We also have to invent problems for profit. We always do.
I love how some people in here are trying to put this down and oversimplify the situation. It's a fact that the world cannot continue on it's current course and remain prosperous. Fucking fact.
Studies like this only further the point that we aren't making enough changes in enough time.
This is a computer simulation, not a study.
Technology they couldn't fathom to add to their employed formulas today will be available tomorrow (figuratively), rendering their commentary here obsolete. New fuels, new energy sources, better refinements, better bioengineering, water purification techniques, better food storage and less wasted, etc. Obviously usage of various non-renewables will have to change. Duh. And it will, because that's what humanity does when needed: adjusts, invents, creates, succeeds.
Tldr: Science! It gets shit done. It always does. And we will adjust and invent as necessary.
To me, a 30-day weather forecast is more exact and meaningful than this. Can someone tell me if it's going to be cold here on May 3rd? But researchers gotta publish, so yea.