The "global warming" or "climate change" issue has become so politicized these days, that it is hard to know who or what to believe. Scientific studies with various claims and counter claims are flying right and left, amidst all sorts of political propaganda and media hype. In such a climate, it's hard to remain objective, or know who or what is correct.
An example of the hysteria sometimes found even among scientists is the hostile reaction the NASA chief received recently for expressing even mild reservations about extreme global warming predictions, and not towing the party line on the need for immediate action. One of his key points was that we don't even know whether the current climate is optimal. In fact, seen from a long term, geologic point of view, the current hysteria seems very unwarranted. Many times in the past, the earth has experienced far warmer temperatures, with sea levels not inches but many meters higher than even the most extreme predictions of global warming alarmists, and life thrived. Indeed, warmer temperatures seem to be on average more conducive to life, including human life. In fact, some contrarians maintain that a somewhat warmer climate might benefit us as well as most life on earth. I can almost hear the gasps at that heresy, but let's all try to keep our cool, so to speak. Among the positive benefits a somewhat warmer globe would be longer growing seasons, greater areas of farmable land, an overall gain in fuel savings (on average we spend more on heating than cooling), greater overall food production, among other benefits (See: http://www.heartland.org/Article.cfm?artId=13860)
Moreover, a number of scientific studies such as the following suggests that the majority of warming (perhaps 75%) is due to cosmic, solar, and geologic events rather than human produced CO2. (http://www.eurekalert.org/pub_releases/2003-08/huoj-gwn081203.php)
The politically correct line seems to assume that all wildlife and ecosystems will suffer from even a slightly warmer earth, that warming is accelerating and mostly man-made, that we can alter it much by reducing carbon emissions, and that we can do the latter without doing massive economic damage and replacing one problem with another. The evidence for each of these appears equivocal at best.
Many global warming alarmists insist that virtually all scientists accept their views, which is simply not the case. Many thousands of scientists, including a signficant portion of climatologists, paleontologists, and others with relevant training and background, take a skeptical or (excuse the term) a temperate stance on the issue. As evidence, over 31,000 scientists have signed a petition manitaining that there is no convincing evidence that human activity is, or will in the near future, cause catastrophic disruption of the earth's climate, and that any there is substantial evidence that increases in CO2 will actually "produce many beneficial effects upon the natural plant and animal environments of the earth" (See the Petition Project: http://www.petitionproject.org/).
In an apparent effort to appeal to emotions, some have suggested that because of global warming, polar bears are on the brink of extinction. However, some of the most thorough studies of polar bear populations in recent years show that polar bears are doing just fine, with more populations growing than declining. http://www.newsnet5.com/dpp/weather/weather_news/three-cheers-for-polar-bears-new-study-shows-population-higher-than-thought
Ironically, in the mid 1970's a number of scientists wrote articles warning that the world was cooling and that if we didn't act somehow to warm it up, we could suffer dire consequences. Some even suggested piling soot on ice caps to help melt them. I guess we're all glad it was never implemented. But lets take a lesson, and exercise a little caution, and avoid the politics and sensationalism surrounding so much of the current debate. Lets try to look objectively at the issue and carefully study all factors and possibilities, before plunging ahead with questionable and possibly even counterproductive efforts. I cringe at the thought of passing lots of new industrial and economic restrictions or spending billions of dollars, or say, dumping tons of iron into the ocean (as some have suggested)--any of which could do more harm than good. I believe in the Physician's Oath: "Above all, do no harm." For a good summary of the controversy, with extensive graphics, see: http://www.friendsofscience.org/assets/documents/FOS%20Essay/Climate_Change_Science.html#Summary