Annals of BotanyNews in Brief Savanna tree and C4 grass acclimation responses across low-to-high CO2 By the year 2100, atmospheric CO2 concentration ([CO2]a) could reach 800 ppm, having risen from ~200 ppm since the Neogene, beginning ~24 Myr ago. Changing [CO2]a affects plant carbon–water balance, with implications... Alex AssiryAugust 11, 2019