1) Continue to make the supply chains more sustainable (regarding materials depletion, water, energy inputs, waste, carbon emissions)
2) Evaluate the 'productive output' of cities (eg economic value, technical and knowledge advancement, cultural, social and political leadership), for comparison with the 'inputs' (including those in product groups summarised above) to create a measure of 'value for carbon' (inspired by the 'value for money' concept)
If we are faced with a national 'carbon budget', we could use the measure of Value For Carbon to prioritise where our carbon budget should be allocated (eg between various cities). We could, for example, decide which cities were good 'value for carbon', which ones were poor 'value for carbon' and look more closely at transforming the cities that are running a deficit against their carbon budgets.
The following diagram, from the same DEFRA report, illustrates where there is the most to gain from influencing city dweller actions, lifestyle choices and product supply chains.