For your Sunday time-wasting pleasure, last month's selections from Astronomy Picture of the Day:
One of the very few reasonable points made by climate skeptics is that it's hard to have a great deal of confidence in computer-model predictions of a system as complex and varied as the global climate system. It is comprised of several subsystems -- the ocean, the atmosphere, the cryosphere, and the biosphere -- each extremely complex in its own right. There is some reassurance to be had in hindcasts and other modeling successes, not the least being the triumph of model predictions over the contradictory satellite records. But there are really so many unknowns, both the known unknowns and the unknown unknowns, that it is reasonable to cast a suspicious eye on a forecast of global mean temperature in the year 2100. I think you'd be hard-pressed to find a climate scientist who would not admit it. But the obfuscators and denialists fail to realize something critical: in decision-making, especially when potential futures are extremely bad, uncertainty is not your friend.
(Part of the How to Talk to a Global Warming Skeptic guide) Objection: There was global cooling in the '40s, '50s, and '60s, even while human greenhouse-gas emissions were rising. Clearly, temperature is not being driven by CO2.
(Part of the How to Talk to a Global Warming Skeptic guide) Objection: Satellite readings, which are much more accurate, show that the earth is in fact cooling. I wonder how long before this one stops coming up?
(Part of the How to Talk to a Global Warming Skeptic guide) Objection: It was way colder than normal today in Wagga Wagga, proof that there is no global warming. Does this even deserve an answer? If we must ...
(Part of the How to Talk to a Global Warming Skeptic guide) Objection: The surface temperature record is full of assumptions, corrections, differing equipment and station settings, changing technology, varying altitudes, and more. It is not possible to claim we know what the "global average temperature" is, much less determine any trend. The IPCC graphs only say what the scientists want them to say.
While I hold firmly to my conviction that economic concerns are not the only or even the paramount considerations when charting a course through a changing climate, nevertheless: economics can't be ignored. Thus, it is very good news that a reputable mainstream economist, Sir Nicholas Stern, has presented a detailed cost-benefit analysis of climate change mitigation and adaptation to the British government.
(Part of the How to Talk to a Global Warming Skeptic guide) Objection: A few glaciers receding today is not proof of global warming. Glaciers have grown and receded differently in many times and places.
(Part of the How to Talk to a Global Warming Skeptic guide) Objection: So 2005 was a record year. Records are set all the time. One really warm year is not global warming. Answer: This is actually not an unreasonable point -- single years taken by themselves can not establish or refute a trend. So 2005 being the hottest globally averaged temperature on record is not convincing. Then how about: