If those 400,000 marchers would all show up at the polls, the outcome of any number of races in the 2014 election would be changed for the better. Deniers would lose and reality-based candidates would win. Legislation would be written to change the way we pollute.
Marches and civil disobedience are powerful tools to help effect change. But unless we take that same spirit and work ethic to the polls as well, nothing will change. Only when politicos are afraid of being voted out of office will they respond to the will of the people.
March.
Then vote.
But if you can only do one of the two, vote.
And they would elect alarmists who legislated and spent money as if climate science is settled.
Tradition is not the worship of ashes, but the preservation of fire. ― Gustav Mahler