Millions of international migrants have recently sought refuge in Europe, animating debates about the best ways to manage migration. Even more people are being displaced within their home countries every year due to natural disasters like floods and storms; and underlying these sudden events is a steady flow of people leaving their rural livelihoods behind and flocking to the cities in an ongoing trend towards urbanization. Across spatial scales, humanity is on the move. And, that much is clear, climate change plays a role in this: whether in the form of unprecedented droughts that drive people to abandon their fields (as likely happened in Syria just before the war) or through differential impacts on countries’ economies that widen the income gaps and fuel international migration. But how large are the effects of climate change - and how do they interact across spatial scales? Little to no quantitative research is available, and the numbers that have been proposed (e.g. of “environmental refugees”) are often crude estimates, and are highly contested. IMPETUS aims for a unified, quantitative modeling approach to understand the linkages between migration, urbanization, and climate change.