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Default Global warming


Global warming


Global Warming, is increase in the average temperature of the atmosphere, oceans, and landmasses of Earth. The planet has warmed (and cooled) many times during the 4.65 billion years of its history. At present Earth appears to be facing a rapid warming, which most scientists believe results, at least in part, from human activities. The prevailing scientific opinion on climate change is that "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," by the burning of fossil fuels, such as coal, oil, and natural gas, which releases into the atmosphere carbon dioxide and other substances known as greenhouse gases , land clearing, and agriculture which leads to warming of the surface and lower atmosphere by increasing the greenhouse effect. Other phenomena such as solar variation and volcanoes have had smaller but non-negligible effects on global mean temperature since 1950. A few scientists disagree about the primary causes of the observed warming. As the atmosphere becomes richer in these gases, it becomes a better insulator, retaining more of the heat provided to the planet by the Sun.

The average surface temperature of Earth is just below 15°C (59°F). Over the last century, this average has risen by about 0.6 Celsius degree (1 Fahrenheit degree). Scientists predict further warming of 1.4 to 5.8 Celsius degrees (2.5 to 10.4 Fahrenheit degrees) by the year 2100. This global temperature rise is expected to melt polar ice caps and glaciers as well as warm the oceans, all of which will expand ocean volume and raise sea level by an estimated 9 to 100 cm (4 to 40 in), flooding some coastal regions and even entire islands. changes in the amount and pattern of precipitation Some regions in warmer climates will receive more rainfall than before, but soils will dry out faster between storms. These changes may increase the frequency and intensity of extreme weather events, such as floods, droughts, heat waves, hurricanes, and tornados. Other consequences include higher or lower agricultural yields, glacier retreat, reduced summer streamflows, species extinctions and increases in the ranges of disease vectors. Warming is expected to affect the number and magnitude of these events; however, it is difficult to connect particular events to global warming. Although most studies focus on the period up to 2100, even if no further greenhouse gases were released after this date warming (and sea level) would be expected to continue to rise for more than a millennium, since carbon dioxide (CO2) has a long average atmospheric lifetime.

This soil desiccation may damage food crops, disrupting food supplies in some parts of the world. Plant and animal species will shift their ranges toward the poles or to higher elevations seeking cooler temperatures, and species that cannot do so may become extinct. The potential consequences of global warming are so great that many of the world's leading scientists have called for international cooperation and immediate action to counteract the problem.
An increase in temperatures can in turn cause other changes, including a rising sea level and. Remaining scientific uncertainties include the exact degree of climate change expected in the future, and especially how changes will vary from region to region across the globe. A hotly contested political and public debate also has yet to be resolved, regarding whether anything should be done, and what could be cost-effectively done to reduce or reverse future warming, or to deal with the expected consequences. Most national governments have signed and ratified the Kyoto Protocol aimed at combating global warming.


History of Global warming


Relative to the period 1860-1900, global temperatures on both land and sea have increased by 0.75 °C (1.4 °F), according to the instrumental temperature record; the urban heat island is not believed to be significant. Since 1979, land temperatures have increased about twice as fast as ocean temperatures (0.25 °C/decade against 0.13 °C/decade). 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. Over the one or two thousand years before 1850, temperature is believed to have been relatively stable, with possibly regional fluctuations such as the Medieval Warm Period or the Little Ice Age.
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. Estimates prepared by the World Meteorological Organization and the UK Climatic Research Unit concluded that 2005 was the second warmest year, behind 1998.
The attribution of recent climate change is clearest for the most recent period of the last 50 years, for which the most detailed data are available.
The anthropogenic emissions of other pollutants-notably sulphate aerosols-exert a cooling effect; this partially accounts for the plateau/cooling seen in the temperature record in the middle of the twentieth century, though this may also be due to intervening natural cycles
Here are gathered in chronological sequence the most important events in the history of climate change science. The list of milestones includes major influences external to the science itself.

1800-1870

Level of carbon dioxide gas (CO2) in the atmosphere, as later measured in ancient ice, is about 290 ppm (parts per million).

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.

1859

Tyndall discovers that some gases block infrared radiation. He suggests that changes in the concentration 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.

1870-1910

Second Industrial Revolution. Fertilizers and other chemicals, electricity, and public health further 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.

1938

Callendar argues that CO2 greenhouse global warming is underway, reviving interest in the question.

1939-1945

World War II. Grand strategy is largely driven by a struggle to control oil fields.

1945

U.S. 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.

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 the radiation 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 far above the boiling point of water.

1960

Downturn of global temperatures since the early 1940s is reported.

Keeling accurately measures CO2 in the Earth’s atmosphere and detects an annual rise. The level is 315 ppm.

1962

Cuban Missile Crisis, peak of the Cold War.

1963

Calculations suggest that feedback with water vapor could make the climate acutely sensitive to changes in CO2 level.

1965

Boulder meeting on causes of climate change, in which Lorenz and others point out the chaotic nature of the 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 orbital shifts, suggesting that the climate system is sensitive to small changes.

1967

International Global Atmospheric Research Program established, mainly to gather data for better short-range weather prediction but including climate.

Manabe and Wetherald make a convincing calculation that doubling CO2 would raise world temperatures a couple of degrees.

1968

Studies suggest a possibility of collapse of Antarctic ice sheets, which would sea levels catastrophically.

1969

Astronauts walk on the Moon, and people perceive the Earth as a fragile whole.

Budyko and Sellers present models of catastrophic ice-albedo feedbacks.

Nimbus III satellite begins to provide comprehensive global atmospheric temperature measurements.

1970

First Earth Day. Environmental movement attains strong influence, spreads concern about global degradation.

Creation of U.S. National Oceanic and Atmospheric Administration, the world’s leading funder of climate research.

Aerosols from human activity are shown to be increasing swiftly. Bryson claims they counteract global warming and may bring serious cooling.

1971

SMIC conference of leading scientists reports a danger of rapid and serious global climate change caused by humans, calls for an organized research effort.

Mariner 9 spacecraft finds a great dust storm warming the atmosphere of Mars, plus indications of a radically different climate in the past.

1972

Ice cores and other evidence show big climate shifts in the past between relatively stable modes in the span of a thousand years or so.

1973

Oil embargo and price rise bring first “energy crisis.”

1974

Serious droughts and other unusual weather since 1972 increase scientific and public concern about climate change, with cooling from aerosols suspected to be as likely as warming; journalists talk of ice age.

1975

Concern about environmental effects of airplanes leads to investigations of trace gases in the stratosphere and discovery of danger to ozone layer.

Manabe and collaborators produce complex but plausible computer models which show a temperature rise of several degrees for doubled CO2.

1976

Studies find that CFCs (1975) and also methane and ozone (1976) can make a serious contribution to the greenhouse effect

Deep-sea cores show a dominating influence from 100,000-year Milankovitch orbital changes, emphasizing the role of feedbacks.

Deforestation and other ecosystem changes are recognized as major factors in the future of the climate.

Eddy shows that there were prolonged periods without sunspots in past centuries, corresponding to cold periods.

1977

Scientific opinion tends to converge on global warming as the biggest climate risk in next century.

1978

Attempts to coordinate climate research in U.S. end with an inadequate National Climate Program Act, accompanied by temporary growth in funding.

1979

Second oil “energy crisis.” Strengthened environmental movement encourages renewable energy sources, inhibits nuclear energy growth.

U.S. National Academy of Sciences report finds it highly credible that doubling CO2 will bring 1.5-4.5EC global warming.

World Climate Research Programme launched to coordinate international research.

1981

Election of Reagan brings backlash against environmental movement; political conservatism is linked to skepticism about global warming.

IBM Personal Computer introduced. Advanced economies are increasingly delinked from energy.

Hansen and others show that sulfate aerosols can significantly cool the climate, raising confidence 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 span of a century in the distant past.

Strong global warming since mid-1970s is reported, with 1981 the warmest year on record.

1983

Reports from U.S. National Academy of Sciences and Environmental Protection Agency spark conflict, as greenhouse warming becomes prominent in mainstream politics.

1985

Villach conference declares expert consensus that some global warming seems inevitable, 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 ice ages, pointing to powerful biological and geochemical feedbacks.

Broecker speculates that a reorganization of North Atlantic Ocean circulation can bring swift and radical climate change.

1987

Montreal Protocol of theVienna Convention imposes international restrictions on emission of ozone-destroying gases.

1988

News media coverage of global warming leaps upward following record heat and droughts plus testimony by Hansen.

Toronto Conference calls for strict, specific limits on greenhouse gas emissions.

Ice-core and biology studies confirm living ecosystems make climate feedback by way of methane, which could accelerate global warming.

Intergovernmental Panel on Climate Change (IPCC) is established.

Level of CO2 in the atmosphere reaches 350 ppm.

After 1988 it is difficult to identify historical milestones. Not only do we lack perspective, but the effort was so large that progress on a given topic, even more than before, came through a variety of results spread over several groups and several years.

A TENTATIVE LIST:

1989

Fossil-fuel and other industries form Global Climate Coalition in US to lobby politicians and convince the media and public that climate science is too uncertain to justify action.

1990

First IPCC report says world has been warming and future warming seems likely. Industry lobbyists and some scientists dispute the tentative conclusions.

1991

Mt. Pinatubo explodes; Hansen predicts cooling pattern, verifying (by 1995) computer models of aerosol effects.

Global warming skeptics emphasize studies indicating that a significant part of 20th-century temperature changes were due to solar influences. (The correlation would fail in the following decade.)

Studies from 55 million years ago show possibility of eruption of methane from the seabed with enormous self-sustained warming.

1992

Conference in Rio de Janeiro produces UN Framework Convention on Climate Change, but US blocks calls for serious action.

Study of ancient climates reveals climate sensitivity in same range as predicted independently by computer models.

1993

Greenland ice cores suggest that great climate changes (at least on a regional scale) can occur in the space of a single decade.

1995

Second IPCC report detects "signature" of human-caused greenhouse effect warming, declares that serious warming is likely in the coming century.

Reports of the breaking up of Antarctic ice sheets and other signs of actual current warming in polar regions begin affecting public opinion.

1997

Toyota introduces Prius in Japan, first mass-market electric hybrid car; swift progress in large wind turbines and other energy alternatives.

International conference produces Kyoto Protocol, setting targets to reduce greenhouse gas emissions if enough nations sign onto a treaty.

1998

The warmest year on record, globally averaged (1995, 1997, and 2001-2006 were near the same level). Borehole data confirm extraordinary warming trend.

Qualms about arbitrariness in computer models diminish as teams model ice-age climate and dispense with special adjustments to reproduce current climate.

1999

Criticism that satellite measurements show no warming are dismissed by National Academy Panel.

Ramanathan detects massive "brown cloud" of aerosols from South Asia.

2000

Global Climate Coalition dissolves as many corporations grapple with threat of warming, but oil lobby convinces US administration to deny problem.

Variety of studies emphasize variability and importance of biological feedbacks in carbon cycle, 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 few scientists.

Bonn meeting, with participation of most countries but not US, develops mechanisms for working towards Kyoto targets.

National Academy panel sees a "paradigm shift" in scientific recognition of the risk of abrupt climate change (decade-scale).

Warming observed in ocean basins; match with computer models gives a clear signature of greenhouse effect warming.

2002

Studies find surprisingly strong "global dimming," due to pollution, has retarded arrival of greenhouse warming, but dimming is now decreasing.

2003

Variety of studies increase concern that collapse of ice sheets (West Antarctica, perhaps Greenland) can raise sea levels faster than most had believed.

Deadly summer heat wave in Europe accelerates divergence between European and US public opinion.

2004

In controversy over temperature data covering past millenium, most conclude climate variations were substantial, but not comparable to the post-1980 warming.

First major book, movie and art work featuring global warming appear.

2005

Kyoto treaty goes into effect, signed by major industrial nations except US. Japan, Western Europe, regional US entities accelerate work to retard emissions.
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