I was recently asked to give a presentation relating to climate change. I've never disputed that the climate is changing -- climate, by definition, is dynamic, and the planet has (thankfully) been warming ever since the end of the Little Ice Age. However, most of the arguments for public consumption that I've heard from the anthropogenic global warming alarmists have been patently fallacious. Many of their advocates have been talking the talk but not walking the walk. Multiple key scientific contributions to alarmist theory have been generated fraudulently. So-called alarmist climate scientists have attempted to stifle scientific debate in journals and meetings, and policy advocates appear to fear any open debate of the subject. The alarmists never point out the benefits that could be realized from global warming. And, proposed policy solutions are not tailored to solving any problem, but rather are tailored to grow a government that is already too big to succeed. With all this nonsense it was easy for me to dismiss the alarmists.
My recent review of the literature and discussions with local climate scientists have led me to modify my opinion. I'm still not an alarmist in any way, but I realize I fell prey, to some extent, to the fallacist's fallacy -- i.e., I dismissed many or most of the alarmists' arguments because so often they were presented fallaciously. However, just because someone presents a fallacious argument, one in which the reasoning is unsound because it is logically invalid, doesn't mean the fallacious argument's conclusions are not true.
There's little doubt that atmospheric carbon dioxide concentrations have steadily increased since the onset of the Industrial Age, and that man's output of carbon dioxide has increased over this time. While increasing temperatures can release more carbon dioxide from the oceans, thus, contributing to the increases in carbon dioxide that are being seen in the atmosphere, increased anthropogenic emissions can also increase the levels, and those increased levels can contribute to an increase in the atmospheric greenhouse effect.
Where I stand now is acknowledging that at least some anthropogenic enrichment of atmospheric carbon dioxide is occurring, and that enrichment of a greenhouse gas has the potential of increasing global temperatures. How much of an increase, and whether the increase is significant or not, however, are still matters for debate in my mind. Also, the spokesmen for anthropogenic global warming need to be scrapped -- they have no credibility. A credible climate scientist who is apolitical and has some decent communications skills should be sought for that role.
That's about where I've stood for over 10 years. What I've refined since then is my appreciation of weather which controls climate. The typical Trenberth diagram showing annual net energy flows including back radiation from GHGs is basically useless since changes in water vapor on an hour by hour basis change the numbers. Not to mention seasons, diurnal, cyclical, etc. Anyone saying that backradiation will increase by X with "water vapor feedback" deserves a big "yeah right".
The most important thing to remember is that while the energy exchanged between earth and space (solar in, heat out) is in equilibrium over the long run (which means that increases in GHG cause warming), that energy flow equilibrium means jack for water vapor. Water vapor will always concentrate unevenly and cause more warming here and less there. Without knowing that distribution (i.e. the unevennes of WV), there is no way to estimate the sensitivity. It is completely incorrect to use the energy flow equilibrium to postulate constant RH.
I guess I should mention models: GIGO. They don't depict convection in enough detail to know what latent heat is transfered to the upper atmosphere and what the all-important distribution of water vapor is. Find me a model that does this: http://weather.unisys.com/surface/sfc_con_dewp.html accurately. Or even more importantly, this: http://www.ssec.wisc.edu/data/east/latest_eastwv.jpg
