That's not what that seems to say at all. It doesn't even look like it says "if we do nothing, we can't grow these crops anymore". It seems to be specifically about stratospheric aerosol injection (a specific geoengineering technique that we haven't even committed to trying as yet), and suggests that if you use it to keep global temperatures stable, there can still be changes in where these crops can grow because changes to things like rainfall and humidity. I've not read the entire thing but from a glance at it's conclusions, their simulations suggest that the crops would remain economically important to their growing regions under all their simulations, just with the viable amount that can be grown and the specific areas for doing it changed per region, and that using SAI to offset warming doesn't simply result in the same yields as not having the warming would have the way one might otherwise expect.