This chapter provides the tools necessary to implement virtually any type of peril in the hazard module of a catastrophe (CAT) model. These tools comprise, for a given peril, the creation of the following: a set of simulated events, a catalogue of hazard intensity footprints, and the main metrics employed in probabilistic hazard assessment (hazard curves and hazard maps). Despite the general purpose of the standard CAT modelling framework, peril-specific CAT models are commonly developed in silos by dedicated experts. In view of the dozens of perils quantified in this textbook, a more generalist approach is employed. An ontology is proposed that harmonizes the description of different perils, going from (1) event source, to (2) event size distribution, to, finally, (3) event intensity footprint. To illustrate how all the previous steps can be wrapped up in one continuous modelling pipeline, an application to probabilistic seismic hazard assessment is also provided.

This chapter describes a range of space weather impacts and introduces anthropogenic (human-induced) space weather through nuclear weapons. The role that space weather and solar variability has on climate is introduced, highlighting the uncertainties and difficulties of making direct connections. Discussion of the probability and effects of asteroid impacts on the global climate system is discussed to compare with the impacts of a global or regional nuclear war. The impacts of nearby supernovas and observations of gamma ray bursts are described with respect to their impacts on the upper atmosphere of the Earth. Supplements provide a discussion of correlation and causation.

A narrative of recurrent causation, the Nemesis hypothesis, holds that the Sun has a companion star, Nemesis, whose orbit perturbs comets from the Oort cloud into earth-crossing orbits leading to mass extinction by impact with a nearly clocklike periodicity. Here I discuss the pursuit of the Nemesis hypothesis as the pursuit of narrative closure. Using a framework drawing on formalist analysis of narratives that distinguishes between the ordering of events in the narrative discourse (the syuzhet) and in their chronological sequence (the fabula), I describe the processes of reading and rereading the fossil and geologic records. The resulting analysis dissolves false dichotomies between nomothetic and idiographic, and catastrophic and uniformitarian approaches in the historical sciences. It also accommodates diverse philosophical views about the nature of epistemic access to the past.