If you click on the authors' names, you'll get enough info to roughly determine their areas of expertise. Based on a few names I clicked, it sounds as though they're focused more on brainstorming potential solutions for energy and resource shortages than evaluating the environmental impacts of those solutions. They'll probably leave the latter part to their peers who are more qualified to make such assessments.

There's no argument that environment impact needs to be evaluated--that's just not what these particular people are qualified to assess. It's unlikely that the entirety of academia will avoid discussing the potential consequences of these ideas. Those who are qualified to do so will.