What Does the Paris Climate Change Agreement Mean for Local Policy? Downscaling the Remaining Global Carbon Budget to Sub-National Areas

Following high profile United Nations climate summits in Glasgow and Paris, sub-national regions and cities are increasingly seeking to set climate targets and policies in line with the Paris Agreement’s goals. Downscaled carbon budgets are a useful framework for setting local mitigation targets related to a specific global temperature change. However, doing so presents a range of methodological issues, including: choices on the appropriate goals to set, the scope of emissions and sectors, the allocation principles to apply, whether offset credits and/or carbon dioxide removals are acceptable and, if so, to what extent. This paper details a novel and transparent methodology for downscaling Paris to sub-national regions, focusing on emissions from energy (power, heat, cooling, surface transport and industry). The effects of different global carbon budgets, zero-emission commitments and allocation methods on the size of sub-national budgets and associated mitigation rates are explored. The resulting budgets and annual emission reduction rates vary significantly, reflecting the implications of both high-level methodological choices and local factors, including economic activity, energy-system structure and population. Recent historical emissions (grandfathering) are judged to best guide the fair allocation of the Paris-aligned carbon budget to the sub-national region or city. In the UK case study presented, adopting a grandfathering approach, the annual mitigation rates range from 7% to 16% between different sub-national areas. The analysis concludes that establishing agreed sub-national allocation principles and boundaries are key to developing coherent national strategies consistent with the Paris Agreement’s temperature and equity commitments