31,000 scientists say “no convincing evidence”.

31,000 scientists reject global warming and say “no convincing evidence” that humans can or will cause global warming? But polls show that of scientists working in the field of climate science, and publishing papers on the topic: 97% of the climate scientists surveyed believe “global average temperatures have increased” during the past century; and 97% think human activity is a significant contributing factor in changing mean global temperatures. What is the significance of these statistics?

31,000 scientists say no convincing evidence of human caused global warming.

Scientific Consensus on Global Warming

While polls of scientists actively working in the filed of climate science indicate strong general agreement that Earth is warming and human activity is a significant factor, 31,000 scientists say there is “no convincing evidence” that humans can or will cause “catastrophic” heating of the atmosphere.

This claim originates from the Oregon Institute of Science and Medicine, which has an online petition (petitionproject.org) that states:

We urge the United States government to reject the global warming agreement that was written in Kyoto, Japan in December, 1997, and any other similar proposals. The proposed limits on greenhouse gases would harm the environment, hinder the advance of science and technology, and damage the health and welfare of mankind.
There is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and disruption of the Earth’s climate. Moreover, there is substantial scientific evidence that increases in atmospheric carbon dioxide produce many beneficial effects upon the natural plant and animal environments of the Earth.

To participate in the petition one only needs to mark a check box to show that one has a Ph.D., M.S., or B.S. degree, and then fill in the fields. Unfortunately, that means that anyone can sign the petition, whether they have a degree or not.

The Oregon Global Warming Petition Form

Since the results are not verifiable, there is no way to know how many signers have actually earned a degree.

Do ‘31,000 scientists say global warming is not real’? Maybe. But more importantly what is the significance of these signatures? The majority of signatures are engineers (10,102). 3,046 are in medicine. 2,965 are in biology, biochemistry and agriculture. 4,822 in chemistry and chemical engineering.

Without formal training in climate science the level of understanding remains unknown among those that signed the petition. A key question is not how many of those that signed the petition know climate physics in sufficient depth, but rather how many of those that signed the petition work directly in the field of climate science.

Only 12% of those who signed…

According to the data on the petition site, only 12% of those who signed the petition are indicated to have affiliation with atmosphere, earth, and environmental science. But there is no indication how many work in the field of climate science?

What do scientists ‘That work in the field’ really think?

What is notable is that the polls indicate there is a perspective difference between working climate scientists and scientists not working in the field of climate. When one examines the experts in the field, one sees a significant divergence from the general view. So the more important question for us is, what do ‘expert’ climate scientists think?

2009 – Examining the Scientific Consensus on Climate Change

1. When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?
2. Do you think human activity is a significant contributing factor in changing mean global temperatures?

  • 90% of participants answered “risen” to question 1.
  • 82% answered ‘yes’ to question 2.

Of those with expertise in climate science:

  • 96.2% (76 of 79) answered “risen” to question 1.
  • 97.4% (75 of 77) answered yes to question 2.


2009 Pew Research Center Poll

  • 84% of scientists say the earth is warming because of human activity.

Asked if they regarded global warming as a very serious problem?

  • Scientists – 70%
  • Public – 47%

Source: Pew Research Center

2008 Poll

Scientists agree that humans cause global warming?

  • 97% of the climate scientists surveyed believe “global average temperatures have increased” during the past century.
  • 84% percent say they personally believe human-induced warming is occurring.
  • 74% agree that “currently available scientific evidence” substantiates its occurrence.
  • 5% believe that that human activity does not contribute to greenhouse warming; the rest are unsure.

Climate scientists are skeptical of the media

  • 1% of climate scientists rate either broadcast or cable television news about climate change as “very reliable.”

Source: STATS Poll (+/-4%), George Mason University

1991 Poll


Changing scientific opinion
In 1991 the Gallup organization conducted a telephone survey on global climate change among 400 scientists drawn from membership lists of the American Meteorological Association and the American Geophysical Union.

We repeated several of their questions verbatim, in order to measure changes in scientific opinion over time. On a variety of questions, opinion has consistently shifted toward increased belief in and concern about global warming. Among the changes:

  • In 1991 only 60% of climate scientists believed that average global temperatures were up, compared to 97% today.
  • In 1991 only a minority (41%) of climate scientists agreed that then-current scientific evidence “substantiates the occurrence of human-induced warming,” compared to three out of four (74%) today.


Source: George Mason University


97% of working climate scientists say the temperature is rising, and human activity is a significant contributing factor.

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