Population
Your right on the population. The earth can "safely" accommodate 2 billion people. We are now over 7 billion strong and in the next 10 years or so we will hit 12 billion. As long as humans keep procreating like rabbits and roaches, the pollution problem will grow exponentially. That is, pollution will be increasing in extraordinary proportions because of greatly increased population.
As far as contrails go, they are caused from the aircraft engines at high altitudes by the hot exhaust mixing in the cold dry air creating water vapor. I heard (and read) of this "chemtrails" malarkey over 20 years ago, and from what I remember it was pretty much written off as a hoax. Jet fuel is clean burning as long as it's of better quality than JP4, and in the states everyone uses JP5 and above. Kerosene would be the optimum, but it's cost is prohibitive.
