https://pjirvine.github.io/files/Parker_Irvine_EF_2018.pdf
Authors. Parker, A. & Irvine, P. J
Venue. Earth's Future 6:456 , author-hosted PDF
How the Institute flags it
frontier 2 times established 1 time
This source carries more than one flag across the corpus. That is not an inconsistency to resolve: the same work can be established evidence for one claim and frontier evidence for another, and the flag belongs to the use rather than to the source.