A new conceptual framework for integrating multiple problems at multiple spatial scales to achieve simultaneous solutions to global environmental issues

Climate change and biodiversity loss and are regarded as major global environmental issues. However, the interactions between these and other environmental issues, which vary in type and magnitude across regions, have not been adequately considered before measures for addressing each major issue are planned, decided, or implemented. To achieve the simultaneous resolution of multiple environmental issues without externalizing the problem (e.g., shifting "wrinkles" to other areas or regions), it is essential to enhance trans-scale integration of top-down management and bottom-up action planning, leveraging the advantages of both approaches.

To date, at the global level, targets for greenhouse gas (GHG) emission reductions and their timelines are typically determined first, followed by allocation to individual countries. This process often overlooks the "ripple effects" of GHG reduction measures on ecosystems and human well-being within each country.

On the other hand, at the local (national) level, policymakers generally possess a good understanding of societal constraints, demands, and capacities for implementing such measures. However, causal interactions among various issues and their cross-border effects are rarely considered or prioritized.

Here, a Double PDCA-cycle framework is proposed to bridge local action plans (bottom-up) with global evaluations and recommendations (top-down):

• First Cycle: Simulation-based assessment to evaluate the external and global impacts of the proposed local action plans before implementation.
• Second Cycle: Post-implementation assessment and iterative modifications based on observed outcomes.

A set of simple dynamic models incorporating the global system and two nations was analyzed under the following assumptions:

• Top-down: Global-scale goal-oriented approach,
• Bottom-up: National-scale goal-oriented approach, and
• Double PDCA-cycle: Integration of both approaches.

Preliminary results from the comparisons of these three assumptions demonstrate the following advantages of the Double PDCA-Cycle Framework:

• Each country can design its local action plan tailored to its unique natural and cultural conditions.
• Appropriate models can be employed to evaluate the globally integrated impacts of local action plans proposed by each country.
• Existing observation and assessment mechanisms can be effectively utilized.