Impact of climate change on farmland NPP: Evidence from multi-scenario projections in Japan

Global agriculture has been significantly impacted by climate change through alterations in temperature regimes, precipitation patterns, and ecosystem productivity. Agriculture in Japan may be particularly fragile due to its limited arable land and a declining agricultural population. This study examines how climate change affects farmland net primary productivity (NPP) in Japan using machine-learning predictions at a 500-m grid resolution across four Shared Socioeconomic Pathways (SSPs) scenarios in the near-, medium-, and long-term. Our results reveal that temperature and NPP are associated through a nonlinear dynamic, with distinct spatial heterogeneity across regions. While moderate warming scenarios show potential benefits for farmland productivity in northern and central regions, extreme warming under SSP3-7.0 and SSP5-8.5 poses risks of productivity decline in some prefectures. Nationwide, agricultural productivity could rise by 7-10 % in the long term compared to the current status. In contrast, warmer southern regions could experience stagnation or decline. The findings highlight the need for region-specific agricultural adaptation policies to optimize agricultural potential while mitigating climate-related risks. These insights contribute to a deeper and more comprehensive understanding of climate change impacts on food security and land-use planning, thereby enabling policymakers to design appropriate policies.