Hear it pronouncedGlobal warming controversy
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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.
History of public opinion
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[1] 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.[2] 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.[3][4]
There has been a debate among public commentators about how much weight and media coverage should be given to each side of the controversy. Andrew Neil of the BBC stated that "There's a great danger that on some issues we're becoming a one-party state in which we're meant to have only one kind of view. You don't have to be a climate-change denier to recognise that there's a great range of opinion on the subject."[5]
The table below shows how public perceptions about the existence and importance of global warming have changed in the U.S. and elsewhere.[6][7][8][9]
| Statement | % agreeing | Year |
|---|---|---|
| Human activity is a significant cause of climate change. | 79 | 2007 |
| Climate change is a serious problem. | 90 | 2006 |
| Climate change is a serious problem. | 78 | 2003 |
| It's necessary to take major steps starting very soon. | 65 | 2007 |
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.[10]
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.[11] 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.[12][13]
A 15-nation poll conducted in 2006 by Pew Global found that there "is a substantial gap in concern over global warming – roughly two-thirds of Japanese (66%) and Indians (65%) say they personally worry a great deal about global warming. Roughly half of the populations of Spain (51%) and France (46%) also express great concern over global warming, based on those who have heard about the issue. But there is no evidence of alarm over global warming in either the United States or China – the two largest producers of greenhouse gases. Just 19% of Americans and 20% of the Chinese who have heard of the issue say they worry a lot about global warming – the lowest percentages in the 15 countries surveyed. Moreover, nearly half of Americans (47%) and somewhat fewer Chinese (37%) express little or no concern about the problem."[14]
A 47-nation poll conducted in 2007 found that "Substantial majorities 25 of 37 countries say global warming is a 'very serious' problem".[15]
Controversy concerning the science
Existence of a scientific consensus
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.[16][17][18] Others maintain that either proponents or opponents have been stifled or driven underground.[19]
The majority of climate scientists agree that global warming is primarily caused by human activities such as fossil fuel burning and deforestation.[20][21][22][23] 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,[24] the American Association for the Advancement of Science,[25] the American Meteorological Society,[26] the International Union for Quaternary Research,[27] and the Joint Science Academies of the major industrialized and developing nations[28][29] explicitly use the word "consensus" when referring to this conclusion.
A 2004 essay by Naomi Oreskes in the journal Science reported a survey of 928 abstracts of peer-reviewed papers related to global climate change in the ISI database.[30] Oreskes claimed that "Remarkably, none of the papers disagreed with the consensus position. ... This analysis shows that scientists publishing in the peer-reviewed literature agree with IPCC, the National Academy of Sciences, and the public statements of their professional societies." Benny Peiser claimed to have found flaws in Oreskes' work,[31] but his attempted refutation is disputed[32][33][34] and has not been published in a peer-reviewed journal. Peiser later withdrew parts of his criticism,[35] also commenting that "the overwhelming majority of climatologists is agreed that the current warming period is mostly due to human impact. However, this majority consensus is far from unanimous."[33][36]
A 2006 op-ed by Richard Lindzen in The Wall Street Journal challenged the claim that scientific consensus had been reached, and listed the Science journal study as well as other sources, including the IPCC and NAS reports, as part of "an intense effort to suggest that the theoretically expected contribution from additional carbon dioxide has actually been detected."[37] Lindzen wrote in The Wall Street Journal on April 12, 2006,[38]
| “ | But there is a more sinister side to this feeding frenzy. Scientists who dissent from the alarmism have seen their grant funds disappear, their work derided, and themselves libeled as industry stooges, scientific hacks or worse. Consequently, lies about climate change gain credence even when they fly in the face of the science that supposedly is their basis. | ” |
Similarly, Timothy Ball asserts that skeptics have gone underground for "job security and fear of reprisals. Even in University, where free speech and challenge to prevailing wisdoms are supposedly encouraged, academics remain silent."[39]
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[19] or risk losing funding.
In response to claims of a consensus on global warming, some skeptics have compared the theory to a religion,[40][41][42] to scientific support for the eugenics movement,[43][44] and to discredited scientific theories such as phlogiston[45] and miasma.[46]
In 2008, Fergus Brown, Roger A. Pielke and James Annan submitted a paper titled "Is there agreement amongst climate scientists on the IPCC AR4 WG1?"[47] It was rejected for publication by the AGU publication EOS and Nature Precedings. Pielke writes: “From this experience, it is clear that the AGU EOS and Nature Precedings Editors are using their positions to suppress evidence that there is more diversity of views on climate, and the human role in altering climate, than is represented in the narrowly focused 2007 IPCC report.”[48]
A survey published in 2009 by Peter Doran and Maggie Zimmerman of Earth and Environmental Sciences, University of Illinois at Chicago of 3146 Earth Scientists found that 97% of active climatologists agree that human activity is causing global warming.[49] A summary from the survey states that:
- "It seems that the debate on the authenticity of global warming and the role played by human activity is largely nonexistent among those who understand the nuances and scientific basis of long-term climate processes."[50]
Heartland Institute's list
On April 29, 2008, environmental journalist Richard Littlemore revealed that a list of "500 Scientists with Documented Doubts of Man-Made Global Warming Scares"[51] propagated by the Heartland Institute included at least 45 scientists who neither knew of their inclusion as "coauthors" of the article, nor agreed with its contents.[52] Many of the scientists asked the Heartland Institute to remove their names from the list; for instance, Gregory Cutter from the Old Dominion University was reported by Littlemore as saying,
| “ | I have no doubts ..the recent changes in global climate are man-induced. I insist that you immediately remove my name from this list since I did not give you permission to put it there. | ” |
However, the Heartland Institute refused to remove any names from the list. In a statement on May 5, 2008, Institute CEO Joseph Bast said that the title of the September 14, 2007 news release announcing the list had been changed to "500 Scientists Whose Research Contradicts Man-Made Global Warming Scares."[53] In the same statement, Bast also charged that the outraged scientists:
| “ | ...have crossed the line between scientific research and policy advocacy. They lend their credibility to politicians and advocacy groups who call for higher taxes and more government regulations to “save the world” from catastrophic warming ... and not coincidentally, to fund more climate research. They are embarrassed -- as they should be -- to see their names in a list of scientists whose peer-reviewed published work suggests the modern warming might be due to a natural 1,500-year climate cycle. | ” |
Bast also stated that:
| “ | The point should be obvious: There is no scientific consensus that global warming is a crisis. | ” |
Petitions
In 1997, the “World Scientists Call For Action” petition was presented to world leaders meeting to negotiate the Kyoto Protocol. The declaration asserted, “A broad consensus among the world's climatologists is that there is now ‘a discernible human influence on global climate.’" It urged governments to make “legally binding commitments to reduce industrial nations' emissions of heat-trapping gases”, and called global warming “one of the most serious threats to the planet and to future generations.”[54] The petition was conceived by the Union of Concerned Scientists as a follow up to their 1992 World Scientists' Warning to Humanity, and was signed by “more than 1,500 of the world's most distinguished senior scientists, including the majority of Nobel laureates in science”[55][56]
To support his claim of a lack of consensus, the website of prominent skeptic Fred Singer's Science and Environmental Policy Project (SEPP) lists four petitions. According to SEPP, these petitions show that "the number of scientists refuting global warming is growing."[57] The petitions are:
- The 1992 "Statement by Atmospheric Scientists on Greenhouse Warming," signed by 47 scientists, claims "such policy initiatives [those concerning the Earth Summit scheduled to convene in Brazil in June 1992] derive from highly uncertain scientific theories. They are based on the unsupported assumption that catastrophic global warming follows from the burning of fossil fuels and requires immediate action. We do not agree."[58]
- The "Heidelberg Appeal" (also from 1992), signed by over 4000 scientists including 72 Nobel Prize winners.[59] This appeal makes no mention of climate change or any other specific environmental issue, but is essentially a plea for policy based on "scientific criteria and not on irrational preconceptions".
- Singer's "Leipzig Declaration on Global Climate Change" (1995 and 1997). Critics point out that most of the signatories lack credentials in the specific field of climate research or even physical science in general.[60] Followup interviews found at least twelve signers who denied having signed the Declaration or had never heard of it.[61]
- The "Oregon Petition", self-signed and unverified by third party, was started in 1998 by physicist Frederick Seitz, past president of the United States National Academy of Sciences. The identical petition card was circulated again in late 2007 and Arthur B. Robinson presented the petition of 31,000 claimed signatories in Washington DC on May 19, 2008.[62] Critics point out that many of the signatories of the petition lack a background in climate-related sciences[63] and that the petition itself mentions only "catastrophic heating" and not the broader issue of global warming. The petition's website claims that all of the 31,000 signatories are qualified scientists with "technical training suitable for the evaluation of the relevant research data."[64] However, anyone with a degree was entitled to sign the list and this would therefore include many who are not qualified to evaluate the complex data and modelling involved.[65]
In April 2006, a group describing itself as "sixty scientists" signed an open letter[66] 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.[67] 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.[68] One of the signatories has since publicly recanted, stating that his signature was obtained by deception regarding the content of the letter.[69] 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.[70][71]
The IPCC
Statements Agreeing with the IPCC Positions
A joint statement issued by the Australian Academy of Sciences, Royal Flemish Academy of Belgium for Sciences and the Arts, Brazilian Academy of Sciences, Royal Society of Canada, Caribbean Academy of Sciences, Chinese Academy of Sciences, French Academy of Sciences, German Academy of Natural Scientists Leopoldina, Indian National Science Academy, Indonesian Academy of Sciences, Royal Irish Academy, Accademia Nazionale dei Lincei (Italy), Academy of Sciences Malaysia, Academy Council of the Royal Society of New Zealand, Royal Swedish Academy of Sciences, and Royal Society (UK) said:
- The work of the Intergovernmental Panel on Climate Change (IPCC) represents the consensus of the international scientific community on climate change science. We recognise IPCC as the world’s most reliable source of information on climate change and its causes, and we endorse its method of achieving this consensus. Despite increasing consensus on the science underpinning predictions of global climate change, doubts have been expressed recently about the need to mitigate the risks posed by global climate change. We do not consider such doubts justified.[72]
Many other science academies and scientific organizations support the conclusions of the IPCC.
In Naomi Oreskes's talk The American Denial of Global Warming,[73] Oreskes recounted the following incident:
| “ | In 1995, the IPCC concluded that the human effect on climate is now discernible. The lead author of the key chapter on detection and attribution...was a scientist of the Lawrence Livermore National Laboratory named Benjamin J. Santer.
When the IPCC report came out, Seitz, Nierenberg, and now a 4th physicist — a man by the name of S. Fred Singer — launched a highly personal attack on Santer. In an open letter to the IPCC, which they sent to numerous members of the US Congress, Singer, Seitz, and Nierenberg accused Santer of making "unauthorized" changes to the IPCC report [...] 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. |
” |
Statements Disagreeing with the IPCC Positions
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.[74]
In blog posts, Roger A. Pielke contends that the IPCC distorted the evidence by not including scientific results that questioned anthropogenic global warming.[75] These criticisms have been described as "failed" by William Connolley.[76][77] 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."[75] 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.[77]
Stephen McIntyre said in his blog that portions of the report were based on in-press data. When he attempted to obtain this data from the authors, the IPCC told him he could not use his reviewer status to obtain in-press data outside the normal journal review process[78]
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",[79] because of comments made at a press conference by Kevin Trenberth of which Landsea disapproved. Trenberth said that "Landsea's comments were not correct";[80] 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.[81] 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".[80]
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.[82] The main claims of the House of Lords Economics Committee were rejected in the response made by the United Kingdom government[83] and by the Stern Review.
John Christy, an IPCC lead author critical of some extreme predictions of climate change, wrote that contributing authors and reviewers have little influence, so that "to say that 800 contributing authors or 2,000 reviewers reached consensus on anything describes a situation that is not reality."[84]
While some critics have argued that the IPCC overstates likely global warming, others have made the opposite criticism. David Biello, writing in the Scientific American, argues that, because of the need to secure consensus among governmental representatives, the IPCC reports give conservative estimates of the likely extent and effects of global warming.[85] Climate scientist James Hansen argues that the IPCC's conservativeness seriously underestimates the risk of sea-level rise on the order of meters—enough to inundate many low-lying areas, such as the southern third of Florida.[86] Roger A. Pielke Sr. has also stated that "Humans are significantly altering the global climate, but in a variety of diverse ways beyond the radiative effect of carbon dioxide. The IPCC assessments have been too conservative in recognizing the importance of these human climate forcings as they alter regional and global climate."[87]
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.[88] Many of the claims about the numbers of individuals listed in the report, whether they are actually scientists,[89] and whether they support the positions attributed to them,[citation needed] have been disputed.
Causes
Attribution to greenhouse gases
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.[90]
- 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. Models and observations agree on this amplification for monthly and interannual time scales but not for decadal time scales in most observed data sets. It is uncertain whether the discrepancy is attributable to deficiencies in model formulation, biases in the observations, or both. The present view is that because of large uncertainties in observed tropospheric temperature trends along with other evidence for tropospheric warming (such as the increasing height of the tropopause), the more likely explanation is observational bias.[91] Furthermore, if greenhouse gases were causing the climate warming then scientists would expect the troposphere to be warming faster than the surface, but observations do not bear this out.[92] Satellite temperature measurements show that tropospheric temperatures are increasing with "rates similar to those of the surface temperature," leading the IPCC to conclude that this discrepancy is reconciled.[93]
- Studies of ice cores show that carbon dioxide levels rise and fall with or after (as much as 1000 years) temperature variations.[94] This argument assumes that current climate change can be expected to be similar to past climate change. While it is generally agreed that variations before the industrial age are mostly timed by astronomical forcing,[95] the current variations, of whatever size, are claimed to be timed by anthropogenic releases of CO2 (thus returning the argument to the importance of human CO2 emissions). Analysis of carbon isotopes in atmospheric CO2 shows that the recent observed CO2 increase cannot have come from the oceans, volcanoes, or the biosphere, and thus is not a response to rising temperatures as would be required if the same processes creating past lags were active now.[96]
- Between 1940 and 1970, global temperatures went down slightly, even though carbon dioxide levels went up. This has been attributed to the cooling effect of sulphate aerosols.[97][98]
- Carbon dioxide accounts for about 383 parts per million by volume (ppm) of the Earth's atmosphere, increasing from 278 ppm in the 1880s to over 380 ppm in 2005. Carbon dioxide causes between 9 and 26% of the natural greenhouse effect.
- Seth Young, a doctoral student in earth sciences at Ohio State, presented his analysis that the Earth had a much higher level of CO2 within the atmosphere during an ice age. In the Ordovician period of the Paleozoic era, he states the Earth had an atmospheric CO2 concentration estimated at 4400ppm[99] (or 0.44% of the atmosphere). However, a recent study suggests the Ordovician period began with a reduction in CO2.[100]
As noted above, climate models are only able to simulate the temperature record of the past century when GHG forcing is included, being consistent with the findings of the IPCC which has stated that: "Greenhouse gas forcing, largely the result of human activities, has very likely caused most of the observed global warming over the last 50 years"[101] (See also: attribution of recent climate change.)
Alternate hypotheses
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).
A few studies claim that the present level of solar activity is historically high as determined by sunspot activity and other factors. Solar activity could affect climate either by variation in the Sun's output or, more speculatively, by an indirect effect on the amount of cloud formation. Solanki and co-workers suggest that solar activity for the last 60 to 70 years may be at its highest level in 8,000 years; Muscheler et al. disagree, suggesting that other comparably high levels of activity have occurred several times in the last few thousand years.[102] Both Muscheler et al. and Solanki et al. conclude that "solar activity reconstructions tell us that only a minor fraction of the recent global warming can be explained by the variable Sun."[103][104]
Another point of controversy is thee correlation of temperature with solar variation
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