CODEC

Since the cold war era, scientists as well as the public have speculated about potentially catastrophic indirect effects associated with the detonations of nuclear weapons causing soot emissions large enough to dim sunlight globally. The term ‘nuclear winter’ was coined, based on back-of-the-envelope calculations. Despite the end of the cold war era the risk of nuclear conflict (NC) persists, 8 nations still maintain a nuclear arsenal capable of causing severe climate perturbations and humanitarian catastrophe. Yet it was only recently that scientists started to study the indirect risks of NC in more detail, harnessing advances in modern climate and crop modeling. These studies corroborate early estimates and show that even limited NC can cause severe and unprecedented disruptions to global food systems. However, these models were originally developed to assess global warming, rather than cooling caused by ‘nuclear winter’, rendering these assessments optimistic as they likely underestimate the impacts. In this project we advance a set of three state-of-the-art crop models to represent impacts associated with cold-temperature damage, excess moisture, and flooding, which leads to more realistic and rigorous conclusions as to what extent NC may affect global food systems. This project provides critical new evidence highlighting that indirect effects of NC extend globally.

Not all damage mechanisms are implemented in crop models. This project aims at improving the representation of different damage functions in the global dynamic vegetation, hydrology, and crop model LPJmL that affect the ability to simulate impacts of NC as well as global warming.

PIK will use the global dynamic vegetation, hydrology, and crop model LPJmL to improve modeling capacities and then to contribute to to the global gridded crop model intercomparison (GGCMI) ensemble simulations.