Rising carbon dioxide is supercharging grass growth in African savannas, study finds

Key Points:

• A University of Sheffield-led study reveals that rising atmospheric carbon dioxide is enhancing grass growth in Africa's water-limited savannas by helping grasses reduce water loss and maintain photosynthesis under dry conditions.
• Analysis of 32 years of data from South Africa's Kruger National Park showed a 28% increase in grass production from 1989 to 2021, a trend most consistent with rising CO₂ levels rather than changes in rainfall, temperature, grazing, or fire.
• Increased grass growth could lead to higher fire risks, altered wildlife habitats, and complex effects on carbon storage, as additional biomass may be consumed by animals or burned, releasing carbon back into the atmosphere.
• Climate models predict that CO₂-driven grass growth increases may continue despite future warming and decreased rainfall, with notable shifts toward taller, more productive grass species potentially reshaping savanna ecosystems.
• The study challenges previous assumptions about C₄ grasses' responsiveness to CO₂ and highlights the need to consider direct CO₂ effects alongside climate variables when forecasting savanna ecosystem changes.