The majority of tropospheric ozone formation occurs when nitrogen oxides (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs) react in the atmosphere in the presence of sunlight. NOx, CO, and VOCs are called ozone precursors. Climate change influences ozone and its precursors through multiple processes.
Changes in air temperature and water content affect the air's chemistry and the rates of chemical reactions that create and remove ozone. Many chemical reaction rates increase with temperature and lead to increased ozone production.
In particular, increasing temperatures increase the decomposition of the pollutant known as peroxyacetylnitrate (PAN), which is a major reservoir species for long range transport of the ozone precursors NOx and HOx. This means increasing temperature decreases the lifetime of PAN, altering the long-range transport of ozone pollution.