Abstract: High-latitude ocean-atmosphere processes play a critical role in driving climate variability across different spatial scales. However, the mechanisms linking high-latitude freshwater forcing to low-latitude climate responses remain poorly understood, particularly during key intervals of the late Quaternary. This presentation discusses two complementary investigations that utilize paleoclimate proxy records and fully coupled Community Earth System Model (CESM) simulations. These studies aim to quantify how freshwater disturbances impact the Atlantic Meridional Overturning Circulation (AMOC) and propagate through the climate system. The first study focuses on how evolving glacial boundary conditions and North Atlantic meltwater forcing during late Marine Isotope Stage 3 (approximately 30,000 years ago) affected temperatures and hydroclimate in South America. This has implications for the extent of tropical glaciation around the timing of Heinrich Event 3. The second study investigates the Baltic Ice Lake (BIL), a significant but often overlooked source of late glacial freshwater. The cycles of filling and catastrophic drainage of this lake coincide with major abrupt climate transitions. By integrating a multi-proxy geochronological framework with isotope-enabled climate simulations, we can quantify the effects of BIL on AMOC, European hydroclimate, and Arctic precipitation. Additionally, we assess how the Early Holocene drainage of BIL influenced the initiation and carbon accumulation of northern Baltic peatlands. Together, these projects shed light on how episodic freshwater forcing at high latitudes reshapes circulation and climate on hemispheric scales. Understanding these processes is crucial for grasping glacial-interglacial transitions and the carbon cycle's sensitivity to abrupt hydrological changes.