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.
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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 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
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Potential Worldwide Precipitation Changes
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. -50 -20 -10 -5 5 10 20 50
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Drought in Africa Lake Faguibine Lake Chad
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.
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Cost to Stabilize CO2 Concentrations
1800 1600 1400 1200 1000 Cost (Trillons U.S. Dollars) 800 600 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). 400 200 450 550 650 750 Carbon Dioxide (ppm)
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Possible Solutions to Global Warming
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Mitigation of Global Warming
Conservation Reduce energy needs Recycling Alternate energy sources Nuclear Wind Geothermal Hydroelectric Solar Fusion? 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?
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Storage of CO2 in Geological Formations
Depleted oil and gas reservoirs CO2 in enhanced oil and gas recovery Deep saline formations – (a) offshore (b) onshore CO2 in enhanced coal bed methane recovery 4 1 3b 3a 2 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. Adapted from IPCC SRCCS Figure TS-7
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Global Warming Myths I would like to take a few minutes to go over some common global warming myths.
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Global Warming Has Stopped?
0.8 1365.2 1365.4 1365.6 1365.8 1366.0 1366.2 1366.4 1366.6 1366.8 Solar Irradiance (W/m2) 0.6 0.4 D Mean Temperature (°C) 0.2 Here we have our usual global surface temperatures. The orange curve represents solar irradiance – the amount of energy received from the Sun. As you can see, the Sun goes through cycles about every ten years. When the Sun’s output is lowest, temperatures tend to level out. So, it’s not surprising that temperatures have been flat for several years as we have been in a very deep solar trough. The concerning thing is that temperatures continue to increase even as solar output has been recently declining. If the leveling of temperatures is due to reduced solar output, we should expect temperatures to go up considerably as the Sun comes out of its solar minimum. It’s like Hugh says, “Wait a few years and see where the evidence leads.” 0.0 -0.2 1975 1980 1985 1990 1995 2000 2005 2010 Year
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Volcanoes Put Out More CO2 Than Fossil Fuel Burning
10 8 Fossil Fuel 6 Carbon (109 metric tons) 4 Another myth is that volcanoes emit more carbon dioxide than fossil fuel burning. Here we see the amount of carbon from volcanoes compared with the amount from fossil fuels. It isn’t even close!. 2 Volcanoes
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Global Warming is Caused by Sunspots
0.8 250 0.6 200 0.4 150 0.2 Sunspots D Mean Temperature (°C) 0.0 100 Another myth is that global warming is caused by sunspots. Here we have our usual global temperature plot, which we can compare to sunspot activity We can see that there is no correlation between the two curves. -0.2 50 -0.4 -0.6 1880 1900 1920 1940 1960 1980 2000 Year
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Hadley Temperatures Vs. Sunspots
1.5 250 1.0 200 0.0 150 D Mean Temperature (°C) Sunspots -0.5 100 We actually have sunspot data from the 18th century. Here the temperature data from Hadley, UK is plotted compared with the number of sunspots Again, there isn’t any correlation. -1.0 50 -1.5 -2.0 1750 1800 1850 1900 1950 2000 Year
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Global Warming is Caused by GCR
1.0 3000 3200 3400 3600 3800 4000 4200 4400 4600 Gamma Cosmic Rays 0.8 0.6 0.4 D Mean Temperature (°C) 0.2 Another myth is that global warming is caused by gamma cosmic rays Here is a plot of global temperatures over the last 60 years When plotted against Gamma Cosmic Rays, one can see that there is no correlation. 0.0 -0.2 -0.4 1950 1960 1970 1980 1990 2000 2010 Year
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CO2 Vs. Sea Level CO2 Vs. Temperature
-120 -100 -80 -60 -40 -20 20 40 Relative Sea Level -10 -8 -6 -4 -2 2 4 6 Temperature 180 200 220 240 260 280 300 320 CO2 (ppmv) Skeptics say there is no correlation between carbon dioxide levels and temperatures. However, if we compare carbon dioxide with sea surface temperatures for the last five glacial cycles, we find that there is a high coincidence of carbon dioxide levels and temperatures in the past. In addition, there is a high correlation between carbon dioxide and sea levels 500000 400000 300000 200000 100000 Time (ybp) Rohling et al Antarctic temperature and global sea level closely coupled over the last five glacial cycles. Nature Geoscience 2:500.
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Global Warming is Due to Urban Heat Islands
Is global warming due to heat island effects? Heat island effects occur when a temperature station gets surrounded by buildings and streets, artificially raising the temperature readings. Here we see a plot of global temperature changes (higher in red and lower in blue) for 2009 compared with What we notice here is that nearly all of the dramatic temperature increases have occurred in the far northern latitudes, where we would be hard pressed to find numerous cities where heat island effects would be expected to be found. 2009 Temperature Changes Compared to -4.1 -4 -2 -1 -.5 -.2 .2 .5 1 2 4 4.1
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Mt. Kilimanjaro’ Glaciers are Melting Because of Global Warming
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 rather than changes due to global warming, since temperatures in the area have not appreciably climbed in recent years.
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Global Warming Primarily Impacts the Northern Hemisphere
Northern vs. Southern Latitude 1920 1960 2000 Year Land vs. Ocean Land Ocean 1.0 Northern Hemisphere Southern Hemisphere 0.8 0.6 0.4 Temperature Change (°C) 0.2 0.0 Is global warming truly global? 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. -0.2 -0.4 -0.6 1920 1960 2000 Year
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Sea Levels Will Rise 5-6 ft?
Present rate is 1.8 ± 0.3 mm/yr (7.4 in/century) Accelerating at a rate of ± mm/yr2 If acceleration continues, could result in 12 in/century sea level rise Scenarios claiming 1 meter or more rise are unrealistic Recently, the California State Lands Commission said that sea levels could rise 55 inches this century, inundating ports Are sea levels going to rise 5 to 6 feet this century? 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. The California State Lands Commission recently claimed that sea levels could rise 55 inches this century, inundating ports in the state. And you wonder why we have a budget crisis.
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Global Temperature Change
Changing Sea Levels 20 Global Temperature Change 10 Relative Sea Level (cm) 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. However, we are talking about only a 7 inch rise in sea levels over the last century. -10 Amsterdam, Netherlands Brest, France Swinoujscie, Poland -20 1700 1750 1800 1850 1900 1950 2000 Adapted from IPCC SYR Figure 2-5
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How Much Temperature Increase?
Global warming alarmists 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 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 What about previously predicted increases?
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Predictions Vs. Reality
DT (°C) 1.5 1.0 0.5 -0.4 Date 1960 1970 1980 1990 2000 2010 2019 Annual Mean Global Temperature Change OBSERVED SCENARIO A SCENARIO B SCENARIO C Exponential Increase in carbon emissions Moderate reduction in carbon emissions Drastic reduction in carbon emissions Observed temps through 1988 In 1988 Jim Hansen published a study that modeled global temperatures as a function of carbon emissions. The graph, shown here, and cleaned up from the original journal scan, shows Hansen’s computer models for temperature as a function of carbon emissions. The white solid line indicates observed temperatures through 1988, when the study was published. The orange dotted line is a computer model of temperatures assuming carbon emissions continued to be produced exponentially The blue dashed line assumed carbon emissions would be moderately curtailed, And the yellow dotted line assumed carbon emissions would be drastically curtailed. What does the actual data look like? It almost exactly follows the drastic reduction projection, even though carbon emiisions have basically gone unchecked since So, past predictions have tended to overestimate the increase in global temperatures. Hansen, J Journal Of Geophysical Research 93:9241.
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Temperature Extrapolation
2.5 2.0 1.5 DT (°C) 1.0 This is our usual plot of temperature over time on a scale that extends to the end of the century. If we extrapolate the line, we get a 2.5 degree temperature increase. However, this assumes that the rate of increase stays constant. Given the past temperature history, it seems likely that temperatures will go through periods of little or no increase, suggesting that the overall temperature increase will be less than 2.5 degrees. If there are positive feedbacks, it is possible that temperatures will move up more quickly. However, even a 2.5 degree centigrade increase is nothing to take lightly. My advice, let’s see what happens in the next ten years as the Sun goes through its solar maximum. It temperatures begin to rise again, I think we have reason to be concerned. If the last 100 year’s increases are part of some natural climate variation, temperatures should level off soon. Time will tell. 0.5 -0.4 1960 1980 2000 2020 2040 2060 2080 2100 Date
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Conclusions Global warming is 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? 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?
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