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INDEX
Acknowledgement Bibliography Facts about global warming Timeline Early warning signs Causes Effects Initiatives Summits Conclusion
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Acknowledgment
Working on this project has been a learning experience. I am now more aware about the pressingproblem of global warming. I would like to thank my professor for giving me this opportunity.
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BIBLIOGRAPHY
http://www.climatehotmap.org
www.wikipedia.com
www.googleimages.com
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FACTS ABOUT GLOBAL WARMING
Global warming is caused by green house gases, which trap in the suns infrared rays in theearths atmosphere, which in turn heat up the earths atmosphere. These green house effect
warming is called as global warming. The effects of green house effect are visible more
prominently in the recent years, with number of natural calamities on the rise in the whole world.
The global warming has happened in the past few years and is evident from the rise inmean temperature of the earths atmosphere. The main causes for the global warming are
attributed to release of green house gases by human activities. The main gases contributing to
green house effect are carbon dioxide, water vapor, methane and nitrous oxide. The largest
producers of these gases are the thermal power plants, which burn the fossil fuels and produce
these gases in large quantities. The second biggest sources of these green house gases are the
road vehicles and industries.
The global warming has led to increase in mean earth surface temperature and thusmelting of polar ice. There are frequent melt down of glaciers that result in floods and other
natural calamities. The melting of ice at the poles had led the mean sea level. And further
increase in temperature may further melt the ice and lead to further increase in mean sea level,
which will engulf low lying countries.
The effect of global warming is very evident on the animal kingdom also. Some animalshave become extinct due to loss of their natural habitat or their inability to evolve to the
rapid changes in the climate. Also there is a change in their life style because of the changes in
the seasons. The migrating birds have changed their time of travel and also their place of
migration.
The effect of global warming can be felt on seasons too. There is shift in season cycle, as thesummers are getting longer than the winters. This has affected the animals and made them to
change their lifestyle accordingly, and those who failed to do so have perished or on the verge of
extinction.
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The global warming is also responsible for the introduction of some new diseases. Thebacteria are more effective and multiply much faster in warmer temperatures compared to cold
temperatures. The increase in temperature has led to increase in the microbes that cause diseases.
Global warming is also effecting the crop production, as the crops are getting destroyed bythe sudden change in temperatures or sudden on set of rains. Also the flash floods and other
natural calamities affect the crop.
As a matter of fact, because of global warming, the earths atmosphere is getting moreunpredictable with heavy rains in the areas, which have scanty rainfall or drought in the areas,
which received good annual rainfall. The months of rainfall has also getting affected.
But there are some people who believe that the global warming is a natural process and cannotdisturb our ecosystem. The earths surface mean temperature was even higher a long time ago,
and the ecosystem has evolved from that temperature to this. So it can evolve further. But the
changes that are happening now are rather fast compared to earlier times.
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TIMELINE
Here are gathered in chronological sequence the most important events in the history of climate
change science. This list includes major influences external to the science itself. Following it is
a list of other external influences.
1800-1870
Level of carbon dioxide gas (CO2) in the atmosphere, as later measured in ancient ice, is about290 ppm (parts per million).Mean global temperature (1850-1870) is about 13.6C.First Industrial Revolution. Coal, railroads, and land clearing speed up greenhouse gas emission,while better agriculture and sanitation speed up population growth.
1824
Joseph Fourier calculates that the Earth would be far colder if it lacked an atmosphere.
1859Tyndall discovers that some gases block infrared radiation. He suggests that changes in theconcentration of the gases could bring climate change.
1896
Arrhenius publishes first calculation of global warming from human emissions of CO2.
1897
Chamberlin produces a model for global carbon exchange including feedbacks.
1870-1910Second Industrial Revolution. Fertilizers and other chemicals, electricity, and public healthfurther accelerate growth.
1914-1918
World War I; governments learn to mobilize and control industrial societies.
1920-1925
Opening of Texas and Persian Gulf oil fields inaugurates era of cheap energy.
1930s
Global warming trend since late 19th century reported.Milankovitch proposes orbital changes as the cause of ice ages. degrees
1938
Callendar argues that CO2 greenhouse global warming is underway, reviving interest in thequestion.
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1939-1945
World War II. Grand strategy is largely driven by a struggle to control oil fields.
1945
US Office of Naval Research begins generous funding of many fields of science, some of which
happen to be useful for understanding climate change.
1956
Ewing and Donn offer a feedback model for quick ice age onset. degrees
Phillips produces a somewhat realistic computer model of the global atmosphere.Plass calculates that adding CO2 to the atmosphere will have a significant effect on theradiation balance.
1957
Launch of Soviet Sputnik satellite. Cold War concerns support 1957-58 International
Geophysical Year, bringing new funding and coordination to climate studies.Revelle finds that CO2 produced by humans will not be readily absorbed by the oceans.
1958
Telescope studies show a greenhouse effect raises temperature of the atmosphere of Venus farabove the boiling point of water.
1960Mitchell reports downturn of global temperatures since the early 1940sKeeling accurately measures CO2 in the Earth's atmosphere and detects an annual rise.The level is 315 ppm. Mean global temperature (five-year average) is 13.9C.
1962
Cuban Missile Crisis, peak of the Cold War.
1963
Calculations suggest that feedback with water vapor could make the climate acutely sensitive tochanges in CO2 level.
1965
Boulder, Colo. meeting on causes of climate change: Lorenz and others point out the chaoticnature of climate system and the possibility of sudden shifts.
1966
Emiliani's analysis of deep-sea cores shows the timing of ice ages was set by small orbitalshifts, suggesting that the climate system is sensitive to small changes.
1967
International Global Atmospheric Research Program established, mainly to gather data forbetter short-range weather prediction, but including climate.
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Manabe and Wetherald make a convincing calculation that doubling CO2 would raise worldtemperatures a couple of degrees.
1968
Studies suggest a possibility of collapse of Antarctic ice sheets, which would raise sea levels
catastrophically.
1969
Astronauts walk on the Moon, and people perceive the Earth as a fragile whole. degreesBudyko and Sellers present models of catastrophic ice-albedo feedbacks. degreesNimbus III satellite begins to provide comprehensive global atmospheric temperaturemeasurements. degrees
1970First Earth Day. Environmental movement attains strong influence, spreads concern aboutglobal degradation. degrees
Creation of US National Oceanic and Atmospheric Administration, the world's leading funderof climate research. degreesAerosols from human activity are shown to be increasing swiftly. Bryson claims they counteractglobal warming and may bring serious cooling. degrees
1971
SMIC conference of leading scientists reports a danger of rapid and serious global changecaused by humans, calls for an organized research effort.Mariner 9 spacecraft finds a great dust storm warming the atmosphere of Mars, plus indicationsof a radically different climate in the past.
1972
Ice cores and other evidence show big climate shifts in the past between relatively stable modesin the space of a thousand years or so, especially around 11,000 years ago.
1973
Oil embargo and price rise bring first "energy crisis". degrees
1974
Serious droughts since 1972 increase concern about climate, with cooling from aerosolssuspected to be as likely as warming; scientists are doubtful as journalists talk of a new ice age.
1975
Warnings about environmental effects of airplanes leads to investigations of trace gases in thestratosphere and discovery of danger to ozone layer.Manabe and collaborators produce complex but plausible computer models which show atemperature rise of several degrees for doubled CO2.
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1976
Studies show that CFCs (1975) and also methane and ozone (1976) can make a seriouscontribution to the greenhouse effect. degreesDeep-sea cores show a dominating influence from 100,000-year Milankovitch orbital changes,emphasizing the role of feedbacks. degrees
Deforestation and other ecosystem changes are recognized as major factors in the future of theclimate. degreesEddy shows that there were prolonged periods without sunspots in past centuries, correspondingto cold periods .
1977
Scientific opinion tends to converge on global warming, not cooling, as the chief climate risk innext century. degrees
1978
Attempts to coordinate climate research in US end with an inadequate National ClimateProgram Act, accompanied by rapid but temporary growth in funding. degrees
1979
Second oil "energy crisis." Strengthened environmental movement encourages renewableenergy sources, inhibits nuclear energy growth. degreesUS National Academy of Sciences report finds it highly credible that doubling CO2 will bring1.5-4.5C global warming. degreesWorld Climate Research Programme launched to coordinate international research. degrees
1981
Election of Reagan brings backlash against environmental movement to power. Politicalconservatism is linked to skepticism about global warming.IBM Personal Computer introduced. Advanced economies are increasingly delinked fromenergy.Hansen and others show that sulfate aerosols can significantly cool the climate, raisingconfidence in models showing future greenhouse warming.Some scientists predict greenhouse warming "signal" should be visible by about the year 2000.
1982
Greenland ice cores reveal drastic temperature oscillations in the space of a century in thedistant past.Strong global warming since mid-1970s is reported, with 1981 the warmest year on record.
1983
Reports from US National Academy of Sciences and Environmental Protection Agency sparkconflict, as greenhouse warming becomes prominent in mainstream politics.
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1985
Ramanathan and collaborators announce that global warming may come twice as fast asexpected, from rise of methane and other trace greenhouse gases.Villach Conference declares consensus among experts that some global warming seemsinevitable, calls on governments to consider international agreements to restrict emissions.
Antarctic ice cores show that CO2 and temperature went up and down together through past iceages, pointing to powerful biological and geochemical feedbacks. degreesBroecker speculates that a reorganization of North Atlantic Ocean circulation can bring swiftand radical climate change.
1987Montreal Protocol of the Vienna Convention imposes international restrictions on emission ofozone-destroying gases. degrees
1988
News media coverage of global warming leaps upward following record heat and droughts plus
testimony by Hansen. degreesToronto conference calls for strict, specific limits on greenhouse gas emissions; UK PrimeMinister Thatcher is first major leader to call for action. degreesIce-core and biology studies confirm living ecosystems give climate feedback by way ofmethane, which could accelerate global warming. degreesIntergovernmental Panel on Climate Change (IPCC) is established. degrees
1989Fossil-fuel and other U.S. industries form Global Climate Coalition to tell politicians and thepublic that climate science is too uncertain to justify action. degrees
1990First IPCC report says world has been warming and future warming seems likely.
1991Mt. Pinatubo explodes; Hansen predicts cooling pattern, verifying (by 1995) computer modelsof aerosol effects. degreesGlobal warming skeptics claim that 20th-century temperature changes followed from solarinfluences. (The solar-climate correlation would fail in the following decade.) degreesStudies from 55 million years ago show possibility of eruption of methane from the seabed withenormous self-sustained warming. degrees
1992Conference in Rio de Janeiro produces UN Framework Convention on Climate Change, but USblocks calls for serious action. degreesStudy of ancient climates reveals climate sensitivity in same range as predicted independentlyby computer models. degrees
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1993
Greenland ice cores suggest that great climate changes (at least on a regional scale) can occur inthe space of a single decade. degrees
1995
Second IPCC report detects "signature" of human-caused greenhouse effect warming, declaresthat serious warming is likely in the coming century. degreesReports of the breaking up of Antarctic ice shelves and other signs of actual current warming inpolar regions begin affecting public opinion. degrees
1997
Toyota introduces Prius in Japan, first mass-market electric hybrid car; swift progress in largewind turbines and other energy alternatives.International conference produces Kyoto Protocol, setting targets to reduce greenhouse gasemissions if enough nations sign onto a treaty.
1998"Super El Nio" causes weather disasters and warmest year on record (approximately matchedby 2005 and 2007). Borehole data confirm extraordinary warming trend.Qualms about arbitrariness in computer models diminish as teams model ice-age climate anddispense with special adjustments to reproduce current climate. degrees
1999
Criticism that satellite measurements show no warming are dismissed by National AcademyPanel.Ramanathan detects massive "brown cloud" of aerosols from South Asia. degrees
2000
Global Climate Coalition dissolves as many corporations grapple with threat of warming, but oillobby convinces US administration to deny problem. degreesA variety of studies emphasize variability and importance of biological feedbacks in carboncycle, liable to accelerate warming.
2001
Third IPCC report states baldly that global warming, unprecedented since end of last ice age, is"very likely," with possible severe surprises. Effective end of debate among all but a fewscientists.Bonn meeting, with participation of most countries but not US, develops mechanisms forworking towards Kyoto targets.National Academy panel sees a "paradigm shift" in scientific recognition of the risk of abruptclimate change (decade-scale).Warming observed in ocean basins; match with computer models gives a clear signature ofgreenhouse effect warming.
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2002
Studies find surprisingly strong "global dimming," due to pollution, has retarded arrival ofgreenhouse warming, but dimming is now decreasing.
2003
Numerous observations raise concern that collapse of ice sheets (West Antarctica, Greenland)can raise sea levels faster than most had believed.Deadly summer heat wave in Europe accelerates divergence between European and US publicopinion.
2004
In controversy over temperature data covering past millenium, most conclude climate variationswere not comparable to the post-1980 warming.
First major books, movie and art work featuring global warming appear.
2005Kyoto treaty goes into effect, signed by major industrial nations except US. Work to retardemissions accelerates in Japan, Western Europe, US regional governments and corporations.Hurricane Katrina and other major tropical storms spur debate over impact of global warmingon storm intensity.
2007
Fourth IPCC report warns that serious effects of warming have become evident; cost ofreducing emissions would be far less than the damage they will cause.Greenland and Antarctic ice sheets and Arctic Ocean sea-ice cover found to be shrinking fasterthan expected.
2009
Many experts warn that global warming is arriving at a faster and more dangerous pace thananticipated just a few years earlier. degreesLevel of CO2 in the atmosphere reaches 385 ppm.Mean global temperature (five-year average) is 14.5C, the warmest in hundreds, perhapsthousands of years.
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Global warming early warning signs
This map illustrates the local consequences of global warming.Events indicated on the map are divided into two categories:
Fingerprints. Some of the events are direct manifestations of a widespread andlong-term trend toward warmer global temperatures, as already documented andprojected to continue by models of a changing climate. These "fingerprints" ofclimate change are indicated with yellow icons.
Harbingers. The map also identifies events that foreshadow the types of impactslikely to become more frequent and widespread with continued warming. These"harbingers" of climate change are indicated with red icons. For these events,evidence for a direct link to long-term climate change cannot be confirmed orruled out at this time.
The Asian region spans polar, temperate, and tropical climates and is home to over 3billion people. As the climate warms, many mountain glaciers may disappear, permafrostwill thaw, and the northern forests are likely to shift further north. Rapid populationgrowth and development in countries like China and India will put additional pressureson natural ecosystems and will lead to a rapid rise in the release of greenhouse gases intothe atmosphere unless steps are taken to curtail emissions.
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Fingerprints1. Llasa, Tibet -- Warmest June on record, 1998. Temperatures hovered above 77
F for 23 days.
2. Garhwal Himalayas, India -- Glacial retreat at record pace. The DokrianiBarnak Glacier retreated 66 ft (20.1 m) in 1998 despite a severe winter. TheGangorti Glacier is retreating 98 ft (30 m) per year. At this rate scientists predictthe loss of all central and eastern Himalayan glaciers by 2035.
3. Tien Shan Mountains, China -- Glacial ice reduced by one quarter in thepast 40 years.
4. Southern India - Heat wave, May 2002. In the state of Andhra Pradeshtemperatures rose to 120F, resulting in the highest one-week death toll on record.This heat wave came in the context of a long-term warming trend in Asia ingeneral. India, including southern India, has experienced a warming trend at a rateof 1F (0.6C) per century.
5. Nepal - High rate of temperature rise. Since the mid-1970s the average airtemperature measured at 49 stations has risen by 1.8F (1C), with high elevationsites warming the most. This is twice as fast as the 1F (0.6C) average warming forthe mid-latitudinal Northern Hemisphere (24 to 40N) over the same time period,and illustrates the high sensitivity of mountain regions to climate change.
6. Taiwan - Average temperature increase. The average temperature for the islandhas risen 1.8-2.5F (1-1.4C) in the last 100 years. The average temperature for2000 was the warmest on record.
7. Afghanistan - 2001 - Warmest winter on record. Arid Central Asia, whichincludes Afghanistan, experienced a warming of 0.8-3.6F (1-2C) during the 20thcentury.
8. Tibet - Warmest decade in 1,000 years. Ice core records from the DasuopuGlacier indicate that the last decade and last 50 years have been the warmest in1,000 years. Meteorological records for the Tibetan Plateau show that annualtemperatures increased 0.4F (0.16C) per decade and winter temperatures
increased 0.6F (0.32C) per decade from 1955 to 1996.
9. Mongolia - Warmest century of the past millennium. A 1,738-year tree-ringrecord from remote alpine forests in the Tarvagatay Mountains indicates that 20thcentury temperatures in this region are the warmest of the last millennium. Treegrowth during 1980-1999 was the highest of any 20-year period on record, and 8of the 10 highest growth years occurred since 1950. The 20th century warminghas been observed in tree-ring reconstructions of temperature from widespread
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regions of Eurasia, including sites in the Polar Urals, Yakutia, and the TaymirPeninsula, Russia. The average annual temperature in Mongolia has increased byabout 1.3F (0.7C) over the past 50 years.
10.Chokoria Sundarbans, Bangladesh - Flooded mangroves. Rising ocean levelshave flooded about 18,500 acres (7,500 hectares) of mangrove forest during thepast three decades. Global sea-level rise is aggravated by substantial deltaicsubsidence in the area with rates as high as 5.5 mm/year.
11.China - Rising waters and temperature. The average rate of sea-level rise was0.09 +/- 0.04 inches (2.3 +/- 0.9 mm) per year over the last 30 years. Global sea-level rise was aggravated locally by subsidence of up to 2 inches (5 cm) per yearfor some regions due to earthquakes and groundwater withdrawal. Also, oceantemperatures off the China coast have risen in the last 100 years, especially sincethe 1960s.
12.Bhutan - Melting glaciers swelling lakes. As Himalayan glaciers melt glaciallakes are swelling and in danger of catastrophic flooding. Average glacial retreatin Bhutan is 100-130 feet (30-40 m) per year. Temperatures in the high Himalayashave risen 1.8F (1C) since the mid 1970s.
13. India - Himalayan glaciers retreating. Glaciers in the Himalayas are retreatingat an average rate of 50 feet (15 m) per year, consistent with the rapid warmingrecorded at Himalayan climate stations since the 1970s. Winter stream flow forthe Baspa glacier basin has increased 75% since 1966 and local wintertemperatures have warmed, suggesting increased glacier melting in winter.
14. Mt. Everest - Retreating glacier.The Khumbu Glacier, popular climbing routeto the summit of Mt. Everest, has retreated over 3 miles (5 km) since 1953. TheHimalayan region overall has warmed by about 1.8F (1C) since the 1970s.
15.Kyrgyzstan - Disappearing glaciers. During 1959-1988, 1,081 glaciers in thePamir-Altai disappeared. Temperatures in the mountains of Kyrgyztan haveincreased by 0.9-2.7 F (0.5-1.5C) since the 1950s.
16. Siberia - Melting permafrost. Large expanses of tundra permafrost are melting.In some regions the rate of thawing of the upper ground is nearly 8 inches (20 cm)per year. Thawing permafrost has already damaged 300 buildings in the cities ofNorilsk and Yakutsk. In Yakutsk, the average temperature of the permanentlyfrozen ground has warmed by 2.7 F (1.5C) during the past 30 years.
Harbingers1. Indonesia -- Malaria spreads to high elevations. Malaria was detected for the
first time as high as 6,900 feet (2103 m) in the highlands of Irian Jaya in 1997.
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2. Philippines -- Coral reef bleaching.3. Indian Ocean -- Coral reef bleaching (inclues Seychelles; Kenya; Reunion;
Mauritius; Somalia; Madagascar; Maldives; Indonesia; Sri Lanka; Gulf ofThailand [Siam]; Andaman Islands; Malaysia; Oman; India; and Cambodia).
4. Persian Gulf-- Coral reef bleaching.5. Korea -- Heavy rains and flooding. Severe flooding struck during July and
August, 1998, with daily rainfall totals exceeding 10 inches (25.4 cm).
6. Indonesia -- Burning rainforest, 1998. Fires burned up to 2 million acres(809,371 hectares) of land, including almost 250,000 acres (101,172 hectares) ofprimary forest and parts of the already severely reduced habitat of the Kalimantanorangutan.
7. Khabarovsk, Russia -- Wildfires threaten tiger habitat, 1998. Drought andhigh winds fueled fires that destroyed 3.7 million acres (1,497,337 hectares) oftaiga and threatened two important nature reserves that are habitat for the onlyremaining Amur tigers.
8. Bangladesh - Link between stronger El Nio events and cholera prevalence.Researchers found a robust relationship between progressively stronger El Nioevents and cholera prevalence, spanning a 70-year period from 1893-1940 and1980-2001. There has been a marked intensification of the El Nio/SouthernOscillation phenomenon since the 1980s, which is not fully explained by theknown shifts in the Pacific basin temperature regime that began in the mid-1970s.Findings by Rodo et al. are consistent with model projections of El Nio
intensification under global warming conditions. The authors make a strong casefor the climate-health link by providing evidence for biological sensitivity toclimate, meteorological evidence of climate change, and evidence ofepidemiological change with global warming. The study likely represents the firstpiece of evidence that warming trends over the last century are affecting humandisease.
9. Lake Baikal, Russia - Shorter freezing period. Winter freezing is about 11days later and spring ice breakup is about 5 days earlier compared to a centuryago. Some regions of Siberia have warmed by as much as 2.5F (1.4C) in just 25years.
10.Iran - Desiccated wetlands, 2001 Ninety percent of wetlands have dried up after2 years of extreme drought. Much of South West Asia has experienced aprolonged three-year drought that is unusual in its magnitude. Out of 102 years ofrecord, 1999, 2000, and 2001 rank as the fifth, third, and seventh driest on record.1999-2000 was the driest winter on record.
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11.Pakistan - Longest drought on record, 1999-2001. The prolonged three-yeardrought, which covers much of South West Asia, has affected 2.2 million peopleand 16 million livestock in Pakistan.
12. Tajikistan - Lowest rainfall in 75 years, 2001. 2001 marked the thirdconsecutive year of drought, which has destroyed half the wheat crop.
13. Korea - Worst drought in 100 years of record, 2001. It coincided with anaverage annual temperature increase in Asias temperate region, which includesKorea, by more than 1.8F (1C) over the past century. The warming has been mostpronounced since 1970.
14.China - Disappearing Lakes, 2001. More than half of the 4,000 lakes in theQinghai province are disappearing due to drought. The severity of the impact isexacerbated by overpumping of aquifers. Annual average temperature in Chinahas increased during the past century, with pronounced warming since 1980. Most
of the warming has been in northern areas, including Qinghai Province, and in thewinter.
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MAJOR CAUSES OF GLOBAL WARMING
1. Greenhouse gasesGreen House effect is an phenomenon in which earth's atmosphere traps the heat from thesun & prevents it from escaping. The phenomenon is so named because earth'satmosphere acts like a greenhouse made of glass in which sunlight enters throughtransparent glass, but the heat released by plants in the form of infrared radiations is notallowed to escape.As a result of this , the temp. increasses inside the greenhouse.In a similar manner, sunlight enters earth's atmosphere and heats the surface of the earth.
But certain gases present in the atmosphere trap the heat emitted by earth's surface & donot allow it to escape.This causes an increase in temp. of earth's atmosphere. This is known as GlobalWarming.The gases causing green house effect are called greenhouse gases. Carbon Dioxide,methane, ozone, and CFCs are the green house gases present in the atmosphere which areresponsible for global warming.Scientific consensus has identified carbon dioxide as the dominant greenhouse gas. Thedominant greenhouse gas overall is water vapor. Water vapor, however, has a very shortatmospheric lifetime (about 10 days) and is very nearly in a dynamic equilibrium in theatmosphere, so it is not a forcing gas in the context of global
warming. Methane and nitrous oxide are also major forcing contributors tothe greenhouse effect. The chart below attributes anthropogenic greenhouse gasemissions to eight main economic sectors, of which the largest contributors are powerstations (many of which burn coal or other fossil fuels), industrial processes (amongwhich cement production is a dominant contributor), transportation fuels (generally fossilfuels), and agricultural by-products (mainly methane from enteric fermentation andnitrous oxide from fertilizer use).
http://en.wikipedia.org/wiki/Greenhouse_gashttp://en.wikipedia.org/wiki/Water_vaporhttp://en.wikipedia.org/wiki/Radiative_forcinghttp://en.wikipedia.org/wiki/Methanehttp://en.wikipedia.org/wiki/Nitrous_oxidehttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Air_pollutantshttp://en.wikipedia.org/wiki/Power_stationshttp://en.wikipedia.org/wiki/Power_stationshttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Industryhttp://en.wikipedia.org/wiki/Cementhttp://en.wikipedia.org/wiki/Transportationhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Agriculturehttp://en.wikipedia.org/wiki/Enteric_fermentationhttp://en.wikipedia.org/wiki/Fertilizerhttp://en.wikipedia.org/wiki/Fertilizerhttp://en.wikipedia.org/wiki/Enteric_fermentationhttp://en.wikipedia.org/wiki/Agriculturehttp://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Transportationhttp://en.wikipedia.org/wiki/Cementhttp://en.wikipedia.org/wiki/Industryhttp://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Coalhttp://en.wikipedia.org/wiki/Power_stationshttp://en.wikipedia.org/wiki/Power_stationshttp://en.wikipedia.org/wiki/Air_pollutantshttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Nitrous_oxidehttp://en.wikipedia.org/wiki/Methanehttp://en.wikipedia.org/wiki/Radiative_forcinghttp://en.wikipedia.org/wiki/Water_vaporhttp://en.wikipedia.org/wiki/Greenhouse_gas -
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2)Land use
Climate change is attributed to land use for two main reasons. While 66% of
anthropogenic CO2emissions over the last 250 years have resulted from burning fossil
fuels, 33% have resulted from changes in land use, primarily deforestation. Deforestationboth reduces the amount of carbon dioxide absorbed by deforested regions and releases
greenhouse gases directly, together with aerosols, through biomass burning that
frequently accompanies it. A second reason that climate change has been attributed to
land use is that the terrestrial albedo is often altered by use, which leads to radiative
forcing. This effect is more significant locally than globally.
3)Livestock and land use
Worldwide, livestock production occupies 70% of all land used for agriculture, or 30% ofthe ice-free land surface of the Earth. Scientists attribute more than 18% of artificial
greenhouse gas emissions to livestock and livestock-related activities such as
deforestation and increasingly fuel-intensive farming practices. The following are the
major causes of global warming due to livestock and livestock activities:
9% of global carbon dioxide emissions
http://en.wikipedia.org/wiki/File:Greenhouse_Gas_by_Sector.pnghttp://en.wikipedia.org/wiki/Land_usehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Deforestationhttp://en.wikipedia.org/wiki/Slash_and_burnhttp://en.wikipedia.org/wiki/Albedohttp://en.wikipedia.org/wiki/Radiative_forcinghttp://en.wikipedia.org/wiki/Radiative_forcinghttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Radiative_forcinghttp://en.wikipedia.org/wiki/Radiative_forcinghttp://en.wikipedia.org/wiki/Albedohttp://en.wikipedia.org/wiki/Slash_and_burnhttp://en.wikipedia.org/wiki/Deforestationhttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Land_usehttp://en.wikipedia.org/wiki/File:Greenhouse_Gas_by_Sector.pnghttp://en.wikipedia.org/wiki/File:Greenhouse_Gas_by_Sector.png -
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35-40% of global methane emissions (chiefly due to entericfermentation and manure)
64% of global nitrous oxide emissions, chiefly due to fertilizer use.
4)Aerosols
With virtual certainty, scientific consensus has attributed various forms of climate
change, chiefly cooling effects, to aerosols, which are small particles or droplets
suspended in the atmosphere. Key sources to which anthropogenic aerosols are
attributed include:
biomass burning such as slash and burn deforestation. Aerosols produced areprimarily black carbon.
industrial air pollution, which produces soot and airborne sulfates, nitrates,and ammonium
dust produced by land use effects such as desertification
Detection vs. attribution
Per capita greenhouse gas emissions by country including land-use change
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Detection of a signal requires demonstrating that an observed change is statistically
significantly different from that which can be explained by natural internal variability.
Attribution requires demonstrating that a signal is:
o unlikely to be entirely due to internal variability;o consistent with the estimated responses to the given combination of anthropogenic and
natural forcing
o not consistent with alternative, physically plausible explanations of recent climate changethat exclude important elements of the given combination of forcing.
Detection does not imply attribution, and is easier to show than attribution. Unequivocal
attribution would require controlled experiments with multiple copies of the climate
system, which is not possible. Therefore, attribution, as described above, can only be
done within some margin of error. For example, the IPCC's Fourth Assessment
Report says "it is extremely likely that human activities have exerted a substantial net
warming influence on climate since 1750," where "extremely likely" indicates a
probability greater than 95%.
Following the publication of the Third Assessment Report (TAR) in 2001, "detection and
attribution" of climate change has remained an active area of research. Some important
results include:
o A review of detection and attribution studies by the International Ad Hoc Detection andAttribution Group found that "natural drivers such as solar variability and volcanic
activity are at most partially responsible for the large-scale temperature changes observed
over the past century, and that a large fraction of the warming over the last 50 yr can be
attributed to greenhouse gas increases. Thus, the recent research supports and strengthens
the IPCC Third Assessment Report conclusion that 'most of the global warming over the
past 50 years is likely due to the increase in greenhouse gases.
oMultiple independent reconstructions of the temperature record of the past 1000years confirm that the late 20th century is probably the warmest period in that time.
o Two papers in the journalSciencein August 2005 resolve the problem, evident at thetime of the TAR, oftropospheric temperature trends. The UAH version of the record
contained errors, and there is evidence of spurious cooling trends in the radiosonde
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record, particularly in the tropics. See satellite temperature measurements for details; and
the 2006 US CCSP report.
o Barnett and colleagues say that the observed warming of the oceans "cannot be explainedby natural internal climate variability or solar and volcanic forcing, but is well simulated
by two anthropogenically forced climate models," concluding that "it is of human origin,
a conclusion robust to observational sampling and model differences"
Warming on other planets?
o Over the last two decades, proxy evidence of local or planetary warming has beenobserved on Mars, Pluto, Jupiter, and Neptune's largest moon Triton. It has sometimes
been asserted in the popular press that this points to a solar explanation for the recent
warming on Earth. Physicist Khabibullo Abdusamatov claims that solar variation has
caused global warming on Earth, and that the coincident warmings "can only be a
straightline consequence of the effect of the one same factor: a long-time change in solar
irradiance." This view is not accepted by other scientists. Planetary physicist Colin
Wilson responded, "His views are completely at odds with the mainstream scientific
opinion," and climate scientist Amato Evan stated, "the idea just isn't supported by the
theory or by the observations." Charles Long ofPacific Northwest National Laboratory,
who studies radiative transfer, says "That's nuts ... It doesn't make physical sense that
that's the case. Jay Pasachoff, an astronomy professor at Williams College, said that
Pluto's global warming was "likely not connected with that of the Earth. The major way
they could be connected is if the warming was caused by a large increase in sunlight. But
the solar constant, the amount of sunlight received each second is carefully monitored by
spacecraft, and we know the Sun's output is much too steady to be changing the
temperature of Pluto." Instead, scientific opinion is that these changes are caused by other
factors, such as orbital irregularities or (in the case of Mars) changes in albedo as a result
of dust storms.
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Effects of global warming
Over the last hundred years or so, the instrumental temperature record has shown a trendin climate of increased global mean temperature, i.e., global warming. Other observed
changes include Arctic shrink age, Arctic methane release, releases of terrestrial carbon
from permafrost regions and Arctic methane release in coastal sediments, and sea level
rise. Global average temperature is predicted to increase over this century, with aprobable increase in frequency of some extreme weather events, and changes in rainfall
patterns. Moving from global to regional scales, there is increased uncertainty over how
climate will change. The probability of warming having unforeseen consequences
increases with the rate, magnitude, and duration of climate change. Some of the physicalimpacts of climate change are irreversible at continental and global scales. Sea level is
expected to rise 18 to 59 cm (7.1 to 23.2 inches) by the end of the 21st century. Due to a
lack of scientific understanding, this sea level rise estimate does not include all of the
possible contributions of ice sheets. Slowing of the Meridional Overturning Circulation isvery likely to occur this century, but temperatures in the Atlantic and Europe will
probably still be higher due to global warming. For a global warming of 14C (relative
to 19902000), there is a moderate chance that partial deglaciation of the Greenland ice
sheet would occur over a period of centuries to millennia. Including the possiblecontribution of partial deglaciation of the West Antarctic Ice Sheet, sea level would rise
by 46 m or more.
The impacts on human systems of climate change will probably be distributed unevenly.
Some regions and sectors are expected to experience benefits while others will
experience costs. With greater levels of warming (greater than 23C, relative to 1990
levels), it is likely that benefits will decline and costs increase. Low-latitude and less-
developed areas are probably at the greatest risk from climate change. With human
systems, adaptation potential for climate change impacts is considerable, although the
costs of adaptation are largely unknown and potentially large. Climate change will likely
result in reduced diversity of ecosystems and the extinction of many species. Adaptation
potential for biological and geophysical systems is estimated to be lower than that for
human systems.
Physical impacts:
1)Effects on weather
Increasing temperature is likely to lead to increasing precipitation but the effects on
storms are less clear. Extra-tropical storms partly depend on the temperature gradient,
which is predicted to weaken in the northern hemisphere as the polar region warms more
than the rest of the hemisphere.
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-i-Extreme weather
Based on future projections of climate change, the IPCC report makes a number of
predictions. It is predicted that over most land areas, the frequency of warm spells or heat
waves will very likely increase. It is likely that:
Increased areas will be affected by drought There will be increased intense tropical cyclone activity There will be increased incidences of extreme high sea level (excluding tsunamis)Storm strength leading to extreme weather is increasing, such as the power dissipation
index of hurricane intensity. Kerry Emanuel writes that hurricane power dissipation is
highly correlated with temperature, reflecting global warming. However, a further study
by Emanuel using current model output concluded that the increase in power dissipation
in recent decades cannot be completely attributed to global warming. Hurricane modelinghas produced similar results, finding that hurricanes, simulated under warmer, high-
CO2 conditions, are more intense, however, hurricane frequency will be reduced.
Worldwide, the proportion ofhurricanes reaching categories 4 or 5with wind speeds
above 56 meters per secondhas risen from 20% in the 1970s to 35% in the
1990s. Precipitation hitting the US from hurricanes has increased by 7% over the
twentieth century. The extent to which this is due to global warming as opposed to
the Atlantic Multi decadal Oscillation is unclear. Some studies have found that the
increase in sea surface temperature may be offset by an increase in wind shear, leading to
little or no change in hurricane activity. Hoyos et al. (2006) have linked the increasing
trend in number of category 4 and 5 hurricanes for the period 19702004 directly to the
trend in sea surface temperatures.
Increases in catastrophes resulting from extreme weather are mainly caused by increasing
population densities, and anticipated future increases are similarly dominated by societal
change rather than climate change. The World Meteorological Organization explains that
though there is evidence both for and against the existence of a detectable anthropogenic
signal in the tropical cyclone climate record to date, no firm conclusion can be made on
this point.They also clarified that no individual tropical cyclone can be directly
attributed to climate change.
Thomas Knutson and Robert E. Tuleya ofNOAA stated in 2004 that warming induced
by greenhouse gas may lead to increasing occurrence of highly destructive category-5
storms. In 2008, Knutson found that Atlantic hurricane and tropical storm frequencies
could reduce under future greenhouse-gas-induced warming. Vecchi and Soden find
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that wind shear, the increase of which acts to inhibit tropical cyclones, also changes in
model-projections of global warming. There are projected increases ofwind shear in the
tropical Atlantic and East Pacific associated with the deceleration of the Walker
circulation, as well as decreases of wind shear in the western and central Pacific. The
study does not make claims about the net effect on Atlantic and East Pacific hurricanes of
the warming and moistening atmospheres, and the model-projected increases in Atlantic
wind shear.
A substantially higher risk of extreme weather does not necessarily mean a noticeably
greater risk of slightly-above-average weather. However, the evidence is clear that severe
weather and moderate rainfall are also increasing. Increases in temperature are expected
to produce more intense convection over land and a higher frequency of the most severe
storms.
-ii-Increased evaporation
Increasing water vapor at Boulder, Colorado.
Over the course of the 20th century, evaporation rates have reduced worldwide ; this is
thought by many to be explained by global dimming. As the climate grows warmer and
the causes of global dimming are reduced, evaporation will increase due to warmer
oceans. Because the world is a closed system this will cause heavier rainfall, with
more erosion. This erosion, in turn, can in vulnerable tropical areas (especially in Africa)
lead to desertification. On the other hand, in other areas, increased rainfall lead to growth
of forests in dry desert areas.
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Scientists have found evidence that increased evaporation could result in more
extreme weather as global warming progresses. The IPCC Third Annual Report says:
"global average water vapor concentration and precipitation are projected to increase
during the 21st century. By the second half of the 21st century, it is likely that
precipitation will have increased over northern mid- to high latitudes and Antarctica in
winter. At low latitudes there are both regional increases and decreases over land areas.
Larger year to year variations in precipitation are very likely over most areas where an
increase in mean precipitation is projected."
-iii-Local climate change
The first recorded South Atlantic hurricane, "Catarina", which hit Brazil in March 2004
In the northern hemisphere, the southern part of the Arctic region (home to 4,000,000
people) has experienced a temperature rise of 1 C to 3 C (1.8 F to 5.4 F) over the last
50 years. Canada, Alaska and Russia are experiencing initial melting ofpermafrost. Thismay disrupt ecosystems and by increasing bacterial activity in the soil lead to these areas
becoming carbon sources instead ofcarbon sinks. A study of changes to eastern Siberia's
permafrost suggests that it is gradually disappearing in the southern regions, leading to
the loss of nearly 11% of Siberia's nearly 11,000 lakes since 1971. At the same time,
western Siberia is at the initial stage where melting permafrost is creating new lakes,
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which will eventually start disappearing as in the east. Furthermore, permafrost melting
will eventually cause methane release from melting permafrost peat bogs.
Prior to March 2004, no tropical cyclone had been observed in the South Atlantic Ocean.
The first Atlantic cyclone to form south of the equator hit Brazil on March 28, 2004 with
40 m/s winds, although some Brazilian meteorologists deny that it was a
hurricane. Monitoring systems may have to be extended 1,600 km (1,000 miles) further
south. There is no agreement as to whether this hurricane is linked to climate change, but
one climate model exhibits increased tropical cyclone genesis in the South Atlantic under
global warming by the end of the 21st century.
2) Glacier retreat and disappearance
A map of the change in thickness of mountain glaciers since 1970. Thinning in orange
and red, thickening in blue.
In historic times, glaciers grew during a cool period from about 1550 to 1850 known as
the Little Ice Age. Subsequently, until about 1940, glaciers around the world retreated as
the climate warmed. Glacier retreat declined and reversed in many cases from 1950 to
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1980 as a slight global cooling occurred. Since 1980, glacier retreat has become
increasingly rapid and ubiquitous, and has threatened the existence of many of the
glaciers of the world. This process has increased markedly since 1995.
Excluding the ice caps and ice sheets of the Arctic and Antarctic, the total surface area
ofglaciers worldwide has decreased by 50% since the end of the 19th century. Currently
glacier retreat rates and mass balance losses have been increasing in
the Andes, Alps,Pyrenees, Himalayas, Rocky Mountains and North Cascades.
The loss of glaciers not only directly causes landslides, flash floods and glacial
lakeoverflow, but also increases annual variation in water flows in rivers. Glacier runoff
declines in the summer as glaciers decrease in size, this decline is already observable in
several regions. Glaciers retain water on mountains in high precipitation years, since the
snow cover accumulating on glaciers protects the ice from melting. In warmer and drier
years, glaciers offset the lower precipitation amounts with a higher meltwater input.
Of particular importance are the Hindu Kush and Himalayan glacial melts that comprise
the principal dry-season water source of many of the major rivers of
the Central, South, East and Southeast Asian mainland. Increased melting would cause
greater flow for several decades, after which "some areas of the most populated regions
on Earth are likely to 'run out of water'" as source glaciers are depleted. The Tibetan
Plateau contains the world's third-largest store of ice. Temperatures there are rising four
times faster than in the rest of China, and glacial retreat is at a high speed compared to
elsewhere in the world.
According to a Reuters report, the Himalayan glaciers that are the sources of Asia's
biggest riversGanges, Indus, Brahmaputra, Yangtze,Mekong, Salween and Yellow
could diminish as temperatures rise. Approximately 2.4 billion people live in the drainage
basin of the Himalayan rivers. India,
China, Pakistan, Bangladesh, Nepal and Myanmar could experience floods followed
by droughts in coming decades. In India alone, the Ganges provides water for drinking
and farming for more than 500 million people. It has to be acknowledged, however, that
increased seasonal runoff of Himalayan glaciers led to increased agricultural productionin northern India throughout the 20th century.
The recession of mountain glaciers, notably in Western North America, Franz-Josef
Land, Asia, the Alps, the Pyrenees, Indonesia and Africa, and tropical and sub-tropical
regions of South America, has been used to provide qualitative support to the rise in
global temperatures since the late 19th century. Many glaciers are being lost to melting
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further raising concerns about future local water resources in these glaciated areas. In
Western North America the 47 North Cascade glaciers observed all are retreating.
Retreat of the Helheim Glacier, Greenland
Despite their proximity and importance to human populations, the mountain and valley
glaciers of temperate latitudes amount to a small fraction of glacial ice on the earth.
About 99% is in the great ice sheets of polar and sub polar Antarctica and Greenland.
These continuous continental-scale ice sheets, 3 kilometres (1.9 mi) or more in thickness,
cap the polar and sub polar land masses. Like rivers flowing from an enormous lake,numerous outlet glaciers transport ice from the margins of the ice sheet to the ocean.
Glacier retreat has been observed in these outlet glaciers, resulting in an increase of the
ice flow rate. In Greenland the period since the year 2000 has brought retreat to several
very large glaciers that had long been stable. Three glaciers that have been researched,
Helheim, Jakobshavn Isbr and Kangerdlugssuaq Glaciers, jointly drain more than 16%
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of the Greenland Ice Sheet. Satellite images and aerial photographs from the 1950s and
1970s show that the front of the glacier had remained in the same place for decades. But
in 2001 it began retreating rapidly, retreating 7.2 km between 2001 and 2005. It has also
accelerated from 20 m /day to 32 m /day. Jakobshavn Isbr in western Greenland had
been moving at speeds of over 24 m /day with a stable terminus since at least 1950. The
glacier's ice tongue began to break apart in 2000, leading to almost complete
disintegration in 2003, while the retreat rate doubled to over 30 m /day.
3)Oceans
The role of the oceans in global warming is a complex one. The oceans serve as a sink for
carbon dioxide, taking up much that would otherwise remain in the atmosphere, but
increased levels of CO2have led to ocean acidification. Furthermore, as the temperatureof the oceans increases, they become less able to absorb excess CO2. Global warming is
projected to have a number of effects on the oceans. Ongoing effects include rising sea
levels due to thermal expansion and melting of glaciers and ice sheets, and warming of
the ocean surface, leading to increased temperature stratification. Other possible effects
include large-scale changes in ocean circulation.
-i-Sea level rise
With increasing average global temperature, the water in the oceans expands in volume,
and additional water enters them which had previously been locked up on land inglaciers, for example, the Greenland and the Antarctic ice sheets. For most glaciers
worldwide, an average volume loss of 60% until 2050 is predicted. Meanwhile, the
estimated total ice melting rate over Greenland is 239 cubic kilometres per year, mostly
from East Greenland. The Antarctic ice sheet, however, is expected to grow during the
21st century because of increased precipitation. Under the IPCC Special Report on
Emission Scenario (SRES) A1B, by the mid-2090s global sea level will reach 0.22 to
0.44 m in above 1990 levels, and is currently rising at about 4 mm per year. Since 1900,
the sea level has risen at an average of 1.7 mm per year; since 1993, satellite altimetry
from TOPEX/Poseidon indicates a rate of about 3 mm per year.
The sea level has risen more than 120 metres since the Last Glacial Maximum about
20,000 years ago. The bulk of that occurred before 7000 years ago. Global temperature
declined after the Holocene Climatic Optimum, causing a sea level lowering of 3.9 in
between 4000 and 2500 years before present. From 3000 years ago to the start of the 19th
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century, sea level was almost constant, with only minor fluctuations. However,
the Medieval Warm Period may have caused some sea level rise; evidence has been
found in the Pacific Ocean for a rise to perhaps 0.9 m above present level in 700 BP.
In a paper published in 2007, the climatologist James Hansen et al. claimed that ice at the
poles does not melt in a gradual and linear fashion, but that another according to the
geological record, the ice sheets can suddenly destabilize when a certain threshold is
exceeded.
Sea level rise due to the collapse of an ice sheet would be distributed nonuniformly
across the globe. The loss of mass in the region around the ice sheet would decrease
the gravitational potential there, reducing the amount of local sea level rise or even
causing local sea level fall. The loss of the localized mass would also change the moment
of inertia of the Earth, as flow in the Earth's mantle will require 1015 thousand years to
make up the mass deficit. This change in the moment of inertia results in true polar
wander, in which the Earth's rotational axis remains fixed with respect to the sun, but the
rigid sphere of the Earth rotates with respect to it. This changes the location of
the equatorial bulge of the Earth and further affects the geoid, or global potential field. A
2009 study of the effects of collapse of the West Antarctic Ice Sheet shows the result of
both of these effects. Instead of a global 5-meter sea level rise, western Antarctica would
experience approximately 25 centimeters of sea level fall, while the United States, parts
of Canada, and the Indian Ocean, would experience up to 6.5 meters of sea level rise.
A paper published in 2008 by a group of researchers at the University of Wisconsin lead
by Anders Carlson used the deglaciation of North America at 9000 years before present
as an analogue to predict sea level rise of 1.3 meters in the next century, which is also
much higher than the IPCC predictions. However, models of glacial flow in the smaller
present-day ice sheets show that a probable maximum value for sea level rise in the next
century is 80 centimeters, based on limitations on how quickly ice can flow below
the equilibrium line altitude and to the sea.
-ii-Temperature rise
From 1961 to 2003, the global ocean temperature has risen by 0.10 C from the surface to
a depth of 700 m. There is variability both year-to-year and over longer time scales, with
global ocean heat content observations showing high rates of warming for 1991 to 2003,
but some cooling from 2003 to 2007. The temperature of the Antarctic Southern
Ocean rose by 0.17 C (0.31 F) between the 1950s and the 1980s, nearly twice the rate
for the world's oceans as a whole . As well as having effects on ecosystems (e.g. by
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melting sea ice, affecting algae that grow on its underside), warming reduces the ocean's
ability to absorb CO2.
-iii-Acidification
Ocean acidification is an effect of rising concentrations ofCO2in the atmosphere, and is
not a direct consequence ofglobal warming. The oceans soak up much of the
CO2 produced by living organisms, either as dissolved gas, or in the skeletons of tiny
marine creatures that fall to the bottom to become chalk or limestone. Oceans currently
absorb about one tonne of CO2 per person per year. It is estimated that the oceans have
absorbed around half of all CO2 generated by human activities since 1800.
In water, CO2 becomes a weakcarbonic acid, and the increase in the greenhouse gas
since the Industrial Revolution has already lowered the average pH of seawater by 0.1
units, to 8.2. Predicted emissions could lower the pH by a further 0.5 by 2100, to a level
probably not seen for hundreds of millennia and, critically, at a rate of change probably
100 times greater than at any time over this period.
There are concerns that increasing acidification could have a particularly detrimental
effect on corals (16% of the world's coral reefs have died from bleaching caused by warm
water in 1998, which coincidentally was the warmest year ever recorded) and other
marine organisms withcalcium carbonate shells.
In November 2009 an article inScienceby scientists at Canada's Department of Fisheries
and Oceans reported they had found very low levels of the building blocks for the
calcium chloride that forms plankton shells in the Beaufort Sea. Fiona McLaughlin, one
of the DFO authors, asserted that the increasing acidification of the Arctic Ocean was
close to the point it would start dissolving the walls of existing plankton: "[the] Arctic
ecosystem may be risk. In actual fact, they'll dissolve the shells." Because cold water
absorbs CO2 more readily than warmer water the acidification is more severe in the polar
regions. McLaughlin predicted the acidified water would travel to the North Atlantic
within the next ten years.
-iv-Shutdown of thermohaline circulation
There is some speculation that global warming could, via a shutdown or slowdown of the
thermohaline circulation, trigger localized cooling in the North Atlantic and lead to
cooling, or lesser warming, in that region. This would affect in particular areas
like Scandinavia and Britain that are warmed by the North Atlantic drift.
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The chances of this near-term collapse of the circulation are unclear; there is some
evidence for the short-term stability of the Gulf Stream and possible weakening of the
North Atlantic drift.[citation needed] However, the degree of weakening, and whether it will be
sufficient to shut down the circulation, is under debate. As yet, no cooling has been found
in northern Europe or nearby seas.[citation needed] Lenton et al. found that "simulations
clearly pass a THC tipping point this century".
-v-Oxygen depletion
The amount of oxygen dissolved in the oceans may decline, with adverse consequences
for ocean life.
5)Ecosystems
Unchecked global warming could affect most terrestrial eco regions. Increasing globaltemperature means that ecosystems will change; some species are being forced out of
their habitats (possibly to extinction) because of changing conditions, while others are
flourishing. Secondary effects of global warming, such as lessened snow cover, rising sea
levels, and weather changes, may influence not only human activities but also
the ecosystem. Studying the association between Earth climate and extinctions over the
past 520 million years, scientists from the University of Yorkwrite, "The global
temperatures predicted for the coming centuries may trigger a new mass extinction
event, where over 50 per cent of animal and plant species would be wiped out."
Many of the species at risk are Arctic and Antarctic fauna such as polar
bears and Emperor Penguins. In the Arctic, the waters ofHudson Bay are ice-free for
three weeks longer than they were thirty years ago, affecting polar bears, which prefer to
hunt on sea ice. Species that rely on cold weather conditions such as gyrfalcons,
and Snowy Owls that prey on lemmings that use the cold winter to their advantage may
be hit hard. Marine invertebrates enjoy peak growth at the temperatures they have
adapted to, regardless of how cold these may be, and cold-blooded animals found at
greater latitudes and altitudes generally grow faster to compensate for the short growing
season. Warmer-than-ideal conditions result in higher metabolism and consequent
reductions in body size despite increased foraging, which in turn elevates the risk
ofpredation. Indeed, even a slight increase in temperature during development impairs
growth efficiency and survival rate in rainbow trout.
Rising temperatures are beginning to have a noticeable impact on birds,
and butterflies have shifted their ranges northward by 200 km in Europe and North
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America. Plants lag behind, and larger animals' migration is slowed down by cities and
roads. In Britain, spring butterflies are appearing an average of 6 days earlier than two
decades ago.
A 2002 article inNature surveyed the scientific literature to find recent changes in range
or seasonal behaviour by plant and animal species. Of species showing recent change, 4
out of 5 shifted their ranges towards the poles or higher altitudes, creating "refugee
species". Frogs were breeding, flowers blossoming and birds migrating an average 2.3
days earlier each decade; butterflies, birds and plants moving towards the poles by 6.1 km
per decade. A 2005 study concludes human activity is the cause of the temperature rise
and resultant changing species behaviour, and links these effects with the predictions
ofclimate models to provide validation for them . Scientists have observed that Antarctic
hair grass is colonizing areas of Antarctica where previously their survival range was
limited.
Mechanistic studies have documented extinctions due to recent climate change:
McLaughlin et al. documented two populations ofBay checkerspot butterfly being
threatened by precipitation change. Parmesan states, "Few studies have been conducted at
a scale that encompasses an entire species" and McLaughlin agreed "few mechanistic
studies have linked extinctions to recent climate change." Daniel Botkin and other
authors in one study believe that projected rates of extinction are overestimated.
Many species of freshwater and saltwater plants and animals are dependent on glacier-fed
waters to ensure a cold water habitat that they have adapted to. Some species of
freshwater fish need cold water to survive and to reproduce, and this is especially true
with Salmon and Cutthroat trout. Reduced glacier runoff can lead to insufficient stream
flow to allow these species to thrive. Ocean krill, a cornerstone species, prefer cold water
and are the primary food source for aquatic mammals such as the Blue Whale.
Alterations to the ocean currents, due to increased freshwater inputs from glacier melt,
and the potential alterations to thermohaline circulation of the worlds oceans, may affect
existing fisheries upon which humans depend as well.
The white lemuroid possum, only found in the mountain forests of northern Queensland,has been named as the first mammal species to be driven extinct by man-made global
warming. The White Possum has not been seen in over three years. These possums
cannot survive extended temperatures over 30 C (86 F), which occurred in 2005. A
final expedition to uncover any surviving White Possums is scheduled for 2009.
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-i-Forests
Pine forests in British Columbia have been devastated by a pine beetle infestation, which
has expanded unhindered since 1998 at least in part due to the lack of severe winters
since that time; a few days of extreme cold kill most mountain pine beetles and have kept
outbreaks in the past naturally contained. The infestation, which (by November 2008) has
killed about half of the province's lodgepole pines (33 million acres or 135,000 km) is an
order of magnitude larger than any previously recorded outbreak and passed via
unusually strong winds in 2007 over the continental divide to Alberta. An epidemic also
started, be it at a lower rate, in 1999 in Colorado, Wyoming, and Montana. The United
States forest service predicts that between 2011 and 2013 virtually all 5 million acres ofColorados lodgepole pine trees over five inches (127 mm) in diameter will be lost.
As the northern forests are a carbon sink, while dead forests are a major carbon source,
the loss of such large areas of forest has a positive feedback on global warming. In the
worst years, the carbon emission due to beetle infestation of forests in British Columbia
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alone approaches that of an average year of forest fires in all ofCanada or five years
worth of emissions from that country's transportation sources.
Besides the immediate ecological and economic impact, the huge dead forests provide a
fire risk. Even many healthy forests appear to