Widespread vegetation greening, as projected in AR4, is occurring in arid shrublands  as a result of increases in leaf area, woody cover and herbaceous production at desert-grassland interfaces . Plant productivity in arid regions has increased  because of improved water-use efficiency associated with elevated CO2  , altered rainfall seasonality and amount  , increases in temperature   and heavy grazing , with the relative importance differing across locations . Woody-plant encroachment into arid shrublands is occurring with high confidence in North America  and southern Africa , and with low confidence in central Asia . In North America, sagebrush steppe changes have been attributed to increases in temperature and earlier snowpack melt .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report