WinACC's Science and Technology Advisory Panel has produced a paper which sets out the technical basis for setting national and local targets to mitigate climate change.  It defines the overall energy budget that the district must keep to take its share of national and global emissions cuts required for there to be a chance of keeping global warming to less than 2 degrees C.  The paper shows that a local cut of 7% year on year until 2050 is required for this.