Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiation, acting as a global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate the destruction of the ozone layer by reacting with chlorofluorocarbons (CFC's).

• Aacting as a global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate  
• Bacting as a global thermostat and thus keeping Earth either from burning up or freezing over, while also accelerating  
• Cact as a global thermostat and thus keep Earth from either burning up or freezing over, while also accelerating  
• Dthey act as a global thermostat that thus keeps Earth either from burning up or freezing over, even though it also accelerates  
• Ethey act as a global thermostat to thus keep Earth from either burning up or freezing over, but they also accelerate