The military has felt for quite a while that global warming is a valid threat. My personal belief is that chemtrail spraying is being done by the military to prevent what they believe is global warming by reflecting sunlight back into space.
About 15 years ago an elderly neighbor (90's at the time) told me the Sun's color has changed, it's whiter than the typical pale yellow she was always used to. At the time I dismissed her claim, as it's well known that elderly skin thins and is more susceptable to sun burns. In addition I thought well if we've cleaned up the air that would cause the solar radiation we received to whiten/brighten. I still think the later. But I also believe that the cure is worse than the disease as respiratory illnesses has increased over the last decade or so even with less air pollutants.