I think this article in Ecological Economics gets at a very important idea. There are planetary boundaries we are at risk of exceeding, most obviously the ability of the atmosphere and oceans to absorb and hold greenhouse gas emissions before reaching some catastrophic tipping point. Then there are catastrophic risks that come out of left field every once in a while, like war, plague, accidents, and asteroid strikes. Since our attention span and ability to respond seems to be severely limited, we really need to understand which of these risks are the most likely and the most consequential, so we know where to focus our efforts.

Planetary boundaries (PBs) and global catastrophic risk (GCR) have emerged in recent years as important paradigms for understanding and addressing global threats to humanity and the environment. This article compares the PBs and GCR paradigms and integrates them into a unified PBs-GCR conceptual framework, which we call Boundary Risk for Humanity and Nature (BRIHN). PBs emphasizes global environmental threats, whereas GCR emphasizes threats to human civilization. Both paradigms rate their global threats as top priorities for humanity but lack precision on key aspects of the impacts of the threats. Our integrated BRIHN framework combines elements from both paradigms’ treatments of uncertainty and impacts. The BRIHN framework offers PBs a means of handling human impacts and offers GCR a theoretically precise definition of global catastrophe. The BRIHN framework also offers a concise stage for telling a stylized version of the story of humanity and nature co-evolving from the distant past to the present to multiple possible futures. The BRIHN framework is illustrated using the case of disruptions to the global phosphorus biogeochemical cycle.