The Paris Agreement will drive climate policy for many years to come. It establishes a science-based cycle of reporting (through the Transparency Framework), assessment (the Global Stocktake) and increasing ambition of action to address climate change (Nationally Determined Contributions, NDC). The Agreement has three main aims: to limit the global temperature increase, to increase the adaptive capabilities of the Parties, and to increase the making finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development. The Paris Agreement covers a range of national actions including setting nationally determined contributions, mitigation (greenhouse gas sinks and REDD+), adaptation, loss and damage, technology transfer, education and public awareness, the global stocktake, capacity building and financial support. Some observations will need to be directly reported to the global stocktake including global temperature trends, the overall impact of NDC on the climate system as well as direct observations of atmospheric composition and emissions. Other observations will contribute indirectly by supporting and enabling adaptation and early warning systems, mitigation, and the transparency framework. The provision of capacity building and associated financial support should also be reported. This document considers the Paris Agreement in some detail and suggests suitable activities that GCOS should undertake or support to assist in the implementation of the Agreement.