Changes in Wood Biomass and Crop Yields in Response to Projected CO2, O3, Nitrogen Deposition, and Climate

As the world's population increases, so will the demand for food and timber resources. Though carbon dioxide (CO2) fertilization and, to a lesser extent, nitrogen (N) deposition are expected to increase future resource production, changes in ozone (O-3) and climate have the potential to decrease production due to increased phytotoxic damage, drought, and heat stress. To determine how crop and timber production may change in the future, we use the Community Land Model version 4.5 with prognostic crops to simulate responses of wood biomass and crop yields to CO2, O-3, N deposition, and climate under Representative Concentration Pathway 8.5 forcings. Generally, rising CO2 increases wood biomass and crop yields, while projected climate change causes decreases. Small projected changes in O-3 and N deposition do not strongly affect yields, though additional research is needed on future O-3 and N deposition trends and impacts. By the end of the 21st century, global wood biomass increases by similar to 16% due to the dominating impact of CO2. The positive effect of CO2 on future crop yields is muted by the negative impacts of climate, with a similar to 5% net global increase. Future projections suggest that rice and wheat yields typically increase under the combination of future forcings, whereas soy and corn yields are regionally variable. While short-term resource management strategies can benefit from planting heat-tolerant species and cultivars, technological advances and intensification, among other management strategies not included here, must be employed to meet the future demand for these resources. As the world's population increases, so will the demand for food and wood resources. Though these resources might increase due to the fertilizing effects of carbon dioxide (CO2) and additional nitrogen (N) created by human sources, food and wood resources might decrease due to other environmental changes, like ground-level ozone (O-3), a toxic air pollutant, and climate, which can cause drought and heat stress. This study uses a global model to understand how food and wood resources may change in the future if there is no climate mitigation. Our results show that global wood biomass will increase by 16% and crop yields will increase by 5% at the end of the 21st century. While CO2 increases wood biomass and crop yields, it does not always outweigh the negative effects of climate, especially for crops like soybean and corn. The future changes in O-3 and additional N were small and therefore did not change resource production very much. With the global food demand expected to increase by 65% and timber by 100%, these results suggest that resources may not increase enough to meet future demand unless additional, intensive management techniques are used, like expansion of managed area and irrigation, development of heat- and drought-tolerant crop and timber varieties, and other technological advances that can increase production in light of future environmental changes.