We consider the question of what is needed for climate services to support sub-Saharan African farmers' adaptation needs at the scale of the climate challenge. Consistent with an earlier assessment that mutually reinforcing supply-side and demand-side capacity constraints impede the development of effective climate services in Africa, our discussion of strategies for scaling up practices that meet farmers' needs, and opportunities to address long-standing obstacles, is organized around: (a) meeting farmers' climate information needs; (b) supporting access, understanding and use; and (c) co-production of services. A widespread gap between available information and farmers' needs is associated with entrenched seasonal forecast convention and obstacles to using observational data. Scalable innovations for producing more locally relevant historical and forecast climate information for farm decision-making are beginning to be adopted. Structured participatory communication processes help farmers relate complex climate information to their experience, and integrate it into their management decisions. Promising efforts to deliver rural climate services strategically combine communication channels that include participatory processes embedded in existing agricultural advisory systems, and innovations in interactive broadcast media. Efforts to engage farmers in co-production of climate services improve delivery to farmers and dialogue among stakeholders, but often with little impact on the usability of available information. We discuss challenges and options for capturing farmers' evolving demands, and aggregating and incorporating this information into iterative improvements to climate services at a national scale. We find evidence that key weaknesses in the supply and the demand sides of climate services continue to reinforce each other to impede progress toward meeting farmers' needs at scale across Africa. Six recommendations target these weaknesses: (1) change the way seasonal forecasts are produced and presented regionally and nationally, (2) use merged gridded data as a foundation for national climate information products, (3) remove barriers to using historical data as a public good, (4) mobilize those who work on the demand side of climate services as an effective community of practice, (5) collectively assess and improve tools and processes for communicating climate information with rural communities, and (6) build iterative co-production processes into national climate service frameworks.

Climate change impacts on agriculture have become evident, and threaten the achievement of global food security. On the other hand, the agricultural sector itself is a cause of climate change, and if actions are not taken, the sector might impede the achievement of global climate goals. Science-policy engagement efforts are crucial to ensure that scientific findings from agricultural research for development inform actions of governments, private sector, non-governmental organizations (NGOs) and international development partners, accelerating progress toward global goals. However, knowledge gaps on what works limit progress. In this paper, we analyzed 34 case studies of science-policy engagement efforts, drawn from six years of agricultural research for development efforts around climate-smart agriculture by the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS). Based on lessons derived from these case studies, we critically assessed and refined the program theory of the CCAFS program, leading to a revised and improved program theory for science-policy engagement for agriculture research for development under climate change. This program theory offers a pragmatic pathway to enhance credibility, salience and legitimacy of research, which relies on engagement (participatory and demand-driven research processes), evidence (building scientific credibility while adopting an opportunistic and flexible approach) and outreach (effective communication and capacity building).