The integrated responses of Australian cotton varieties to warmer temperatures, elevated atmospheric [CO2], and altered VPD were assessed in this thesis. Cotton responds strongly to changes in VPD, and hence the VPD environment should be characterised in future climate change studies. Elevated [CO2] impacts cotton growth, physiology and water use, although the magnitude is largely dependent on air temperature and water availability. With elevated [CO2], there are benefits of increased leaf and plant level WUE; however, glasshouse experiments indicate that warmer temperatures may negate the positive impact of increased WUEP with elevated [CO2]. Glasshouse experiments indicate that warmer growing temperatures may increase plant water use and reduce tolerance of water deficits, potentially leading to increased demand for water in Australian cotton production systems; however, this is yet to be determined for plants grown in the field. Therefore, modern cultivars with smaller, more compact growth habits and higher photosynthetic capacity may have an advantage over older cultivars in terms of water use, but there is currently no evidence to suggest that older cultivars are more responsive to elevated [CO2] and warmer temperatures than modern cultivars. These studies also have explored the utility of CETA chambers to assess the integrated effect of projected climate change for cotton grown in the field. Despite limitations of these chambers in terms of meaningful comparisons between chamber and non-chamber treatments, CETA chambers proved a successful method of elevating atmospheric [CO2] and applying conditions of a projected climate to field-grown cotton.