Global warming

3.341013824879 (1085)
Posted by sonny 03/17/2009 @ 02:13

Tags : global warming, environment, sciences

News headlines
Most Voters Support the Fight Against Global Warming - U.S. News & World Report
The poll, conducted by the Mellman Group, a Democratic firm, and released by the Pew Environmental Group, finds that 77 percent of voters favor action "to reduce global warming emissions" and that only 22 percent of voters say they would view members...
Global Warming Threatens Pacific's Bountiful Coral Triangle - Voice of America
Most climate researchers say the emission of so-called greenhouse gases, many of them burning fuels such as oil and coal, contribute to warming global temperatures. They say those rising temperatures will cause severe weather disturbances that could...
Global warming in perspective: today's Google news results -
"The vast majority of experts, 95 percent, maybe even 99 percent, agree that global warming is taking place," said Kirby Donnelly, head of environmental and ... But you probably already knew that, right? If you're reading commentary on global warming...
Global Warming May Exceed Infections as Health Threat - Bloomberg
By Michelle Fay Cortez and Alex Morales May 14 (Bloomberg) -- Global warming is the biggest public health threat of the 21st century, eclipsing infectious diseases, water shortages and poverty, a team of medical and climate-change researchers concluded...
Dems' climate bill shy on tax credit help - The Associated Press
WASHINGTON (AP) — The House Democrats' bill to limit gases blamed for global warming would generate a fraction of the money President Barack Obama wanted to get from it to pay for a middle-class tax credit. Leaders of the House Energy Committee...
What if global-warming fears are overblown? -
By Jon Birger, senior writer John Christy says that global warming has been overestimated. NEW YORK (Fortune) -- With Congress about to take up sweeping climate-change legislation, expect to hear more in coming weeks from John Christy, director of the...
AP Interview: Gore, volunteers target Congress - The Associated Press
The nonprofit group founded by Gore has trained about 3000 people to deliver their own versions of the climate change slideshow that made him the star of the Oscar-winning documentary "An Inconvenient Truth" and the leading US voice on global warming....
Global warming--err, sorry--make that twenty days and twenty nights -
For years now, Al Gore and other global warming alarmists have been talking about the threat of melting ice. Their principal concerns have been Greenland and the Antarctic. They have said--repeatedly--that if the West Antarctic ice sheet melts,...
Global warming, green technology--and global competition -
The country is the world's second-largest market for wind turbines, gaining rapidly on the US In carmaking, China's BYD Auto has leapfrogged global giants, launching the first mass-produced hybrid that plugs into an electrical outlet....
Colleges fall for global warming hype - Augusta Chronicle
I was sickened and scared when I read David Skorton's (president of Cornell University) guest column "Save economy -- stop global warming" (May 7). He says he represents a consortium of 600 college and university presidents representing 5 million...

Global warming

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.

Global warming is the increase in the average temperature of the Earth's near-surface air and the oceans since the mid-twentieth century and its projected continuation. Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 100 years ending in 2005. The Intergovernmental Panel on Climate Change (IPCC) concludes that anthropogenic greenhouse gases are responsible for most of the observed temperature increase since the middle of the twentieth century, and natural phenomena such as solar variation and 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 30 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries.

Climate model projections summarized in the latest IPCC report indicate that global surface temperature will likely rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the twenty-first century. The uncertainty in this estimate arises from the use of models with differing climate sensitivity, and the use of differing estimates of future greenhouse gas emissions. Some other uncertainties include how warming and related changes will vary from region to region around the globe. Although most studies focus on the period up to 2100, warming is expected to continue beyond 2100, even if emissions have stopped, because of the large heat capacity of the oceans and the lifespan of CO2 in the atmosphere.

Increasing global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, likely including an expanse of the subtropical desert regions. Other likely effects include Arctic shrinkage and resulting Arctic methane release, shrinkage of the Amazon rainforest (already very damaged by deforestation from logging and farming), increases in the intensity of extreme weather events, changes in agricultural yields, modifications of trade routes, glacier retreat, species extinctions and changes in the ranges of disease vectors.

Political and public debate continues regarding the appropriate response to global warming. The available options are mitigation to reduce further emissions; adaptation to reduce the damage caused by warming; and, more speculatively, geoengineering to reverse global warming. Most national governments have signed and ratified the Kyoto Protocol aimed at reducing greenhouse gas emissions.

The causes of the recent warming are an active field of research. The scientific consensus is that the increase in atmospheric greenhouse gases due to human activity has caused most of the warming observed since the start of the industrial era, and the observed warming cannot be satisfactorily explained by natural causes alone. This attribution is clearest for the most recent 50 years, which is the period when most of the increase in greenhouse gas concentrations took place and for which the most complete measurements exist.

The greenhouse effect was discovered by Joseph Fourier in 1824 and first investigated quantitatively by Svante Arrhenius in 1896. It is the process by which absorption and emission of infrared radiation by atmospheric gases warm a planet's lower atmosphere and surface. Existence of the greenhouse effect as such is not disputed. The question is instead how the strength of the greenhouse effect changes when human activity increases the atmospheric concentrations of particular greenhouse gases.

Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F), without which Earth would be uninhabitable. On Earth the major greenhouse gases are water vapor, which causes about 36–70 percent of the greenhouse effect (not including clouds); carbon dioxide (CO2), which causes 9–26 percent; methane (CH4), which causes 4–9 percent; and ozone, which causes 3–7 percent.

Human activity since the industrial revolution has increased the atmospheric concentration of various greenhouse gases, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs and nitrous oxide. The atmospheric concentrations of CO2 and methane have increased by 36% and 148% respectively since the beginning of the industrial revolution in the mid-1700s. These levels are considerably higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from ice cores. Less direct geological evidence indicates that CO2 values this high were last seen approximately 20 million years ago. Fossil fuel burning has produced approximately three-quarters of the increase in CO2 from human activity over the past 20 years. Most of the rest is due to land-use change, in particular deforestation.

CO2 concentrations are expected to continue to rise due to ongoing burning of fossil fuels and land-use change. The rate of rise will depend on uncertain economic, sociological, technological, and natural developments. The IPCC Special Report on Emissions Scenarios gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100. Fossil fuel reserves are sufficient to reach this level and continue emissions past 2100 if coal, tar sands or methane clathrates are extensively exploited.

The Earth's climate changes in response to external forcings, including those related to greenhouse gases, variations in its orbit around the Sun (orbital forcing), changes in solar luminosity, and volcanic eruptions which are all examples of the Earth's own variation in temperatures, for which the UNFCCC uses the term climate variability. There are also positive and negative feedbacks which determine how the climate will respond to external forcing.

None of the effects of forcing are instantaneous. The thermal inertia of the Earth's oceans and slow responses of other indirect effects mean that the Earth's current climate is not in equilibrium with the forcing imposed. Climate commitment studies indicate that even if greenhouse gases were stabilized at 2000 levels, a further warming of about 0.5 °C (0.9 °F) would still occur.

One alternative hypothesis to the consensus view that anthropogenic forcing has caused most of the recent temperature increase is that recent warming may be the result of variations in solar activity.

A paper by Peter Stott and colleagues suggests 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. They nevertheless conclude that even with an enhanced climate sensitivity to solar forcing, most of the warming since the mid-20th century is likely attributable to the increases in greenhouse gases. Another paper suggests that the Sun may have contributed about 45–50 percent of the increase in the average global surface temperature over the period 1900–2000, and about 25–35 percent between 1980 and 2000.

A different hypothesis is that variations in solar output, possibly amplified by cloud seeding via galactic cosmic rays, may have contributed to recent warming. It suggests magnetic activity of the sun is a crucial factor which deflects cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate.

One predicted effect of an increase in solar activity would be a warming of most of the stratosphere, whereas an increase in greenhouse gases should produce cooling there. The observed trend since at least 1960 has been a cooling of the lower stratosphere. Reduction of stratospheric ozone also has a cooling influence, but substantial ozone depletion did not occur until the late 1970s. Solar variation combined with changes in volcanic activity probably did have a warming effect from pre-industrial times to 1950, but a cooling effect since. In 2006, Peter Foukal and colleagues found no net increase of solar brightness over the last 1,000 years. Solar cycles led to a small increase of 0.07 percent in brightness over the last 30 years. This effect is too small to contribute significantly to global warming. One paper by Mike Lockwood and Claus Fröhlich found no relation between global warming and solar radiation since 1985, whether through variations in solar output or variations in cosmic rays. Henrik Svensmark and Eigil Friis-Christensen, the main proponents of cloud seeding by galactic cosmic rays, disputed this criticism of their hypothesis. A 2007 paper found that in the last 20 years there has been no significant link between changes in cosmic rays coming to Earth and cloudiness and temperature.

When a warming trend results in effects that induce further warming, the process is referred to as a positive feedback; when the effects induce cooling, the process is referred to as a negative feedback. The primary positive feedback involves water vapor. The primary negative feedback is the effect of temperature on emission of infrared radiation: as the temperature of a body increases, the emitted radiation increases with the fourth power of its absolute temperature. This provides a powerful negative feedback which stabilizes the climate system over time.

Global temperatures 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). 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. The Northern Hemisphere has more land than the Southern Hemisphere, so it warms faster. The Northern Hemisphere also has extensive areas of seasonal snow and sea-ice cover subject to the ice-albedo feedback. More greenhouse gases are emitted in the Northern than Southern Hemisphere, but this does not contribute to the difference in warming because the major greenhouse gases persist long enough to mix 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. Estimates prepared by the World Meteorological Organization and the Climatic Research Unit concluded that 2005 was the second warmest year, behind 1998. Temperatures in 1998 were unusually warm because the strongest El Niño-Southern Oscillation in the past century occurred during that year.

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, though the cooling may also be due in part to natural variability. James Hansen and colleagues have proposed that the effects of the products of fossil fuel combustion—CO2 and aerosols—have, for the short term, largely offset one another, so that net warming in recent decades has been driven mainly by non-CO2 greenhouse gases.

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. Ruddiman's interpretation of the historical record, with respect to the methane data, has been disputed.

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.

A rapid buildup of greenhouse gases amplified 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.

Sudden releases of methane from clathrate compounds (the clathrate gun hypothesis) have been hypothesized as both a cause for and an effect of 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).

Scientists have studied global warming with computer models of the climate. These models are based on physical principles including fluid dynamics and radiative transfer and are designed to be simplifications of the actual climate system. All modern climate models include an atmospheric model that is coupled to an ocean model and models for ice cover on land and sea. Some models also include treatments of chemical and biological processes. These models project a warmer climate due to increasing levels of greenhouse gases. Although a large amount of the variation in model outcomes depends on the greenhouse gas emissions used as inputs, the temperature effect of a specific greenhouse gas concentration (climate sensitivity) varies depending on the model used.

Global climate model projections of future climate depend on estimates of greenhouse gas emissions, most often those from the IPCC Special Report on Emissions Scenarios (SRES). In addition to human-caused emissions, some models also include a simulation of the carbon cycle; this generally shows a positive feedback, though this response is uncertain. Some observational studies also show a positive feedback. The representation of clouds is one of the main sources of uncertainty in present-generation models, though progress is being made on this problem.

Including uncertainties in future greenhouse gas concentrations and climate sensitivity, the IPCC anticipates a warming of 1.1 °C to 6.4 °C (2.0 °F to 11.5 °F) by the end of the 21st century, relative to 1980–1999. A 2008 paper predicts that the global temperature will not increase during the next decade because of short-term natural climate cycles.

Models are also 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. Although these models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects, they do suggest that the warming since 1975 is dominated by man-made greenhouse gas emissions.

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. Comparing model predictions with current climate is a good way to test the predictive power of models. While a 2007 study by David Douglass and colleagues found that the models did not accurately predict observed changes in the tropical troposphere, a 2008 paper published by a 17-member team led by Ben Santer noted errors in the Douglass study, and found instead that the models and observations were not statistically different. Not all effects of global warming are accurately predicted by the climate models used by the IPCC. For example, observed Arctic shrinkage has been faster than that predicted.

Although it is difficult to connect specific weather events to global warming, an increase in global temperatures may in turn cause broader changes, including glacial retreat, Arctic shrinkage, 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. These changes are not likely to be reversible on timescales shorter than a thousand years. Other effects may include changes in agricultural yields, addition of new trade routes, 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 that of the Larsen Ice Shelf, sea level rise, changes in rainfall patterns, and increased intensity and frequency of extreme weather events are attributable in part 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.

Social and economic effects of global warming may be exacerbated by growing population densities in affected areas. Temperate regions are projected to experience some benefits, such as fewer deaths due to cold exposure. 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. 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 (see Atlantic Multidecadal Oscillation), 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.

Additional anticipated effects include sea level rise of 0.18 to 0.59 meters (0.59 to 1.9 ft) in 2090-2100 relative to 1980-1999, repercussions to agriculture, possible slowing of the thermohaline circulation, reductions in the ozone layer, increasingly intense (but less frequent) hurricanes and extreme weather events, lowering of ocean pH, oxygen depletion in the oceans, and the spread of diseases such as malaria and dengue fever, as well as Lyme disease, hantavirus infections, bubonic plague, and cholera. 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. However, few mechanistic studies have documented extinctions due to recent climate change and one study suggests that projected rates of extinction are uncertain.

Some economists have tried to estimate the aggregate net economic costs of damages from climate change across the globe. Such estimates have so far yielded no conclusive 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).

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 one percent, and that in a worst-case scenario global per capita consumption could fall 20 percent. 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. Others have supported the general attempt to quantify economic risk, even if not the specific numbers.

Preliminary studies suggest that costs and benefits of mitigating global warming are broadly comparable in magnitude.

According to United Nations Environment Programme (UNEP), economic sectors likely to face difficulties related to climate change include banks, agriculture, transport and others. Developing countries dependent upon agriculture will be particularly harmed by global warming.

The broad agreement among climate scientists that global temperatures will continue to increase has led some nations, states, corporations and individuals to implement responses. These responses to global warming can be divided into mitigation of the causes and/or effects of global warming, and adaptation to the changing global environment.

By far the largest amount of political time and effort has gone into reducing in greenhouse gas emissions, principally through the Kyoto protocol. These efforts have been largely unsuccessful. Other approaches include carbon sequestration and certain geoengineering techniques.

The world's primary international agreement on combating global warming is the Kyoto Protocol, an amendment to the UNFCCC negotiated in 1997. The Protocol now covers more than 160 countries globally and over 55 percent of global greenhouse gas emissions. Only the United States and Kazakhstan have not ratified the treaty, with the United States historically being the world's largest emitter of greenhouse gases. This treaty expires in 2012, and international talks began in May 2007 on a future treaty to succeed the current one.

Many environmental groups encourage individual action against global warming, often by the consumer, but also by community and regional organizations. Others have suggested a quota on worldwide fossil fuel production, citing a direct link between fossil fuel production and CO2 emissions.

There has also been business action on climate change, including efforts at increased energy efficiency and limited moves towards use of alternative fuels. In January 2005 the European Union introduced its European Union Emission Trading Scheme, a greenhouse gas emissions trading scheme through which companies, in conjunction with government, agree to cap their emissions or to purchase credits from those below their allowances. Australia announced its Carbon Pollution Reduction Scheme in 2008. United States President Barack Obama has announced he will introduce an economy wide cap and trade scheme.

The IPCC's Working Group III is responsible for crafting reports that deal with the mitigation of global warming and analyzing the costs and benefits of different approaches. In the 2007 IPCC Fourth Assessment Report, they conclude that no one technology or sector can be completely responsible for mitigating future warming. They find there are key practices and technologies in various sectors, such as energy supply, transportation, industry, and agriculture, that should be implemented to reduced global emissions. They estimate that stabilization of carbon dioxide equivalent between 445 and 710 ppm by 2030 will result in between a 0.6 percent increase and three percent decrease in global gross domestic product.

Geoengineering would involve the deliberate modification of Earth's environment on a large scale "to suit human needs and promote habitability". It can be divided two major approaches. The first is remediation, in which greenhouse gases would be removed from the atmosphere, principally by carbon sequestration methods such as air capture. The second is solar radiation management, in which incoming solar radiation would be reduced, such as by the insertion of stratospheric sulfur aerosols. The slow pace of action to reduce greenhouse gas emissions have led some scientists to suggest that these techniques may be necessary. Whilst some cool roof and tree planting projects are underway, no planetary-scale geoengineering has yet been attempted.

Increased publicity of the scientific findings surrounding global warming has resulted in political and economic debate. Poor regions, particularly Africa, appear at greatest risk from the projected effects of global warming, while their emissions have been small compared to the developed world. At the same time, developing country exemptions from provisions of the Kyoto Protocol have been criticized by the United States and Australia, and used as part of a rationale for continued non-ratification by the U.S. In the Western world, the idea of human influence on climate has gained wider public acceptance in Europe than in the United States.

The issue of climate change has sparked debate weighing the benefits of limiting industrial emissions of greenhouse gases against the costs that such changes would entail. There has been discussion in several countries about the cost and benefits of adopting alternative energy sources in order to reduce carbon emissions. Business-centered organizations, conservative commentators, and companies such as the Competitive Enterprise Institute and ExxonMobil have downplayed IPCC climate change scenarios, funded scientists who disagree with the scientific consensus, and provided their own projections of the economic cost of stricter controls. Likewise, environmental organizations and a number of public figures have emphasized the potential risks of climate change and promote the implementation of GHG emissions reduction measures. Some fossil fuel companies have scaled back their efforts in recent years, or called for policies to reduce global warming.

Another point of contention is the degree to which emerging economies such as India and China should be expected to constrain their emissions. According to recent reports, China's gross national CO2 emissions may now exceed those of the U.S. China has contended that it has less of an obligation to reduce emissions since its per capita emissions are roughly one-fifth that of the United States. India, also exempt from Kyoto restrictions and another of the biggest sources of industrial emissions, has made similar assertions. The U.S. contends that if it must bear the cost of reducing emissions, then China should do the same.

A variety of issues are often raised in relation to global warming. One is ocean acidification. Increased atmospheric CO2 increases the amount of CO2 dissolved in the oceans. CO2 dissolved in the ocean reacts with water to form carbonic acid, resulting in acidification. Ocean surface pH is estimated to have decreased from 8.25 near the beginning of the industrial era to 8.14 by 2004, and is projected to decrease by a further 0.14 to 0.5 units by 2100 as the ocean absorbs more CO2. Since organisms and ecosystems are adapted to a narrow range of pH, this raises extinction concerns, directly driven by increased atmospheric CO2, that could disrupt food webs and impact human societies that depend on marine ecosystem services.

Global dimming, the gradual reduction in the amount of global direct irradiance at the Earth's surface, may have partially mitigated global warming in the late 20th century. From 1960 to 1990 human-caused aerosols likely precipitated this effect. Scientists have stated with 66–90% confidence that the effects of human-caused aerosols, along with volcanic activity, have offset some of the global warming, and that greenhouse gases would have resulted in more warming than observed if not for these dimming agents.

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.

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Politics of global warming

Daniel Patrick Moynihan, Pioneer of the political treatment of the Greenhouse Effect

The politics of global warming have involved policy decisions, legislation, and political debate over the science of and response to global warming. The political struggle over global warming has involved various governmental bodies, special-interest groups, and scientific organizations.

The moderate political viewpoint has been largely abandoned in the US due to Congress' inability to pass any significant CO2 regulation despite the overwhelming popular support for such measures. Also there is substantial evidence showing that the oil industry is working hard to thwart any legislation that would limit CO2 production. Given the US government's intransigence despite the clamor for change by the popular and scientific communities, the political rhetoric has become more extreme if only to get government to move even slightly in the direction of CO2 control.

In most English-speaking countries, support for action to mitigate global warming, such as ratification and implementation of the Kyoto Protocol is strong on the political left.

In some countries the political right are fighting on a platform of taking tough action against global warming, while in others the political right either dispute the scientific consensus on global warming or oppose action to mitigate global warming, instead favoring adaption. All European countries have ratified the Kyoto Protocol, and all have supported strong reductions in greenhouse gas emissions.

In June 2005, US State Department papers showed the administration thanking Exxon executives for the company's "active involvement" in helping to determine climate change policy, including the U.S. stance on Kyoto. Input from the business lobby group Global Climate Coalition was also a factor.

Also, the White House removed key portions of a Centers for Disease Control and Prevention (CDC) report given to the U.S. Senate Environment and Public Works Committee about the dangers to human health of global warming. According to one CDC official familiar with both the CDC version and the version given to the Senate, the version given to the Senate was "eviscerated." The White House prevented the Senate and thus the public from receiving key CDC estimates in the report about diseases likely to flourish in a warmer climate, increased injuries and deaths from severe weather such as hurricanes, more respiratory problems from drought-driven air pollution, an increase in waterborne diseases including cholera, increases in vector-borne diseases including malaria and hantavirus, mental health problems such as depression and post-traumatic stress, and how many people might be adversely affected because of increased warming.

Similarly, according to the testimony of senior officers of the Government Accountability Project, the White House attempted to bury the report "National Assessment of the Potential Consequences of Climate Variability and Change," produced by U.S. scientists pursuant to U.S. law. Some U.S. scientists resigned their jobs rather than give in to White House pressure to underreport global warming.

The United States, although a signatory to the Kyoto Protocol, has neither ratified nor withdrawn from the protocol — though their one-time representative, Condoleezza Rice, remarked that the Protocol was "unacceptable" at the time it was presented to her. The protocol is non-binding over the United States unless ratified. The current President, George W. Bush, has indicated that he does not intend to submit the treaty for ratification, not because he does not support the general idea, but because of the strain he believes the treaty would put on the economy; he emphasizes the uncertainties he asserts are present in the climate change issue.

From 1989 to 2005, oil and gas industries gave $179.5 million to U.S. federal candidates and parties. In October 2003 and again in June 2005, the McCain-Lieberman Climate Stewardship Act failed a vote in the US Senate. . In the 2005 vote, Republicans opposed the Bill 49-6, while Democrats supported it 37-10. .

In January 2007, Democratic House Speaker Nancy Pelosi announced she would form a United States Congress subcommittee to examine global warming. The US government announced that it was withdrawing funding from the lobby groups it had been supporting that aimed to discount the evidence for global warming.

See also Asia-Pacific Partnership for Clean Development and Climate.

The Global Warming Pollution Reduction Act of 2007 was introduced by Senators Bernie Sanders (I-VT) and Barbara Boxer (D-CA) on January 15, 2007. The measure would provide funding for R&D on geologic sequestration of carbon dioxide, set emissions standards for new vehicles and a renewable fuels requirement for gasoline beginning in 2016, establish energy efficiency and renewable portfolio standards beginning in 2008 and low-carbon electric generation standards beginning in 2016 for electric utilities, and require periodic evaluations by the National Academy of Sciences to determine whether emissions targets are adequate.

There is a Report about federal climate change legislation as if the states matter.

US officials, such as Philip Cooney, have repeatedly edited scientific reports from US government scientists, many of whom, such as Thomas Knutson, have been ordered to refrain from discussing climate change and related topics.

Climate scientist James Hansen, director of NASA's Goddard Institute for Space Studies, claimed in a widely cited New York Times article in 2006 that his superiors at the agency were trying to "censor" information "going out to the public." NASA denied this, saying that it was merely requiring that scientists make a distinction between personal, and official government, views in interviews conducted as part of work done at the agency. Several scientists working at the National Oceanic and Atmospheric Administration have made similar complaints; once again, government officials said they were enforcing long-standing policies requiring government scientists to clearly identify personal opinions as such when participating in public interviews and forums.

Critics writing in the Wall Street Journal editorial page claim that the survey was itself unscientific.

Attempts to suppress scientific information on global warming and other issues have been described by Chris Mooney as constituting a Republican War on Science.

Papers presented at an International Scientific Congress on Climate Change, held in 2009 under the sponsorship of the University of Copenhagen in cooperation with nine other universities in the International Alliance of Research Universities (IARU), maintained that the climate-change skepticism which is so prevalent in the USA "was largely generated and kept alive by a small number of conservative think tanks, often with direct funding from industries having special interests in delaying or avoiding the regulation of greenhouse gas emissions".

Several lawsuits have been filed over global warming. For example, Massachusetts v. Environmental Protection Agency before the Supreme Court of the United States forced the US government to regulate greenhouse gases under the Clean Air Act. A similar approach was taken by California Attorney General Bill Lockyer who filed a lawsuit California v. General Motors Corp. to force car manufacturers to reduce vehicles' emissions of carbon dioxide. A third case, Comer v. Murphy Oil, was filed by Gerald Maples, a trial attorney in Mississippi, in an effort to force fossil fuel and chemical companies to pay for damages caused by global warming.

However, 195 US cities representing more than 50 million Americans - have committed to reducing carbon emissions to 7% below 1990 levels. In 2005, California (the world's sixth largest economy) committed to reducing emissions to 2000 levels by 2010, 1990 levels by 2020, and 80% below 1990 levels by 2050. Measures to meet these targets include tighter automotive emissions standards, and requirements for renewable energy as a proportion of electricity production. The Union of Concerned Scientists has calculated that by 2020, drivers would save $26 billion per year if California’s automotive standards were implemented nationally.

Gov. Schwarzenegger also announced he would seek to work with Prime Minister Tony Blair of Great Britain, and various other international efforts to address global warming, independently of the federal government.

On September 8, 2006, Arizona Governor Janet Napolitano signed an executive order calling on the state to create initiatives to cut greenhouse gas emissions to the 2000 level by the year 2020 and to 50 percent below the 2000 level by 2040.

Seven Northeastern US states are involved in the Regional Greenhouse Gas Initiative, a state level emissions capping and trading program. It is believed that the state-level program will apply pressure on the federal government to support Kyoto Protocol.

The US government has worked to undermine state efforts to mitigate global warming. Transportation Secretary Mary Peters, with White House approval, personally directed US efforts to urge governors and dozens of members of the House of Representatives to block California’s first-in-the-nation limits on greenhouse gases from cars and trucks, according to e-mails obtained by Congress.

Pope Benedict XVI told up to half a million people, over a hillside near the Adriatic city of Loreto on the day Catholic Church marks its annual Save Creation Day, that world leaders must make courageous decisions to save the planet "before it is too late" .

One of the biggest opponents of action on global warming has been the fossil fuels energy industry, and particularly the oil industry, such as ExxonMobil, which regularly publishes papers minimizing the threat of global warming. In 1998, the company started providing financial support to organizations and individuals who disagreed with the scientific consensus that human activities were contributing to climate change. One of the groups that received funds from the company was the Competitive Enterprise Institute. ExxonMobil also helped create the "Global Climate Science Team" whose members were active climate contrarians. According to a study by the Union of Concerned Scientists, between 1998 and 2005, ExxonMobil dispersed roughly $16 million to organizations that were challenging the scientific consensus view. After heavy criticism from the press and environmental groups in late 2006 and early 2007, ExxonMobil began distancing itself from these organizations.

One sector of the energy industry that has no problem with the greenhouse gas arguments is the nuclear industry. Margret Thatcher was one of the first major political figures to suggest that the nuclear power was a "green" solution. This was largely regarded with derision at the time but it is the ultimate goal of Tony Blair's solution to tomorrow's energy needs and probably explains his enthusiasm for CO2 emission controls.

Indeed as many countries move towards legally binding engagements to Kyoto targets, including fines for failing to achieve them, many governments may find this a convenient excuse for otherwise unpopular expansions of their nuclear programs.

Nuclear power produces fewer CO2 emissions than fossil fuel plants; the exact level remains somewhat controversial; Greenpeace assert that nuclear power produces about one third of the CO2 emissions as equivalent fossil fuels energy over the lifetime of an installation.

Thousands of protesters marched on the international day of action on December 3, 2005, which coincided with the first meeting of the Parties in Montreal. The planned demonstrations were endorsed by the Assembly of Movements of the World Social Forum.

Christian environmental groups are also increasingly active on climate change, such as The Evangelical Climate Initiative.

In New Zealand, the Climaction Coalition has blockaded the main thoroughfares of Auckland City on two occasions, calling for Free and Frequent Public Transport to reduce the city's dependency on cars. They argue that such a measure would also help reduce global warming if repeated in other cities throughout the world.

Many celebrities have become involved with green campaigning. They include Charlize Theron, Morgan Freeman, Natalie Portman, Tom Hanks, Susan Sarandon, Salma Hayek, Brad Pitt, Keanu Reeves, Alanis Morissette, Leonardo DiCaprio, Joanne Woodward. Others who have become better known to the public because of their environmental statements include Al Gore, Prince Albert of Monaco.

The debate over global warming was raised to a considerably higher profile when former Vice President Al Gore was given an Academy Award for his documentary film, An Inconvenient Truth. Gore has made a considerable number of public appearances to promote the film and the subject-matter within it.

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Global warming controversy

Reproduction of the temperature record using historical forcings

The global warming controversy is a dispute regarding the nature, causes, and consequences of global warming. The disputed issues include the causes of increased global average air temperature, especially since the mid-20th century, whether this warming trend is unprecedented or within normal climatic variations, and whether the increase is wholly or partially an artifact of poor measurements. Additional disputes concern estimates of climate sensitivity, predictions of additional warming, and what the consequences of global warming will be. The debate is vigorous in the popular media and on a policy level, with individuals, corporations, and political organizations all being involved.

In the European Union, global warming has been a prominent and sustained issue. All European Union member states ratified the 1997 Kyoto Protocol, and many European countries had already been taking action to reduce greenhouse gas emissions prior to 1990 (for example, Margaret Thatcher advocated action against man-made climate change in 1988 and Germany started to take action after the Green Party took seats in Parliament in 1983). Both "global warming" and the more politically neutral "climate change" were listed by the Global Language Monitor as political buzzwords or catch phrases in 2005. In Europe, the notion of human influence on climate gained wide acceptance more rapidly than in many other parts of the world, most notably the United States.

The table below shows how public perceptions about the existence and importance of global warming have changed in the U.S. and elsewhere.

A June 2007 Ipsos Mori poll conducted in the UK found 56 percent of respondents believed scientists were still questioning climate change. The survey suggested that terrorism, graffiti and crime were all of more concern than climate change. Ipsos Mori's head of environmental research, Phil Downing, said people had been influenced by counter-arguments.

The Canadian science broadcaster and environmental activist, David Suzuki, reports that focus groups organized by the David Suzuki Foundation showed the public has a poor understanding of the science behind global warming. This is despite recent publicity through different means, including the films An Inconvenient Truth and The 11th Hour.

An example of the poor understanding is public confusion between global warming and ozone depletion or other environmental problems.

A 47-nation poll conducted in 2007 found that "Substantial majorities 25 of 37 countries say global warming is a 'very serious' problem".

Environmental groups, many governmental reports, and the non-U.S. media often state that there is virtually unanimous agreement in the scientific community in support of human-caused global warming, although there is less agreement on the specific consequences of this warming. Opponents either maintain that most scientists consider global warming "unproved," dismiss it altogether, or highlight the dangers of focusing on only one viewpoint in the context of unsettled science. Others maintain that either proponents or opponents have been stifled or driven underground.

The majority of climate scientists agree that global warming is primarily caused by human activities such as fossil fuel burning and deforestation. The conclusion that global warming is mainly caused by human activity and will continue if greenhouse gas emissions are not reduced has been endorsed by more than 50 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries. The U.S. National Academy of Sciences, the American Association for the Advancement of Science, the American Meteorological Society, the International Union for Quaternary Research, and the Joint Science Academies of the major industrialized and developing nations explicitly use the word "consensus" when referring to this conclusion.

At least one survey of the scientific community has found the opposite problem -- New Scientist notes that in surveys a much larger fraction of U.S. scientists consistently state that they are pressured by their employers or by U.S. government bodies to deny that global warming results from human activities or risk losing funding.

In response to claims of a consensus on global warming, some skeptics have compared the theory to a religion, to scientific support for the eugenics movement, and to discredited scientific theories such as phlogiston and miasma.

In April 2006, a group describing itself as "sixty scientists" signed an open letter to the Canadian Prime Minister Stephen Harper to ask that he revisit the science of global warming and "Open Kyoto to debate." As with the earlier statements, critics pointed out that many of the signatories were non-scientists or lacked relevant scientific backgrounds. For example, the group included David Wojick, a journalist, and Benny Peiser, a social anthropologist. More than half the signatories cited past or emeritus positions as their main appointments. Only two (Richard Lindzen and Roy Spencer) indicated current appointments in a university department or a recognized research institute in climate science. One of the signatories has since publicly recanted, stating that his signature was obtained by deception regarding the content of the letter. In response shortly afterward another open letter to Prime Minister Harper endorsing the IPCC report and calling for action on climate change was prepared by Gordon McBean and signed by 90 Canadian climate scientists initially, plus 30 more who endorsed it after its release.

Many other science academies and scientific organizations support the conclusions of the IPCC.

They followed this with an op-ed piece in the Wall Street Journal entitled "A Major Deception on Global Warming". This piece was written by Seitz, in which he claimed that the effect of the alleged changes was "to deceive policy makers and the public".

Now Santer replied, in a letter to the editor of the Wall Street Journal, and in the response he explained that he had made changes, but those changes were in response to the peer review process. In other words, totally normal scientific practice...This account was corroborated by the Chairman of the IPCC and by all of the other authors of the chapters. In fact, over 40 scientists were co-authors of this chapter. This letter was signed by Santer and 40 others and published in the Wall Street Journal in June 1996. And Santer was also formally defended by the American Meteorological Society.

But neither Seitz nor Singer ever retracted the charges, which was then repeated — many times, over and over again — by industry groups and think-tanks. And in fact, if you google "Ben Santer", these same charges are still in the Internet today. In fact, one site said that it was proven in 1996 that Santer had fraudulently altered the IPCC report.

The work of the IPCC has attracted controversy and criticism, including some from experts invited by the IPCC to submit reports or serve on its panels.

In blog posts, Roger A. Pielke contends that the IPCC distorted the evidence by not including scientific results that questioned anthropogenic global warming. These criticisms have been described as "failed" by William Connolley. Pielke also perceived a conflict of interest in the IPCC assessment process, since the "same individuals who are doing primary research in the role of humans on the climate system are then permitted to lead the assessment! ... Assessment Committees should not be an opportunity for members to highlight their own research." There is no obvious solution to this problem, since scientists with sufficient knowledge of the field to serve on the IPCC and scientists who have written noteworthy papers in the field are essentially the same group.

Christopher Landsea, a hurricane researcher, said of "the part of the IPCC to which my expertise is relevant" that "I personally cannot in good faith continue to contribute to a process that I view as both being motivated by pre-conceived agendas and being scientifically unsound", because of comments made at a press conference by Kevin Trenberth of which Landsea disapproved. Trenberth said that "Landsea's comments were not correct"; the IPCC replied that "individual scientists can do what they wish in their own rights, as long as they are not saying anything on behalf of the IPCC" and offered to include Landsea in the review phase of the AR4. Roger Pielke, Jr. commented that "Both Landsea and Trenberth can and should feel vindicated... the IPCC accurately reported the state of scientific understandings of tropical cyclones and climate change in its recent summary for policy makers".

In 2005, the House of Lords Economics Committee wrote that "We have some concerns about the objectivity of the IPCC process, with some of its emissions scenarios and summary documentation apparently influenced by political considerations." It doubted the high emission scenarios and its "played-down" positive aspects of global warming. The main claims of the House of Lords Economics Committee were rejected in the response made by the United Kingdom government and by the Stern Review.

On Dec 10, 2008, a report was released by the U.S. Senate Committee on Environment and Public Works Minority members, under the leadership of the Senate's most vocal global warming skeptic Jim Inhofe. The timing of the report coincided with the UN global warming conference in Poznan, Poland. It claims to summarize scientific dissent from the IPCC. Many of the claims about the numbers of individuals listed in the report, whether they are actually scientists, and whether they support the positions attributed to them, have been disputed.

Attribution of recent climate change discusses how global warming is attributed to anthropogenic GHGs. Correlation of CO2 and temperature is not part of this evidence. Nonetheless, one argument against anthropogenic global warming claims that rising levels of carbon dioxide (CO2) and other greenhouse gases (GHGs) do not correlate with global warming.

Scientists opposing the mainstream scientific assessment of global warming express varied opinions concerning the cause of global warming. Some say only that it has not yet been ascertained whether humans are the primary cause of global warming (e.g., Balling, Lindzen, and Spencer). Others attribute global warming to natural variation (e.g., Soon and Baliunas), ocean currents (e.g., Gray), increased solar activity (e.g., Shaviv and Veizer), cosmic rays (e.g., Svensmark), or unknown natural causes (e.g., Leroux).

Another point of controversy is the correlation of temperature with solar variation.

There are many interesting palaeoclimate studies that suggest that solar variability had an influence on pre-industrial climate. There are also some detection–attribution studies using global climate models that suggest there was a detectable influence of solar variability in the first half of the twentieth century and that the solar radiative forcing variations were amplified by some mechanism that is, as yet, unknown. However, these findings are not relevant to any debates about modern climate change. Our results show that the observed rapid rise in global mean temperatures seen after 1985 cannot be ascribed to solar variability, whichever of the mechanisms is invoked and no matter how much the solar variation is amplified.

Svensmark and Friis-Christensen dispute this in a recent reply arguing that tropospheric air temperature records, as opposed to the surface air temperature data used by Lockwood and Fröhlich, do show a significant negative correlation between cosmic-ray flux and air temperatures up to 2006. A linear warming trend of about 0.14 K/decade is however left unaccounted for. As of October 2007, this reply has not yet been published in a peer-reviewed journal.

The consensus position (as represented for example by the IPCC Fourth Assessment Report) says that solar radiation may have increased by 0.12 W/m² since 1750, compared to 1.6 W/m² for the net anthropogenic forcing. The TAR said, "The combined change in radiative forcing of the two major natural factors (solar variation and volcanic aerosols) is estimated to be negative for the past two, and possibly the past four, decades." The AR4 makes no direct assertions on the recent role of solar forcing, but the previous statement is consistent with the AR4's figure 4.

The "pause" in warming from the 1940s to 1960's is generally attributed to aerosol forcing, which acts to cool the climate. More recently, this forcing has (relatively) declined, which may have enhanced warming, though the effect is regionally varying. See global dimming. Another example of this is Ruckstuhl et al.(2008) who found a 60% reduction in aerosol concentrations over Europe causing solar brightening.

Skeptics have questioned the accuracy of the instrumental temperature record on the basis of the urban heat island effect, the quality of the surface station network and what they view as unwarranted adjustments to the temperature record.

Skeptics contend that stations located in more populated areas could show warming due to increased heat generated by cities, rather than a global temperature rise. The IPCC Third Assessment Report acknowledges that the urban heat island is an important local effect, but cites analyses of historical data indicating that the effect of the urban heat island on the global temperature trend is no more than 0.05 °C (0.09 °F) degrees through 1990. More recently, Peterson (2003) found no difference between the warming observed in urban and rural areas. Stephen McIntyre analyzed Peterson's raw data and found "actual cities have a very substantial trend of over 2 °C per century relative to the rural network—and this assumes that there are no problems with rural network—something that is obviously not true since there are undoubtedly microsite and other problems." McIntyre has not published his results in a peer-reviewed journal.

Parker (2006) found that there was no difference in warming between calm and windy nights. Since the urban heat island effect is strongest for calm nights and is weak or absent on windy nights, this was taken as evidence that global temperature trends are not significantly contaminated by urban effects. Pielke and Matsui published a paper disagreeing with Parker's conclusions.

More recently, Roger A. Pielke and Stephen McIntyre have criticized the US instrumental temperature record and adjustments to it, and Pielke and others have criticized the poor quality siting of a number of weather stations in the United States. In response, Anthony Watts began a volunteer effort to photographically document the siting quality of these stations. Based on the work of Watts, Stephen McIntyre has completed a reconstruction of U.S. temp history using only those weather stations identified so far as meeting the requirements to be CRN level 1 (excellent) or level 2 (good) stations. The higher quality stations indicate the warmest years in the U.S. were 1934 and 1921, followed by 1998 and 2006. McIntyre has made all of his methods, data and code available for others to reproduce his findings. McIntyre's analysis has not been published in the peer-reviewed literature.

Using a combination of surface temperature history and ocean heat content, Stephen E. Schwartz has proposed an estimate of climate sensitivity of 1.9 ± 1.0 K for doubled CO2. , revised upwards from 1.1 ± 0.5 K. Grant Foster, James Annan, Gavin Schmidt, and Michael E. Mann argue that there are errors in both versions of Schwartz's analysis. Astronomer Nir Shaviv also has proposed a low value for climate sensitivity. Petr Chylek and co-authors have also proposed low climate sensitivity to doubled CO2, estimated to be 1.6 K ± 0.4 K.

Richard Lindzen proposed an Infrared Iris hypothesis of compensating meteorological processes that tend to stabilize climate change. Roy Spencer et al. discovered "a net reduction in radiative input into the ocean-atmosphere system" in tropical intraseasonal oscillations that "may potentially support" the idea of an "Iris" effect, although they point out that their work is concerned with much shorter time scales. If confirmed, this effect might reduce the positive "amplifying" feedback assumed in climate models.

The "standard" set of scenarios for future atmospheric greenhouse gases are the IPCC SRES scenarios. The purpose of the range of scenarios is not to predict what exact course the future of emissions will take, but what it may take under a range of possible population, economic and societal trends. Climate models can be run using any of the scenarios as inputs to illustrate the different outcomes for climate change. No one scenario is officially preferred, but in practice the "A1b" scenario roughly corresponding to 1%/year growth in atmospheric CO2 is often used for modelling studies.

There is debate about the various scenarios for fossil fuel consumption. Global warming skeptic Fred Singer stated that "some good experts believe" that atmospheric CO2 concentration will not double since economies are becoming less reliant on carbon.

Conventional predictions of future temperature rises depend on estimates of future GHG emissions (see SRES) and the climate sensitivity. Models referenced by the Intergovernmental Panel on Climate Change (IPCC) predict that global temperatures are likely to increase by 1.1 to 6.4 °C (2.0 to 11.5 °F) between 1990 and 2100. Others have proposed that temperature increases may be higher than IPCC estimates. One theory is that the climate may reach a "tipping point" where positive feedback effects lead to runaway global warming; such feedbacks include decreased reflection of solar radiation as sea ice melts, exposing darker seawater, and the potential release of large volumes of methane from thawing permafrost.

Some scientists, such as David Orrell or Henk Tennekes, say that climate change cannot be accurately predicted. Orrell says that the range of future increase in temperature suggested by the IPCC rather represents a social consensus in the climate community, but adds that "we are having a dangerous effect on the climate".

A 2007 study by David Douglass and coworkers concluded that the 22 most commonly used global climate models used by the IPCC were unable to accurately predict accelerated warming in the troposphere when tuned to match actual surface warming, concluding that "projections of future climate based on these models should be viewed with much caution." This result contrasts a similar study of 19 models which found that discrepancies between model predictions and actual temperature were likely due to measurement errors.

There is considerable confidence that climate models provide credible quantitative estimates of future climate change, particularly at continental scales and above. This confidence comes from the foundation of the models in accepted physical principles and from their ability to reproduce observed features of current climate and past climate changes. Confidence in model estimates is higher for some climate variables (e.g., temperature) than for others (e.g., precipitation). Over several decades of development, models have consistently provided a robust and unambiguous picture of signifi cant climate warming in response to increasing greenhouse gases.

Kesten Green and J. Scott Armstrong have criticized the validity of model projections of future climate, arguing "Advocates of complex climate models claim that they are based on well-established laws of physics. But there is clearly much more to the models than physical laws, otherwise the models would all produce the same output, which they do not, and there would be no need for confidence estimates for model forecasts, which there certainly is. Climate models are, in effect, mathematical ways for experts to express their opinions." Green and Armstrong contend that the possibility of accurate long-term climate forecasts has never been proven, and argue that simple methods always outperform more complex forecasting methods. The work of Green and Armstrong has been criticized for showing insufficient domain knowledge to evaluate their own criteria and for failing to distinguish between forecasts based on past experience and projections based on physical models.

Roger A. Pielke claims melting Arctic sea ice is a result of regional warming and not global warming.

The Antarctica cooling controversy relates to the question of whether or not current temperature trends in Antarctica contradict or cast doubt on the theory of global warming. Observations unambiguously show the Peninsula to be warming. The trends elsewhere show both warming and cooling but are smaller and dependent on season and the timespan over which the trend is computed. Climate models predict that future trends in Antarctica are much smaller than in the Arctic.

To the extent that a controversy exists it is confined to the popular press and blogs; there is no evidence of a related controversy within the scientific community. Various skeptics, most notably Michael Crichton, have asserted the findings of Doran et al. contradict global warming. Peter Doran, the lead author of the paper, stated that "... our results have been misused as "evidence" against global warming by Crichton in his novel 'State of Fear'..." Others, for example RealClimate, agree there is no contradiction.

Scientific journals and funding agencies generally require authors of peer-reviewed research to archive all of the data necessary to reproduce their research. If another scientist attempts to reproduce the research and needs additional data, authors are expected (with few exceptions) to provide the data, metadata, methods and source code that may be necessary.

Dr David Legates has claimed that Mann, Bradley and Hughes 1998, famous for its hockey stick shaped historic temperature reconstruction, serves as an example of climate scientists not abiding by these policies and suggested that legislators might ultimately take action to enforce them.

In the U.S. global warming is often a partisan political issue. Republicans tend to oppose action against a threat that they regard as unproved, while Democrats tend to support actions that they believe will reduce global warming and its effects through the control of greenhouse gas emissions. Recently, bipartisan measures have been introduced.

The other point that leads to major controversy—because it could have significant economic impacts—is whether action (usually, restrictions on the use of fossil fuels to reduce carbon-dioxide emissions) should be taken now, or in the near future; and whether those restrictions would have any meaningful effect on global temperature.

Due to the economic ramifications of such restrictions, there are those, including the Cato Institute, a libertarian think tank, who feel strongly that the negative economic effects of emission controls outweigh the environmental benefits. They claim that even if global warming is caused solely by the burning of fossil fuels, restricting their use would have more damaging effects on the world economy than the increases in global temperature.

Ultimately, however, a strictly economic argument for or against action on climate change is limited at best, failing to take into consideration other potential impacts of any change.

The Kyoto protocol is the most prominent international agreement on climate change, and is also highly controversial. Some argue that it goes too far or not nearly far enough in restricting emissions of greenhouse gases. Another area of controversy is the fact that China and India, the world's two most populous countries, both ratified the protocol but are not required to reduce or even limit the growth of carbon emissions under the present agreement even though when listed by greenhouse gas emissions per capita, they have rankings of 121st largest per capita emitter at 3.9 Tonnes of CO2e and 162nd largest per capita emitter at 1.8 Tonnes of CO2e respectively, compared with for example the USA at position of the 14th largest per capita CO2e emitter at 22.9 Tonnes of CO2e. Nevertheless, China is the world's second largest producer of greenhouse gas emissions, and India 4th (see: countries by greenhouse emissions). Various predictions see China overtaking the US in total greenhouse emissions between late 2007 and 2010, and according to many other estimates, this already occurred in 2006.

Additionally, high costs of decreasing emissions may cause significant production to move to countries that are not covered under the treaty, such as India and China, claims Fred Singer. As these countries are less energy efficient, this scenario is claimed to cause additional carbon emissions.

The only major developed nation which has signed but not ratified the Kyoto protocol is the USA (see signatories). The countries with no official position on Kyoto are mainly African countries with underdeveloped scientific infrastructure or are oil producers.

Both sides of the controversy have alleged that access to funding has played a role in the willingness of credentialed experts to speak out.

Several skeptical scientists—Fred Singer, Fred Seitz and Patrick Michaels—have been linked to organizations funded by ExxonMobil and Philip Morris for the purpose of promoting global warming skepticism (see section: Risks of passive smoking). Similarly, groups employing global warming skeptics, such as the George C. Marshall Institute, have been criticized for their ties to fossil fuel companies.

On February 2, 2007, The Guardian stated that Kenneth Green, a Visiting Scholar with AEI, had sent letters to scientists in the UK and the U.S., offering US$10,000 plus travel expenses and other incidental payments in return for essays with the purpose of "highlight the strengths and weaknesses of the IPCC process," specifically regarding the IPCC Fourth Assessment Report.

A furor was raised when it was revealed that the Intermountain Rural Electric Association (an energy cooperative that draws a significant portion of its electricity from coal-burning plants) donated $100,000 to Patrick Michaels and his group, New Hope Environmental Services, and solicited additional private donations from its members.

The Union of Concerned Scientists have produced a report titled 'Smoke, Mirrors & Hot Air', that criticizes ExxonMobil for "underwriting the most sophisticated and most successful disinformation campaign since the tobacco industry" and for "funnelling about $16 million between 1998 and 2005 to a network of ideological and advocacy organizations that manufacture uncertainty on the issue." In 2006 Exxon claimed that it was no longer going to fund these groups though that claim has been challenged by Greenpeace.

A number of global warming skeptics, such as the following, assert that grant money is given preferentially to supporters of global warming theory. Atmospheric scientist Reid Bryson said in June 2007 that "There is a lot of money to be made in this... If you want to be an eminent scientist you have to have a lot of grad students and a lot of grants. You can't get grants unless you say, 'Oh global warming, yes, yes, carbon dioxide.'" Similar claims have been advanced by climatologist Marcel Leroux, NASA's Roy Spencer, climatologist and IPCC contributor John Christy, University of London biogeographer Philip Stott, and Accuracy in Media.

Richard Lindzen, the Alfred P. Sloan Professor of Meteorology at MIT, makes the specific claim that " the winter of 1989 Reginald Newell, a professor of meteorology , lost National Science Foundation funding for data analyses that were failing to show net warming over the past century." Lindzen also suggests four other scientists "apparently" lost their funding or positions after questioning the scientific underpinnings of global warming. Lindzen himself, however, has been the recipient of money from energy interests such as OPEC and the Western Fuels Association, including "$2,500 a day for his consulting services", as well as funding from federal sources including the National Science Foundation, the Department of Energy, and NASA.

In recent years some skeptics have changed their positions regarding anthropogenic global warming. Ronald Bailey, author of Global Warming and Other Eco-Myths (published by the Competitive Enterprise Institute in 2002), stated in 2005, "Anyone still holding onto the idea that there is no global warming ought to hang it up". By 2007, he wrote "Details like sea level rise will continue to be debated by researchers, but if the debate over whether or not humanity is contributing to global warming wasn't over before, it is now.... as the new IPCC Summary makes clear, climate change Pollyannaism is no longer looking very tenable". Others have shifted from claims that global warming is unproven to advocating adaptation, sometimes also calling for more data, rather than take immediate action on mitigation through consumption/emissions reduction of fossil fuels. "Despite our intuition that we need to do something drastic about global warming, we are in danger of implementing a cure that is more costly than the original affliction: economic analyses clearly show that it will be far more expensive to cut carbon dioxide emissions radically than to pay the costs of adaptation to the increased temperatures," says Danish academic Bjørn Lomborg. Lomborg has been severely questioned by groups in Denmark. Nordhaus and Schellenberger present similar, more sophisticated, arguments in favor of adaption.

Others argue that if developing nations reach the wealth level of the United States this could greatly increase CO2 emissions and consumption of fossil fuels. Large developing nations such as India and China are predicted to be major emitters of greenhouse gases in the next few decades as their economies grow.

The adaptation only plan is also endorsed by oil companies like ExxonMobil, "ExxonMobil’s plan appears to be to stay the course and try to adjust when changes occur. The company’s plan is one that involves adaptation, as opposed to leadership," says this Ceres report.

Some find this shift and attitude disingenuous and indicative of an inherent bias against prevention (i.e. reducing emissions/consumption) and for the prolonging of profits to the oil industry at the expense of the environment. "Now that the dismissal of climate change is no longer fashionable, the professional deniers are trying another means of stopping us from taking action. It would be cheaper, they say, to wait for the impacts of climate change and then adapt to them" says UK Journalist George Monbiot in an article addressing the supposed economic hazards of addressing climate change. Others argue that adaptation alone will not be sufficient. See also Copenhagen Consensus.

To be sure, though not emphasized to the same degree as mitigation, adaptation to a climate certain to change has been included as a necessary component in the discussion early as 1992, and has been all along. However it was not to the exclusion, advocated by the skeptics, of preventative mitigation efforts, and therein, say carbon cutting proponents, lies the difference.

Many climate scientists state that they are put under enormous pressure to distort or hide any scientific results which suggest that human activity is to blame for global warming. A survey of climate scientists which was reported to the US House Oversight and Government Reform Committee noted that "Nearly half of all respondents perceived or personally experienced pressure to eliminate the words 'climate change', 'global warming' or other similar terms from a variety of communications." These scientists were pressured to tailor their reports on global warming to fit the Bush administration's climate change scepticism. In some cases, this occurred at the request of a former oil-industry lobbyist. In a report by NASA's Office of the Inspector General it has been revealed that NASA officials censored and suppressed scientific data on global warming in order protect the Bush administration from controversy close to the 2004 presidential election.

U.S. officials, such as Philip Cooney, have repeatedly edited scientific reports from US government scientists, many of whom, such as Thomas Knutson, have been ordered to refrain from discussing climate change and related topics. Attempts to suppress scientific information on global warming and other issues have been described by journalist Chris Mooney in his book The Republican War on Science.

Climate scientist James Hansen, director of NASA's Goddard Institute for Space Studies, claimed in a widely cited New York Times article in 2006 that his superiors at the agency were trying to "censor" information "going out to the public." NASA denied this, saying that it was merely requiring that scientists make a distinction between personal, and official government, views in interviews conducted as part of work done at the agency. Several scientists working at the National Oceanic and Atmospheric Administration have made similar complaints; once again, government officials said they were enforcing long-standing policies requiring government scientists to clearly identify personal opinions as such when participating in public interviews and forums.

On the other hand, some American climatologists who have expressed doubts regarding the certainty of human influence in climate change have been criticized by politicians and governmental agencies. Oregon Governor Ted Kulongoski publicly clarified that Oregon does not officially appoint a "state climatologist" in response to Oregon State University's George Taylor's use of that title. As a result of scientific doubts he has expressed regarding global warming, the Delaware Department of Natural Resources and Environmental Control reportedly attempted to remove David Legates from his office of Delaware State Climatologist. In late 2006, Virginia Governor Tim Kaine (D) reportedly began an investigation of Virginia State Climatologist and global warming skeptic Patrick Michaels.

Critics writing in the Wall Street Journal editorial page claim that the survey was itself unscientific.

Several lawsuits have been filed over global warming. For example, Massachusetts v. Environmental Protection Agency before the Supreme Court of the United States forces the US government to regulate greenhouse gases under the Clean Air Act. A similar approach was taken by California Attorney General Bill Lockyer who filed a lawsuit California v. General Motors Corp. to force car manufacturers to reduce vehicles' emissions of carbon dioxide. This lawsuit was found to lack legal merit and was tossed. A third case, Comer v. Murphy Oil USA, Inc., a class action lawsuit filed by Gerald Maples, a trial attorney in Mississippi, in an effort to force fossil fuel and chemical companies to pay for damages caused by global warming. Described as a nuisance lawsuit, it was dismissed by District Court. The Sierra Club sued the U.S. government over failure to raise automobile fuel efficiency standards, and thereby decrease carbon dioxide emissions.

A betting market on climate futures, like other kinds of futures markets, could be used to establish the market consensus on climate change. British climate scientist James Annan proposed bets with global warming skeptics concerning whether future temperatures will increase. Two Russian solar physicists, Galina Mashnich and Vladimir Bashkirtsev, accepted the wager of US$10,000 that the average global temperature during 2012-2017 would be lower than during 1998-2003. Annan first directly challenged Richard Lindzen. Lindzen had been willing to bet that global temperatures would drop over the next 20 years. Annan claimed Lindzen wanted odds of 50-1 against falling temperatures. Lindzen, however, claims that he asked for 2-1 odds against a temperature rise of over 0.4 °C. The Guardian columnist George Monbiot challenged Myron Ebell of the Competitive Enterprise Institute to a GB£5,000 bet of global warming versus global cooling. Annan and other proponents of the consensus state they have challenged other skeptics to bets over global warming that were not accepted, including Annan's attempt in 2005 to accept a bet that had been offered by Patrick Michaels in 1998 that temperatures would be cooler after ten years. A different, $6,000-to-$9,000 bet, where both sides expect warming but differ on the amount, with one break-even point at 0.15 °C/decade, was made between Dr David Evans and Brian Schmidt. Dr Evans' reasons are described here.

Many of the critics of the consensus view on global warming have disagreed, in whole or part, with the scientific consensus regarding other issues, particularly those relating to environmental risks. Chris Mooney, author of The Republican War on Science, has argued that the appearance of overlapping groups of skeptical scientists, commentators and think tanks in seemingly unrelated controversies results from an organised attempt to replace scientific analysis with political ideology. Mooney claims that the promotion of doubt regarding issues that are politically, but not scientifically, controversial has become increasingly prevalent under the Bush Administration and constitutes a "Republican war on science". This is also the subject of a recent book by Environmental lawyer Robert F. Kennedy Jr. entitled Crimes Against Nature: How George W. Bush and Corporate Pals are Plundering the Country and Hijacking Our Democracy. Another book on this topic is The Assault on Reason by former U.S. Vice-President Al Gore. Earlier instances of this trend are also covered in the book The Heat Is On by Ross Gelbspan.

Some critics of the scientific consensus on global warming have argued that these issues should not be linked and that reference to them constitutes an unjustified ad hominem attack. Political scientist Roger Pielke, Jr., responding to Mooney, has argued that science is inevitably intertwined with politics.

Human emissions of chlorofluorocarbons (CFCs) lead to depletion of the ozone layer in the atmosphere and intensify ozone holes over the Antarctic. This concept was politically controversial in the 1990s but was broadly accepted in the scientific community (e.g., by the U.S. National Academy of Sciences and other national academies); Paul Crutzen, Mario Molina, and F. Sherwood Rowland were awarded the 1995 Nobel Prize in Chemistry for discovering the chemical mechanism that links CFCs to ozone depletion. The Montreal Protocol was negotiated under the auspices of the United Nations and is widely seen as a model for the Kyoto Protocol. The scientific basis of ozone depletion has been disputed by some global warming skeptics and related institutions, including Sallie Baliunas, Patrick Michaels, Kary Mullis, Steven Milloy, Fred Singer, and Frederick Seitz.

By the early 1980s, concerns began to arise regarding the health risks of passive smoking and whether policy responses such as smoking bans are appropriate. Medical, governmental, and UN organizations such as the United States Surgeon General, the United States Environmental Protection Agency, and the International Agency for Research on Cancer (IARC) of the World Health Organization have concluded that the scientific evidence shows that passive smoking is harmful. The risks of passive smoking were disputed by some global warming skeptics and related institutions, including Richard Lindzen, Steven Milloy, Fred Singer (1994), Fred Seitz, Michael Crichton, Michael Fumento in 1997 the Cooler Heads Coalition (Consumer Alert) and the Institute of Public Affairs. According to the Union of Concerned Scientists criticism of the scientific consensus on smoking and on global warming was embodied in The Advancement of Sound Science Coalition, a lobby group directed by Milloy and established with support from Philip Morris and subsequently from ExxonMobil. Science advisors to TASSC included Fred Singer, Fred Seitz and Patrick Michaels. TASSC originally campaigned against restrictions on passive smoking, and later on global warming.

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Source : Wikipedia