INTRODUCTION
Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly 78% nitrogen and 21% oxygen, trace amounts of other gases, and water vapor. This mixture of gases is commonly known as air. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.
Global warming happened when increasing in the earth's average atmospheric temperature that causes corresponding changes in climate and that may effect of human industry and agriculture. Global warming are rising sea levels, flooding, melting of polar ice caps and glaciers. Global warming through its history and currently appears to be undergoing such warming. In the other word, global warming is the observe increase in the average temperature of the Earth’s atmosphere and oceans in recent decades.
In my opinion there is nothing impossible in this world, same as these phenomena of the global warming. There must be the way that we can found to reduce global warming. So I do not agree that nothing can be done to reduce global warming phenomena.
QUESTION:
Some think that nothing can be done to reduce global warming as it is a natural phenomenon that takes place as and when the earth ages with time. Do you agree or disagree? Support your position with at least three logical arguments.
i) Activity 1: Identify the main topics in the assignment question.
Global warming as natural phenomena.
ii) Activity 2: Search for at least TWO (2) articles from the e-journal databases
(From OUM TSDAS Digital Library) that are related to the assignment topic. Attach the article together with the assignment.
Article 1
Evidence Of Global Warming
If the voices of future generations could be heard, they would plead for action on climate change. The unborn children of tomorrow will bear the heavy burden of our indifference.
Graph of Historical Trend of Warming Temperatures
Carbon Dioxide Increasing in Atmosphere
Methane Also Increasing
More Frequent Extreme Weather
Disappearing Glaciers
Melting Arctic Sea Ice
Melting Antarctic Sea Ice
Greenland's Ice Sheet Melting
Tropical Diseases Spreading
Oceans Warming With Coral Bleaching & Disintegration
Carbon Dioxide Increasing in Atmosphere
The atmospheric levels of the greenhouse gas carbon dioxide, have increased since pre-industrial times from 280 part per million (ppm) to 377.5 ppm (2004 Carbon Dioxide Information Analysis Center), a 34% increase. Carbon dioxide concentrations in the atmosphere are the highest in 650,000 years. Carbon dioxide is a by-product of the burning of fossil fuels, such as gasoline in an automobile or coal in a power plant generating electricity.
Methane Also Increasing
Levels of atmospheric methane, a powerful greenhouse gas, have risen 145% in the last 100 years. [18] Methane is derived from sources such as rice paddies, bovine flatulence, bacteria in bogs and fossil fuel production. Back to Top of Page
More Frequent Extreme Weather
The year 1999 was the fifth-warmest year on record since the mid-1800's; 1998 being the warmest year. According to Thomas Karl, director of the National Climatic Data Center (NOAA), the current pace of temperature rise is "consistent with a rate of 5.4 to 6.3 degrees Fahrenheit per century." By comparison, the world has warmed by 5 to 9 degrees Fahrenheit since the depths of the last ice age, 18,000 to 20,000 years ago.
The potential for floods and droughts is increasing."....... the heating from increased greenhouse gases enhances the hydrological cycle and increases the risk for stronger, longer-lasting or more intense droughts, and heavier rainfall events and flooding, even if these phenomena occur for natural reasons. Evidence, although circumstantial, is widespread across the United States. Examples include the intense drought in the central southern U.S in 1996, Midwest flooding in spring of 1995 and extensive flooding throughout the Mississippi Basin in 1993 even as drought occurred in the Carolinas, extreme flood events in winters of 1992-93 and 1994-95 in California but droughts in other years (e.g, 1986-87 and 1987-88 winters)," says Dr. Kevin Trenberth of the National Oceanic and Atmospheric Administration (NOAA). [6]
Disappearing Glaciers Ice is melting all over the planet. Glaciers are melting on six continents.
If present warming trends continue, all glaciers in Glacier National Park could be gone by 2030. [54] The park's Grinnell Glacier is already 90% gone. Pictured here is the glacier prior to its meltdown. [120]
Because of global warming, the glaciers of the Ruwenzori range in Uganda are in massive retreat.
The Bering Glacier, North America's largest glacier, has lost 7 miles of its length, while losing 20-25% of parts of the glacier.
Ice cores taken from the Dunde Ice Cap in the Qilian Mountains on the northeastern margin of the Qinghai-Tibetan Plateau indicate that the years since 1938 have been the warmest in the last 12,000 years.
The melting is accelerating. The Lewis Glacier on Mt. Kenya (In Kenya) has lost 40% of its mass during the period 1963-1987 or at a much faster clip than during 1899-1963. [29]
See Gary Braasch's Pictures of Receding Glaciers
See More Images of Receding Glaciers
Ohio State University researcher Lonnie Thompson on global warming and retreating glaciers
In southern Peru the rate of melting of the Qori Kalis glacier during the 8 year period 1983 to 1991 was 3 times the pace of the previous 20 years, 1963 to 1983. "By the time we probably know what they are doing, it will be far too late to worry about it because they are going to be like galloping glaciers," says Ellen Mosley Thompson, climate expert at Ohio State University. [30] The Qori Kalis is receding at about two feet per day. Sitting beside the glacier, one could witness the melting hour by hour. [120]
In a study that appeared in the journal, Science, September 15, 2000, a team led by Lonnie G. Thompson, including Ellen Mosley-Thompson, both of Ohio State, analyzed ice cores that came from deep within a glacier more than 20,000 feet high in the Himalayas. The results of their research showed that the past 100 years have been the hottest period in 1,000 years high in the Himalayas. Also their research supports other studies that demonstrated a dramatic decline in water levels of glacier-fed rivers, and that the high elevations are warming much more than the global average (one degree F). Mosley-Thompson says, "For these rivers to continue to flow year-round, they have to be fed by ice in the high mountains. The question then is where will the river flow come from during the dry season?" [59]
Greenland's glaciers are moving more rapidly to the sea, caused, perhaps, by melt water lubricating the base of the glaciers. See below for another look at dwindling ice mass in Greenland.
The Tasman Glacier in New Zealand has thinned by more than 100 meters in the past century. Glaciers in New Zealand have shrunk about 26% between 1890 and 1998. [54]
The melting of the Gangotri Glacier in India is accelerating with an average rate of retreat of 30 meters annually. The rate between 1935 and 1990 was 18 meters per year and 7 meters annually between 1842 and 1935. [54]
A glacier from which Sir Edmund Hillary and Tenzing Norgay set out to conquer Mount Everest nearly 50 years ago has retreated three miles up the mountain due to global warming. The head of the Nepal Mountaineering Association, Tashi Jangbu Sherpa, says " that Hillary and Tenzing would now have to walk two hours to find the edge of the glacier which was close to their original base camp." [114]
Portage Glacier in the Chugach National Forest, south of Anchorage, is another casualty of climate change, say scientists at the University of Alaska Fairbanks. These researchers found that melting glaciers are responsible for at least 9 percent of the global sea-level rise over the past century.
Back to Top of Page
Melting Arctic Sea Ice
The Arctic, with an area about the size of the United States, is seeing average temperatures similar to the Antarctic, almost 5 degrees Fahrenheit warmer than the planet as a whole Arctic sea ice has shrunk by 250 million acres -- an area the size of California, Maryland and Texas combined.
In a N.Y Times article (Nov. 17, 1999) it was reported that scientists have discovered that from 1993 through 1997 average Arctic sea ice thickness was six feet. This represents a significant reduction in Arctic sea ice from 1958 through 1976 when average thickness measured 10 feet. This means that in less than 30 years, there has been a 40% loss of arctic sea ice. In a Washington Post article (Dec. 3, 1999) it was noted that in the Arctic, sea ice is shrinking at a rate of 14,000 square miles annually, an area larger than Maryland and Delaware combined.
According to a report by Norwegian scientists, the arctic sea ice in about 50 years could disappear entirely each summer. Researchers at the Nansen Environmental and Remote Sensing Center based their predictions on satellite pictures. These pictures showed that the Arctic winter icescapes decreased by 6% (a Texas-size area) during the last 20 years. [61]
Melting Antarctic Sea Ice
The Antarctic Peninsula has seen an increase in average temperatures of almost 5 degrees Fahrenheit in the last 50 years. Heavy sea ice has been the norm in the Antarctic, but in the 1990's sea ice disintegration has begun, notes Robin Ross, a biological oceanographer with the University of California at Santa Barbara. During the year 1998, the Antarctic displayed a record low in winter sea ice. Back to Top of Page
Greenland's Ice Sheet Melting
In a recent study by researchers from NASA's Goddard Space Flight Center shows that Greenland's ice sheet, about 8% of the Earth's grounded ice (Antarctica possessing 91% of land ice), is losing ice mass. A NASA high-tech aerial survey shows that more than 11 cubic miles of ice is melting along Greenland's coasts yearly, accounting for 7% of the annual global sea level rise. Measurements over the last century suggest that sea level has risen 9 inches, enough to cause flooding in low-lying areas, when a storm occurs. Sea level increase could worsen, if the present trend continues, says William Krabill, lead author of the NASA study. [53] Back to Top of Page
Tropical Diseases Spreading
A recent study by New Zealand doctors, researchers at the Wellington School of Medicine's public health department said outbreaks o f dengue fever in South Pacific islands are directly related to global warming. [9] Global warming is projected to significantly increase the range conducive to the transmission of both dengue and yellow fevers. [10] Back to Top of Page
Oceans Warming With Coral Bleaching & Disintegration
Devastating loss of coral in the Caribbean - March, 2006
In March, 2006 researchers discovered devastating loss of coral in the Caribbean off Puerto Rico and the Virgin Islands. "It's an unprecedented die-off," said National Park Service fisheries biologist Jeff Miller, who last week checked 40 official monitoring stations in the Virgin Islands. "The mortality that we're seeing now is of the extremely slow-growing reef-building corals. These are corals that are the foundation of the reef ... We're talking colonies that were here when Columbus came by have died in the past three to four months."...............Miller noted that some of the devastated coral can never be replaced because it only grows the width of one dime each year.
If coral reefs die "you lose the goose with golden eggs" that are key parts of small island economies, said Edwin Hernandez-Delgado, a University of Puerto Rico biology researcher. While investigating the widespread loss of Caribbean coral, Hernandez-Delgado found a colony of 800-year-old star coral — more than 13 feet high — that had just died in the waters off Puerto Rico.........."We did lose entire colonies," he said. "This is something we have never seen before."
"We haven't seen an event of this magnitude in the Caribbean before," said Mark Eakin, coordinator of the National Oceanic and Atmospheric Administration's Coral Reef Watch.
Tom Goreau of the Global Coral Reef Alliance says that compared to coral areas in the Indian and Pacific ocean, where warming waters have brought about a 90% mortality rate, the Caribbean is healthier.
The Caribbean is actually better off than areas of the Indian and Pacific ocean where mortality rates — mostly from warming waters — have been in the 90 percent range in past years, said Tom Goreau of the Global Coral Reef Alliance. Goreau called what's happening worldwide "an underwater holocaust."
"The prognosis is not good," said biochemistry professor M. James Crabbe of the University of Luton near London. "If you want to see a coral reef, go now, because they just won't survive in their current state."
Read more in AP Science Writer Seth Borenstein's article in the San Francisco Chronicle
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A Doubling of Atmospheric CO2 will Stunt Coral Growth
The Earth is on a trajectory to double its atmospheric carbon dioxide (above 700 ppm) by the year 2065. Scientists say that this will result in a 30% drop in the amount of calcium that tropical oceans can retain, whereby coral growth would be stunted by the lack of calcium in these ocean waters. [34] [87] This would threaten the capability of coral to repair itself in the event of storm damage and from coral-chewing predators. Robert W. Buddemeier, senior chemist with the Kansas Geological Survey says, "There is growing agreement that doubling CO2 in the atmosphere means a 15% decline in the coral population."[116]
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Ninth International Coral Reef Symposium October 2000
In October, 2000 at the Ninth International Coral Reef Symposium, held on the island of Bali, researchers warned that more than 25% of the world's coral reefs have been destroyed by pollution and global warming. Scientists emphasized that most of the damage to coral is inflicted by global warming through coral bleaching, the result of higher water temperatures heating the coral. The warming waters stress the coral, which then expels the microscopic plants or algae that give the coral color and nourishes it. Most of the remaining coral could be dead in 20 years, if global warming and pollution continue. Coral reefs around the Maldives and Seychelles islands in the Indian Ocean have taken the brunt of warming seas, as 90% of these corals have been killed over the past two years. Some of the coral reefs, long described as undersea rainforests, home to marine ecosystems that sustain thousands of species of fish and other marine life, have been alive for up to 2.5 million years. [62]
At the Ninth International Coral Reef Symposium, oceanographers said that the El Nino weather pattern two years ago, that led to an increase in ocean water temperature by up to 6 degrees Fahrenheit, did heavy damage to coral reefs. Australian scientist Ove Hoegh-Guldberg warns that in 20 years coral will be sitting in a "hot soup" and will not survive. Millions of people depend on coral for income ($400 billion annually in fishing and tourism revenue) and food. [62]
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World's Coral Reefs Will be Dead Within 50 Years
According to Rupert Ormond, a marine biologist from Glasgow University, the world's coral reefs will be dead within 50 years because of global warming, and there is nothing we can do to save them, a scientist warned on September 5, 2001. In a conference held by the British Association for the Advancement of Science, he said, "It is hard to avoid the conclusion that most coral in most areas will be lost. We are looking at a loss which is equivalent to the tropical rain forests." He also mentioned that if humans were to stop pumping out greenhouse gases, such as carbon dioxide, tomorrow in a bid to halt the process, it would still be too late to save the reefs. "I don't know what can be done, given that there's a 50-year time lag between trying to limit carbon dioxide levels and any effect on ocean temperature. "We are looking at a gradual running down of the whole system.
Over time, the diversity of coral fish will die," Ormond said. He also said that the only cause for optimism was that new coral reefs could start to emerge in colder waters such as the north Atlantic Ocean and Mediterranean Sea. Humankind will also suffer directly as the dead reefs are eroded and shorelines that have been protected for the last 10,000 years are now vulnerable without their natural defenses.
Go directly to information source (September 6, 2001) or [104]
(Note: Sometimes referenced articles are not available)
CAUSE OF GLOBAL WARMING
Carbon Dioxide from Power Plants
In 2002 about 40% of U.S. carbon dioxide emissions stem from the burning of fossil fuels for the purpose of electricity generation. Coal accounts for 93 percent of the emissions from the electric utility industry. The principal greenhouse gas, released by coal and 25% less carbon dioxide than oil, for the same amount of energy produced.
Carbon Dioxide Emitted from Cars
About 20% carbon dioxide emissions comes from the burning of gasoline in internal-combustion engines of cars and light trucks (minivans, sport utility vehicles, pick-up trucks, and jeeps). Vehicles with poor gas mileage contribute the most to global warming. Each gallon of gas a vehicle consumes, 19.6 pounds of carbon dioxide are emitted into the air.
Sports utility vehicles were built for rough terrain, off road driving in mountains and deserts. When they are used for city driving, they are so much overkill to the environment. If one has to have a large vehicle for their family, station wagons are an intelligent choice for city driving, especially since their price is about half that of a sports utility. Inasmuch as SUV's have a narrow wheel base in respect to their higher silhouette, they are four times as likely as cars to rollover in an accident.
Nitrous oxide
Another greenhouse gas is Nitrous oxide (N2O), a colorless, non-flammable gas with a sweetish odour, commonly known as "laughing gas", and sometimes used as an unaesthetic. Oceans and rainforests naturally produce nitrous oxide. Nitrous oxide is broken down in the atmosphere by chemical reactions that involve sunlight.
Deforestation
After carbon emissions caused by humans, deforestation is the second principle cause of atmospheric carbon dioxide. Deforestation is responsible for 25% of all carbon emissions entering the atmosphere, by the burning and cutting of about 34 million acres of trees each year.
Carbon in Atmosphere and Ocean
The atmosphere contains about 750 billion tons of carbon, while 800 billion tons are dissolved in the surface layers of the world's oceans.
Emissions stem from burning of fossil fuels
The U.S in 2000 produced 1,583 million metric tons of carbon from burning fossil fuel, nearly 14% more than its levels in 1990. Transportation, mostly exhaust from motor vehicles, accounted for 515 million metric tons, or 33%. [109] Electricity generation from fossil fuel burning accounts for about 33% of the U.S's carbon emissions
Emission comes from burning of gasoline
When gasoline burns, the carbon and hydrogen separate. The hydrogen combines with oxygen to form water (H2O), and carbon combines with oxygen to form carbon dioxide (CO2). A carbon atom has an atomic weight of 12, and each oxygen atom has an atomic weight of 16, giving each single molecule of CO2 an atomic weight of 44 (12 from carbon and 32 from oxygen).Therefore, to calculate the amount of CO2 produced from a gallon of gasoline, the weight of the carbon in the gasoline is multiplied by 44/12 or 3.7. Since gasoline is about 87% carbon and 13% hydrogen by weight, the carbon in a gallon of gasoline weighs 5.5 pounds (6.3 lbs. x .87). We can then multiply the weight of the carbon (5.5 pounds) by 3.7, which equals 20 pounds of CO2.
WHAT WE CAN DO TO REDUCE GLOBAL WARMING
• When replacing home appliances, use energy efficient models. For example, replacing an old refrigerator using 320 watts with a new one using 85 watts could make a big difference.
• Use cars and light trucks that get good gas mileage. In fact tell your friend that driving a sport utility vehicle adds to global warming and pollution.
• Place an insulating cover around water heater.
• Insulate walls and ceilings, and lower heating bills.
• A car needs only about 2 minutes to warm up. Taking more time only wastes fuel and contributes to global warming.
• Take public transit whenever possible.
• When shopping for groceries, bring your own cloth bag to the market. Not using paper grocery bags help saves trees that absorb carbon dioxide.
Article 2
GLOBAL WARMING
Global warming refers to the increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation.The global average air temperature near the Earth's surface rose 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the last 100 years. The Intergovernmental Panel on Climate Change (IPCC) concludes, "most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations via the greenhouse effect.
Natural phenomena such as solar variation combined with volcanoes
Probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward. These basic conclusions have been endorsed by at least 30 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries. However, a few individual scientists disagree with some of the main conclusions of the IPCC.
An increase in global temperatures is expected to cause other changes, including sea level rise, increased intensity of extreme weather events, and changes in the amount and pattern of precipitation. Other effects of global warming include changes in agricultural yields, glacier retreat, species extinctions and increases in the ranges of disease vectors.
An increase in global temperatures
It is expected to cause other changes, including sea level rise, increased intensity of extreme weather events, and changes in the amount and pattern of precipitation. Other effects of global warming include changes in agricultural yields, glacier retreat, species extinctions and increases in the ranges of disease vectors. Most national governments have signed and ratified the Kyoto Protocol, aimed at reducing greenhouse gas emissions.
The greenhouse effect
It was discovered by Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896. It is the process by which absorption and emission of infrared radiation by atmospheric gases warms a planet's atmosphere and surface.
The warming causes more water vapor to be evaporated, and so forth until a new dynamic equilibrium concentration of water vapor is reached with a much larger greenhouse effect than that due to CO2 alone.
Feedback effects due to clouds are an area of ongoing research. Seen from below, clouds emit infrared radiation back to the surface, and so exert a warming effect. Seen from above, the same clouds reflect sunlight and emit infrared radiation to space, and so exert a cooling effect. Whether the net effect is warming or cooling depends on details such as the type and altitude of the cloud. These details are difficult to represent in climate models, in part because clouds are much smaller than the spacing between points on the computational grids of climate models.
Another related issue that may have partially mitigated global warming in the late twentieth century is global dimming, the gradual reduction in the amount of global direct irradiance at the Earth's surface.
Ozone depletion, the steady decline in the total amount of ozone in Earth's stratosphere, is frequently cited in relation to global warming. Although there are areas of linkage, the relationship between the two is not strong.
Solar variation
Hypotheses have been proposed that variations in solar output, possibly amplified by cloud feedbacks, may have contributed to recent warming.[29] A difference between this mechanism and greenhouse warming is that an increase in solar activity should warm the stratosphere while greenhouse warming should cool the stratosphere. Cooling in the lower stratosphere has been observed since at least 1960,[30] which would not be expected if solar activity were the main contributor to recent warming. (Reduction of stratospheric ozone also has a cooling influence but substantial ozone depletion did not occur until the late 1970s.) Phenomena such as solar variation combined with changes in volcanic activity have probably had a warming effect from pre-industrial times to 1950, but a cooling effect since 1950.[1] A related hypothesis is that cosmic rays may affect climate by influencing the generation of cloud condensation nuclei.[31]
A few papers suggest that the Sun's contribution may have been underestimated. Two researchers at Duke University have estimated that the Sun may have contributed about 40–50% of the global surface warming over the period 1900–2000, and about 25–35% between 1980 and 2000.[32] Stott and coauthors suggest that climate models overestimate the relative effect of greenhouse gases compared to solar forcing; they also suggest that the cooling effects of volcanic dust and sulfate aerosols have been underestimated.[33] Nevertheless, they conclude that even with an enhanced climate sensitivity to solar forcing, most of the warming during the latest decades is attributable to the increases in greenhouse gases.
In 2006, a team of scientists from the United States, Germany, and Switzerland found no net increase of solar brightness over the last thousand years. Solar cycles lead to a small increase of 0.07% in brightness over the last 30 years. This effect is far too minute to contribute significantly to global warming.[34][35] A 2007 paper by Lockwood and Fröhlich found no relation between global warming and solar radiation since 1985, whether through variations in solar output or variations in cosmic rays.[36]
Temperature changes
Two millennia of mean surface temperatures according to different reconstructions, each smoothed on a decadal scale. The unsmoothed, annual value for 2004 is also plotted for reference.
Global temperatures on both land and sea have increased by 0.75 °C (1.35 °F) relative to the period 1860–1900, according to the instrumental temperature record. This measured temperature increase is not significantly affected by the urban heat island effect. Since 1979, land temperatures have increased about twice as fast as ocean temperatures (0.25 °C per decade against 0.13 °C per decade).[37] Temperatures in the lower troposphere have increased between 0.12 and 0.22 °C (0.22 and 0.4 °F) per decade since 1979, according to satellite temperature measurements. Temperature is believed to have been relatively stable over the one or two thousand years before 1850, with possibly regional fluctuations such as the Medieval Warm Period or the Little Ice Age.
Sea temperatures increase more slowly than those on land both because of the larger effective heat capacity of the oceans and because the ocean can lose heat by evaporation more readily than the land.[38] Since the northern hemisphere has more land mass than the southern it warms faster; also there are extensive areas of seasonal snow cover subject to the snow-albedo feedback. Although more greenhouse gases are emitted in the northern than southern hemisphere this does not contribute to the asymmetry of warming as the major gases are essentially well-mixed between hemispheres.
Based on estimates by NASA's Goddard Institute for Space Studies, 2005 was the warmest year since reliable, widespread instrumental measurements became available in the late 1800s, exceeding the previous record set in 1998 by a few hundredths of a degree.[39] Estimates prepared by the World Meteorological Organization and the Climatic Research Unit concluded that 2005 was the second warmest year, behind 1998.[40][41]
Anthropogenic emissions of other pollutants—notably sulfate aerosols—can exert a cooling effect by increasing the reflection of incoming sunlight. This partially accounts for the cooling seen in the temperature record in the middle of the twentieth century,[42] though the cooling may also be due in part to natural variability.
Paleoclimatologist William Ruddiman has argued that human influence on the global climate began around 8,000 years ago with the start of forest clearing to provide land for agriculture and 5,000 years ago with the start of Asian rice irrigation.[43] Ruddiman's interpretation of the historical record, with respect to the methane data, has been disputed.[44]
Pre-human climate variations
Curves of reconstructed temperature at two locations in Antarctica and a global record of variations in glacial ice volume.Earth has experienced warming and cooling many times in the past. The recent Antarctic EPICA ice core spans 800,000 years, including eight glacial cycles timed by orbital variations with interglacial warm periods comparable to present temperatures.[45]
A rapid buildup of greenhouse gases caused warming in the early Jurassic period (about 180 million years ago), with average temperatures rising by 5 °C (9 °F). Research by the Open University indicates that the warming caused the rate of rock weathering to increase by 400%. As such weathering locks away carbon in calcite and dolomite, CO2 levels dropped back to normal over roughly the next 150,000 years.[46][47]
Sudden releases of methane from clathrate compounds (the clathrate gun hypothesis) have been hypothesized as a cause for other warming events in the distant past, including the Permian-Triassic extinction event (about 251 million years ago) and the Paleocene-Eocene Thermal Maximum (about 55 million years ago).
Climate models
The projected temperature increase for a range of stabilization scenarios (the coloured bands). The black line in middle of the shaded area indicates 'best estimates'; the red and the blue lines the likely limits. From the work of IPCC AR4, 2007.
Calculations of global warming prepared in or before 2001 from a range of climate models under the SRES A2 emissions scenario, which assumes no action is taken to reduce emissions.
The geographic distribution of surface warming during the 21st century calculated by the HadCM3 climate model if a business as usual scenario is assumed for economic growth and greenhouse gas emissions. In this figure, the globally averaged warming corresponds to 3.0 °C (5.4 °F).
Main article: Global climate model
Scientists have studied global warming with computer models of the climate. These models are based on physical principles of fluid dynamics, radiative transfer, and other processes, with some simplifications being necessary because of limitations in computer power. These models predict that the effect of adding greenhouse gases is to produce a warmer climate.[48] However, even when the same assumptions of future GHG levels are used, there still remains a considerable range of climate sensitivity.
Including uncertainties in future greenhouse gas concentrations and climate modelling, the IPCC anticipates a warming of 1.1 °C to 6.4 °C (2.0 °F to 11.5 °F) between 1990 and 2100.[1] Models have also been used to help investigate the causes of recent climate change by comparing the observed changes to those that the models project from various natural and human derived causes.
Current climate models produce a good match to observations of global temperature changes over the last century, but do not simulate all aspects of climate.[49] These models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects; however, they suggest that the warming since 1975 is dominated by man-made greenhouse gas emissions.
Most global climate models, when run to project future climate, are forced by imposed greenhouse gas scenarios, generally one from the IPCC Special Report on Emissions Scenarios (SRES). Less commonly, models may be run by adding a simulation of the carbon cycle; this generally shows a positive feedback, though this response is uncertain (under the A2 SRES scenario, responses vary between an extra 20 and 200 ppm of CO2). Some observational studies also show a positive feedback.[50][51][52]
The representation of clouds is one of the main sources of uncertainty in present-generation models, though progress is being made on this problem.[53] There is also an ongoing discussion as to whether climate models are neglecting important indirect and feedback effects of solar variability.
Attributed and expected effects
Main article: Effects of global warming
Sparse records indicate that glaciers have been retreating since the early 1800s. In the 1950s measurements began that allow the monitoring of glacial mass balance, reported to the WGMS and the NSIDC.
Though it is difficult to connect specific weather events to global warming, an increase in global temperatures may in turn cause other changes, including glacial retreat and worldwide sea level rise. Changes in the amount and pattern of precipitation may result in flooding and drought. There may also be changes in the frequency and intensity of extreme weather events. Other effects may include changes in agricultural yields, reduced summer streamflows, species extinctions and increases in the range of disease vectors.
Some effects on both the natural environment and human life are, at least in part, already being attributed to global warming. A 2001 report by the IPCC suggests that glacier retreat, ice shelf disruption such as the Larsen Ice Shelf, sea level rise, changes in rainfall patterns, increased intensity and frequency of extreme weather events, are being attributed in part to global warming.[54] While changes are expected for overall patterns, intensity, and frequencies, it is difficult to attribute specific events to global warming. Other expected effects include water scarcity in some regions and increased precipitation in others, changes in mountain snowpack, and adverse health effects from warmer temperatures.[55]
Increasing deaths, displacements, and economic losses projected due to extreme weather attributed to global warming may be exacerbated by growing population densities in affected areas, although temperate regions are projected to experience some minor benefits, such as fewer deaths due to cold exposure.[56] A summary of probable effects and recent understanding can be found in the report made for the IPCC Third Assessment Report by Working Group II.[54] The newer IPCC Fourth Assessment Report summary reports that there is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic Ocean since about 1970, in correlation with the increase in sea surface temperature, but that the detection of long-term trends is complicated by the quality of records prior to routine satellite observations. The summary also states that there is no clear trend in the annual worldwide number of tropical cyclones.[1]
Additional anticipated effects include sea level rise of 110 to 770 millimeters (0.36 to 2.5 ft) between 1990 and 2100,[57] repercussions to agriculture, possible slowing of the thermohaline circulation, reductions in the ozone layer, increased intensity and frequency of hurricanes and extreme weather events, lowering of ocean pH, and the spread of diseases such as malaria and dengue fever. One study predicts 18% to 35% of a sample of 1,103 animal and plant species would be extinct by 2050, based on future climate projections.[58] Two populations of Bay checkerspot butterfly are being threatened by changes in precipitation, though few mechanistic studies have documented extinctions due to recent climate change.[59]
Economics
Some economists have tried to estimate the aggregate net economic costs of damages from climate change across the globe. Such estimates have so far failed to reach onclusive findings; in a survey of 100 estimates, the values ran from US$-10 per tonne of carbon (tC) (US$-3 per tonne of carbon dioxide) up to US$350/tC (US$95 per tonne of carbon dioxide), with a mean of US$43 per tonne of carbon (US$12 per tonne of carbon dioxide).[56] One widely-publicized report on potential economic impact is the Stern Review; it suggests that extreme weather might reduce global gross domestic product by up to 1%, and that in a worst case scenario global per capita consumption could fall 20%.[60] The report's methodology, advocacy and conclusions have been criticized by many economists, primarily around the Review's assumptions of discounting and its choices of scenarios,[61] while others have supported the general attempt to quantify economic risk, even if not the specific numbers.[62][63]
In a summary of economic cost associated with climate change, the United Nations Environment Programme emphasizes the risks to insurers, reinsurers, and banks of increasingly traumatic and costly weather events. Other economic sectors likely to face difficulties related to climate change include agriculture and transport. Developing countries, rather than the developed world, are at greatest economic risk.[64]
iii) Activity 3: Read the articles and make notes on the key issues related to the assignment topic.
1) EVIDENCE OF GLOBAL WARMING
a) Carbon Dioxide Increasing in Atmosphere
b) More Frequent Extreme Weather
c) Melting Arctic Sea Ice
d) Melting Antarctic Sea Ice
2) CAUSE OF GLOBAL WARMING
a) Carbon Dioxide from Power Plants
b) Carbon Dioxide Emitted from Cars
c) Emissions stem from burning of fossil fuels
d) Emission comes from burning of gasoline
e) Nitrous oxide
f) Deforestation
g) Carbon in Atmosphere and Ocean
3) WHAT WE CAN DO TO REDUCE ENERGY USE
a) When replacing home appliances, use energy efficient models. For example, replacing an old refrigerator using 320 watts with a new one using 85 watts could make a big difference.
b) Use cars and light trucks that get good gas mileage. In fact tell your friends that driving sports utility vehicle adds to global warming and pollution.
c) Place an insulating cover around water heater.
d) Insulate walls and ceilings, and lower heating bills.
e) A car needs only about 2 minutes to warm up. Taking more time only wastes fuel and contributes to global warming.
f) Take public transit whenever possible.
iii) Activity 4: Write essay based on your notes.
GLOBAL WARMING AS NATURAL PHENOMENA
Table of Content:
1. Burning of fossil fuels
1.1 Emissions stem from burning of fossil fuels
2. Burning of gasoline
2.1 Emission comes from burning of gasoline
3. Reason why global warming is deforestation.
3.1 Among another reason of global warming is deforestation.
INTRODUCTION
As we know, global warming means an increased global temperature and it is happen based on several reason. Some people think that nothing can be done to reduce global warming. It seem like the earths will destroyed if we as a human don’t care about global warming phenomena. This matter is very important to all of us in the world to concern about global warming. Also we must take part in finding the best way to help and to save our earth.
There is a lots of reason why is global warming happens. Here I would like to state three logical arguments about cause of global warming and what humans can do to save our earth.
1. Burning of fossil fuels
1.1 Emissions stem from burning of fossil fuels
Emissions stem from burning of fossil fuels for the purpose of electricity is the one of the reason to contribute global warming; that activities will emissions carbon dioxide and it’s usually comes from the electric utility industry. From this factor, to reduce global warming we can follow the principle of greenhouse gas, released by coal and 25% less carbon dioxide than oil, for the same amount of energy produced.
2. Burning of gasoline
2.1 Emission comes from burning of gasoline
Emission comes from burning of gasoline in internal-combustion engines of cars and light trucks (jeeps, sport utility vehicles and minivan). Therefore we cannot use a poor gas mileage because it will contribute the most of global warming. Sports utility vehicles were built for rough terrain, off road driving in mountains and deserts. When they are used for city driving, they are so much overkill to the environment. Therefore high temperatures are likely to become more extreme and we found that the greenhouse gases, which are directly influenced by human activities found, are carbon dioxide, methane, nitrous oxide, the chlorofluorocarbons (CFCs) and Ozone. If car manufacturers were to increase their fleets' average gas mileage about 3 miles per gallon, this country could save a million barrels of oil every day. In that way we can reduce the phenomena of the global warming.
3. Reason why global warming is deforestation
3.1 Among another reason of global warming is deforestation.
Deforestation is the second principle cause of atmospheric carbon dioxide. By burning and cutting trees in the forest, it will cause carbon emissions entering the atmosphere. By means of that we are losing millions of acres of rainforests each year, the equivalent in area to the size of our state. We are also losing temperate forests. As global warming worsens and temperatures rise, the forests become more stressed and this in turn may cripple temperate forests' ability to absorb carbon dioxide.
CONCLUSION
This kind of human activities must be control by the government to threat an animal live and to protect our forest too. If not, the animal will lose their habitat. Burning and cutting trees must be control to ensure the atmosphere free from the emission of the carbon dioxide. If we going for shopping to the market that using a paper grocery bag, we don’t use that. We can bring our own cloth bag and that will help to saves tree that absorb carbon dioxide.
At last we have found that many things human can do to save the Earth's atmosphere. There is one more simple thing that we can do example, we can warm up our car only about 3 minutes before drive, taking more time only wastes fuel and contributes to global warming. That is very simple thing but it will give us more benefit and reduce global warming. So overall I do not agree that nothing can be done to reduce global warming as it is a natural phenomena.
BIBLIOGRAPHY
Houghton, J. T. Global Warming: The Complete Briefing.
Port Chester, NY, USA: Cambridge University Press, 1997. p 22.
http://site.ebrary.com/lib/unitemlibrary/
Houghton, J. T. Global Warming: The Complete Briefing.
Port Chester, NY, USA: Cambridge University Press, 1997. p 10.
http://site.ebrary.com/lib/unitemlibrary
Website: http://en.wikipedia.org/wiki/Global_warming
Title: Global Warming
Weart, Spencer (2006), "The Public and Climate Change", in Weart, Spencer, The Discovery of Global Warming, American Institute of Physics, http://www.aip.org/history/climate/Public.htm. Retrieved on 2007-04-14
Climate Change: Basic Information. United States Environmental Protection Agency (2006-12-14). Retrieved on 2007-02-09.
“In common usage, 'global warming' often refers to the warming that can occur as a result of increased emissions of greenhouse gases from human activities.” United Nations Framework Convention on Climate Change, Article I. United Nations Framework Convention on Climate Change. Retrieved on 2007-01-15.
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