Final answer:
Chlorine Monoxide is the chemical that indicates the destruction of the upper ozone layer, due to its formation from chlorofluorocarbons (CFCs) that release chlorine atoms as a result of ultraviolet light exposure.
Step-by-step explanation:
The chemical in the upper stratosphere that indicates the upper ozone layer is being destroyed is Chlorine Monoxide. Ozone (O3) in the stratosphere is crucial for absorbing ultraviolet light from the Sun and thereby protecting life on Earth. The industrial compounds known as chlorofluorocarbons (CFCs) were largely responsible for ozone depletion through the release of chlorine atoms when they were exposed to ultraviolet light. These chlorine atoms then react with ozone, leading to its destruction. The international community has taken steps to phase out CFCs, aiding in the gradual healing of the stratospheric ozone layer.