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It is not true that there is overwhelming scientific consensus about the probability of climate change. While I would agree that most scientists think that it i

It is not true that there is overwhelming scientific consensus about the probability of climate change. While I would agree that most scientists think that it is most likely that "global warming is real", there is a great deal of uncertainty among even the worlds leading climate scientists about the probability of global warming. A few years ago I ran a betting game among students and faculty in the MIT climate program, the idea was to develop some feeling for the 'community consensus' of the likelyhood of global warming. The conclusion: ~71% chance of global warming over the next century. http://www.sethjohn.com/PAOC%20CFM/slide1.html http://www.sethjohn.com/PAOC%20CFM/slide1.html

timr 19y ago
http://www.sciencemag.org/cgi/content/full/306/5702/1686 http://www.sciencemag.org/cgi/content/full/306/5702/1686 "That hypothesis was tested by analyzing 928 abstracts, published in refereed scientific journals between 1993 and 2003, and listed in the ISI database with the keywords "climate change" (9). The 928 papers 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. Of all the papers, 75% fell into the first three categories, either explicitly or implicitly accepting the consensus view; 25% dealt with methods or paleoclimate, taking no position on current anthropogenic climate change. Remarkably, none of the papers disagreed with the consensus position. Admittedly, 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. This analysis shows that scientists publishing in the peer-reviewed literature agree with IPCC, the National Academy of Sciences, and the public statements of their professional societies. Politicians, economists, journalists, and others may have the impression of confusion, disagreement, or discord among climate scientists, but that impression is incorrect."
- sethjohn 19y ago
  There are really a couple of separate issues here. First, it is important to distinguish between the general scientific agreement about past climate changes and the greater confusion about the probability of future climate changes. One of the main reasons why there is such broad agreement among the community is that scientists have tended to focus on the answerable questions such as "has the earth been getting warmer over the last X years" rather than the thornier question of "what caused the earth to get warmer" and "will the earth continue to get warmer." Very few scientific papers have been written that make predictions on the question of future climate. It is also important to remember that while there is generally scientific consensus that global warming is "probably" happening (whatever that means!) or that it is "probably" caused by humans, there is a great deal of uncertaintly about exactly what the probabilities are. If you could get all scientists to agree that there was about a 71% chance that the next century would be warmer, does that count as "scientific consensus that climate change is likely"?
  - timr 19y ago
    Read the article. What caused the earth to get warmer? "the National Academy of Sciences report, Climate Change Science: An Analysis of Some Key Questions, begins: "Greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise" [p. 1 in (5)]. The report explicitly asks whether the IPCC assessment is a fair summary of professional scientific thinking, and answers yes: "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" [p. 3 in (5)]." Will it continue? Directly from the IPCC report: http://www.grida.no/climate/ipcc_tar/wg1/035.htm#temperature http://www.grida.no/climate/ipcc_tar/wg1/035.htm#temperature "Global mean temperature continues to increase for hundreds of years at a rate of a few tenths of a degree per century after concentrations of CO2 have been stabilised, due to long time-scales in the ocean....If greenhouse gas concentrations were stabilised (even at present levels), sea level would nonetheless continue to rise for hundreds of years....The loss of a substantial fraction of the total glacier mass is likely. Areas that are currently marginally glaciated are most likely to become ice-free."
    - sethjohn 19y ago
      Both the National Academy of Sciences and the IPCC are essentially political organizations (in the sense that their purpose is to inform policy, I don't mean to suggest that they are partisan) and what they say should not be conflated with the scientific literature on climate change. Scientists are working very hard to understand past and future climate change, but it is an incredibly complex problem. (For analogy, can political scientists predict who will be elected president in 2012?...it's possible to make some good guesses but there are a lot of factors and it's hard to know what will happen.) Sure, there is general agreement on some points and organizations such as the IPCC are doing a noble job of trying to synthesize the mountains of complex science into a few simple statements, but I think you are drastically oversiplifying the case when you say that "99.99% of the world's scientists, based on careful interpretation of many thousands of peer-reviewed studies, agree that global warming is real, and is caused by human activity. A vanishingly small handful of scientists happen to disagree with this assessment, based mostly upon their opinion and politics."

timr 19y ago

http://www.sciencemag.org/cgi/content/full/306/5702/1686 http://www.sciencemag.org/cgi/content/full/306/5702/1686 "That hypothesis was tested by analyzing 928 abstracts, published in refereed scientific journals between 1993 and 2003, and listed in the ISI database with the keywords "climate change" (9). The 928 papers 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. Of all the papers, 75% fell into the first three categories, either explicitly or implicitly accepting the consensus view; 25% dealt with methods or paleoclimate, taking no position on current anthropogenic climate change. Remarkably, none of the papers disagreed with the consensus position. Admittedly, 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. This analysis shows that scientists publishing in the peer-reviewed literature agree with IPCC, the National Academy of Sciences, and the public statements of their professional societies. Politicians, economists, journalists, and others may have the impression of confusion, disagreement, or discord among climate scientists, but that impression is incorrect."

sethjohn 19y ago
There are really a couple of separate issues here. First, it is important to distinguish between the general scientific agreement about past climate changes and the greater confusion about the probability of future climate changes. One of the main reasons why there is such broad agreement among the community is that scientists have tended to focus on the answerable questions such as "has the earth been getting warmer over the last X years" rather than the thornier question of "what caused the earth to get warmer" and "will the earth continue to get warmer." Very few scientific papers have been written that make predictions on the question of future climate. It is also important to remember that while there is generally scientific consensus that global warming is "probably" happening (whatever that means!) or that it is "probably" caused by humans, there is a great deal of uncertaintly about exactly what the probabilities are. If you could get all scientists to agree that there was about a 71% chance that the next century would be warmer, does that count as "scientific consensus that climate change is likely"?
- timr 19y ago
  Read the article. What caused the earth to get warmer? "the National Academy of Sciences report, Climate Change Science: An Analysis of Some Key Questions, begins: "Greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise" [p. 1 in (5)]. The report explicitly asks whether the IPCC assessment is a fair summary of professional scientific thinking, and answers yes: "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" [p. 3 in (5)]." Will it continue? Directly from the IPCC report: http://www.grida.no/climate/ipcc_tar/wg1/035.htm#temperature http://www.grida.no/climate/ipcc_tar/wg1/035.htm#temperature "Global mean temperature continues to increase for hundreds of years at a rate of a few tenths of a degree per century after concentrations of CO2 have been stabilised, due to long time-scales in the ocean....If greenhouse gas concentrations were stabilised (even at present levels), sea level would nonetheless continue to rise for hundreds of years....The loss of a substantial fraction of the total glacier mass is likely. Areas that are currently marginally glaciated are most likely to become ice-free."
  - sethjohn 19y ago
    Both the National Academy of Sciences and the IPCC are essentially political organizations (in the sense that their purpose is to inform policy, I don't mean to suggest that they are partisan) and what they say should not be conflated with the scientific literature on climate change. Scientists are working very hard to understand past and future climate change, but it is an incredibly complex problem. (For analogy, can political scientists predict who will be elected president in 2012?...it's possible to make some good guesses but there are a lot of factors and it's hard to know what will happen.) Sure, there is general agreement on some points and organizations such as the IPCC are doing a noble job of trying to synthesize the mountains of complex science into a few simple statements, but I think you are drastically oversiplifying the case when you say that "99.99% of the world's scientists, based on careful interpretation of many thousands of peer-reviewed studies, agree that global warming is real, and is caused by human activity. A vanishingly small handful of scientists happen to disagree with this assessment, based mostly upon their opinion and politics."