four men stepped out when the helicopter landed
The author is saying that because of humans and the ways they are impacting earth is causing irreparable changes like causing animals to go extinct, etc.
Schaffer mistakenly told his assistant to strike alarm Box 342, and as a result, firefighters were directed to an incorrect location during the Chicago fire of 1871.
This is the best example of adding concrete details. It specifically says which alarm box Schaffer told his assistant. The original sentence makes it seem as the miscommunication was the big problem. While it was a problem, the fact that the firefighters went to the incorrect location is really the reason the Chicago fire of 1871 was so devastating. Including these details makes the writing much clearer and easier for the reader to follow.
