A regional nuclear conflict would compromise global food security

Nonindustrial pretreatment and enzymes can yield sufficient calories from lignocellulosic biomass for human survival

Following a global catastrophe causing reduced sunlight, the environment would become unfavorable for crop growth. Under such conditions, people might need to convert inedible plant biomass into food to meet their daily nutritional requirements. However, the possibility of converting biomass into food under low-resource conditions has not been thoroughly studied. To address this uncertainty, we evaluated the potential for using resources available in a typical household to extract sugars from willow biomass and meet the carbohydrate needs of an adult. Grinding willow biomass in a household blender for 24 min produced willow particles similar to those produced in a laboratory-scale Wiley mill. Thermal treatments of these particles with hot water extraction, pressure cooking, or microwaving only extracted 0.5%-0.8% (w/w) glucose from the biomass. Household acid or alkali treatments yielded only 0.5% (w/w) glucose. These sugar yields would be insufficient to provide nutrition to an adult. In contrast, enzymatic hydrolysis of pretreated willow at 50°C for 72 h yielded 2%-8% (w/w) glucose, and pretreating willow with sodium hydroxide and pressure before enzymatic treatment increased glucose yields to 28% (w/w). With this pretreatment approach and subsequent enzymatic conversion, ~1.4 kg of biomass/day could potentially fulfill the energy needs of an adult under post-catastrophic conditions. We posit that while biomass can be successfully pretreated for enzymatic deconstruction at a household level, producing sufficient enzymes for efficient sugar extraction from inedible plant biomass in a post-catastrophic environment might not be feasible at the household scale, thus requiring community-scale infrastructure and coordination.

Mitigating imported fuel dependency in agricultural production: Case study of an island nation's vulnerability to global catastrophic risks

A major global catastrophe would likely disrupt trade in liquid fuels. Countries dependent on imported oil products might struggle to sustain industrial agriculture. Island nations importing 100% of refined fuels are particularly vulnerable. Our case study aimed to estimate the agricultural land area and biofuel volumes needed to feed the population of New Zealand in the absence of trade. Results showed that stored diesel would quickly be exhausted with ordinary use (weeks) and even with strict rationing (months). To preserve fuel, we found that farming wheat (requiring as little as 5.4 million liters [L] of diesel per annum) was more fuel-efficient than potatoes (12.3) or dairy (38.7) to feed the national population under a climate-as-usual scenario. In a nuclear winter scenario, with reduced agricultural yields, proportionately greater diesel is needed. The wheat would require 24% of current grain-cropped land, and the canola crop used as feedstock for the required biofuel would occupy a further 1%-7%. Investment in canola biodiesel or renewable diesel refineries could ensure supply for the bare minimum agricultural liquid fuel needs. Were subsequent analysis to favor this option as part of a fuels resilience response and as a tradeoff for routine food use, expansion in refining and canola cropping before a catastrophe could be encouraged through market mechanisms, direct government investment, or a combination of these. Logistics of biofuel refining scale-up, post-catastrophe, should also be analyzed. Further, biodiesel produced in normal times would help the nation meet its emissions reduction targets. Other countries should conduct similar analyses.

Storable, neglected, and underutilized species of Southern Africa for greater agricultural resilience

The Southern African region suffers from drought and food system uncertainty with increased risks due to climate change, natural disasters, and global catastrophes. Increasing crop diversity with more appropriate and resilient crops is an effective way of increasing food system resilience. We focus on crop species that are native or naturalized to an area because of their increased resilience than those that are not naturally occurring. Additionally, crops that are easily stored are more useful in times of drought and disaster. In this systematic review, we use scientific interest in neglected and underutilized species (NUS) from Southern Africa to help define next steps toward their cultivation and development as a marketable crop. We found that although scientific interest is minimal for storable Southern African NUS, these crops are worth scaling up due to their economic and nutritional value. We outline next actionable steps and specific NUS for production in a more agrobiodiverse and resilient agriculture system.

Air quality improvements can strengthen China's food security

Air pollution exerts crucial influence on crop yields and impacts regional and global food supplies. Here we employ a statistical model using satellite-based observations and flexible functional forms to analyse the synergistic effects of reductions in ozone and aerosols on China's food security. The model consistently shows that ozone is detrimental to crops, whereas aerosol has variable effects. China's maize, rice and wheat yields are projected to increase by 7.84%, 4.10% and 3.43%, respectively, upon reaching two air quality targets (60 μg m-3 for peak-season ozone and 35 μg m-3 for annual fine particulate matter). Average calories produced from these crops would surge by 4.51%, potentially allowing China to attain grain self-sufficiency 2 years earlier than previously estimated. These results show that ozone pollution control should be a high priority to increase staple crop edible calories, and future stringent air pollution regulations would enhance China's food security.

Assessing lignocellulosic biomass as a source of emergency foods

Catastrophes such as a nuclear war would generate atmospheric soot and reduce sunlight, making it difficult to grow crops. Under such conditions, people might turn to inedible plant biomass for nutrition, but the convertibility and nutritional content of this biomass have not been rigorously analyzed. We found that if plant biomass were converted into food at 30% efficiency, 6.7 kg of biomass per day would yield adequate carbohydrates, but contain potentially toxic or insufficient levels of other nutrients for a family of four. Therefore, exploiting biomass with low mineral content for carbohydrates and consuming other sources of protein, fat, and vitamins such as edible insects/single-cell proteins and vitamin supplements could provide a balanced diet in a global catastrophic environment.

Public health and nuclear winter: addressing a catastrophic threat

Despite the end of the Cold War, the world still has thousands of nuclear weapons and adversarial relations between the countries that possess them. A nuclear war could cause large and abrupt global environmental change known as nuclear winter, with potentially devastating public health consequences. A significant line of natural science research characterizes nuclear winter and its potential effect on global food security, but less has been done on the human impacts and policy implications. Therefore, this Viewpoint proposes an interdisciplinary research and policy agenda to understand and address the public health implications of nuclear winter. Public health research can apply existing tools developed for the study of other environmental and military issues. Public health policy institutions can help build preparedness and community resilience to nuclear winter. Given the extreme potential severity of nuclear winter, it should be treated as a major global public health challenge to be addressed by public health institutions and researchers.

Island refuges for surviving nuclear winter and other abrupt sunlight-reducing catastrophes

Some island nations in the Southern Hemisphere might survive a severe sun-reducing catastrophe such as nuclear winter and be well placed to help reboot-collapsed human civilization. Such islands must be resilient to the cascading effects abrupt sunlight reduction scenarios (ASRS) would impose beyond the impacts on agricultural systems. We aimed to identify island nations whose societies are most likely to survive nuclear winter or other ASRS. We also aimed to conduct a case study of one island nation to consider how it might enhance its resilience and therefore its chance of aiding a global reboot of complex technological society. We performed a threshold analysis on food self-sufficiency under severe nuclear winter conditions to identify islands. We then profiled each island across global macroindices representing resilience factors reported in the literature. We undertook a case study of the island nation of New Zealand. The island nations of Australia, New Zealand, Iceland, the Solomon Islands, and Vanuatu appear most resilient to ASRS. However, our case-study island nation of New Zealand is threatened in scenarios of no/low trade, has precarious aspects of its energy supply, and shortcomings in manufacturing of essential components. Therefore, inadequate preparations and critical failures in these systems could see rapid societal breakdown. Despite some islands' favorable baseline conditions and apparent food security even in a severe ASRS, cascading impacts through other socioecological systems threaten complex functioning. We identified specific resilience measures, many with cobenefits, which may protect island nodes of sustained complexity in ASRS.

Seaweed extract and arbuscular mycorrhiza co-application affect the growth responses and essential oil composition of Foeniculum vulgare L

The influence of arbuscular mycorrhiza fungi (AMF) inoculation, seaweed extract (SWE) foliar use, and their co-applications were evaluated on the growth-associated traits, antioxidant potential, essential oil profile, and the nutrients content of fennel plants. A factorial experiment was conducted as a completely randomized design with two factors and four replications in the greenhouse. The factors were: AMF inoculation (not inoculated and inoculated with 5 g kg^-1) and SWE foliar application (0, 0.5, 1.5, or 3 g L^-1). The highest root colonization percentage was recorded in plants treated with AMF + 3 g L^-1 of SWE. The top recorded plant height, leaf number, leaf dry weight, biomass, thousand seed weight (TSW), total soluble proteins and total soluble carbohydrates content, antioxidant activity, and essential oil content belonged to AMF + 3 g L^-1 of SWE. Furthermore, the co-application of AMF + SWE resulted in a considerable enhancement of the photosynthetic pigments content and, in N, P, K, Fe, Zn, and Mn contents in the shoots and roots. The GC-FID and GC-MS analysis revealed that (E)-anethole (73.28-76.18%), fenchone (5.94-8.26%), limonene (4.64-6.58%), methyl chavicol (2.91-3.18%), and (Z)-β-ocimene (1.36-2.01%) were the principal essential oil constituents. The top (E)-anethole and fenchone contents were obtained by AMF + SWE. Altogether, the simultaneous application of AMF and SWE could be introduced as an environment-friendly strategy to reach reliable growth responses, especially in fennel plants' enriched with some precious essential oil constituents.

Mathematical optimization of frost resistant crop production to ensure food supply during a nuclear winter catastrophe

This study aimed to estimate the optimal mix of frost resistant crops and land area needed to provide basic nutrition during various nuclear winter scenarios for New Zealand (NZ), a temperate island nation. It used linear programming to minimize land area required for cropping while producing enough food to achieve dietary energy and protein requirements for the whole population. The potential agricultural impacts of three nuclear winter scenarios on NZ, were sourced from the literature. The optimized combinations of frost resistant crops that were found to feed the entire population were, in descending order: wheat and carrots; sugar beet; oats; onions and carrots; cabbage and barley; canola and cabbage; linseed and parsnip; rye and lupins; swede and field beans; and cauliflower. But in terms of current production levels of these frost resistant crops in NZ, there would be a 26% shortfall for the "war without a nuclear winter" scenario and a 71% shortfall for the severe nuclear winter scenario (150 Tg of soot in the stratosphere with a 61% decline in crop yields). In conclusion, at current production levels, frost resistant food crops could not feed all NZ citizens following a nuclear war. There is a need for the NZ Government to conduct a detailed pre-war analysis on how these shortfalls are best addressed. For example, by: increased pre-war production of these crops and/or post-war scalability; growing enough frost sensitive crops (i.e., in greenhouses or the warmest parts of the country); and/or ensuring continuing production of food derived from livestock fed on frost resistant grasses.

Structural Evolution of Global Soybean Trade Network and the Implications to China

China experiences a serious shortage of soybean supplies and relies heavily on international trade with high vulnerability and large uncertainty, which maybe sows food security risks. It is of great significance to analyze the structural evolution of the global soybean trade network and its implications to China for ensuring food security. This paper constructed a global soybean trade network (GSTN) and analyzed the structural evolutionary characteristics of GSTN from 2000 to 2020 using the complex network analysis method and simulated the impact of targeted destruction on China through scenario analysis. The results showed that GSTN was gradually complex exhibiting a small word and a scale-free network property. The global soybean exporter was dominated by some major soybean-producing countries in America. The US played an important role in maintaining GSTN's robustness. China was the world's largest soybean importer; unfortunately, its soybean imports relied heavily on a few countries, and the anti-interference ability of China's soybean trade tended to decline. Therefore, China's soybean trade was increasingly vulnerable to being tightly controlled by other countries when some uncertain factors occurred, such as trade frictions and changes in policy decisions from importing and exporting countries. The US and Brazil were key countries with significant soybean trade ties to China. To assess the impact of the two countries on China's soybean trade, targeted destruction method was used through destroying them in the network. Targeted destruction scenario analysis indicated the two countries played important roles in the anti-interference ability of China's soybean trade. Brazil played a positive role in China's control of soybean trade flows, while the US did not. Some policies for China's soybean production and international trade were proposed. A balance between the domestic production and import of soybean is needed. Optimizing the soybean trade import system and seeking more trade partners is crucial. Improving soybean self-sufficiency is the fundamental way to reduce the high-import dependence. The study provided some insights for coping with international market fluctuations and improving the sustainability of China's soybean trade.

Assumptions, uncertainty, and catastrophic/existential risk: National risk assessments need improved methods and stakeholder engagement

Two key shortcomings of national risk assessments (NRAs) are: (1) lack of justification and transparency around important foundational assumptions of the process, (2) omission of almost all the largest scale risks. Using a demonstration set of risks, we illustrate how NRA process assumptions around time horizon, discount rate, scenario choice, and decision rule impact on risk characterization and therefore any subsequent ranking. We then identify a neglected set of large-scale risks that are seldom included in NRAs, namely global catastrophic risks and existential threats to humanity. Under a highly conservative approach that considers only simple probability and impact metrics, the use of significant discount rates, and harms only to those currently alive at the time, we find these risks have likely salience far greater than their omission from national risk registers might suggest. We highlight the substantial uncertainty inherent in NRAs and argue that this is reason for more engagement with stakeholders and experts. Widespread engagement with an informed public and experts would legitimize key assumptions, encourage critique of knowledge, and ease shortcomings of NRAs. We advocate for a deliberative public tool that can support informed two-way communication between stakeholders and governments. We outline the first component of such a tool for communication and exploration of risks and assumptions. The most important factors for an "all hazards" approach to NRA are ensuring license for key assumptions and that all the salient risks are included before proceeding to ranking of risks and considering resource allocation and value.

Impact of the Tambora volcanic eruption of 1815 on islands and relevance to future sunlight-blocking catastrophes

Island nations may have potential long-term survival value for humanity in global catastrophes such as sun-blocking catastrophes from nuclear winter and large magnitude volcanic eruptions. One way to explore this issue further is to understand the impact on islands after the largest historically observed volcanic eruption: that of Mt Tambora in 1815. For each of the 31 large, populated islands selected, we conducted literature searches for relevant historical and palaeoclimate studies. We also analysed results from a reconstruction (EKF400v2), which uses atmospheric-only general circulation model simulations with assimilated observational and proxy data. From the literature review, there was widespread evidence for weather/climate anomalies in 1815-1817 for these islands (29/29 for those with data). But missing data was an issue for other dimensions such as impaired food production (seen in 8 islands out of only 12 with data). Based on the EKF400v2 reconstruction for temperature anomalies (compared to the relatively "non-volcanic" reference period of 1779 to 1808), the islands had lower temperature anomalies in the 1815-1818 period than latitudinally equivalent continental sites (at 100 km and 1000 km inland). This was statistically significant for the great majority of the comparisons for group analyses by hemisphere, oceans, and temperate/tropical zone. When considering just the islands, all but four showed statistically anomalous temperature reductions in the 1816-1817 period (for most p < 0.00001). In the peak impact year of 1816, the lowest anomalies were seen for islands in the Southern Hemisphere (p < 0.0001), the Indian Ocean (p < 0.0001), and in the tropics and subtropics of the Southern Hemisphere (p = 0.0057). In conclusion, the findings of both the literature review and reconstruction simulations suggest climatic impacts of the Tambora eruption for nearly all these 31 large islands, albeit less than for continental sites. Islands with the smallest temperature anomalies were in the Southern Hemisphere, in particular the Indian Ocean and the tropics and subtropics of the Southern Hemisphere.

Food resilience in a dark catastrophe: A new way of looking at tropical wild edible plants

A global sun-blocking catastrophe is more plausible than anyone would like to think. Models have consistently shown the devastating effects these events could have to the world's agricultural systems for upwards of 15 years. New shade-, drought-, and cool-tolerant crops and more food stockpile sources must be found if there would be any hope of feeding the global population in such a scenario. Wild edible plants (WEPs) are important buffers of food security to indigenous peoples, impoverished peoples, and those in areas with erratic growing seasons across the globe. Here, we suggest WEP species that have the potential to be scaled up through cultivation in post-catastrophe conditions, and the use of foraged food stockpiles to function as stop-gap foods until conventional agriculture returns. We also propose policy initiatives for habitat protection, education programs, and general preparedness.

Global food insecurity and famine from reduced crop, marine fishery and livestock production due to climate disruption from nuclear war soot injection

Atmospheric soot loadings from nuclear weapon detonation would cause disruptions to the Earth’s climate, limiting terrestrial and aquatic food production. Here, we use climate, crop and fishery models to estimate the impacts arising from six scenarios of stratospheric soot injection, predicting the total food calories available in each nation post-war after stored food is consumed. In quantifying impacts away from target areas, we demonstrate that soot injections larger than 5 Tg would lead to mass food shortages, and livestock and aquatic food production would be unable to compensate for reduced crop output, in almost all countries. Adaptation measures such as food waste reduction would have limited impact on increasing available calories. We estimate more than 2 billion people could die from nuclear war between India and Pakistan, and more than 5 billion could die from a war between the United States and Russia—underlining the importance of global cooperation in preventing nuclear war.

Microbiota Communities of Healthy and Bacterial Pustule Diseased Soybean

Soybean is an important source of protein and for a wide range of agricultural, food, and industrial applications. Soybean is being affected by Xanthomonas citri pv. glycines, a causal pathogen of bacterial pustule disease, result in a reduction in yield and quality. Diverse microbial communities of plants are involved in various plant stresses is known. Therefore, we designed to investigate the microbial community differentiation depending on the infection of X. citri pv. glycines. The microbial community's abundance, diversity, and similarity showed a difference between infected and non-infected soybean. Microbiota community analysis, excluding X. citri pv. glycines, revealed that Pseudomonas spp. would increase the population of the infected soybean. Results of DESeq analyses suggested that energy metabolism, secondary metabolite, and TCA cycle metabolism were actively diverse in the non-infected soybeans. Additionally, Streptomyces bacillaris S8, an endophyte microbiota member, was nominated as a key microbe in the healthy soybeans. Genome analysis of S. bacillaris S8 presented that salinomycin may be the critical antibacterial metabolite. Our findings on the composition of soybean microbiota communities and the key strain information will contribute to developing biological control strategies against X. citri pv. glycines.

Potential impacts of climate change on agriculture and fisheries production in 72 tropical coastal communities

Climate change is expected to profoundly affect key food production sectors, including fisheries and agriculture. However, the potential impacts of climate change on these sectors are rarely considered jointly, especially below national scales, which can mask substantial variability in how communities will be affected. Here, we combine socioeconomic surveys of 3,008 households and intersectoral multi-model simulation outputs to conduct a sub-national analysis of the potential impacts of climate change on fisheries and agriculture in 72 coastal communities across five Indo-Pacific countries (Indonesia, Madagascar, Papua New Guinea, Philippines, and Tanzania). Our study reveals three key findings: First, overall potential losses to fisheries are higher than potential losses to agriculture. Second, while most locations (> 2/3) will experience potential losses to both fisheries and agriculture simultaneously, climate change mitigation could reduce the proportion of places facing that double burden. Third, potential impacts are more likely in communities with lower socioeconomic status.

Ending nuclear weapons before they end us: current challenges and paths to avoiding a public health catastrophe

The United Nations Treaty on the Prohibition of Nuclear Weapons (TPNW)-an important planetary health good-entered into legal force in January 2021. Evidence of the consequences of nuclear war, particularly the global climatic and nutritional effects of the abrupt ice age conditions from even a relatively small regional nuclear war, indicates that these are more severe than previously thought. None of the nine nuclear-armed states is disarming; instead, all invest enormously in new and more hazardous nuclear weapons. Nor has any of the 32 states claiming reliance on another state's nuclear weapons yet ended such reliance. These factors, abrogation of existing nuclear arms control agreements, policies of first nuclear use and war fighting, growing armed conflicts worldwide, and increasing use of information and cyberwarfare, exacerbate dangers of nuclear war. Evidence-based advocacy by health professionals on the planetary health imperative to eliminate nuclear weapons has never been more urgent.

Nutrition in Abrupt Sunlight Reduction Scenarios: Envisioning Feasible Balanced Diets on Resilient Foods

Abrupt sunlight reduction scenarios (ASRS) following catastrophic events, such as a nuclear war, a large volcanic eruption or an asteroid strike, could prompt global agricultural collapse. There are low-cost foods that could be made available in an ASRS: resilient foods. Nutritionally adequate combinations of these resilient foods are investigated for different stages of a scenario with an effective response, based on existing technology. While macro- and micronutrient requirements were overall met, some-potentially chronic-deficiencies were identified (e.g., vitamins D, E and K). Resilient sources of micronutrients for mitigating these and other potential deficiencies are presented. The results of this analysis suggest that no life-threatening micronutrient deficiencies or excesses would necessarily be present given preparation to deploy resilient foods and an effective response. Careful preparedness and planning-such as stock management and resilient food production ramp-up-is indispensable for an effective response that not only allows for fulfilling people's energy requirements, but also prevents severe malnutrition.

Climate impacts on global agriculture emerge earlier in new generation of climate and crop models

Potential climate-related impacts on future crop yield are a major societal concern. Previous projections of the Agricultural Model Intercomparison and Improvement Project's Global Gridded Crop Model Intercomparison based on the Coupled Model Intercomparison Project Phase 5 identified substantial climate impacts on all major crops, but associated uncertainties were substantial. Here we report new twenty-first-century projections using ensembles of latest-generation crop and climate models. Results suggest markedly more pessimistic yield responses for maize, soybean and rice compared to the original ensemble. Mean end-of-century maize productivity is shifted from +5% to -6% (SSP126) and from +1% to -24% (SSP585)-explained by warmer climate projections and improved crop model sensitivities. In contrast, wheat shows stronger gains (+9% shifted to +18%, SSP585), linked to higher CO₂ concentrations and expanded high-latitude gains. The 'emergence' of climate impacts consistently occurs earlier in the new projections-before 2040 for several main producing regions. While future yield estimates remain uncertain, these results suggest that major breadbasket regions will face distinct anthropogenic climatic risks sooner than previously anticipated.

Large potential for crop production adaptation depends on available future varieties

Climate change affects global agricultural production and threatens food security. Faster phenological development of crops due to climate warming is one of the main drivers for potential future yield reductions. To counter the effect of faster maturity, adapted varieties would require more heat units to regain the previous growing period length. In this study, we investigate the effects of variety adaptation on global caloric production under four different future climate change scenarios for maize, rice, soybean, and wheat. Thereby, we empirically identify areas that could require new varieties and areas where variety adaptation could be achieved by shifting existing varieties into new regions. The study uses an ensemble of seven global gridded crop models and five CMIP6 climate models. We found that 39% (SSP5-8.5) of global cropland could require new crop varieties to avoid yield loss from climate change by the end of the century. At low levels of warming (SSP1-2.6), 85% of currently cultivated land can draw from existing varieties to shift within an agro-ecological zone for adaptation. The assumptions on available varieties for adaptation have major impacts on the effectiveness of variety adaptation, which could more than half in SSP5-8.5. The results highlight that region-specific breeding efforts are required to allow for a successful adaptation to climate change.

Toward practical stratospheric aerosol albedo modification: Solar-powered lofting

Many climate intervention (CI) methods have been proposed to offset greenhouse gas-induced global warming, but the practicalities regarding implementation have not received sufficient attention. Stratospheric aerosol injection (SAI) involves introducing large amounts of CI material well within the stratosphere to enhance the aerosol loading, thereby increasing reflection of solar radiation. We explore a delivery method termed solar-powered lofting (SPL) that uses solar energy to loft CI material injected at lower altitudes accessible by conventional aircraft. Particles that absorb solar radiation are dispersed with the CI material and heat the surrounding air. The heated air rises, carrying the CI material to the stratosphere. Global model simulations show that black carbon aerosol (10 microgram per cubic meter) is sufficient to quickly loft CI material well into the stratosphere. SPL could make SAI viable at present, is also more energy efficient, and disperses CI material faster than direct stratospheric injection.

Atmospheric opacity has a nonlinear effect on global crop yields

Agricultural impacts of air pollution, climate change and geoengineering remain uncertain due to potentially offsetting changes in the quantity and quality of sunlight. By leveraging year-to-year variation in growing-season cloud optical thickness, I provide nonlinear empirical estimates of how increased atmospheric opacity alters sunlight across the Earth's surface and how this affects maize and soy yields in the United States, Europe, Brazil and China. I find that the response of yields to changes in sunlight from cloud scattering and absorption is consistently concave across crops and regions. An additional day of optimal cloud cover, relative to a clear-sky day, increases maize and soy yields by 0.4%. Changes in sunlight due to changes in clouds have decreased the global average maize and soy yields by 1% and 0.1% due to air pollution and may further decrease yields by 1.8% and 0.4% due to climate change.

Marine wild-capture fisheries after nuclear war

Nuclear war, beyond its devastating direct impacts, is expected to cause global climatic perturbations through injections of soot into the upper atmosphere. Reduced temperature and sunlight could drive unprecedented reductions in agricultural production, endangering global food security. However, the effects of nuclear war on marine wild-capture fisheries, which significantly contribute to the global animal protein and micronutrient supply, remain unexplored. We simulate the climatic effects of six war scenarios on fish biomass and catch globally, using a state-of-the-art Earth system model and global process-based fisheries model. We also simulate how either rapidly increased fish demand (driven by food shortages) or decreased ability to fish (due to infrastructure disruptions), would affect global catches, and test the benefits of strong prewar fisheries management. We find a decade-long negative climatic impact that intensifies with soot emissions, with global biomass and catch falling by up to 18 ± 3% and 29 ± 7% after a US-Russia war under business-as-usual fishing-similar in magnitude to the end-of-century declines under unmitigated global warming. When war occurs in an overfished state, increasing demand increases short-term (1 to 2 y) catch by at most ∼30% followed by precipitous declines of up to ∼70%, thus offsetting only a minor fraction of agricultural losses. However, effective prewar management that rebuilds fish biomass could ensure a short-term catch buffer large enough to replace ∼43 ± 35% of today's global animal protein production. This buffering function in the event of a global food emergency adds to the many previously known economic and ecological benefits of effective and precautionary fisheries management.

Analysis and vulnerability of the international wheat trade network

Wheat is one of the three basic cereals providing the necessary calorific intake for most of the world's population. For this reason, its trade is critical to many countries in order to fulfil their internal demand and strategic stocks. In this paper, we use complex network analysis tools to study the international wheat trade network and its evolving characteristics for the period 2009-2013. To understand the vulnerability of each country's dependence on the imports of this crop we have performed different analyses, simulating shocks of varying intensities for the main wheat producers, and observed the population affected by the production drop. As a result, we conclude that globally the network is slightly more resilient than four years previously, although at the same time some developing countries have slipped into a vulnerable situation. We have also analysed the effects of a global shock affecting all major producers, assessing its impact on every country. Some comments on the COVID-19 outbreak and the political decisions taken by governments following the pandemic declaration are included, observing that given their capital-intensive characteristics, no negative effects should currently be expected in the wheat market.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12571-020-01117-9.