The outcome of the Durban Climate Conference in December 2011 will lead to a more fragmented Climate regime after 2012. While a few countries may continue with the Kyoto Protocol, its governance and its rules, the majority of countries will proceed with the bottomup approach of voluntarily proposing and reviewing reduction targets at least until 2020 when a new global treaty may come into force. Designing this transition period will be a major challenge. This ICPIA synthesis paper includes lessons from different ICPIA work packages in order to draw conclusions for improving the design of the climate regime for the time after 2012 and after 2020. The paper concludes that finding a common ground on important design features, such as accounting or new market mechanisms, in the short term will impact the ability to create a comprehensive agreement on the long term.