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Global 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.
Contents [hide]
1 History
1.1 Public opinion
1.2 Related controversies
2 Scientific
2.1 Consensus
2.2 IPCC
2.3 Greenhouse gases
2.4 Solar variation
2.5 Aerosols forcing
2.6 Instrumental temperature record
2.7 Climate sensitivity
2.8 Infrared iris hypothesis
2.9 Internal radiative forcing
2.10 Temperature predictions
2.11 Forecasts confidence
2.12 Models vs empirical forcasts
2.13 Arctic shrinkage
2.14 Antarctica cooling
2.15 Data archiving and sharing
3 Political
3.1 Kyoto Protocol
3.2 Funding for partisans
3.3 Changing positions of skeptics
3.4 Political pressure on scientists
3.5 Litigation
3.6 Betting
4 References
History
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 % agree 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]
Related controversies
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, such as ozone depletion and passive smoking. 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.[16] Political scientist Roger Pielke, Jr., responding to Mooney, has argued that science is inevitably intertwined with politics.[17]
Scientific
Consensus
Main articles: Scientific opinion on climate change, Consensus on climate change controversy, and Climate change denial
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.[18][19][20] Others maintain that either proponents or opponents have been stifled or driven underground.[21]
On April 29, 2008, environmental journalist Richard Littlemore revealed that a list of "500 Scientists with Documented Doubts of Man-Made Global Warming Scares"[22] distributed 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.[23] Many of the scientists asked the Heartland Institute to remove their names from the list.
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."[24] 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."[25][26]
IPCC
Main article: Intergovernmental Panel on Climate Change
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.[27] ”
Many other science academies and scientific organizations support the conclusions of the IPCC.
In Naomi Oreskes's talk The American Denial of Global Warming,[28] 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.
”
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.[29]
In blog posts, Roger A. Pielke contends that the IPCC distorted the evidence by not including scientific results that questioned anthropogenic global warming.[30] These criticisms have been described as "failed" by William Connolley.[31][32] 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."[30] 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.[32]
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[33]
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",[34] because of comments made at a press conference by Kevin Trenberth of which Landsea disapproved. Trenberth said that "Landsea's comments were not correct";[35] 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.[36] 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".[35]
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.[37] The main claims of the House of Lords Economics Committee were rejected in the response made by the United Kingdom government[38] 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."[39]
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.[40] 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.[41] 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."[42]
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.[43] Many of the claims about the numbers of individuals listed in the report, whether they are actually scientists,[44] and whether they support the positions attributed to them,[citation needed] have been disputed.
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.[45]
Reproduction of the temperature record using historical forcingsGeneral 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.[46] 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.[47] 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.[48]
Studies of ice cores show that carbon dioxide levels rise and fall with or after (as much as 1000 years) temperature variations.[49] 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,[50] 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.[51]
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.[52][53]
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[54] (or 0.44% of the atmosphere). However, a recent study suggests the Ordovician period began with a reduction in CO2.[55]
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"[56]
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.[57] 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.[58]
However, The Stern report,[59] like many other reports, notes the past correlation between CO2 emissions and economic growth and then extrapolates using a "business as usual" scenario to predict GDP growth and hence CO2 levels, concluding that:
“ Increasing scarcity of fossil fuels alone will not stop emissions growth in time. The stocks of hydrocarbons that are profitable to extract are more than enough to take the world to levels of CO2 well beyond 750ppm with very dangerous consequences for climate change impacts. ”
According to Lawrence Livermore National Laboratory, "the earth would warm by 8 degrees Celsius (14.4 degrees Fahrenheit) if humans use the entire planet’s available fossil fuels by the year 2300."[60]
Solar variation
See also: Solar variation theory
400 year history of sunspot numbers.
Last 30 years of solar variability.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.[61] 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."[62][63]
Another point of controversy is the correlation of temperature with solar variation.[64]
Solar physicists Mike Lockwood and Claus Fröhlich reject the claim that the warming observed in the global mean surface temperature record since about 1850 is the result of solar variations.[65] Lockwood and Fröhlich conclude that:
“ 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[66] 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.[67] 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."[68] 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.
Aerosols forcing
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 in Ruckstuhl's paper who found a 60% reduction in aerosol concentrations over Europe causing solar brightening.[69][70]
“ [...] the direct aerosol effect had an approximately five times larger impact on climate forcing than the indirect aerosol and other cloud effects. The overall aerosol and cloud induced surface climate forcing is ~+1 W m-2 dec-1 and has most probably strongly contributed to the recent rapid warming in Europe. ”
Instrumental temperature record
Main articles: Instrumental temperature record and Urban heat island
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[citation needed]. 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.[71] More recently, Peterson (2003) found no difference between the warming observed in urban and rural areas.[72] 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."[73] 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.[74] Pielke and Matsui published a paper disagreeing with Parker's conclusions.[75]
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.[76][77] In response, Anthony Watts began a volunteer effort to photographically document the siting quality of these stations.[78] 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.[79] 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.
Climate sensitivity
Equilibrium climate sensitivity refers to the equilibrium change in global mean surface temperature following a doubling of the atmospheric (equivalent) CO2 concentration. This value is estimated by the IPCC Fourth Assessment Report as "likely to be in the range 2 to 4.5 °C with a best estimate of about 3 °C."
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.[80] , revised upwards from 1.1 ± 0.5 K.[81] Grant Foster, James Annan, Gavin Schmidt, and Michael E. Mann[82][83] argue that there are errors in both versions of Schwartz's analysis. Astronomer Nir Shaviv also has proposed a low value for climate sensitivity.[84][85] Petr Chylek and co-authors have also proposed low climate sensitivity to doubled CO2, estimated to be 1.6 K ± 0.4 K.[86]
Infrared iris hypothesis
Richard Lindzen proposed an Infrared Iris hypothesis of compensating meteorological processes that tend to stabilize climate change.[87] 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.[88] If confirmed, this effect might reduce the positive "amplifying" feedback assumed in climate models.
Internal radiative forcing
Roy Spencer hypothesizes there is an "Internal Radiative Forcing" affecting climate variability,[89][90]
“ [...] mixing up of cause and effect when observing natural climate variability can lead to the mistaken conclusion that the climate system is more sensitive to greenhouse gas emissions than it really is. . . . it provides a quantitative mechanism for the (minority) view that global warming is mostly a manifestation of natural internal climate variability. ”
“ [...] low frequency, internal radiative forcing amounting to little more than 1 W m-2, assumed to be proportional to a weighted average of the Southern Oscillation and Pacific Decadal Oscillation indices since 1900, produces ocean temperature behavior similar to that observed: warming from 1900 to 1940, then slight cooling through the 1970s, then resumed warming up to the present, as well as 70% of the observed centennial temperature trend. ”
Temperature predictions
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 |
