The problem with global warming is that environmentalists are trying to act that its cause is a known fact. It is not. 

As a refresher, here is the theory of human induced global warming in short:

The molecule CO2 is a green house gas.  More specifically, when the sun's energy passes through our atmosphere and comes into contact with the carbon atoms, it holds some of that energy. As a result, heat is trapped in the atmosphere which increases the surface temperature of the Earth.

The primary source of energy used by humans involves using carbon-based energy sources.  The worst of these are fossil fuels.  Fossil fuels are so problematic because they represent carbon that was taken out of the atmosphere millions of years ago and stored underground in the form of oil, coal, etc.  When we burn these fuels, the carbon that was trapped is released and combines with O2 to form CO2 and goes back into the atmosphere.

Since 1975, the mean temperature has gone up with the last few years being some of the warmest years on record.  The environmentalist lobby has made a strong case that humans are the cause -- CO2 is higher today than it has been in millions of years, it's a green house gas, and we're tons of it into the atmosphere every day.

The problem with that theory is that it doesn't explain why global temperatures were going down between 1940 and 1975.  To me, it screams weak science.

Correlation doesn't equal causation. CO2 is indeed a greenhouse gas. But we have no understanding yet about how much it really can affect temperatures.  Contrary to what some have claimed, CO2 increases have not preceded increased temperatures. On the contrary -- increased temperatures have led to more CO2 in the atmosphere historically (which isn't surprising). 

CO2 definitely has an affect on temperatures, we just don't know if it's significant or not.  For instance, all bodies of mass have a gravitational pull. You and I exert a gravitational pull (mine seems to increase every year...).  But compared to the Earth, it's insignificant.  CO2 could, in fact, turn out to be much the same thing in terms of temperature change.  Sure, CO2 is a green house gas but the amount in the atmosphere one would need to increase global temperatures could be ridiculously high.

What amazes me is how eagerly people have been to join the Human-induced global warming bandwagon even with the elephant in the room -- the time between 1940 and 1975 when temperatures were decreasing.  To me, that alone should have bred a healthy scientific skepticism in the CO2 theory of global warming.

The weather is getting warmer but we really don't have a clue why yet.  That doesn't mean we shouldn't be trying to find ways to "reduce our footprint".  I support that.  But what I don't support is the vilification of CO2 while forgetting about the dangers of sulfur dioxide, methane, NOx, etc. Watching people support monstrous things like bio-diesel (because it's "carbon neutral") sends shivers up my spine.

I certainly could be in error but I really do think that in a decade or two at most we will discover that CO2 isn't quite the boogeyman we thought it was and that other causes of global warming will be found (or even that mean temperatures start to decrease even as discussed here).

Until some environmentalist can explain why the temperature went down between 1940 and 1975 even has CO2 levels were skyrocketing, I think this talk about "human caused global warming" should show a bit more humility.  Shrillness is no substitute for logic and reason.