In recent decades, grain self-sufficiency has been a key security issue for certain countries, such as Russia, China, India, and France. Climate change may affect agricultural production and possibly influence the grain self-sufficiency of some countries, threatening their food security. This article provides an updated integrated assessment of the impact of climate change on grain self-sufficiency at the country level. The study links climatic variables projected by global climate models to economic variables simulated by a global multi-region multi-sector economic model. Although climate change may considerably reduce land productivity, our simulation results show that climate change in the long term modestly impacts regional grain self-sufficiency, as the direct effects on yield are largely canceled out by changes in grain production via adaptation measures taken by producers in response to market signals. Behavioral changes of consumers also contribute modestly to cancel out the adverse impact on land productivity. In the RCP8.5 climate change scenario, the adverse impact of climate change on land productivity in 2100 may reach 25% of the current level, but declines to 5% when changes in production and consumption are considered, thus indicating the role of long-term adaptation by economic agents.