section_path: Environmental Impact/Launches
section_name: Launches
paragraph_text: Launches
  
  Rocket launches release numerous pollutants into every layer of the atmosphere, especially affecting the atmosphere above the tropopause where the byproducts of combustion can reside for extended periods. These pollutants can include black carbon, CO, nitrogen oxides (NO), aluminium and water vapour, but the mix of pollutants is dependent on rocket design and fuel type. The amount of green house gases emitted by rockets is considered trivial as it contributes significantly less, around 0.01%, than the aviation industry yearly which itself accounts for 2-3% of the total global greenhouse gas emissions.
  
  Rocket emissions in the stratosphere and their effects are only beginning to be studied and it is likely that the impacts will be more critical than emissions in the troposphere. The stratosphere includes the ozone layer and pollutants emitted from rockets can contribute to ozone depletion in a number of ways. Radicals such as NO, HO, and ClO deplete stratospheric O through intermolecular reactions and can have huge impacts in trace amounts. However, it is currently understood that launch rates would need to increase by ten times to match the impact of regulated ozone-depleting substances. Whilst emissions of water vapour are largely deemed as inert, H O is the source gas for HO and can also contribute to ozone loss through the formation of ice particles. Black carbon particles emitted by rockets can absorb solar radiation in the stratosphere and cause warming in the surrounding air which can then impact the circulatory dynamics of the stratosphere. Both warming and changes in circulation can then cause depletion of the ozone layer.