If all the world’s ice melts, sea levels will rise 250 feet. We know this, because it has happened before in the distant past. Even though such an outcome is probably centuries away even in a worst case climate change scenario, sea level rise will disrupt coastal real estate long before it rises 250 feet. The disruptions already being seen in some areas through King Tides and during storms could disrupt many more communities over the next few decades. But how soon could it happen, and will the disruption come from sea level rise itself, or from real estate markets’ anticipation of sea level rise? This External Brain examines the evidence for how to answer these questions through the risk management frame of existing homeowners, who face a very different situation as compared to potential home buyers. This External Brain can help users counter the workings of confirmation bias in their home purchasing and ownership decision-making that could prove costly indeed.