Global warming controversy

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The global warming controversy is a debate about the causes of the increase in global average air temperature since the mid-1800s, the prediction of additional warming, and the consequences of that warming. An additional issue is whether the modern warming period is unprecedented or within normal climatic variations.

The debate is often heated, as it affects public policy, in particular the question of whether and how to reduce human-caused emissions of greenhouse gases.


The existence of global warming since the end of the Little Ice Age in the mid 1800s is not controversial. It is accepted by virtually all scientists in climate-related fields. The controversy focuses on the causes of that warming, especially the warming after World War II; the likelihood and magnitude of future warming; and whether additional warming would be harmful or beneficial.

Actions have been proposed to slow down warming, on the premise that (1) it is likely to be large enough to cause harm, (2) it is mostly caused by human activities and (3) it is possible to curtail those activities sufficiently to reduce predicted harm. These proposals are controversial on political and economic grounds, regardless of any scientific controversy.

Some of the main areas of controversy include:

  • Whether the climate is changing beyond natural variations in the historical temperature record
  • Whether human/industrial activity is responsible for the change and if so, to what extent
  • The effect of predicted depletion of fossil fuels, both individually as e.g. oil runs out and users turn to the higher polluting coal and overall as to whether there are sufficient available reserves to cause the more extreme climate change scenarios{fact}
  • The effectiveness of policies to reduce CO2 emissions
  • The size of future changes in climate
  • The regional effects of climate change
  • The consequences of climate change

Among climate scientists there is widespread agreement that global warming is primarily caused by human activities such as fossil fuel burning and deforestation. The debate is more vigorous in the popular media and on a policy level; questions include whether there is a scientific consensus on the extent and rate of anthropogenic global warming (AGW), and in particular whether there is sufficient evidence to justify immediate and far-reaching actions to ameliorate its effects. Those who believe such a consensus exists express a wide range of opinions: some merely recognize the validity of the observed increases in temperature, while others support measures such as the Kyoto Protocol which are intended to reduce the magnitude of future global warming. Still others believe that environmental damage will be so severe that immediate steps must be taken to reduce carbon dioxide and methane emissions, even if the precise results are unknown, and even if there are substantial economic costs to doing so. One example of an attempt to force action is the Sierra Club suing the U.S. government over failure to raise automobile fuel efficiency standards, and thereby decrease carbon dioxide emissions.

Another part of the debate relates to political or policy decisions and their rationales. For example, one such argument relates to the above mentioned Kyoto Protocol—developing countries such as China or India are exempt from the rules. If another country they are competing with economically is not exempt, what is the appropriate course of action in that case for the competitor? Thus, the entire issue becomes one that is not constrained by the bounds of science or facts or proof; it becomes one that is about politics and policy. Money and funding enter the equation too.

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



In the European Union, global warming has been a prominent and sustained issue. Both "global warming" and the more politically neutral "climate change" were listed as political buzzwords or catch phrases in 2005. In Europe the notion of human influence on climate has gained wider acceptance than in many other parts of the world, most notably the United States.

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.[9] Recently, bipartisan measures have been introduced.

Kevin E. Trenberth provides evidence for the controversy that occurs when science meets the political arena:


"The SPM was approved line by line by governments. . . .The argument here is that the scientists determine what can [be] said, but the governments determine how it can best be said. Negotiations occur over wording to ensure accuracy, balance, clarity of message, and relevance to understanding and policy. The IPCC process is dependent on the good will of the participants in producing a balanced assessment. However, in Shanghai, it appeared that there were attempts to blunt, and perhaps obfuscate, the messages in the report, most notably by Saudi Arabia. This led to very protracted debates over wording on even bland and what should be uncontroversial text... The most contentious paragraph in the IPCC (2001) SPM was the concluding one on attribution. After much debate, the following was carefully crafted: "In the light of new evidence, and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse-gas concentrations."

Public perceptions about the global warming evolved more slowly in the U.S. than in Europe, but have moved substantially in recent years. A Taylor Nelson Sofres poll reported by ABC News in 2006 reported that 85 percent of Americans believed in 2006 that global warming "probably is occurring," as opposed to 80 percent who believed so in 1998. Less than 40 percent were "very sure" of it, however. In 1998, 31 percent of the public said global warming was "extremely important" or "very important" to them, personally; in 2006, 49 percent said so.

According to a report on August 16, 2006, by Dr. David Suzuki of the David Suzuki Foundation, the general public has a poor understanding of global warming. This is despite recent publicity through different means, including the film An Inconvenient Truth. On July 20, 2006, Dr. David Suzuki commented that public opinion on climate change and the film was being deliberately twisted by an expensive campaign of public relations.

As scientific evidence for global warming mounted, the debate entered the public arena and leading political figures took up the issue.

    Controversy concerning the science

    Existence of a scientific consensus

Outside the scientific community, there are questions regarding the proportion of scientists who agree or disagree on the existence of human-caused warming. Environmental groups, many governmental reports, and the non-U.S. media often claim virtually unanimous agreement in the scientific community. Opponents either maintain that most scientists consider global warming "unproved," dismiss it altogether, or decry the dangers of consensus science. Still, others maintain that opponents have been stifled or driven underground.

A 2004 essay by Naomi Oreskes in the journal Science reported a survey of abstracts of peer-reviewed papers related to global climate change in the ISI database. Oreskes stated that of the 928 abstracts analyzed, "none contradicted" the view of the major scientific organizations that "the evidence for human modification of climate is compelling." Benny Peiser claimed to have found flaws in her work, writing

"Oreskes, a professor of history, claims to have analyzed 928 abstracts on global climate change, of which 75% either explicitly or implicitly accept the view that most of the recent warming trend is man-made. When I checked the same set of abstracts [plus an additional two hundred found in the same ISI data bank], I discovered that just over a dozen explicitly endorse the "consensus," while the vast majority of abstracts does not mention anthropogenic global warming.

In order to include only "hard science" papers rather than opinion pieces or editorials, Oreskes excluded the Social Sciences Citation Index and the Arts & Humanities Citation Index and set the search to include only Articles, while Peiser searched for all document types in all indices, and the interpretation of the remaining parts of his attempted refutation is further disputed.In a later op-ed piece in Canada's National Post, Peiser makes no further reference to his review, instead asserting,


"An unbiased analysis of the peer-reviewed literature on global warming will find hundreds of papers (many of them written by the world’s leading experts in the field) that have raised serious reservations and outright rejection of the concept of a "scientific consensus on climate change." The truth is, there is no such thing."

Peiser also stated:

"...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."

Timothy Ball asserts that those who oppose the "consensus" have gone underground: "No doubt passive acceptance yields less stress, fewer personal attacks and makes career progress easier. What I have experienced in my personal life during the last years makes me understand why most people choose not to speak out; job security and fear of reprisals. Even in University, where free speech and challenge to prevailing wisdoms are supposedly encouraged, academics remain silent."

A 2006 op-ed by Richard Lindzen in The Wall Street Journal challenged the claim that scientific consensus had been reached on the issue, and listed the Science journal study as well as other sources, including the IPCC and NAS reports, as part of "a persistent effort to suggest . . . that the theoretically expected contribution from additional carbon dioxide has actually been detected." Lindzen wrote in the Wall Street Journal on April 12, 2006,

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.

To support their claim of a lack of consensus, the Web site of prominent skeptic S. 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."[24] The petitions are:

  • The 1992 "Statement by Atmospheric Scientists on Greenhouse Warming" ("...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.")

Critics point out this is more than a decade old and only has 46 signatories.

Critics point out that the Heidelberg Appeal makes no mention at all of climate or climate change, much less global warming.
Critics point out that most of the signatories lack credentials in the specific field of climate research.

Followup interviews found that many of the purported signers denied having signed the Declaration or had never heard of it.  

  • The "Oregon Petition," which was circulated in 1998 by physicist Frederick Seitz.
Critics point out that many of the signatories of the Petition lack a background in climatology.The petition itself mentions only "catastrophic heating" and not the broader issue of global warming.

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. One of the signatories has since publicly recanted, stating that his signature was obtained by deception regarding the content of the letter.

    Temperature measurements

    Urban heat islands

Main article: Urban heat island

Skeptics, such as John Daly and Vincent Gray, questioned the accuracy of the temperature records on the basis of the Urban heat island effect, contending 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 warmings observed in urban and rural areas.

    Average temperature

One paper has questioned whether a global average temperature is a meaningful concept.


    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 points out that rising levels of carbon dioxide (CO2) and other greenhouse gases (GHGs) do not correlate with global warming.

Reproduction of the temperature record using known forcings

Reproduction of the temperature record using known forcings

  • Studies of ice cores show that carbon dioxide levels rise and fall with or after (as much as 1000 years) temperature variations [36]. 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.

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).

  • Between 1940 and 1970, global temperatures went down slightly, even though carbon dioxide levels went up. This could be attributed to the cooling effect of sulphate aerosols.
  • The amount of carbon dioxide in the atmosphere is small, accounting for 0.0381% of the Earth's atmosphere. The anthropogenic proportion of this is likely to be no more than a third (i.e. no more than the measured increase over the last 350 years). Carbon dioxide itself causes only 9-26% the natural greenhouse effect. These proportions should not be enough to cause significant effects.
  • The Earth has been in an ice age with a much higher level of CO2. The Ordovician period of the Paleozoic era, the Earth was in an ice age with atmospheric CO2 estimated at 4400ppm (or .44% of the atmosphere). However, a recent study suggests the Ordovician period began with a reduction in CO2.
  • Claim: If greenhouse gases were causing the climate warming then scientists would expect to the troposphere to be warming faster than the surface, but observations do not bear this out
  • . Response: satellite temperature measurements do indeed show that tropospheric temperatures are increasing and there is no discrepancy.

As noted above, climate models are only able to simulate the temperature record of the past century when GHG forcing is included, which some insist strongly points to the importance of GHGs, as does attribution of recent climate change.

    Solar Activity

The observed global warming may be explained by increased solar activity, 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 by an indirect effect on the amount of cloud formation. Solanki et al. (2004 - Max Planck Institute, Germany) 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. 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." "Solanki concluded based on their analysis that there is a 92% probability that solar activity will decrease over the next 50 years.

400 year history of sunspot numbers.
400 year history of sunspot numbers.
Last 30 years of solar variability.
Last 30 years of solar variability.

Another point of controversy is the correlation of temperature with solar variation. An article in The Telegraph about a 2004 study at the Max Planck Institute for Solar System Research in Germany quoted Sami Solanki saying "the Sun is burning more brightly than at any time during the past 1,000 years" and although "the increased solar brightness over the past 20 years has not been enough to cause the observed climate changes, the impact of more intense sunshine on the ozone layer and on cloud cover could be affecting the climate more than the sunlight itself." According to the Stanford Solar Center, at most 25% of recent global temperature variation can be attributed to solar irradiance. When the 11-year sun cycle is accounted for, there still remains a significant, 0.75 °C (1.35 °F) increase in recorded global temperatures.

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.

    Predictions of temperature rises

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 likely rises may be higher or lower.  

    Predictions of greenhouse gas rises

There is some debate about the various scenarios for fossil fuel consumption. Global warming skeptic S. Fred Singer has stated:

Let me deal first of all with the question of the future levels of carbon dioxide in the atmosphere. The fact is that people disagree about this. Some good experts believe that carbon dioxide will never even double [in/near] the atmosphere. They believe that the so-called decarbonization of our economy, which has been ongoing for some time, will continue. That is, we will use less and less fossil fuels to produce a unit of GNP.

The Stern report, 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. The report states:

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.

Similarly, Lawrence Livermore National Laboratory suggest, "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."[52] However others believe the climate will reach a "tipping point" leading to run away global warming as e.g. warming causes sea ice to melt reducing the area of reflective ice.[2]

There is also debate over whether the atmosphere is capable of self limiting the amount of CO2. Fred Palmer of the Western Fuels Association states:

"there's a debate over what humans actually could--if you had everybody on earth consuming the amount of fossil fuels that we do in the United States, for example--how much CO2 you would ultimately end up with in the air. There is one body of thought that says that the mechanisms of the planet--the biosphere--that because it responds positively to more CO2, which is the Greening of the Planet Earth thesis, that the biosphere will soak this up so that you really don't have much of a risk of ever getting above--much above--1,000 parts per million." 

Regional effects

Two positive results of global warming have been predicted for Canada. The freeing up of the ice-strewn North-West passage will create an alternative to the Suez and Panama Canals for East-West shipping. Extended growing seasons and a shift north for human habitable land are also possible.


Political and social aspects of the controversy

See also: Politics of global warming

As more evidence has become available over the existence of global warming debate has moved to further controversial issues, including:

  1. The social and environmental impacts
  2. The appropriate response to climate change
  3. Whether decisions require less uncertainty

The single largest issue is the importance of a few degrees rise in temperature:


"we talk about a few degrees warming, most people say, "A few degrees? So what? If I change my thermostat a few degrees, I'll live fine. The trees over there on the north side of the slope are already 5 degrees cooler than the trees on the south side of the slope." Of course, if you look carefully, you find they have different trees on the north side and the south side. So the point is that one or two degrees is about the experience that we have had in the last 10,000 years, the era of human civilization. There haven't been--globally averaged, we're talking--fluctuations of more than a degree or so. So we're actually getting into uncharted territory from the point of view of the relatively benign climate of the last 10,000 years, if we warm up more than a degree or two. (Stephen H. Schneider)"


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 who feel strongly 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.[54]


"The linkage between coal, electricity, and economic growth in the United States is as clear as it can be. And it is required for the way we live, the way we work, for our economic success, and for our future. Coal-fired electricity generation. It is necessary. (Fred Palmer)"


Conversely, others feel strongly that early action to reduce emissions would help avoid much greater economic costs later, and would reduce the risk of catastrophic, irreversible change.

    Kyoto Protocol

Main article: Kyoto Protocol

The Kyoto protocol is the most prominent international agreement on climate change, and is also highly controversial. Some argue that it goes too far in restricting emissions of greenhouse gases; others argue that the cuts in emissions it would introduce are far too small.[56] Another area of controversy is the fact that India and China, the world's two most populous countries, both ratified the protocol but are not required to reduce carbon emissions under the present agreement. Furthermore, it has also been argued that it would cause more damage to the economy of the U.S. than to those of other countries, thus providing an unfair economic advantage to some countries.Additionally, the 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.  As these countries are less energy efficient, this could cause additional carbon emissions. In 1998, U.S. Senator Robert Byrd of West Virginia wrote Resolution S. 98 that opposed ratification of the Kyoto treaty, and in turn the U.S. Senate voted 95 to 0 against the treaty.

The only major developed nations which have not signed the Kyoto protocol are the USA and Australia. However, on November 30, 2006, The Hon Greg Hunt MP Parliamentary Secretary to the Minister for the Environment and Heritage for Australia said: "First, climate change is both real and soluble. The deniers are wrong: that is, those who argue there is insufficient evidence. The doomsayers are also wrong: that is, those who argue that we are coming to an unavoidable and catastrophic end." The New York Times reports that in the U.S., "The climate here has definitely changed. Legislation to control global warming that once had a passionate but quixotic ring to it is now serious business. Congressional Democrats are increasingly determined to wrest control of the issue from the White House and impose the mandatory controls on carbon dioxide emissions that most smokestack industries have long opposed." The countries with no official position on Kyoto are mainly African countries with underdeveloped scientific infrastructure or oil producing countries.

See also: List of Kyoto Protocol signatories

Is global warming beneficial or detrimental?

Many researchers predict disastrous consequences    for a warming of 2 to 4.5 °C (3.6 to 8.1 °F), which the IPCC projects is likely within the 21st century unless strong, early mitigation measures are adopted.

Other researchers    feel that up to 1.5 °C (2.7 °F) of warming would increase crop yields and stabilize weather. Many of these    doubt a larger warming is likely. In response, some note that the belief in beneficial effects and doubt of extreme warming should be independent if these conclusions were in fact neutrally derived from scientific research.

    Funding for partisans

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

Some global warming skeptics, like the George C. Marshall Institute, have been criticized for their alleged links 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 that with the purpose of "highlight[ing] the strengths and weaknesses of the IPCC process," specifically regarding the IPCC Fourth Assessment Report.

Scientists, critical of some aspects of the discussion and their donors, dispute the validity of this guilt by association or ad hominem argument. For instance, Donald Kennedy of Science said, "I don't think it's unethical any more than most lobbying is unethical," and, " ...donations to skeptics amounts to 'trying to get a political message across'"[65]

The Union of Concerned Scientists have produced a report titled 'Smoke, Mirrors & Hot Air', "According to the report, ExxonMobil has funneled nearly $16 million between 1998 and 2005 to a network of 43 advocacy organizations that seek to confuse the public on global warming science."

The Center for the Study of Carbon Dioxide and Global Change, a skeptic group, when confronted about the funding of a video they put together ($250,000 for "The Greening of Planet Earth" from an oil company) stated, "We applaud Western Fuels for their willingness to publicize a side of the story that we believe to be far more correct than what at one time was 'generally accepted.' But does this mean that they fund The Center? Maybe it means that we fund them!"

Accuracy in Media published a report in 2002 entitled "Science for Sale: the Global Warming Scam," in which they allege that "global warming is driven more by the search for funding than the search for scientific truth." Richard S. Lindzen, who is the Alfred P. Sloan Professor of Meteorology at the Massachusetts Institute of Technology, makes the specific claim that "in the winter of 1989 Reginald Newell, a professor of meteorology at the Massachusetts Institute of Technology, lost National Science Foundation funding for data analyses that were failing to show net warming over the past century." Lindzen also cites numerous cases where political advocacy groups arranged funding for scientists who were friendly to the theory of anthropogenic global warming.

A recent film, The Great Global Warming Swindle alleged that the theory of anthropogenic global warming was a "scam" promoted by a multi-billion dollar industry. In response, supporters of the theory accused the film-makers of promoting a conspiracy theory.


The evolving position of some skeptics

In recent years some skeptics have changed their positions regarding AGW. Ronald Bailey, author of Global Warming and Other Eco Myths, now says "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" (see also Former global warming skeptics). Others have shifted from claims that global warming is unproven to advocating adaptation, sometimes also calling for more data, rather than take immediate action 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 statistician Bjørn Lomborg.

"There are alternatives to its [the "the climate-change crusade's"] insistence that the only appropriate policy response is steep and immediate emissions reductions.... a greenhouse-gas-emissions cap ultimately would constrain energy production. A sensible climate policy would emphasize building resilience into our capacity to adapt to climate changes.... we should consider strategies of adaptation to a changing climate. A rise in the sea level need not be the end of the world, as the Dutch have taught us." says Steven F. Hayward of the neoconservative American Enterprise Institute. Hayward also advocates the use of "orbiting mirrors to rebalance the amounts of solar radiation different parts of the earth receive."

In 2001 Richard Lindzen said in response to the question, "Kyoto aside for a moment, should we be trying to reduce carbon dioxide emissions? Do our concerns about global warming require action?" "We should prioritize our responses. You can't just say, "No matter what the cost, and no matter how little the benefit, we'll do this. If we truly believe in warming, then we've already decided we're going to adjust...The reason we adjust to things far better than Bangladesh is that we're richer. Wouldn't you think it makes sense to make sure we're as robust and wealthy as possible? And that the poor of the world are also as robust and wealthy as possible?" 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 conservative National Center for Policy Analysis whose "Environmental Task Force" contains a number of climate change skeptics including Sherwood Idso and S. Fred Singer says "The growing consensus on climate change policies is that adaptation will protect present and future generations from climate-sensitive risks far more than efforts to restrict CO 2 emissions".

Interestingly 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.

The Bush administration has also joined the adaptation only bandwagon. "In a stark shift for the Bush administration, the United States has sent a climate report [U.S. Climate Action Report 2002] to the United Nations detailing specific and far-reaching effects it says global warming will inflict on the American environment. In the report, the administration also for the first time places most of the blame for recent global warming on human actions -- mainly the burning of fossil fuels that send heat-trapping greenhouse gases into the atmosphere". The report however "does not propose any major shift in the administration's policy on greenhouse gases. Instead it recommends adapting to inevitable changes instead of making rapid and drastic reductions in greenhouse gases to limit warming." This position apparently precipitated a similar shift in emphasis at the COP 8 climate talks in New Delhi several months later, "The shift satisfies the Bush administration, which has fought to avoid mandatory cuts in emissions for fear it would harm the economy. 'We're welcoming a focus on more of a balance on adaptation versus mitigation,' said a senior American negotiator in New Delhi. 'You don't have enough money to do everything.'"

The White House emphasis on adaptation was not well received however, "Despite conceding that our consumption of fossil fuels is causing serious damage and despite implying that current policy is inadequate, the Report fails to take the next step and recommend serious alternatives. Rather, it suggests that we simply need to accommodate to the coming changes. For example, reminiscent of former Interior Secretary Hodel’s proposal that the government address the hole in the ozone layer by encouraging Americans to make better use of sunglasses, suntan lotion and broad-brimmed hats, the Report suggests that we can deal with heat-related health impacts by increased use of air-conditioning. Report at 82. Far from proposing solutions to the climate change problem, the Administration has been adopting energy policies that would actually increase greenhouse gas emissions. Notably, even as the Report identifies increased air conditioner use as one of the 'solutions' to climate change impacts, the Department of Energy has decided to roll back energy efficiency standards for air conditioners"  letter from 11 State Attorneys General to George W. Bush.

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.

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.

    Political pressure on scientists

Climate scientist James E. Hansen, director of NASA's Goddard Institute for Space Studies, claimed in a widely cited New York Times article [93] 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. The BBC's long-running current affairs series Panorama recently investigated the issue, and was told that "scientific reports about global warming have been systematically changed and suppressed."

Mike Hulme, director of the Tyndall Centre for Climate Research, wrote how increasing use of pejorative terms like "catastrophic," "chaotic" and "irreversible," had altered the public discourse around climate change: "This discourse is now characterized by phrases such as 'climate change is worse than we thought', that we are approaching 'irreversible tipping in the Earth's climate', and that we are 'at the point of no return'. I have found myself increasingly chastised by climate change campaigners when my public statements and lectures on climate change have not satisfied their thirst for environmental drama and exaggerated rhetoric."

According to an Associated Press release on January 30, 2007,

"Climate scientists at seven government agencies say they have been subjected to political pressure aimed at downplaying the threat of global warming.
"The groups presented a survey that shows two in five of the 279 climate scientists who responded to a questionnaire complained that some of their scientific papers had been edited in a way that changed their meaning. Nearly half of the 279 said in response to another question that at some point they had been told to delete reference to "global warming" or "climate change" from a report."

Critics however claim that the survey was itself unscientific.

    Global warming litigation

Several lawsuits have been filed over global warming. For example, Massachusetts v. Environmental Protection Agency (case 05-1120 pending before the Supreme Court of the United States), was filed to force the Federal Government to regulate greenhouse gasses 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.

    Betting over global warming

A betting market on climate futures, like other kinds of futures markets, could be used to establish the market consensus on climate change. Few skeptics have been willing to bet against the IPCC consensus position, however. 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. 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.

    Assertions by supporters and opponents

Listed here are some of the assertions made by supporters and opponents of the hypothesis of anthropogenic global warming not discussed above. Assertions are included solely because they have been made by one side or the other, without comment on their scientific validity or lack thereof.

    Assertions by supporters

Supporters of the anthropogenic global warming hypothesis assert that:

  • The fact that carbon dioxide absorbs and emits IR radiation has been known for over a century.
  • Gas bubbles trapped in ice cores give us a detailed record of atmospheric chemistry and temperature back more than eight hundred thousand years, with the temperature record confirmed by other geologic evidence. This record shows a correlation between atmospheric carbon dioxide and temperature.
  • The recent rise in carbon dioxide and other greenhouse gases is greater than any in hundreds of thousands of years[108] and this is human-caused, as shown by the isotopic signature of CO2 from fossil fuels.
  • The historical temperature record shows a rise of 0.4–0.8 °C over the last 100 years.
  • The current warmth is unusual in the past 1000 years (see Temperature record of the past 1000 years).
  • Climate change attribution studies, using both models and observations, find that the warming of the last 50 years is likely caused by human activity; natural variability (including solar variation) alone cannot explain the recent change.
  • Climate models can reproduce the observed trend only when greenhouse gas forcing is included.
  • The IPCC reports correctly summarize the state of climate science.
  • Humankind is performing a great geophysical experiment, and if it turns out badly—however that is defined—we cannot undo it. We cannot even abruptly turn it off. Too many of the things we are doing now have long-term ramifications for centuries to come.
  • Climate models predict more warming, sea level rise, more frequent and severe storms, drought and heat waves, spread of tropical diseases, and other climactic effects in the future.
  • The current warming trend will accelerate when melting ice exposes more dark sea and land that will reflect less sunlight; and when the tundra thaws and releases large quantities of trapped greenhouse gases.
  • Atlantic hurricane trends have been recently linked to climate change.    
  • The Precautionary principle requires that action should be taken now to prevent or mitigate warming.    

Proponents of the anthropogenic global warming hypothesis tend to support the IPCC position, and thus represent the scientific consensus (though with considerable differences over details, and especially over what action should be taken).  

    Assertions by opponents

Some of the assertions made in opposition to the hypothesis of anthropogenic global warming include:

  • The relationship between historic temperatures and CO2 levels, based on ice-core samples, shows that carbon dioxide levels rise after global temperatures rise.
  • IPCC draws firm conclusions unjustified by the science, especially given the acknowledged weakness of cloud physics in the climate models.
  • The influential "Hockey Stick" study by Mann has been shown to contain errors .
  • Using "consensus" as evidence is an appeal to the majority argument rather than scientific discussion. Some have proposed that, because the issue has become so politicized, climatologists who disagree with the consensus may be afraid to speak out for fear of losing their positions or funding.
  • Climate models will not be able to predict the future climate until they can predict solar and volcanic activity, changes in sea temperature, and changes to cosmic ray levels that make the low level clouds that cool the earth, and take into account other recently discovered feedback mechanisms.    
  • Water vapor, not CO2, is the primary greenhouse gas. Depending on the referenced source, water vapor and water droplets account for 36-70% of the greenhouse effect, while CO2 accounts for 9-26%.
  • Global warming is largely a result of reduced low-altitude cloud cover from reduced Galactic cosmic rays (GCRs). It is similar in concept to the Wilson cloud chamber but on a global scale, where earth's atmosphere acts as the cloud chamber.    
  • The concern about global warming is analogous to the concern about global cooling in the 1970s. The concern about global cooling was unnecessarily alarmist. Therefore, the concern about global warming is likely to be equally alarmist.
  • The Medieval warm period, which lasted from the 10th to the 14th century, had above-average temperatures for at least Western Europe, and possibly the whole Earth. This period was followed by the Little Ice Age, which lasted until the 19th century, when the Earth began to heat up again.
  • Satellite temperature records show less warming than surface land and sea records.
  • Climatic changes equal to or even more severe than those on Earth are also happening on other bodies within this solar system, including Mars, Jupiter, Pluto and Triton.

Opponents tend to define themselves in terms of opposition to the IPCC position. They generally believe that climate science is not yet able to provide us with solid answers to all of the major questions about global climate. Opponents often characterize supporters' arguments as alarmist and premature, emphasizing what they perceive as the lack of scientific evidence supporting global-warming scenarios.

Many opponents also say that, if global warming is real and man-made, no action need be taken now, because:

  • Future scientific advances or engineering projects will remedy the problem before it becomes serious, and do it for less money.
  • There is a distinct correlation between GDP growth and greenhouse-gas emissions. If this correlation is assumed to be a causation, a cutback in emissions might lead to a decrease in the rate of GDP growth