19. November 2010 13:03
Ask most climatologists, and they will tell you Global Warming is real and caused by humans. In other words, the consensus of climatologists is clear. Now, while one can somewhat glibly declare that the consensus is irrelevant, and demand clear-cut scientific tests a layperson can personally understand before accepting a hypothesis, it is not rational to do so. When a plethora of tests are required to test a hypothesis, and domain expertise is required to understand and synthesize those tests to attain the likelihood of that hypothesis, the rational thing to do is to outsource the assessment of that hypotheses to domain experts. This reasoning is described in more detail here.
When a scientific consensus exists but clear-cut tests do not, the matter is not settled, but the onus shifts to the contrarians to present a consistent set of claims that refute the prevailing view. If they fail to so, a rational layperson should side with the consensus. At the top-right of this page you can see a break-down of the major contentions of this issue, phrased as yes-no questions. I found these questions to be the most revealing:
Are the causes of climate change well understood?
Do negative feedback loops mostly cushion the effect of atmospheric CO2 increases?
Does cosmic radiation significantly affect earth's climate?
Through examining these arguments, I've come to the belief that the claims of climate skeptics are rife with inconsistency. Perhaps the most egregious inconsistency, is claiming Earth's climate is too complex to understand, while simultaneously claiming that climate change is very likely caused by nature. Such inconsistencies are exactly what you'd expect from contrarians whose skeptical thought passes through a polarized filter. These inconsistent claims are promoted by leading climate skeptics with impressive scientific credentials such as S. Fred Singer and Roy Spencer. S. Fred Singer is a particularly important figure because he heads the NIPCC (Non Governmental International Panel on Climate Change), a coalition very representative of the skeptical viewpoint.
I believe scores of bright climatologists with idealistic truth-seeking tendencies that override their fear of peer-suicide have had ample opportunity to provide convincing refutations of AGW. Given the amount of time I've spent so far seeking such refutations, I'm getting discouraged that any solid objections exist. (To address concerns I may have conducted a motivated search, I actually started out leaning towards the skeptical side.) Given the consensus and the lack of a coherent objections to that consensus, I believe AGW is likely to be true. However, I leave the door open to the possibility that AGW is false so long as we await clear-cut tests.
Expert opinions here.