Extinctions

What are some of the factors that lead to species’ extinctions and what is the evidence that humans
are causing a sixth extinction at a rate 1000 times the background extinction rate?
For this discussion, | would like for you to find scientific articles that address the ways in which human activity is causing the extinction levels to rise far above the background extinction rate. Please include the full citation for the your and DOI (if available) and a short summary of the article that explains how human activities are causing extinction rates to skyrocket.