He is best known for his research on terrestrial trophic cascades, particularly the role of the gray wolf (Canis lupus) in North America as an apex predator and a keystone species that shapes food webs and landscape structures via “top-down” pressures.

The article suggests "To prevent widespread misery and catastrophic biodiversity loss, humanity must practice a more environmentally sustainable alternative to business as usual."

[10] Ripple, along with his frequent coauthor, Robert Beschta, have studied, published, and publicized the positive impact that gray wolves have had on the Yellowstone National Park ecosystem since their reintroduction in 1995 and 1996.

[18] He has coauthored papers with other scientists in the field of trophic cascades and apex predators,[19] including an exhaustive review of the status and ecological impacts of the world's 31 largest mammalian carnivores.

[23] Ripple also co-authored an assessment of the carbon opportunity cost of animal-sourced food production[24] and a study on the climate mitigation potential of substituting beans for beef.