This paper focuses upon the methodological challenges of deepening understanding of howagricultural and food sectors can mitigate greenhouse gas emissions, whilst at the same timeadapting to the impacts of climate change. Agriculture and food systems are inherently complex,and exploring uncertainty in this context requires an approach that presents the reality of anuncertain future in a manner that does not paralyse, but rather facilitates strategic planning. Aparticipatory scenario process is presented which developed quantitative and qualitative foodsystem scenarios, articulating pathways to 2°C and 4°C futures framed within a cumulativeemissions budget, accounting for emissions along the supply chain from production toconsumption. The process addresses four key challenges, namely: the need to re-frame policydiscourse away from end-point targets and towards cumulative emissions budgets; the need toconsider adaptation to higher levels of climate change than is currently considered; the importanceof supply chain emissions; and how to work with stakeholders to consider the level of changeimplicit within this policy re-framing.Whilst mitigation policies reducing emissions from the agricultural sector are commonly framedby end-point targets, mitigation efforts need to be placed within the context of wider emissionsof greenhouse gases and consider cumulative emissions of greenhouse gases. Under a cumulativeemissions approach, for certain levels of climate change, a limited amount of greenhouse gasescan be emitted , thus global temperatures rise as cumulative emissions rise. For the sameclimate impact, if emissions are not cut sufficiently in the early years, more rapid rates of reductionare needed in later years to remain in budget, also affecting long-term targets . For instance,the UK's 2050 target of reducing emissions by 80% from 1990 levels (70% for agriculture) willneed to be strengthened if emissions are not cut sufficiently early on. The profile of agriculturalemissions differs vastly to that of other sectors, dominated by emissions of methane (CH4) andharder to reduce emissions of nitrous oxide (N2O); the cumulative emissions framing in thiscontext points to the importance of mitigation measures which can be deployed within a shorttimeframe such as changes to consumption and away from technological solutions.Mitigation efforts also continue to be framed in terms of avoiding ?dangerous' climate change, yet the reality is that in the absence of meaningful reductions to date, and uncertainty overa future global agreement to cap greenhouse gas emissions, it is increasingly unlikely that globalmean temperatures will remain below the 2°C threshold associated with ?dangerous' climatechange. Even at this level of global warming there is a high likelihood of increased risks ofextreme weather events, increased water stress, wildfire frequency and floods . A moreextreme, but still not a worst-case outcome of rising greenhouse gas emissions, would be a 4°Ctemperature rise over a similar timescale (by 2100) . Studies suggest that with 4°C as a globalaverage, impacts include temperature increases of 6 to 10°C compared with the current hottestdays within cities such as Rome or Chicago. Examples of other impacts include drought eventsoccurring twice as frequently across southern Africa and the Mediterranean basin; a 40%reduction in the maize and wheat yields in low latitudes and a 30% decrease in rice yields inIndia, China and South East Asia . Thus, nowhere will the impacts of climate change be morekeenly felt than in the agricultural sector where depending on the level of future climate impacts,important food producing regions may no longer be able to sustain production. Responses tomore difficult growing conditions include increasing agricultural inputs, such as fertilizers, orprotecting growing environments from extreme weather, measures which potentially increasegreenhouse gas emissions exacerbating the risk of more severe climate change .The third challenge when thinking about food system futures is the highly globalised food supplysystem; 40% of food consumed in the UK is sourced from outside the UK , accounting foremissions on a territorial (or production) basis excludes emissions associated with the overseas239/639production, processing and transportation of food. Supply chain emissions can be more readilyconsidered using a consumption approach to emission's accounting; supply chain emissions fromUK food supply chains are 11% of total consumption based emissions . When developingscenarios along a whole supply chain, with mitigation efforts required across many differentsectors such as agricultural production, retailers and processors, the benefits of involvingstakeholders in the research are clear. Although a project team may bring together appropriateexpertise, scenarios can be made richer and more plausible through the inclusion of many differentforms of knowledge and experience.Taking these points together, the challenge is to approach mitigation in tandem with adaptationto higher levels of climate change than have previously been considered. Clearly the potentiallyhighly damaging impacts require that radical futures are explored, but within a process thatemphasises solution focused scenarios avoiding alarmist messages in favour of identifyingopportunities and exploring alternative pathways. The process must also break planning for thelonger term into shorter time frames consistent both with typical short term planning horizons,but also consistent with the need for near-term measures consistent with the cumulative emissionsframing.These challenges were addressed through the development of a participative, backcastingscenario process which developed quantitative and qualitative food system scenarios andarticulating pathways to 2°C and 4°C futures framed within a cumulative emissions budget,accounting for emissions along the supply chain from production to consumption. The paperfocuses upon how the methodology issues thrown up by each of the identified challenges wereovercome.