Scientific Opinion on Climate Change

An Inconvenient Truth

Directed by Davis Guggenheim
Produced by Lawrence Bender
Scott Burns
Laurie David
Starring Al Gore
Music by Michael Brook
Editing by Jay Lash Cassidy
Dan Swietlik
Distributed by Paramount Classics
Release date(s) May 24, 2006
Running time 94 min.
Country USA
Language English
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Statements by organizations

Various prominent bodies have commented on global warming, most notably the Intergovernmental Panel on Climate Change (IPCC). National and international scientific groups have issued statements both detailing and summarizing the current state of scientific knowledge on the earth's climate.

Intergovernmental Panel on Climate Change (IPCC)

In 2007, as part of its Fourth Assessment Report, the IPCC concluded that human actions are "very likely" the cause of global warming, meaning a 90% or greater probability.[1]

"The world's leading climate scientists said global warming has begun, is very likely caused by man, and will be unstoppable for centuries, ... . The phrase very likely translates to a more than 90 percent certainty that global warming is caused by man's burning of fossil fuels. That was the strongest conclusion to date, making it nearly impossible to say natural forces are to blame."[3]

"The report said that an increase in hurricane and tropical cyclone strength since 1970 more likely than not can be attributed to man-made global warming. The scientists said global warming's connection varies with storms in different parts of the world, but that the storms that strike the Americas are global warming-influenced."[4]

"On sea levels, the report projects rises of 7-23 inches by the end of the century. That could be augmented by an additional 4-8 inches if recent surprising polar ice sheet melt continues."[5]

Joint science academiesí statement

In 2005 the national science academies of the G8 nations, plus Brazil, China and India, three of the largest emitters of greenhouse gases in the developing world, signed a statement on the global response to climate change. The statement stresses that the scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action [6], and explicitly endorsed the IPCC consensus.

US National Research Council, 2001

In 2001 the Committee on the Science of Climate Change of the National Research Council published Climate Change Science: An Analysis of Some Key Questions [7]. This report explicitly endorses the IPCC view of attribution of recent climate change as representing the view of the science community:

The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability. Human-induced warming and associated sea level rises are expected to continue through the 21st century... The IPCC's conclusion that most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations accurately reflects the current thinking of the scientific community on this issue. [8]

American Meteorological Society

The American Meteorological Society (AMS) statement adopted by their council in 2003 said:

There is now clear evidence that the mean annual temperature at the Earth's surface, averaged over the entire globe, has been increasing in the past 200 years. There is also clear evidence that the abundance of greenhouse gases in the atmosphere has increased over the same period. In the past decade, significant progress has been made toward a better understanding of the climate system and toward improved projections of long-term climate change... Human activities have become a major source of environmental change. Of great urgency are the climate consequences of the increasing atmospheric abundance of greenhouse gases... Because greenhouse gases continue to increase, we are, in effect, conducting a global climate experiment, neither planned nor controlled, the results of which may present unprecedented challenges to our wisdom and foresight as well as have significant impacts on our natural and societal systems. [9]

Federal Climate Change Science Program, 2006

On May 2, 2006, the Federal Climate Change Science Program commissioned by the Bush administration in 2002 released the first of 21 assessments that concluded that there is clear evidence of human influences on the climate system (due to changes in greenhouse gases, aerosols, and stratospheric ozone) [10]. The study said that observed patterns of change over the past 50 years cannot be explained by natural processes alone, though it did not state what percentage of climate change might be anthropogenic in nature.

Other organizations

Other scientific organizations have made position statements on climate change.

Recent Surveys of scientists

Various surveys have been conducted to determine a scientific consensus on global warming. Unfortunetly few have been conducted within the last ten years. Greenspan believes that scientific consensus has only been reached in the last ten years, so we are conducting a survey of scientists and average people.

The current statistics on the public perception of climate change are: 14% of US citizens never heard of climate change and global warming; only 41% of US citizens believe that global warming is a serious problem. That is a serious problem because the solution to global warming must include the United States. We are the leading emitter of greenhouse gases. It's no wonder that politicians in this country are not motivated to ratify the Kyoto Protocol.

Oreskes, 2004

In December 2004, an article by geologist and historian of science Naomi Oreskes summarized a study of the scientific literature on climate change.[2] The essay concluded that there is a scientific consensus on the reality of anthropogenic climate change. The author analyzed 928 abstracts of papers from refereed scientific journals between 1993 and 2003, listed with the keywords "global climate change". The abstracts were divided into six categories: explicit endorsement of the consensus position, evaluation of impacts, mitigation proposals, methods, paleoclimate analysis, and rejection of the consensus position. 75% of the abstracts were placed in the first three categories, thus either explicitly or implicitly accepting the consensus view; 25% dealt with methods or paleoclimate, thus taking no position on current anthropogenic climate change; none of the abstracts disagreed with the consensus position, which the author found to be "remarkable". It was also pointed out, "authors evaluating impacts, developing methods, or studying paleoclimatic change might believe that current climate change is natural. However, none of these papers argued that point."

Bray and von Storch, 2003

A survey[3] was conducted in 2003 by Dr. Dennis Bray and German climatologist Hans von Storch. Bray's submission to Science on December 22, 2004 was rejected [4] but the survey's results were reported through non-scientific venues[5] [6] [7]. The survey has been criticized on the grounds that it was performed on the web with no means to verify that the respondents were climate scientists. The survey required entry of a username and password, but this information was circulated to a climate skeptics mailing list [13] and elsewhere on the internet.[8] The survey received 530 responses from 27 different countries. One of the questions asked was "To what extent do you agree or disagree that climate change is mostly the result of anthropogenic causes?", with a value of 1 indicating strongly agree and a value of 7 indicating strongly disagree. The results showed a mean of 3.62, with 50 responses (9.4%) indicating "strongly agree" and 54 responses (9.7%) indicating "strongly disagree". The same survey indicates a 72% to 20% endorsement of the IPCC reports as accurate, and a 15% to 80% rejection of the thesis that "there is enough uncertainty about the phenomenon of global warming that there is no need for immediate policy decisions".

Alleged U.S. governmental interference in reporting

According to an Associated Press release of 30 January 2007 [19]:

"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 references to "global warming" or "climate change" from a report."


  1. ^ "Warming 'very likely' human-made", BBC News, BBC, 2007-02-01. Retrieved on 2007-02-01.
  2. ^ Naomi Oreskes (December 3, 2004). "Beyond the Ivory Tower: The Scientific Consensus on Climate Change". Science 306 (5702): 1686. DOI:10.1126/science.1103618.  (see also for an exchange of letters to Science)
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  8. ^ [1][2]

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© 2007 Greenspan
Photo and design credits: © 2007 John Chiappone