If they are announcing this in the mainstream media you can be assured that they have already done spraying.

"Holdren, director of the White House Office of Science and Technology, outlined the idea of shooting either sulphur dioxide particles, aluminium oxide dust or specially designed aerosols into the stratosphere - the upper level of the atmosphere between ten and 30 miles above the Earth's surface.

It is hoped that this would cool the planet by artificially reflecting sunlight back into space before it can be absorbed.

Naval guns, rockets, high-flying aircraft and even hot air balloons have been put forward as possible ways of firing the agent into the air. "

http://www.dailymail.co.uk/sciencetech/article-1168637/Obama-pollution-partic...


The spraying chemicals from planes is chemtrails.
Obviously chemtrails do exist, anyone that says differently has a serious case of cognitive dissonance.