More than 100 days after 196 world leaders did the improbable and signed an international deal in Paris to cut greenhouse gas emissions, there remains much to sort out.

To start, the Paris Agreement has to be ratified. It seems policymakers learned from past hiccups not only when formulating the Agreement, but also when designing the ratification process. Unlike previous deals, the Paris Agreement requires 55 countries representing at least 55% of global emissions to ratify the deal if it is to come into force by 2020.

The ball is already rolling. Fiji was the first to ratify in February, with Palau soon following suit. The Marshall Islands in March completed the Pacific Island vanguard. Perhaps most significantly, the US and China — making something of a habit of joint climate-related announcements — declared that they would both take steps to approve the Agreement “as early as possible [in 2016]”. Those two countries account for around 40% of global emissions.

Although political progress continues apace, the implications of the Paris Agreement for research remain somewhat less certain. Contained within the deal is a request from the UNFCCC for the IPCC to produce a special report regarding the impacts of, and pathways to, 1.5 °C of warming. Academics are divided on the best response. For instance, Mike Hulme (Nature Clim. Change 6, 222–224; 2016) recently argued that the request represents a legitimate opportunity for the IPCC to provide the best available scientific advice to policymakers, while at the same time working to reform the mechanisms of science–policy interaction. Reto Knutti and colleagues (Nature Geosci. 9, 13–18; 2016) suggest that whether the world aims for 1.5 °C or 2 °C is something of a moot point, however, as the mitigation actions for both pathways look largely the same. Glen Peters (Nature Clim. Change http://doi.org/bd6v; 2016) argues that the utility of any special report lies in resolving fundamental uncertainties around the 1.5 °C 'aspiration', rather than fixating on unachievable mitigation pathways.

The IPCC met in April to discuss, among other things, how to handle the UNFCCC's request. Their decision on whether to proceed with the report is symbolically important, as it indicates what role the IPCC anticipates playing in the policymaking process.

That decision is just a starting point, however. Other avenues of research — from scrutinizing countries' intended nationally determined contributions, to investigations into overshoot and rebound, analysis of attribution relating to loss and damage, and many more — will continue to emerge from the Paris Agreement. Nature Climate Change hopes to represent each strand in the coming months and years.