Earth experienced a long-term cooling trend during the middle-late Devonian, culminating in the Late Paleozoic Ice Age (LPIA)-the longest icehouse in Earth's history. The onset of glaciation has been attributed to CO2 removal through silicate weathering, however previous carbon cycle models have failed to reproduce its timing. Here, we build a high-resolution climate emulator using the Community Earth System Model and couple it with the SCION Earth Evolution model to better simulate continental weathering. This new framework successfully aligns modeled carbon drawdown and glaciation onset with geological proxy data. We find that additional cooling was driven by increased continental exposure during long-term marine regression associated with Pangea's assembly, which boosted global weatherability and increased albedo. Our results highlight that changes in continental exposure are critical for long-term climate evolution, and that high-resolution climate models are needed to understand these impacts.