An environmental emission monitoring system may include satellites configured to sense GHG emissions data for an AOI, and a server. The server may be configured to obtain the sensed GHG emissions data from the satellites, obtain geospatial positions of stationary GHG emitting point sources within the AOI, and generate expected stationary GHG emission data for the stationary GHG emitting point sources within the AOI and based upon the geospatial positions. The server may also be configured to obtain geospatial path data for GHG emitting vehicles moving within the AOI, generate expected vehicle GHG emission data for the GHG emitting vehicles moving within the AOI and based on the geospatial path data, and compare a sum of the expected stationary GHG emission data and expected vehicle GHG emission data with the sensed GHG emissions data to identify any stationary GHG emitting point source and any GHG emitting vehicle outside of a respective GHG emission threshold.