Ian Galbally first discovered processes (ozone destruction at the earth's surface, nitric oxide emissions from soils, organic emissions from grasses) and first identified chemicals (photochemical ozone in Australian cities, carbon tetrachloride as a global pollutant) that underpin the Montreal Protocol and air quality protection in Australian cities. He devised an innovative method for indirectly measuring motor vehicle emissions that has had major impact on urban air quality management in Australia and abroad. He is responsible for the development of current good practice guidelines and uncertainty management for greenhouse gas inventories adopted for reporting by the nations of the world.