With the kinds of environmental abuses and neglect that was taking place in the 1950s and 60s, it was inevitable that a green movement of some sort would start, just as in the 1850s, it was inevitable that an abolition movement would grow. In that time period, the book Uncle Tom's Cabin sold hundreds of thousands of copies and changed minds, increasing the size and momentum of the anti-slavery movement.
Silent Springdid something similar. It took a fledgling movement and an unknown debate topic and brought it into specific relief. It made it into a national discussion, and there were magazine and journal and scientific and political responses to it.
Did it change history? Yes it did. Just not all by itself. The car was already running, her book just stepped on the gas.