J.C. Moore Online » Greenhouse Effect

Global Warming in Pictures

admin — Thu, 01 Sep 2011 16:13:12 +0000

Science is about using observation and reason to understand the physical world. Some people are suspicious of computer models and theories; so here is the basic data about global warming in pictures and graphs.

Ice Ages: In the past, the Earth’s temperature has varied from the Ice Ages to the much warmer temperatures of the interglacial periods. Ice core data gives a good picture of what has happened to the Earth’s temperature in the last half million years, as shown by the blue line. The changing temperatures are attributed to the Milankovitch Cycles, small variations in the Earth’s orbit that cause the Earth to receive different amounts of sunlight. The Earth becomes slowly warmer during the periods where the solar energy increases. As the Earth begins to be warmed by sunlight, CO2 becomes less soluble in the ocean and the CO2 concentration in the atmosphere increases, which further amplifies the warming since CO2 is a greenhouse gas.

As you can see in the graph, the red line shows how intricately the CO2 concentrations and temperatures are related. The CO2 concentration drops to about 180 ppm during the glacial periods and rises to about 290 ppm during the warmer interglacial periods. As the far right of the graph shows, we are now in an interglacial period that began about 6000 years ago. The Milankovitch Cycles predict that Earth should slowly cool for the next 20,000 years, but it is warming instead. Please note that the concentration of CO2 did not rise above 300 ppm in any previous warmer periods but on the far right side of the graph, the red line indicating the CO2 concentration is now approaching 380 ppm. http://www.daviesand.com/Choices/Precautionary_Planning/New_Data/IceCores1.gif

Current CO2 Levels: In the past, the warming oceans released the CO2 as a natural process. However, man is now putting about 30 billion tons of carbon dioxide into the air each year. Much of it stays there and the Keeling curve below shows how CO2 is building up in air. What might that mean for man? In 2011, the CO2 concentration reached 387 ppm, far higher than it has been for perhaps 15 million years.

http://susty.com/image/keeling-curve-carbon-dioxide-parts-per-million-co2-summer-uptake-by-trees-plants-soils-graph-red-line-illustration-image.jpg

This article explains what the Earth may have been like then: ”The last time carbon dioxide levels were apparently as high as they are today — global temperatures were 5 to 10 degrees Fahrenheit higher , the sea level was approximately 75 to 120 feet higher, there was no permanent sea ice cap in the Arctic, and very little ice on Antarctica and Greenland.”

Earth’s Temperature: Carbon dioxide is one of the greenhouse gases that warm the Earth. NASA’s graph below shows how its increase is changing the Earth’s temperature. Though the Earth’s mean temperature varies widely from year to year, the graph on the right is a moving average that allows you to see the trend in the temperature much easier.

htp//data.giss.nasa.gov/gistemp/2010november/fig2.gif

The effect of particulates, which cool the Earth, can be seen around 1991 when Mount Pinaturbo exploded. The flat place in the graph from about 1940 to 1970 is attributed to particulates generated by World War II, atmospheric atomic bomb testing, and postwar industrialization – before particulate emissions were regulated. Clearly, the Earth is getting warmer.

Effect on the Earth: Scientist tell us that the increasing CO2 concentration is leading to a warmer Earth, more extreme weather, melting glaciers and polar ice, crop failure, droughts, and wildfires. We have certainly experienced many of those things recently, which should make us think about what effect our activities are having on the Earth. Many of the changes in the Earth are subtle, but here are two of NASA’s pictures that clearly show how the Earth is changing. Between 1979 and 2003, about 30% of the Arctic ice has disappeared.

This has greatly affected the way of life of the native Inuit who live and hunt on the Polar ice. While they may adapt, their way of life and culture which sustained them for centuries will be destroyed. The Polar bears, uniquely adapted to live in on the Polar ice, have been put on the threatened species list because their habitat is clearly declining. As their habitat disappears, so will be the Polar bear. It is something man should think about – as our habitat is deteriorating, also.

Bits and pieces 10: Global Warming in Pictures

admin — Thu, 01 Sep 2011 02:16:02 +0000

Science is about using observation and reason to understand the physical world. Some people are suspicious of computer models and theories; so here is the basic data about global warming in pictures.

Ice core data gives a good picture of what has happened to the Earth in the last several ice ages. Please note that the concentration of CO2 did not rise above 300 ppm in the warmer interglacial periods but now the CO2 concentration is 387 ppm – much higher than any time in the ice core record:

http://www.daviesand.com/Choices/Precautionary_Planning/New_Data/IceCores1.gif

CO2: Man is now putting about 30,000,000,000 tons of carbon dioxide into the air each year. Much of it stays there and you can see how it is building up in air:

http://susty.com/image/keeling-curve-carbon-dioxide-parts-per-million-co2-summer-uptake-by-trees-plants-soils-graph-red-line-illustration-image.jpg

Temperature: CO2 is one of the greenhouse gases that warm the Earth and NASA’s graph shows how its increase is changing the Earth’s temperature:

http://data.giss.nasa.gov/gistemp/2010november/fig2.gif

Changing Earth: Many of the changes in the Earth are subtle but here is one of NASA’s pictures that clearly shows how the Earth is changing:

http://jcmooreonline.com/wp-content/uploads/2011/08/Arctic-1.jpg

The full article, with pictures, is here: http://jcmooreonline.com/2011/09/01/global-warming-in-pictures/

Is Global Warming a Hoax?

admin — Tue, 10 May 2011 18:26:17 +0000

Sen. James Inhofe (R –OK) is famous for his statement, “Global warming is a hoax”. The local Tulsa newspaper often carries letters giving the opposing viewpoint. For example, Corey Cohen, recently wrote, “Sen. Inhofe, please cease your effort to stop EPA’s ability to limit greenhouse gas emissions. The science of global warming and climate change is obvious and known. For example, excessive CO2 in the atmosphere absorbs heat reflected from the ground and traps that heat in the atmosphere, melting glaciers and ice and snow packs all around the planet. A given molecule of CO2 in the atmosphere has a life of approximately 100 years. The implications are fairly obvious: rising sea levels, loss of fresh water for humans and unpredictable growing seasons for Oklahoma farmers and their winter wheat crops due to atmospheric heating.” (1)

Mr. Jack Williams replied (2) by “pointing out a few facts” to defend Senator Inhofe’s position:

“1. More than 31,000 scientists signed a petition opposing the concept of man-made global warming.

2. More than 100 top climate scientists have expressed their opposition.

3. A dozen recognized scientists from nine countries who initially were global-warming proponents have changed their opinion and now oppose it in light of recently published information.

4. Earth has undergone many cooling and warming periods during its history.

5. Carbon dioxide constitutes less than 0.1 percent of the atmosphere while water vapor, at least as effective a greenhouse gas as CO2, ranges from about 20 to 100 times its concentration, and is quite variable.

6. There has been no measurable increase in global temperatures during the past decade.

7. The polar bear population dramatically increased during the past decade, as has ice thickness on Antarctica.”

It’s always nice to get alleged facts in a numbered list, where it is possible to check them one by one.

Endorsements: Facts one, two and three, fall into the category of endorsements, and as with many endorsement, it is not always clear how well qualified those who endorse the position are, or whether the numbers listed are significant. There are about 23 million graduates with degrees in science and engineering. If 31,000 scientists signed the Oregon Petition, that is about 0.13% of those – hardly significant. Even then, the petition appears to be a hoax. In 1989, the Petition was mailed to thousands of Bachelor of Science students. It was formatted to appear as if it came from the National Academy of Science, but the organization quickly responded that the information was misleading and “the petition does not reflect the conclusions of expert reports of the Academy.” The mailing collected 17,000 signatures and 14,000 have been added since. Most anyone could sign it, many who signed were misled, and many were not scientists at all, as it is possible to get BS degrees in fields such as journalism, sociology, education, philosophy… (3)

Endorsements that matter: All the major scientific organizations in the world have endorsed a statement such as that of the American Chemical Society, ”Careful and comprehensive scientific assessments have clearly demonstrated that the Earth’s climate system is changing rapidly in response to growing atmospheric burdens of greenhouse gases and absorbing aerosol particles. There is very little room for doubt that observed climate trends are due to human activities. The threats are serious and action is urgently needed to mitigate the risks of climate change.” (4) A recent CNN poll found that 97% of scientists who are actively engaged in research in climate science agree that global warming is caused by man. (5) There is clearly a consensus among scientists on the matter and those making policy would be wise to heed it.

Warming and Cooling: Point four is a fact, but it is not relevant to what is happening today. The Earth has in the past had many natural warming and cooling periods but the current warming trend is not part of those. In the past, ice ages and warmer interglacial periods have occurred in roughly 100,000-year cycles. These are attributed to the Milankovitch cycles. These cycles are small variations in the eccentricity, axial tilt, and precession of the Earth’s orbit that cause the amount of sunlight the Earth receives to increase and decrease in predictable cycles The cycles predict that a slow cooling trend, which began some 6,000 years ago, will continue for the next 23,000 years. The current warming trend is too rapid and in the wrong direction for the Milankovitch Cycles to be the cause. (6)

Greenhouse gases: Point five is also a fact, but it incorrectly downplays the role of CO2 in determining the Earth’s temperature. In 1956, G.N. Plass calculated (7) that doubling the concentration of CO2 in the air would cause a 3 to 4 C increase in the Earth’s temperature. Many dismissed his work, as it seemed impossible that CO2, which made up only 0.03% of the air, could have such a large effect on temperature. However, in 1997, J.T. Kiehl found (8) that, under clear sky conditions, CO2 accounted for 26% of the greenhouse effect – with water vapor accounting for most of the rest. More recent research (9) has confirmed their work, and CO2 has been labeled the “Control Knob” for the Earth’s temperature. Recent research in the Journal of Climate, covering the last five ice ages, has experimentally confirmed Plass’ work. The Earth is warming because of the greenhouse gases we emit, and research finds the increase in CO2 is the main cause.

Temperature record: Fact six is based on the idea that 1998 was so hot, it couldn’t have been hotter since. However, NASA’s temperature record shows that 2005 and 2010 are tied for the warmest year on record and the last decade has been the hottest in recorded history – and the trend is yet upward (10). There have been attempts to discredit NASA’s temperature data by challenging the accuracy of the temperature recording stations, but a study of that issue by the American Geophysical Union found that claim to be false. (11) NASA has put men on the Moon and brought them home safely, and they certainly should be able to measure temperatures on the Earth correctly.

Polar Bears: It’s true that the Polar bear population has increased, but not because the Polar ice is increasing. The bears were hunted nearly to extinction, and their population is increasing because restrictions were placed on hunting them from aircraft . Recently, Polar bears have been put on the threatened species list, not because of their numbers, but because their habitat is disappearing. Satellite measurements of the Arctic sea ice have shown that both the volume and extent of the sea ice has decreased remarkably over the last 30 years. (12) Polar bears are uniquely adapted to live and hunt on the Arctic Sea ice. As it disappears, so will the Polar bears.

Claiming something as “fact” does not make it so. And, even facts can be misleading if the inferences drawn from them are in error. If Senator Inhofe bases his position on facts such as those listed by Mr. Williams, it is easy to see why he incorrectly thinks global warming is a hoax.

(1)http://www.tulsaworld.com/opinion/article.aspx?subjectid=62&articleid=20110313_222_G2_CUTLIN933913

(2)http://www.tulsaworld.com/opinion/article.aspx?subjectid=62&articleid=20110403_62_G2_InhisM784632

(3) http://jcmooreonline.com/2010/01/29/the-oregon-petition-how-can-31000-scientists-be-wrong/

(4) http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change#General_science

(5) http://articles.cnn.com/2009-01-19/world/eco.globalwarmingsurvey_1_global-warming-climate-science-human-activity

(6) http://jcmooreonline.com/2010/12/31/science-global-warming-and-the-ice-age-mystery/

(7) http://www.aip.org/history/climate/co2.htm#M_25_

(8) http://journals.ametsoc.org/doi/abs/10.1175/1520-0477%281997%29078%3C0197:EAGMEB%3E2.0.CO;2

(9) http://www.sciencemag.org/content/330/6002/356.abstract

(10) http://data.giss.nasa.gov/gistemp/2010november/fig2.gif

(11)http://www.agu.org/pubs/crossref/2010/2009JD013094.shtml

(12) http://climateprogress.org/wp-content/uploads/2011/01/NSIDC-12-10.gif

V Share This

Science, Global Warming, and the Ice Age Mystery

admin — Sat, 01 Jan 2011 01:17:49 +0000

In the early 1800′s, scientists began a search for the cause of the ice ages. That search has led to a discovery of the factors that affect the Earth’s temperature, an understanding of the current global warming, and the solution to the mystery of the ice ages. *

The Data: Science is a way of understanding nature by using observation and reason. Man has always been keenly interested in the weather, but temperature records before 1850 were mostly historical accounts of storms, heat waves, or when bodies of water froze. Thermometers came into use in about 1850, allowing more accurate temperature records. One of the most useful records is NASA’s graph of the Earth’s annual mean temperature, which was compiled from ships logs, weather stations, and satellite measurements. It serves as a scorecard for telling whether the Earth is getting warmer or cooler. NASA’s data has small random variations from year to year because of factors such as sunspots, weather events, ocean currents, and particulates from volcanic eruptions. However, NASA’s graph shows that the Earth’s temperature has clearly trended upward since 1880 – with the exception of a curious plateau from 1945 to 1975 followed by a steeper rise in temperature. The Earth’s mean temperature is now 1.3 F higher than in 1880, and the last decade has been the hottest on record. Any theories or causes put forward to explain the global warming trend must be consistent with the temperature observations.

Possible Causes: Nineteenth century scientists realized from geological evidence that the Earth had gone through many ice ages that alternated with ages of warmer climate. Much of the early research on global warming was a search for the cause of the ice ages. Scientists found that many small variables cause the Earth to warm and cool, but the main three causes are the Sun, particulates, and greenhouse gases.

The Sun’s output seems to have been reasonably stable over the last several million years. Satellite measurements over the last 30 years have shown that while solar radiation has declined ever so slightly during that time, the Earth continued to warm – so clearly changes in the Sun’s output is not the cause of the recent warming. The amount of sunlight the Earth receives does, however, depend on the Milankovitch Cycles. These cycles are small variations in the eccentricity, axial tilt, and precession of the Earth’s orbit that cause the solar insolation, the amount of sunlight the Earth receives, to vary slightly in predictable cycles. Ice core data shows that ice ages tend to occur in roughly 100,000-year cycles that match the timing of the Milankovitch cycles. The temperature between the ice ages and the warm periods, however, are much greater than would be caused by the changes in solar radiation alone. Though a clue to the cause of the ice ages, the Milankovitch Cycles are not the cause of the current warming. They predict a minor cooling trend, which began some 6,000 years ago, will continue for the next 23,000 years. The current warming trend is too rapid and in the wrong direction for the Milankovitch Cycles to be the cause.

Particulates cause the Earth to cool by reflecting incoming sunlight back into space. The role of particulates in cooling the Earth became apparent in 1816 when ash from the explosive eruption of Mt.Tambora caused that year to be called “the year without a summer”, worldwide. The curious plateau in NASA’s temperature record from 1945 to 1975 was primarily caused by particulates from sources such as WW II, atmospheric nuclear testing, and increased industrialization. Research during the early 1970′s showed a huge increase in aerosol particulates from power production, factories, and vehicles – and some alarmists even speculated that we might cause another ice age. Particulates are visible and cause immediate health problems, so by 1980 most industrialized countries had restrictions on particulate emissions. Particulates cannot be the cause of global warming, but reducing their sources can cause the temperature to rise as can be seen in the temperature record after 1980.

The Greenhouse Effect was discovered in the early1800′s when scientists realized that the Earth was kept warm at night because the atmosphere trapped invisible heat rays rising from the surface. Around 1860, John Tyndall identified the invisible rays as infrared radiation and found the main gases that trapped the heat rays to be water vapor and CO2. The amount of water in the air remains relatively constant because of the water cycle. When the humidity is low, water evaporates, and when the humidity gets too high, it rains. However, CO2 has no such restrictions. Since CO2 makes up only a few hundredths of a percent of the air, it was at first dismissed as a possible cause of warming, especially since it was thought that plants and the oceans would absorb any excess.

In 1896, Svante Arrhenius, while still pursuing the idea that variations in CO2 might be the cause of the ice ages, laboriously calculated the effect of cutting the amount of CO2 in the atmosphere by half. He found that doing so would lower the temperature of Europe by 4-5 C, perhaps enough to bring on an ice age. He also found that doubling the amount of CO2 might raise the temperature of the atmosphere by 6-7 C. No one was concerned as Arrhenius’ model of the atmosphere was very crude and it was inconceivable that the amount of CO2 in the air could ever double. Some scientists speculated that man should intentionally add more CO2 to the air to ward off another ice age.

As models of the atmosphere improved, a number of scientists tried to get a better estimate of the effect of doubling the amount of CO2 on the Earth’s temperature, but the increasing complexity of the models made the calculations daunting. A breakthrough came with the development of computers. In 1956, G.N. Plass calculated that doubling the concentration of CO2 in the air would cause a 3 to 4 C increase in the Earth’s temperature. ** Many dismissed his work, as it seemed impossible that CO2, which made up only 0.03% of the air, could have such a large effect on temperature. However, in 1997, J.T. Kiehl found that, under clear sky conditions, CO2 accounted for 26% of the greenhouse effect – with water vapor accounting for most of the rest. More recent research has confirmed their work . Clearly, CO2 could have a significant effect on the Earth’s temperature if it was increasing. But was it?

CO2: In 1900, Arvid Hgbom calculated the amount of CO2 emitted by industrial sources and, surprisingly, found that man was adding CO2 to the atmosphere at roughly the same rate as volcanoes. No one thought much of it as, at that rate, it would take centuries for the amount of CO2 to increase significantly. However, after a protracted heat wave during the 1930′s, Guy Callendar re-examined previous temperature and CO2 measurements and found not only that the Earth was getting warmer, but also that atmospheric CO2 concentrations were increasing rapidly. Callendar’s work was mostly ignored, but a few scientists began monitoring the concentration of CO2 more closely. Their results were sporadic but, by 1958, Charles Keeling had established accurate procedures for measuring atmospheric CO2. His lab was eventually moved to the Mauna Loa observatory, far away from most CO2 sources. His graph showing how CO2 varies with time, now called the Keeling curve, proved to be an important piece of evidence. It showed that the oceans and plants were not taking up CO2 nearly as fast as man was producing it. Over the last century, the atmospheric CO2 concentration has risen from 280 parts per million (ppm) to 385 ppm, a 38% increase, and the Earth’s temperature has risen by 0.8 0C, well in line with Plass’ prediction. The role of CO2 as the major cause of global warming had been convincingly established. There is yet one more piece of evidence that confirms that conclusion.

Ice Ages: It was now possible to solve the mystery of the ice ages. The Milankovitch cycles alone cannot explain the changes in the Earth’s temperature during the cycles, but the process becomes clear if CO2 is included. The ice core data shows that the concentration of CO2 falls to about 180 ppm during an ice age and rises to about 280 ppm during the warm part of the cycle. The changing CO2 concentration happens because the solubility of CO2 in water varies with temperature. In the part of the cycle where the Earth is warmed by the increasing solar radiation, the oceans release CO2, which further amplifies the warming by the greenhouse effect. In the part of the cycle where the solar energy decreases, the oceans cool, the CO2 dissolves again, and another ice age begins. The concentration of CO2 in the atmosphere is the “control knob” for the Earth’s temperature – and we have now turned the knob up to 380 ppm and are moving it even higher. The Earth will surely get warmer.

* Much of the historical data came from this excellent AIP article.

** Recent research in the Journal of Climate, covering the last five ice ages, has experimentally confirmed Plass’ estimate of the climate sensitivity.

Science, Climate Change, and the Greenhouse Effect

admin — Mon, 13 Dec 2010 17:14:59 +0000

In the 1800′s, scientist began to understand the role greenhouse gases had in keeping the Earth warm. The greenhouse effect is now a well established scientific principle. Both the science and the data show that current global warming is caused by the increasing CO2 in the atmosphere.

Greenhouse Effect: Most gardeners know how greenhouses work. In the daytime, the sun’s radiation (visible and UV) comes in through the glass and warms the plants and soil. The glass stops the heat radiation in the infrared (IR) region from passing back through and the greenhouse stays warm enough to keep the plants from freezing, even at night. The Earth works much the same way except greenhouse gases, primarily water and carbon dioxide, play the role of the glass and trap some of the leaving IR radiation. Winter nights on Earth would be very cold without greenhouse gases.

Earth’s Energy Balance: Of the Sun’s energy coming to Earth, 30% is reflected immediately back into space by particles in the air, by clouds, and by the surface. Another 20% is absorbed by the atmosphere where it runs the weather cycle. The remaining 50% heats the land and oceans. All the absorbed heat is eventually radiated back into space as infrared radiation. It’s a balanced energy budget, 100% in and 100% back out. Anything that reflects more light back into space, such as an increase in particulate matter in the air, would cause the Earth to cool. Anything that delays the energy’s trip back to space, such as an increase in greenhouse gases, would cause the Earth to warm. There are many small things that affect the Earth’s energy balance, but the main three are the Sun, particulates, and greenhouse gases.The ash from the explosive eruption of Mt.Tambora in 1816 caused that year to be called the year without a summer, worldwide.

The Sun: Certainly a change in the Solar radiation the Earth receives would cause a change in the Earth’s temperature. Small wobbles in the Earth’s orbit, the Milankovitch Cycles, are variations in the eccentricity, axial tilt, and precession of the Earth’s orbit. They affect the amount of solar radiation the Earth receives in predictable cycles. Both scientists and skeptics agree that these cycles are responsible for the Ice Ages that occur in roughly 100,000-year intervals. In the part of the cycle where the Earth receives more solar radiation, the oceans slowly warm and release CO2. The CO2 further amplifies the warming by the greenhouse effect. As the Earth moves into the part of the cycle where it receives less solar radiation, the oceans slowly cool, the CO2 dissolves back into the oceans and another ice age starts. The patterns of wobble in the Earth’s orbit are predictable and the model predicts that a minor cooling trend, which began some 6,000 years ago, will continue for the next 23,000 years. The current warming trend is too rapid and in the wrong direction to be a part of the Milankovitch Cycles.

The Sun also has cycles where its output varies slightly such as Sunspots activity. They cause the amount of solar radiation to vary in approximately 11-year cycles. However, the effects of Sunspots are so small that they do not show up above the other small variations in NASA’s temperature record.(see below). Long term variations in the Sun’s intensity are not responsible for the current warming. The graph of solar irradiance from 1880 to the present in this article shows that the Sun’s intensity increased slightly from 1880 to 1960 and then has declined slightly since 1960. Satellite measurements of solar radiation show also that the solar radiation reaching Earth has declined slightly over the last 30 years – yet the Earth still warmed.

Temperature Data: The best temperature data we have clearly shows the Earth is getting warmer. NASA has compiled the Earth’s average temperature for each year since 1880 by using ships logs, weather stations, and satellite measurements. In the graph below , each square dot shows how far that year’s average temperature was above or below the 1970 value. Although the data varies widely from year to year because of random factors such as sunspots, weather events, ocean current, and particulates from volcanoes and man’s activities, the trend is clearly upward. The solid red and blue lines are moving averages, which make the trend easier to follow.

Credit: NASA/JPL/MSSS

Temperature Trend: The greenhouse effect links some of the causes of the temperature trend to man’s activities. The trend took a turn upward in about 1920. That was when the automobile, industrialization, and energy production began further increasing the carbon dioxide concentration in the air. The trend was flat from about 1945 to 1975 and that can be attributed mostly to particulates. There was an increase in particulates after 1945 from many sources such as WW II, atmospheric nuclear testing, and increased industrialization. Research during the early 1970′s showed a huge increase in aerosols from power production, increased industrialization, and vehicles and some alarmists even speculated that we might be causing another ice age. Particulates are visible and cause immediate health problems so by 1980 most industrialized countries had restrictions on particulate release. During the period from1945 to 1975 the CO2 concentration had continued to rise but its effect had been masked by the particulates. Reducing the particulates in the air allowed the full effect of the CO2 to be felt, causing the Earth’s temperature to begin to rise again. The effect of particulates and the reliability of the temperature record can clearly be seen in the graph above. In 1991, Mt. Pinaturbo erupted spewing about 10 cubic kilometers of ash into the air which caused an immediate 0.3 °C temperature drop for the entire Earth, lasting until about 1995.

Causality: Although the greenhouse effect is a well accepted principle, skeptics sometimes claim the correlation between global warming and CO2 does not constitute causality. However, G.N. Plass, in 1956, calculated the climate sensitivity of the Earth to CO2. He found that doubling the concentration of CO2 in the air would cause a 3 to 4 °C increase in the Earth’s temperature. A number of more recent studies have confirmed his work and have shown that, though the concentration of CO2 in the air is small, it accounts for about 25% of the greenhouse effect. No natural occurrences such as volcanoes, sunspots, fires, or dust storms can account for the major trend in the data. Certainly, the increasing amount of CO2 in the air is causing the Earth to warm.

Man’s Role: Man’s activities, mainly through deforestation and burning fossil fuels, have released large amounts of CO2 into the air. In the last century, man’s emission of CO2 from fossil fuels have increased to over 30 billion tons annually and the concentration of CO2 in the air has risen from 280 parts per million (ppm) to 385 ppm. The processes that remove carbon dioxide from the air takes decades or longer so as the carbon dioxide concentration slowly built up, the Earth became a better greenhouse. The concentration of carbon dioxide in the air is now 38% higher than in 1880 and the Earth’s temperature is about 0.8°C (or 1.3 °F) higher. Clearly, man’s activities are mainly responsible for increasing the CO2 concentration in the air – and the increasing CO2 concentration is causing global warming.

v Share this.

Climate Change and the Greenhouse Effect

admin — Wed, 12 Aug 2009 14:47:13 +0000

Most gardeners know how greenhouses work. In the daytime, the sun’s radiation (visible and UV) comes in through the glass and warms the plants and soil. The glass stops the heat radiation ( infrared ) from passing back through and the greenhouse stays warm enough to keep the plants from freezing, even at night. The Earth works pretty much the same way except there is no glass. Greenhouse gases, primarily water and carbon dioxide, play the role of the glass and trap some of the radiation. Winter nights on Earth would be very cold without greenhouse gases.

Of the Sun’s energy coming to Earth, 30% is reflected immediately back into space by particles in the air, by clouds, and by the surface. Another 20% is absorbed by the atmosphere where it runs the weather cycle. The remaining 50% heats the land and oceans. All the absorbed heat is eventually radiated back into space as infrared radiation. It’s a balanced energy budget, 100% in and 100% back out. Anything that reflects more light back into space, such as an increase in particulate matter in the air, would cause the Earth to cool. Anything that delays the energy’s trip back to space, such as an increase in greenhouse gases, would cause the Earth to warm.

The best data we have clearly shows the Earth is getting warmer. NASA has compiled the Earth’s average temperature for each year since 1880 by using ships logs, weather stations, and satellite measurements. In the graph below , each square dot shows how far that year’s average temperature was above or below the 1970 value. The solid red line is the moving average, which makes the trend easier to follow. Although the data varies widely from year to year, the trend is clearly upward.

http://data.giss.nasa.gov/gistemp/2007/ Credit: NASA/JPL/MSSS

The greenhouse effect links the temperature increase to man’s activities. The trend starts upward in about 1920. That was when the automobile, industrialization, and energy production began increasing the carbon dioxide concentration in the air. . The processes that remove carbon dioxide from the air take decades, so as the carbon dioxide concentration slowly built up, the Earth became a better greenhouse. The concentration of carbon dioxide in the air is now 50% higher than in 1920 and the Earth’s temperature is about 0.8°C (or 1.3 °F) higher. No natural occurrences such as volcanoes, sunspots, fires, or dust storms can account for the major trend in the data.