UNFCCC stands for United Nations Framework Convention on Climate Change, which was adopted in 1992. The Convention has near universal membership (197 Parties) and is the parent treaty of the 2015 Paris Agreement and the 1997 Kyoto Protocol. The ultimate objective the UNFCC and its subsidiary treaties is to stabilize greenhouse gas concentrations in the atmosphere at a level that will prevent dangerous human interference with the climate system. Every year, the parties to the UNFCCC meet in what is known as the Conference of Parties (COP). The Paris Agreement was adopted in at COP 21. Greta Thunberg famously addressed the COP24 in 2018.
The UNFCCC eHandbook (link below) provides an overview of the UN climate change regime, including the UNFCCC, the Paris Agreement, and Kyoto Protocol. This handbook provides an excellent introduction and summary of the three major climate change treaties - the UNFCCC, Kyoto Protocol and Paris Agreement - as well as the negotiation process and issues covered by the UN climate change regime - mitigation, adaptation and support.
The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change. The IPCC was created in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to provide governments at all levels with scientific information that they can use to develop climate policies. IPCC reports are also a key input into international climate change negotiations.
The IPCC prepares comprehensive Assessment Reports which include contributions from each working group as well as a Synthesis Report integrating these contributions and any Special Reports prepared in that assessment cycle. The IPCC also prepares Special Reports focusing on specific issues and Methodology Reports that provide practical guidelines for the preparation of greenhouse gas inventories.
At the link below, you can find all three types of reports, as well as technical papers.
Law, Climate Emergency and the Australian Megafires by 
Non-governmental Actors in International Climate Change Law: The Case of Arctic Indigenous Peoples by 
Legal Issues on Climate Change and International Trade Law by 
The Oxford Handbook of International Climate Change Law by 
