Since the conclusion of the UN climate conference in Durban, South Africa (COP 17) last year, there has been robust debate on the merits of its outcomes.Some argue that the deal – including a new Durban Platform to negotiate the climate regime’s long-term future, a second commitment period for the Kyoto Protocol, and an array of decisions to implement the Cancun Agreements – is an inadequate answer to a world facing rapidly increasing greenhouse gas emissions. Others point to encouraging elements of the Durban package, such as a renewed commitment to international collaboration, a vision of an ambitious post-2020 settlement, and a series of steps designed to facilitate creative thinking on closing the emissions gap.It’s worth noting that the negotiations taking place this week and next in Bonn, Germany, are occurring exactly 20 years after the UN Framework Convention on Climate Change (UNFCCC) was opened for signature. Two decades of intensive intergovernmental bargaining have laid a foundation for progress, but have yet to bring us within reach of holding the global average temperature increase to 2˚ Celsius above preindustrial levels.In this light, the Durban outcomes offer more questions than answers. In Bonn, delegates will begin the long process of addressing these outstanding concerns. Four key issues to watch are:Fleshing out the Durban Platform. The Durban Platform identifies a destination, but the route still needs to be designed. Electing chairs and other such housekeeping will be important business. However, it’s also important to move forward on substance. Establishing workshops is crucial, particularly on a pre-2020 mitigation program as well as a work plan on a new legal agreement. Without these first steps, negotiators may arrive at COP 18 in Qatar with little to build on.Managing detail in the Kyoto Protocol (KP) and Long-term Cooperative Action (LCA) tracks. Parties who sign up to a second Kyoto Protocol commitment period have committed to reduce emissions by at least 25-40 percent below 1990 levels by 2020. In Durban, the EU was the key player in determining whether the Kyoto Protocol would survive into a second commitment period. In Bonn, the key questions will be aimed at the Europeans once more. How will the EU approach its commitments in a second period? Will it formally put forward a 20 percent emissions reduction target and seek to increase ambition later? There will also likely be difficult discussions on the length of the commitment period as well as on the scale of emissions reductions that Parties will commit to. On the LCA, managing the agenda will likely prove difficult. As many as 15 separate items dealing with measurement, reporting, and verification require further clarification and implementation.Balancing ambition and equity. Various submissions from countries and observer organizations contain interesting ideas for generating ambition inside and outside the UNFCCC. The workshops in Bonn provide an opportunity to see which ideas have the most traction. However, progress on ambition is likely to hinge on similar progress with equity, the broad concept that traditionally defines burden sharing in the UNFCCC. The Durban Platform omitted reference to equity and “common but differentiated responsibilities,” but in the ensuing months a succession of statements and submissions have again put equity front and center. Resolving the equity question is key to unlocking the good will and trust needed to advance the rest of the agenda. Can countries come to Bonn with open minds and creative thinking about how to operationalize equity into a regime that is growing in complexity each year? Will we see concrete proposals from Parties, or just a series of speaking points?Coalition building. The emergence of new coalitions has been a major feature of the climate regime in recent months. The informal alliance in Durban between the European Union, least developed countries, and Alliance of Small Island States was vital in rejuvenating negotiations during COP 17’s last days and in driving adoption of the final package. Will that alliance persist in Bonn? If so, what impact will it have on the agenda in 2012? Similarly, coordination between the BASIC countries (Brazil, South Africa, India, and China) reached new heights in Durban and has remained evident in recent months, most notably in their pronouncements on equity.There is an old truism that asking the right questions takes as much skill as giving the right answers. Durban provided a platform to address crucial questions. Bonn will be a first chance to gauge if Parties have the resolve to answer them.