What study is this? We have 7.9 billion people on the planet right now and the negative consequences are enormous. There is no way on God's green Earth we are going to 10 billion by 2050 - peacefully and feed, clothe, house and employ them . There is not enough energy for that and even if there was, we could not use it without completely wrecking the planet. We are already in serious overshoot and can not sustain 10 billion people within this socio-economic-energy paradigm with anything approaching what the West calls "civilization".
William E. Rees is professor emeritus of human ecology and ecological economics at the University of British Columbia and has this to say about the prospects of the human enterprise.