D.W.
When my son does that I ignore him. If we are out somewhere and I can I will leave where we are at. If he is hungry and screams though I will give him for example a banana when we are in the grocery store so, he will be quiet. You can also put him in time out when he screams. my sons pack and play is full with toys so, I put him in his crib when he acts up. I let him sit in there and scream. after a few minutes I ask him if he is going to stop. If he says yes, I take him out and if he says no he stays in there. After a few minutes more I will ask again if he is going to be good and if he says yes then i will take him out. You have to be consistent,keep your voice down and be firm but fair. Everything will be fine. He is starting the terrible two behavior a few months early. It goes from about 18 months until around 3. Good luck. Just keep your cool and everything will work out.