Not quite true Scott.
Northern Hemisphere has warmed by 0.6 C over the last 100 years. Most of it occurred prior to 1950. i.e. prior to the big advent of the automobile.
Take a look at historical data for the 1930's and 1940's. You'll find they do not differ significantly from that experienced in the 1980's and 90's. What drove the climate change at that point, certainly not automobiles?
And while I am no huge fan of Bush, his climate change stance in not signing the Kyoto protocol is a very wise thing to do. While the intent of the protocol is noble, even it's architect's will tell you that it will make a negligible difference with tremendous impacts on taxation levels.
Look for a moment at who is pushing this so very hard. Europe. Consider for a moment the size of the average European country compared to say Canada or the United States. You know why the US and Canada are the largest per capita emitters of CO2? I just told you why. LIfestyle is a factor as well, there is no denying that, however the public transport that is so practical in Europe is not functional here because of large geography.
Kyoto is also flawed in that it puts no penalties on developing nations such as India and China. That is tremendously problematic. China is set for a huge economic boom with all the trappings that we enjoy in North America. You don't really think they'll turn around and sign on to reduce emissions, do you?
Kyoto is as much about economics as anything else. Vladimir Putin is contemplating signing the protocol and it is essential for Russia to do so, due to the need for a majority of nations to do so. Putin has said he will sign only if Russia is allowed to be a full partner in the European Union. Not because he sees a need to reduce emissions, but because he wants to be part of Europe's plans to function as a world economic power, derailing the US in the process.
A couple of points to consider with respect to the 'science' behind it. The IPCC document is not peer reviewed and certainly is not constructed solely by climate scientists. The bulk are economists, sociologists, etc. Not hard climate science.
Think about error. Remember statistics class and the 68-95-99 rule? That equates to the number of standard deviations and the amount of error under a bell curve. I can't speak to what is allowable or normal in Engineering publications, but the bulk of biological publications use two standard deviations, or a 95% confidence interval. Roughly that means 95% of the time, a given expected result will occur, with only 5% margin of error. Those much vaunted climate scenarios that forecast temperature increases of variously 1.5-6 C over the next 100 years? Three standard deviations in the calculation, not publishable in just about any other field, yet the norm here. 32% chance of error. Now I am quite confident that no engineering firm would accept that number for a structural calculation, would they?
My offhand comment above regarding why models don't have negative impacts should be better explained. Think of a graph with an x/y axis, zero at the origin. That is the graph those temperature increase calculations fall into. Think however of a graph with negative values as well. Being a Minnesota boy, you know damn well that temperature can drop below zero. Why then does the IPCC document and calculations show no possibility of this occurring? Think about the movie that started this discussion. While I happily right it off as bunk, look at the premise that it shows, a massive ice age in North America. Kerry, Gore and all sorts of other climate change believers suggest this as a possibility, yet their own model calculations do not allow for it. Why? Because the models are insufficient.
Search for articles by Christy and Spencer out of Alabama. Legitimate scientists beyond a doubt, yet they are on the outs in the climate science world. Why? They don't share in the boon that is climate change. Their work shows that the satellite record shows no significant warming in the troposphere. That is counter to the surface record. And speaking of the surface record, contemplate the urban heat island effect. Is it warmer in downtown Minneapolis than it is out on your grandparents farm on any given day? Most likely, yet the weather station for Minneapolis historically has not moved, yet a huge concrete urban jungle has sprawled around it. No effect?
Think about the historical temperature record for a moment. Contrast that with the geographical structure of the Earth's surface: 2/3 covered by water with no historical temperature record. Africa has a poor historical temperature record, as does most of the rest of the Southern Hemisphere. So we're saying we're warming based on temperature records from less than 1/3 of the available data. Also consider that most of the historical records were taken from rather primitive data recorders inside a Stevenson screen and recorded visually and manually prior to the 1980's (and probably in most places for that decade as well). Can you imagine someone on a cold blizzardy Minnesota day wandering out to a screen, popping it open and and missing by a degree Farenheit every so often? I think that's well within the reasonable expectation of error. Yet that one degree F is precisely equal to the 0.6 C the planet has "warmed" over the last century. Hmm, error versus measurement being the same?
North America from San Diego to Churchill were warm from the 1880's until the end of the 1940's. We then entered a period of cooler temperatures during the 1950's, 1960's and into the mid 70s. Most temperature considerations are based on 30 year rolling averages. So for any determination from the last 25 years, that average has been pre-biased by having what was abnormally cool temperatures during the preceding decades. I'm not sure if you're old enough to remember the mid 70s but at that time the big fear was the coming ice age, not global warming.
If you want an interesting read, find Bjorn Lomborg's book. Oh sure, he is ridiculed in the pages of Scientific American, but a Danish inquiry into complaints vindicated him and resoundingly criticized his critics.
Put it this way, we are indeed warming, but is it because we are coming out of the last ice age or because humans are driving it? I'm not for a moment suggesting modifying our lifestyle is not in order, but hell, the provincial government I work for that decentralized us for votes (hello, Putin?) rambles incessantly about climate change, yet I still have to drive 60 miles each way to work to satisfy their inability to give up a few votes. Hypocrisy at it's finest.
Read deeper than what the media want to say. Take a very careful look at historical temperatures. Long term.
Climate change is a neat theory, but just that. It's grandest problem is that proponents are happy to blame anything on it and feel quite reasonable to do so. That foot of snow we got here two weeks ago: global warming. Not precisely but they blamed it on increased variability. But the variability is not increased. It has happened before, lots of times. And it will happen again. I just find it all too entertaining because regardless of whether it's hot and dry or cold and wet or any combination thereof, it's climate change and it's never happened before. Until you look at the history books.