Andrew Wetzler from the NRDC Switchboard blog has several observations on the new regs. Wetzler criticizes the administration's position that the ESA cannot be used to regulate greenhouse gas emissions on a "harm to listed species" theory. Wetzler contends that, although a more precise causal chain may be necessary for establising liability under Section 9 of the ESA (pertaining to take), such cause-and-effect precision is not necessary for triggering Section 7 liability.
But this seems to ignore that Section 7's jeopardy avoidance duty only attaches to federal activities that cause jeopardy or adverse modification of critical habitat. It seems just plain common sense to apply a traditional "but for" causal analysis to interpret that trigger. And thus, it doesn't seem unreasonable at all for the administration to conclude that it is impossible to connect any discrete harm to a listed species (which presumably would form the basis of jeopardy finding) to the emissions from a particular project.