Final answer:
The GCMs in the 1990 IPCC FAR projected global climate impacts of increased greenhouse gases, informing climate change understanding and policy.
Step-by-step explanation:
The General Circulation Models (GCMs) used in the IPCC First Assessment Report (FAR) served the purpose of projecting the impacts of increased greenhouse gas concentrations on global climate. Given that the First Assessment Report was released in 1990, these models played a crucial role in shaping early understanding and policy directions regarding climate change.
They provided simulations based on various emissions scenarios to illustrate potential future climate developments, such as temperature rises and changing precipitation patterns, which have significant implications for ecosystems, human health, and economies worldwide.