It wasn't so long ago, that there was a quite different campaign warning of the dangers of climate change. In the 1970's, the climate crisis du jour was global cooling. This is because temperatures had been declining for several decades, from the 1940's through the 1970's. It was predicted at the time that we were headed towards a global cooling catastrophe (loss of farmland, severe storms, etc) if the trends were to continue according to the best models science had to offer. The prevailing theory at the time was that aerosols given off by factories, automobiles, deforestation, farming, etc. was reflecting sunlight back into space from the atmosphere, causing cooling throughout the planet.
It turns out those models were wrong. In the 1980's the trend reversed, and we had global warming throughout the 1990's. In particular, 1998 was the warmest year on record. What were climate scientists to do? The new paradigm was that the cooling effect of aerosols was counteracted by the effect of greenhouse gases, particularly carbon dioxide, which has been increasing consistently since the Industrial Revolution. So the new mantra has become that our consumption of fossil fuels is gumming up the global climate system, causing it to warm up like a car with its windows up on a hot summer day. When reconstructing temperatures from the past and projecting them into the future, we had the hockey stick model, where due to accelerating carbon dioxide levels, we would have accelerating temperatures, until the planet turned into a smoldering cauldron, much like Venus.
However, it just so happens that if you take the hot, steamy year of 1998 as a reference point, we've had global cooling1:
Which Leads us to Dr. Miklós Zágoni, a climate specialist who worked for NASA. Since the climate predictions of massive global warming turned out to be wrong as of late, he tasked himself to refine the climate models. It turned out that the carbon dioxide model for global warming made a flawed assumption in its equation. Namely, to simplify one of the thermodynamics equations, an assumption was made that the atmosphere has infinite height. Since I have an engineering degree, it's not unusual to see equations simplified using assumptions--with the understanding that the results would be identical when the assumptions are made. In this case though, Dr. Zágoni discovered that accelerating heating would not happen, that there would be a ceiling to the amount of global warming due to carbon dioxide. This sounds like good news! We won't all die, and we won't need complex and onerous carbon legislation! Dr. Zágoni's reward? He was summarily defrocked and excommunicated by NASA.
Is this really about science, or is it as much about orthodoxy, bureaucratic inertia, and grant money? Perhaps if we have problems predicting weather into the news ten days, maybe we should be wary of making temperature predictions for the next 100 years.
Update 2008/3/31: I think the best model that explains global warming (as opposed to the prevailing anthropogenic CO2-based theory of global warming) is the one which ties global temperatures directly to solar activity. The increased presence of CO2 in the atmosphere would be explained mostly that it would be released from the oceans as they warmed; as opposed to being a cause of the warming they would be a symptom.
1 It was actually a challenge to find temperature data for the past 10 years. A little too convenient, if you ask me.