Something that’s rarely ever talked about is that in addition to all the other problems, we are actively preventing species from moving as they attempt to adapt to changes in the environment and climate.
We have erected massive barriers to movement (roads, agricultural areas, suburbs & urbanized areas, dams, etc) that many species can’t cross effectively in order to make the physical movements and changes in range they need to. This is true of both animals and plants.
On top of that, we have policies that aim to keep species in their places and to prevent natural movement of species. Many of the well meaning species protection regulations are limited in geographic scope and result in engaging in habitat and wildlife management aimed at keeping a species in a place that it was, but that may not longer be suitable as a result of environmental changes.
We don’t make good distinctions between natural movement of species into new areas and anthropogenic introductions. As a result species that make a natural transition into an adjacent region often get treated as “invasive” and lumped into the same category as species that were introduced from overseas.
This is going to have a very large impact on species survival as the environmental changes ramp ip in severity, and it’s one that’s going largely unnoticed, other than by a few groups looking at large scale landscape connectivity. Unfortunately, much of the connectivity work results in narrow corridors, which are better than nothing, but don’t really lead to a permeable landscape, which is what species need.
When it comes to the environmental challenges and how to rank them, it’s almost impossible to know where to begin, and they’re all intertwined with each other in any event.