The best first step is to acknowledge that they are upset. Have them sit down and explain. If they are speaking loudly, speak in a lower volume.
Answer: consumers would soon run out of food?
Three elements need to be present in an ecosystem to work - producers, consumers, and decomposers. The producers would produce, consumers to consume what is produced and decomposers to decompose.
If there were no producers, it would create a void at the beginning of the food chain, preventing it from functioning. Consumers would soon run out of food. They would starve and soon may die unless they could move to another habitat.
