Author: Robert Fofrich Navarro, UC Postdoctoral Fellow and IDRE Fellow – Institute of the Environment and Sustainability

Many climate pathways aiming to limit mean global temperatures to 2°C rely on biogenic negative emission solutions to achieve large and rapid reductions in atmospheric CO₂ over the next few decades. However, land-based climate mitigation measures require significant land allocation and occupy limited land resources necessary for ecosystems and agriculture, thereby posing a direct risk to local wildlife, regional food security, and agrarian economies. Energy crop cultivation in tropical environments is of particular concern, given that these regions host most of the world’s intact carbon-rich forests and biodiversity. Furthermore, numerous crops in tropical regions are grown at the limits of their climatic niche, making their cultivation unsuitable under various climate futures without additional adaptive measures. We thus conduct an analysis of the historical climatology of rainfed harvested areas for commonly used first-generation energy crops, utilizing daily and quarter-degree resolution historical climate data from ERA5 and rainfed crop ranges from the Food and Agriculture Organization Global Agroecological Zones (FAO GAEZ). Additionally, we assess the suitability of these crops in tropical regions across various levels of climate warming using climate projections from the 6th Phase of the Coupled Model Intercomparison Project (CMIP6) and explore the inherent tradeoffs in land use and allocation, considering competing international objectives such as climate change mitigation, ecosystem conservation, and agricultural needs within these tropical regions. We find that exceeding 2°C of global warming could render many bioenergy crops unviable in tropical regions. In contrast, in scenarios that avoid 2°C, we identify clear tradeoffs between energy crop cultivation, tropical biodiversity conservation, natural carbon stocks, and regional food production.