It's not science. It's sales and marketing. Are you familiar with the actual mechanisms behind it?
The greenhouse effect is not a bad thing. Without it, our planet would not support life as we know it, as the average temperature would be too cold to support liquid water.
Water vapor is the single most potent greenhouse gas in the atmosphere, trapping more heat than carbon dioxide and methane put together. Estimates of the impact of water vapor on global warming vary widely from a minimum of 60% of all greenhouse effect to 98% of all greenhouse effect, but even at the minimum of 60%, that leaves 40% of greenhouse effect to be shared by all other chemicals combined, including carbon dioxide and methane (which has ten times the greenhouse capacity pound for pound as carbon dioxide).
Now then, looking at Carbon Dioxide, we find that only .117% of atmospheric carbon dioxide is directly attributable to human technology such as automobiles. .117% is a rather small amount. If we were to measure out .117% of a football field, it comes out to 4.212 inches, barely long enough to get off the touchdown line.
So, if humans ceased all technological activity, we would still see 99.883% of the carbon dioxide remain in the atmosphere, assuming all other factors remain stable (which is, of course, silly.)
Over the last few years, there have been very careful studies in Antarctica which clearly show global temperatures rising together with atmospheric carbon dioxide. Global warmers love submitting these research papers with the usual "Ah HA!" type comment, but on reading the papers it is clear that the global warmers stopped at the abstract, because what these recent studies show is that Carbon Dioxide levels increased AFTER the rise in global temperature.
Let me re-state that. Studies of Antarctic ice show that the Earth would get warmer, and THEN Carbon Dioxide levels would increase. And there is nothing at all mysterious about this. Carbon dioxide is a very unique chemical in that it is more effectively dissolved in liquids in lower temperatures. Normally, air will hold more water when warm, sugar will dissolve in water more quickly when warm, but carbon dioxide will escape from solution as the temperature rises, which is why your beer will soak your shirt if it is too warm when you open it.
So, as the sun warms the Earth (as recorded in the ice) carbon dioxide dissolved in the oceans and lakes bubbles into the sky like too-warm soda pop fizzing over the top of the glass, and as the Antarctic ice reveals, winds up in the atmosphere.
Now, this is not to say that I think we should waste our planet's resources. Quite the contrary, I think we need to be very careful of what we have, because we are not likely to get a replacement planet any time soon. But the global warming "hype" is exactly that, hype to sell products and policies.