A carbon-aware vehicle routing system is provided for improving computational efficiency during route planning. The system stores road network data in memory and employs a processing circuit to execute a routing application. A route search region is established between a vehicle's current location and destination. Assessment points within the route search region are evaluated to identify high-emission points when carbon-emission levels exceed a predefined threshold. One or more high-emission spatial zones are defined using proximity-based expansion or graph connectivity relationships among adjacent high-emission points. The system constructs a route-search graph topology corresponding to a subgraph of the route search region that excludes the high-emission spatial zones. By reducing the number of nodes and edges involved in route computation, the system decreases computational load and resource intensity. A candidate route is generated through route computation performed on the reduced graph topology.