K.L.
You have a real talented climber it sounds like. I will let others give the suggestiong on how to stop him but PLEASE, get the brackets to hook his dresser to the wall. Since he is pulling the drawers out it wont be long and he will be climbing in them like stairs to get on top of the dresser soon. It wont take much to tip the dresser over on top of him, which can and has been deadly to many toddlers. Please hook it to the wall so he cant. Its easy. L brackets and a few screws. It can save his life until you find a way to stop him from climbing.