The global warming controversy (or climate change debates) concerns past or present public debates over certain aspects of climate change: whether it is occurring (climate change deniers dispute this), how much has occurred in modern times, what has caused it (attribution of climate change), what its effects will be, whether action should be taken to curb it now or later, and so forth. In the scientific literature, there is a very strong consensus that global surface temperatures have increased in recent decades and that the trend is caused by human-induced emissions of greenhouse gases.The controversy is, by now, mostly political rather than scientific: there is a scientific consensus that global warming is happening and is caused by human activity. Public debates that also reflect scientific debate include estimates of how responsive the climate system might be to any given level of greenhouse gases (climate sensitivity). Disputes over the key scientific facts of global warming are more prevalent in the media than in the scientific literature, where such issues are treated as resolved, and such disputes are more prevalent in the United States and Australia than globally.Climate change remains an issue of widespread political debate, often split along party political lines, especially in the United States.

Scientific consensus
Debates around the processes of scientific consensus
Authority of the IPCC
Deniers have generally attacked either the IPCC's processes, scientist or the synthesis and executive summaries; the full reports attract less attention. Some of the criticism has originated from experts invited by the IPCC to submit reports or serve on its panels. For example, John Christy, a contributing author who works at the University of Alabama in Huntsville, explained in 2007 the difficulties of establishing scientific consensus on the precise extent of human action on climate change:

Contributing authors essentially are asked to contribute a little text at the beginning and to review the first two drafts. We have no control over editing decisions. Even less influence is granted the 2,000 or so reviewers. Thus, to say that 800 contributing authors or 2,000 reviewers reached consensus on anything describes a situation that is not reality.

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 "Landsea's comments were not correct"; the IPCC replied "individual scientists can do what they wish in their own rights, as long as they are not saying anything on behalf of the IPCC".In 2005, the House of Lords Economics Committee wrote, "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 said that the IPCC had "played-down" what the committee called "some positive aspects of global warming". The main statements of the House of Lords Economics Committee were rejected in the response made by the United Kingdom government.On 10 December 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 denier Jim Inhofe. It says it summarizes scientific dissent from the IPCC. Many of its statements 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.

Emphasizing studies that are regarded as flawed
Dennis T. Avery, a food policy analyst at the Hudson Institute, wrote an article titled "500 Scientists Whose Research Contradicts Man-Made Global Warming Scares" published in 2007, by the Heartland Institute. The list was immediately called into question for misunderstanding and distorting the conclusions of many of the named studies and citing outdated, flawed studies that had long been abandoned. Many of the scientists included in the list demanded their names be removed. At least 45 scientists had no idea they were included as "co-authors" and disagreed with the conclusions of the document. The Heartland Institute refused these requests, stating that the scientists "have no right—legally or ethically—to demand that their names be removed from a bibliography composed by researchers with whom they disagree".

Debates around details in the science
Discussions around locations of temperature measurement stations
There have been attempts to raise public controversy over the accuracy of the instrumental temperature record on the basis of the urban heat island effect, the quality of the surface station network, and assertions that there have been unwarranted adjustments to the temperature record.Weather stations that are used to compute global temperature records are not evenly distributed over the planet, and their distribution has changed over time. There were a small number of weather stations in the 1850s, and the number did not reach the current 3000+ until the 1951 to 1990 periodThe 2001 IPCC Third Assessment Report (TAR) acknowledged that the urban heat island is an important local effect, but cited 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. Peterson (2003) found no difference between the warming observed in urban and rural areas.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.In 2005, Roger A. Pielke and Stephen McIntyre criticized the US instrumental temperature record and adjustments to it, and Pielke and others criticized the poor quality siting of a number of weather stations in the United States. A study in 2010 examined the siting of temperature stations and found that those measurement stations that were poorly showed a slight cool bias rather than the warm bias which deniers had postulated.The Berkeley Earth Surface Temperature group carried out an independent assessment of land temperature records, which examined issues raised by deniers, such as the urban heat island effect, poor station quality, and the risk of data selection bias. The preliminary results, made public in October 2011, found that these factors had not biased the results obtained by NOAA, the Hadley Centre together with the Climatic Research Unit (HadCRUT) and NASA's GISS in earlier studies. The group also confirmed that over the past 50 years the land surface warmed by 0.911 °C, and their results closely matched those obtained from these earlier studies.

Apparent discrepancy for tropospheric temperature increases in the tropics
General circulation models and basic physical considerations predict that in the tropics the temperature of the troposphere should increase more rapidly than the temperature of the surface. A 2006 report to the U.S. Climate Change Science Program noted that models and observations agreed on this amplification for monthly and interannual time scales but not for decadal time scales in most observed data sets. Improved measurement and analysis techniques have reconciled this discrepancy: corrected buoy and satellite surface temperatures are slightly cooler and corrected satellite and radiosonde measurements of the tropical troposphere are slightly warmer. Satellite temperature measurements show that tropospheric temperatures are increasing with "rates similar to those of the surface temperature", leading the IPCC to conclude in 2007 that this discrepancy is reconciled.

"Antarctica cooling controversy"
Global dimming
Forecasts confidence
The IPCC stated in 2010 it has increased confidence in forecasts coming from General Circulation Models:

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 significant climate warming in response to increasing greenhouse gases.
A few scientists believe this confidence in the models' ability to predict future climate is not earned.

Funding for scientists who are skeptics or deniers
Debates over most effective response to warming
Climate change deniers insist on debating whether action (such as the restrictions on the use of fossil fuels to reduce carbon-dioxide emissions) should be taken now or in the near future. Because of the economic ramifications of such restrictions, there are those, including the Cato Institute, a libertarian think tank, who argue that the negative economic effects of emission controls outweigh the environmental benefits. They state 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. Conversely, the general consensus is that early action to reduce emissions would help avoid much greater economic costs later, and would reduce the risk of catastrophic, irreversible change.

Society and culture
Media coverage and public opinion
The theory that increases in greenhouse gases would lead to an increase in temperature was first proposed by the Swedish chemist Svante Arrhenius in 1896, but climate change did not arise as a political issue until the 1990s. It took many years for this particular issue to attract any type of popular attention.In the United States, the mass media devoted little coverage to global warming until the drought of 1988, and James E. Hansen's testimony to the Senate, which explicitly attributed "the abnormally hot weather plaguing our nation" to global warming. Global warming in the U.S. gained more attention after the release of the 2006 documentary An Inconvenient Truth, featuring Al Gore.The British press also changed its coverage at the end of 1988, following a speech by Margaret Thatcher to the Royal Society advocating action against human-induced climate change. According to Anabela Carvalho, an academic analyst, Thatcher's "appropriation" of the risks of climate change to promote nuclear power, in the context of the dismantling of the coal industry following the 1984–1985 miners' strike was one reason for the change in public discourse. At the same time environmental organizations and the political opposition were demanding "solutions that contrasted with the government's". In May 2013 Charles, Prince of Wales took a strong stance criticising both climate change deniers and corporate lobbyists by likening the Earth to a dying patient. "A scientific hypothesis is tested to absolute destruction, but medicine can't wait. If a doctor sees a child with a fever, he can't wait for [endless] tests. He has to act on what is there."In 2007, the BBC announced the cancellation of a planned television special Planet Relief, which would have highlighted the global warming issue and included a mass electrical switch-off. The editor of BBC's Newsnight current affairs show said: "It is absolutely not the BBC's job to save the planet. I think there are a lot of people who think that, but it must be stopped." Author Mark Lynas said "The only reason why this became an issue is that there is a small but vociferous group of extreme right-wing climate 'sceptics' lobbying against taking action, so the BBC is behaving like a coward and refusing to take a more consistent stance."There are differences between the opinion of scientists and that of the general public. A 2009 poll, in the US by Pew Research Center found "[w]hile 84% of scientists say the earth is getting warmer because of human activity such as burning fossil fuels, just 49% of the public agrees". A 2010 poll in the UK for the BBC showed "Climate scepticism on the rise". Robert Watson found this "very disappointing" and said "We need the public to understand that climate change is serious so they will change their habits and help us move towards a low carbon economy."

See also
Attitude polarization
Climate change conspiracy theory
History of climate change policy and politics
Manufactured controversy
Science wars
Skeptical Science
Right-wing antiscience
Politicization of science


== References ==