Climate change increases risks of continued range retractions of Karoo succulents in South Africa , dry argan woodlands in Morocco , epiphytic cacti in Brazil  and other plant species exposed to higher aridity. Projected increases in heat and aridity could increase mortality of trees and shrubs in Sonoran Desert ecosystems in the USA , reduce sagebrush in arid ecosystems of the western USA , and contribute to the replacement of perennial grasses with xeric shrubs in the southwestern USA . CO2 fertilization and warmer conditions, combined with changes in timing and availability of moisture, could increase invasive grasses and wildfire in desert ecosystems of Australia and southwestern USA, where wildfire has historically been absent or infrequent . Trends of woody encroachment may continue in some North American and African drylands or at least not reverse . Impacts of woody encroachment on drylands may show a slight increase in carbon, but a decline in water and huge negative impacts on biodiversity, with a tendency for open ecosystem species to be most affected . Expansion of grasses into these arid shrublands has the potential to transform them rapidly, especially through the acceleration of the fire cycle . While the impact of increased aridity may be offset by changing water use efficiency by plants under high CO2 concentrations, limiting the expansion of dryland ecosystems , increased plant growth in response to elevated CO2, which results in increased water consumption, may counteract this. Increased water use efficiency is therefore not expected to counterbalance increased evaporative demand . There is medium confidence that succulent species will be particularly vulnerable to increased heat and aridity due to reduced physiological performance, loss of seed banks, lower germination rates and increased mortality .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report