Anthropocene under dark skies: The compounding effects of nuclear winter and overstepped planetary boundaries

The analysis of global catastrophic events often occurs in isolation, simplifying their study. In reality, risks cascade and interact. This is a fact that is all too familiar due to COVID-19. Therefore, it is essential to consider how global risks interact. This investigation explores the interplay between nuclear winter and planetary boundaries. It may seem reasonable to assume that respecting planetary boundaries, which ensure a safe planetary operating space, before a nuclear war is always preferable. However, that does not always seem to be the case. For instance, increasing nitrogen emissions presently could act as a nutrient buffer during nuclear winter. Contrastingly, mitigating climate change, means an even larger temperature drop in nuclear winter in comparison with pre-industrial times. Nevertheless, this explorative study also highlights planetary boundaries whose preservation contributes to human survival, both now and after nuclear war. The best example being biosphere integrity, as conserving it has no direct downsides and will make the Earth system more resilient to resist the shock of a nuclear winter.