From the RealClimate blog ( http://www.realclimate.org/index.php/archives/2008/06/north-pole-notes ) post "North Pole Notes" (comment #449):

1. Jim Eager Says:
   9 July 2008 at 10:44

   Re Paul @ 430: “To those of us who aren’t 'believers', there is a lot of debate. And there are a lot of legitimate questions that frankly, those of us who look at it from the outside have. For the debate to be 'over', it has to be accepted science.”

   But that’s just it, Paul, within the scientific community anthropogenic causation of increasing greenhouse gases, greenhouse gas-induced warming, and potential climate effects and impacts of increased warming are accepted science. If the foundations of that science were still being debated you would find that debate in the form of papers published in the relevant scientific journals and presented at the relevant scientific conferences. What you do see is plenty debate about the details of competing forcings and natural variability and the underlining mechanics of the climate system (as you say, science is always evolving), but what you do not see are legitimate papers showing that the basic science of greenhouse gas forcing is wrong.

   To be sure a ‘debate’ over whether or not human activity is altering the climate still rages, but it is not a clear-headed objective debate about the science among scientists actually working in the relevant fields, it’s a debate about the science and its impact on human society in the court of public opinion. Those are two entirely different debates that should not be confused. That a substantial portion of the public does not widely accept the science does not make it a scientific debate.

   Paul: “Even Evolution is a “theory” not proven scientific fact”

   There you go with another oft-repeated canard of misunderstanding. Here’s one thing you should keep in mind: the general usage of the word “theory” and the scientific usage of the word ‘theory’ are not at all the same.

   In general usage a ‘theory’ immediately follows the observation or experience of a single phenomenon or event, or a group of seemingly related phenomena or events, and that’s often pretty much as far as the process goes. Think ‘conspiracy theory’. This is why “evolution (or global warming) is only a theory” is used dismissively to discount evolution (and global warming).

   But in science, a theory is the end product of the scientific process, which starts with observation of phenomena, forming an hypothesis to explain the phenomena, designing a means to test the hypothesis, analyzing and interpreting the results of the tests, refining the hypothesis to account for observed discrepancies, retesting and refining repeatedly as needed, publishing the results for review and duplication of results by peers, consensus acceptance of the hypothesis by peers. Only at the end of the process, when peer consensus becomes overwhelming does a hypothesis have any chance of becoming accepted as a theory.

   In science theories are as good as it gets. There are no proven scientific ‘facts’, only well supported, consistent theories that have withstood all attempts to disprove them.