A New Ocean State After Nuclear War

Abstract

Nuclear war would produce dire global consequences for humans and our environment. We simulated climate impacts of US‐Russia and India‐Pakistan nuclear wars in an Earth System Model, here, we report on the ocean impacts. Like volcanic eruptions and large forest fires, firestorms from nuclear war would transport light‐blocking aerosols to the stratosphere, resulting in global cooling. The ocean responds over two timescales: a rapid cooling event and a long recovery, indicating a hysteresis response of the ocean to global cooling. Surface cooling drives sea ice expansion, enhanced meridional overturning, and intensified ocean vertical mixing that is expanded, deeper, and longer lasting. Phytoplankton production and community structure are highly modified by perturbations to light, temperature, and nutrients, resulting in initial decimation of production, especially at high latitudes. A new physical and biogeochemical ocean state results, characterized by shallower pycnoclines, thermoclines, and nutriclines, ventilated deep water masses, and thicker Arctic sea ice. Persistent changes in nutrient limitation drive a shift in phytoplankton community structure, resulting in increased diatom populations, which in turn increase iron scavenging and iron limitation, especially at high latitudes. In the largest US‐Russia scenario (150 Tg), ocean recovery is likely on the order of decades at the surface and hundreds of years at depth, while changes to Arctic sea‐ice will likely last thousands of years, effectively a “Nuclear Little Ice Age.” Marine ecosystems would be highly disrupted by both the initial perturbation and in the new ocean state, resulting in long‐term, global impacts to ecosystem services such as fisheries.

Food Security after Nuclear Winter: A Preliminary Agricultural Sector Analysis for Aotearoa New Zealand

“…55 There may also be complex nuclear winter effects on sea-ice and oceans that impact on fisheries for very long periods. 29…”

“…The scientific understanding of the impacts of abrupt sunlight reduction catastrophes has evolved as well. 26–29…”

“…The scientific understanding of the impacts of abrupt sunlight reduction catastrophes has evolved as well. [26][27][28][29] Given the above, we aimed to begin to explore the food security issues for NZ after such catastrophes by describing the current food export economy as well as the potential food supply when accounting for the climate impacts of a nuclear winter. In this preliminary work, we focused on the food export sector as the data appeared to provide a much clearer picture of food production than the far more diverse and complex domestic food production sector.…”

Impact of the Tambora Volcanic Eruption of 1815 on Islands and Relevance to Future Sunlight-Blocking Catastrophes

“…but also includes climatic impacts on different types of crops (as per Kandlbauer et al 18 ). Complex impacts on sea-ice and oceans of reduced sunlight also need to be considered (including impacts on sheries), as per work on nuclear winter 9 . Further work with historical records on food prices in markets may also clarify food production and food insecurity issues in some islands after the Tambora eruption.…”

Sudden Reduction of Antarctic Sea Ice Despite Cooling After Nuclear War

“…Here, we perform the first analysis of impacts of a nuclear winter on Antarctic sea ice through climate modeling experiments. Nuclear war's environmental impact has been explored previously using climate models to investigate other aspects of the climate system (Coupe et al., 2019, 2021; Harrison et al., 2022). As up to 150 Tg of smoke enters the upper atmosphere, sudden climate change is likely as solar radiation is blocked from reaching the ground (Coupe et al., 2019; Robock et al., 2007).…”