Historically in natural systems when there are large changes in the environment, such as deforestation, salination of waterways or introduction of more a more successful niche occupant you see massive die off of the apex species.

In this case there are 8 billion members of the apex species. Humans will survive, but it's not going to be much fun until the new normal emerges.

Technology will help, but it will only cushion the fall, not prevent it, and only if we react quickly enough to reduce the impact. When enough people start starving they will start looking for food and water wherever they can find it, and they won't be very charitable towards those who they believe caused the problem.