I just took some pics this morning of the skies cross crossed with contrails and most of them widening out into cloudy skies.  I took an earth science class years ago and remember them saying that while CO2 is considered the number one greenhouse gas, that technically water vapor is the number one greenhouse gas as cloudy skies will affect temperature and climate more than CO2. Now you look at large parts of the earth covers in clouds from contrails and one can only conclude that increased global temperatures would be a plausible outcome of increased cloud cover.  Whether there are chemicals or not in these trails, they still have a big impact on temperature and climate.