The last interglacial prior to our current period occurred around 120,000 years ago. At that time, natural forces brought about a much higher sea level than today. Distinguishing the role of natural forces from human influences on the climate is a critical and controversial topic, particularly when considering the rapid rise in the global average temperature in the last century or so. The implications are profound for climate forecasts and the need for climate policy responses. If natural forces are likely to halt or even reverse the current warming trend within a few decades, only limited investments would be needed to counter the prospective effects of climate change. But if the recent pace of warming is likely to be sustained or even accelerate in the future, a more urgent and substantial policy response is required.