In a large jar or sealable pitcher, mix together all ingredients except sparkling water and dry ice and chill overnight.
Let sangria come to room temperature, then pour into a large cast-iron footed dutch oven or a punch bowl. Let come to room temperature, then pour in sparkling water.
Line a colander with cheesecloth. Using tongs, set ice chunk in cheesecloth, then tie ends of cheesecloth over ice (don't touch the ice).
Lower dry-ice parcel into cauldron. Carbon dioxide gas (harmless at this concentration) should start to billow forth immediately and will last about a half-hour. Replenish dry ice parcel if needed.
*Pomegranate molasses deepens the flavor and color of the sangria. Find it at well-stocked grocery stores, Middle Eastern markets, and online. Dry ice is available at many grocery stores, often sold by the pound or in 5-lb. chunks. To break it, put it in the sink and crack with a chisel and hammer, and use tongs (not your hands) to pick it up.