What is the IPCC's assessment style and what shaped it?

The Intergovernmental Panel on Climate Change (IPCC) is one of the best-known global expert organizations. Its main objective is to supply policymakers with policy-relevant recent scientific information about climate change. The way in which the IPCC is obtaining this information is called an assessment. But assessments can be performed in a wide variety of ways. An important step, then, in understanding what this important organization does and why, is to figure out what characterizes the particular type of assessment it performs. The main objective of this paper is to contribute to the literature dedicated to understanding the work of IPCC by outlining the characteristics of the IPCC's assessment style and providing an in-depth analysis of the factors that have contributed to its development. As it will be argued here, understanding the climate-scientific-specific obstacles that had to be overcome by the IPCC in the process of pursuing its objectives is crucial for understanding why the IPCC is performing the type of assessment that it does and also for understanding some of the most important controversies associated with it.