Some fascinating research which links excessive ethnic diversity to environmental degradation and poor enforcement of environmental policies:
"We find that all indices of social fragmentation are negatively linked to measures of environmental quality"
https://link.springer.com/article/10.1007%2Fs10640-012-9619-6"There is evidence that some aspects of social capital are associated with better environmental performance."
https://journals.sagepub.com/doi/abs/10.1177/1070496511405153"Using the Environmental Performance Index developed by Columbia and Yale Universities in collaboration with the World Economic Forum, this study finds that countries with moderate levels of ethnic diversity experience the greatest environmental performance as they reap the benefits of a civically engaged society with creative, innovative, and efficient human talent pool and do not bear the negative effects of a highly fractionalized society that typically suffers from poor communication and social cohesion, among other societal ills."
https://journals.sagepub.com/doi/abs/10.1177/1070496509355274It would be interesting to learn more on the researchers' methods and conclusions. I'll be contacting the authors of these studies to see if we can gain some more insight, so stay tuned for more details.
I am curious to know, for example, just how diverse a society needs to be in order to be considered "moderate" and thereby "reap the benefits of a civically engaged society with creative, innovative, and efficient human talent pool". Since ethnic diversity has been linked to lower social capital (i.e. civic engagement) in other studies, I am skeptical that there will be evidence showing that White displacement is necessary to obtain those perks.