A Food-System Carbon Shift
Tropical islands support important terrestrial and coastal carbon stores while facing strong pressures from development, land conversion, tourism, and climate change. In Hainan Island, food production, aquaculture, processing, and associated supply-chain activities have become increasingly important sources of greenhouse gas emissions within a rapidly developing regional economy.
Authors Zichen Li, Zhaohai Bai, and colleagues from Hainan University, the Chinese Academy of Sciences, and Nanjing University reconstructed the carbon budget of Hainan's food system from 1952 to 2020. Their life cycle assessment framework incorporated offshore ecosystems, land-use and land-use change, crop cultivation, livestock, aquaculture, food processing and consumption, wastewater treatment, and on-farm and off-farm energy use.
Seven Decades of Rising Emissions
Gross food-system emissions increased from 3.29 Mt CO₂ eq in 1952 to 15.13 Mt CO₂ eq in 2020. The analysis attributes this rise principally to fertilizer-related emissions, expansion of tropical crop cultivation, aquaculture growth, and increased energy demand along the food value chain. Nitrogen fertilizer application increased from 223 kg ha⁻¹ to 627 kg ha⁻¹ over the historical period.
Hainan's food system shifted from a net carbon sink to a net emission source by 1970. It sequestered 2.77 Mt CO₂ eq in 1952, retained net sequestration of 1.31 Mt CO₂ eq in 1962, and recorded net emissions of 0.92 Mt CO₂ eq in 1970. A sensitivity analysis of pre-1990 land-use assumptions changed the estimated magnitude of early sequestration but did not alter the conclusion that the system had become a net emission source by 1970.
Trade and Technology in the 2060 Outlook
Export-oriented agricultural production became an increasingly important component of the island's emissions profile. Export-related emissions rose from 0.12 Mt CO₂ eq, or 3.6% of emissions, in 1952 to 5.37 Mt CO₂ eq, or 35%, in 2020. The authors identify high-input tropical crops and industrialized aquaculture as major contributors to this trade-linked carbon burden.
Scenario projections indicate that government management measures alone would reduce projected 2060 net emissions from 6.78 Mt CO₂ eq under business as usual to 4.11 Mt CO₂ eq. Under technological optimization, the food system could become a net sink of 2.85 Mt CO₂ eq. The most ambitious pathway combines technological measures with a structural transition that prioritizes regional food security, moderates expansion of resource-intensive exports, and supports forest, mangrove, and seagrass restoration.
A Conditional Pathway to Net Sequestration
Under the food-system transition scenario, Hainan's food system could achieve absolute net sequestration of 13.55 Mt CO₂ eq by 2060, representing a 20.33 Mt CO₂ eq reduction in net emissions relative to the business-as-usual pathway. Monte Carlo analysis produced a median sequestration estimate of 13.02 Mt CO₂ eq, with a 95% uncertainty interval of 6.47 to 19.29 Mt CO₂ eq.
The authors emphasize that this outcome represents an upper-bound mitigation pathway, not a forecast of expected development. Its feasibility depends on sustained policy support, widespread adoption of low-carbon technologies, land-use governance, ecological restoration capacity, trade arrangements, and attention to potential effects on farm income, employment, rural livelihoods, and food security. The framework offers a context-sensitive reference for tropical islands seeking to align food-system development with carbon-neutrality objectives.
Corresponding Author: Lin Ma or Hongwei Zhao
Original Source: https://doi.org/10.1007/s44246-026-00298-w
Contributions: Zichen Li and Zhaohai Bai contributed to conceptualization, formal analysis, visualization, and writing the original draft. Xiaoyang Shan and Bo Hu contributed to writing, reviewing, and editing the manuscript. Lin Ma contributed to conceptualization, review, and editing. Hongwei Zhao contributed to conceptualization, writing, review and editing, project administration, and funding acquisition.
