Cumulative impacts require cumulative mitigation
This was the take-home message from the International Association for Impact Assessment (IAIA) meeting in Porto (2012). The authors were Canter and Ross.
There were many more papers on cumulative effects and on climate change than I remember from previous conferences. Interestingly, cumulative is largely understood in the local context rather than the global. SEA was advocated as a necessary tool for managing cumulative impacts. There was increasingly talk of Strategic Health Impact Assessment, especially from WHO, and a growing sense of what that might look like.
Mitigation measures include offsets and trading.