Agriculture and the global human civilization dependent on it relies on access to sunlight. Several global catastrophes could partially block the sun, which would result in significant reductions in agricultural output and the potential for mass human starvation. The three most probable sun-obscuring scenarios include: (1) bolide (asteroid/comet) impact, (2) a super volcanic eruption or continental basalt flows, or (3) and nuclear war with the burning of cities (nuclear winter) [1
]. Although these are low probability events, they have finite non-zero probabilities [3
], with the most probable being nuclear war. Two estimates based on quantitative models indicate the chance of full-scale nuclear war is ∼1% per year [4
]. This is significant as most of the nuclear powers possess more than the pragmatic limit of nuclear weapons (where the direct physical negative consequences of nuclear weapons use are counter to national interests) [6
]. Even a modest release of nuclear weapons on target cities as a one-sided [6
] or regional nuclear war [7
] could create a nuclear autumn that would starve millions throughout the world [6
]. In addition, there are other less-severe risks to the agricultural system. These include: (1) abrupt climate change [11
], (2) super weed [12
], (3) extirpating crop pathogen [13
], (4) complete loss of pollinators [14
], (5) super bacterium [15
], or (6) super crop pest [16
]. Prevention of these catastrophes would obviously be preferable, but despite the highest probability severe sun-blocking risk being under human control, at present global de-nuclearization appears unlikely in the short term and there are not reliable options for the other large risks.
Therefore, a backup plan is desirable. Previous work has analyzed alternative food supplies that could be viable in these scenarios and optimistically found that the global human population could be maintained even in the most severe catastrophes (e.g., 5 years of blocked sunlight) converting wood and fossil fuels to food [3
]. These calculations were, however, based on macronutrients and although the number of kilocalories could be produced to feed everyone globally, micronutrients were not evaluated in detail. Micronutrients play a central part in metabolism and in the maintenance of human tissue function and are therefore critical for human health [18
]. To provide a complete viable backup food supply for conventional agricultural collapse further research is required [19
]. Previous work has been done on the basics of minerals [17
] and therefore this paper will focus on vitamins to begin to fill in these knowledge gaps. This preliminary study briefly summarizes the alternative food pathways and then evaluates the micronutrients (specifically vitamins) available to meet the percent of the US recommended daily allowance (US RDA) as well as the average requirement defined by the European Food Safety Authority (EFSA) with these foods and closest analogous foods when data are not available. In some global catastrophes some human populations may only have access to a single alternate food. For these situations, the micronutrient profile for a person on a 2100 kcal diet of each alternate food is evaluated for risk of disease. Ideally, populations would have access to an array of alternative foods. For these scenarios, a representative alternative food diet with adequate micronutrients is developed and analyzed. These results are discussed to develop a method to viably produce vitamins to fortify the entire human population for this sun-blocking scenario and other agricultural catastrophic scenarios.
There is good evidence of having complete access to micronutrients (vitamins + minerals) to benefit patients suffering from critical illnesses [18
]. Most benefits from micronutrients appear to come from a well-balanced diet [18
], which is what should be the goal of each community in an alternative food scenario. The minerals could largely be mined and have been investigated previously. Though this mix of alternative foods shown in the sample diet shown in Table 1
and Table 2
would provide adequate vitamins, not every person may have access to this mix. In particular, poorer people would only have access to the lower cost alternative foods. Based on current prices, these would likely be bacteria, enzymatic sugar, fish, and leaf extract [52
]. In addition, vitamin requirements could be different for different people at various stages of their lives. Therefore, it is useful to have additional ways of providing vitamins. One method would be removing vitamins from certain alternate foods to use as supplements for those people who do not eat those particular alternate foods. For instance, if many people do not want to eat significant amounts of bacteria (and the other major nutrient sources shown in Figure 1
are not available), the vitamin E could be removed from the methane-digesting bacteria and fed as a supplement. Another potentially low-cost source of vitamins would be bacteria that can grow on fiber. A higher cost source of vitamins would be bacteria that can grow on food that is digestible by humans.
Humanity has already established methods to synthesize some vitamins [53
]. This could potentially be expanded in catastrophic scenarios which block the sun, but retain industry, and potentially form a multivitamin pill. However, this would not be feasible in scenarios where industry is disabled: electricity could be disrupted by a solar storm, high-altitude electromagnetic pulses from nuclear detonations, or a super computer virus [54
]. Non-industry scenarios would generally still have sunlight, so farming nearly any crop by hand would be feasible. However, it may be that high calorie per hectare crops need to be favored, which could have less than optimal nutrition.
One other option for vitamins would be growing plants with artificial light. However, this is very inefficient and therefore expensive, so it should only be used as a last resort [56
]. In addition, again, this would not be feasible without industry and electricity.
The most extreme scenario is losing industry and the sun. This could occur if the sun is blocked and if international cooperation breaks down. Alternatively, if there is high solar dependent renewable energy penetration (photovoltaics, concentrating solar power, wind power, hydropower, and biofuels), a loss of the sun could mean a collapse of industry as well in the short term. The benefits of making the transition to renewable energy anyway is that large stores of fossil fuel assets would be preserved and could be tapped over time to both provide for energy needs in an extreme sunlight-blocking catastrophe as well as act as a source of alternative foods. Finally, full-scale nuclear war could be coupled with multiple high-altitude electromagnetic pulses (HEMPs). In these scenarios, alternate foods would be required, but industrial synthesis of vitamins would not be possible. Therefore, other techniques such as growing bacteria rich in certain vitamins may be required.
It is clear, however, from this study that far more work needs to be done in this area. First, much better nutritional information is needed about the alternative foods themselves, which are less common (e.g., extracting tea from leaves of different species). Thus, future work is needed to quantify the vitamin content of some of the actual alternative foods (instead of proxies). In addition, detailed nutritional profiles of all the variants of different alternative foods must be analyzed carefully for strategic application (e.g., for a region capable of only producing fish, what is the ideal mushroom types needed to compliment the fish nutrient profile?). In addition, a more granular analysis is needed for the available specific alternative foods in a given area (e.g., what type of fish is available in a given region and what is its nutritional profile). Similarly, the nutritional information (both macro and micro) of secondary sources of alterative foods must be quantified (e.g., the nutritional makeup of chicken is well known, but how does that change if chicken is grown on only bacterial-pre-digested wood?). This information would allow for the analysis of a bare minimum of alternative food diversity that would prevent major diseases such as scurvy. In addition, the nutritional requirements of a low-calorie diet should also be looked at carefully in the cases where human activity would reduce if inadequate calories were available from any of the alternative food pathways in a particular region. Once an alternate food diet is estimated to be safe with analytical methods, trials on animals and eventually humans would provide final validation.
In the Hyogo Framework for Action [57
], this study supports preparedness and identifying risks. Previous work has shown that investing in interventions using alternative foods is cost effective in both the US [58
] and globally [59
]. However, to be prepared, these solutions for food catastrophes must be distributed, so this is a gap in the Post 2015 Framework for Disaster Risk Reduction in that this area is not adequately addressed. Training for these types of catastrophes could be integrated into existing training efforts. In the scenarios that are the focus of this work (sun being blocked) or lesser agricultural tragedies, industry will still generally be functioning, and so will cities. Future work could be quantifying vitamins for the scenarios of losing industry and losing industry and the sun (and vitamins for animals in all the scenarios). Ensuring that everyone could have adequate nutrition would reduce the chance of civilization collapsing, from which humanity might not recover. This reduced chance would benefit the far future, which has been-argued to have overwhelming importance [60
]. Finally, malnutrition and hunger-related disease, results in about 6 million preventable deaths per year in children under 5 years old currently [61
]. This problem when the global agricultural system is functioning is trivial compared to any of the catastrophic situations when it is not. Although research in alternative foods could help feed today’s starving, the fact there are still millions of hungry people when there is adequate food shows that the economics and politics of feeding people both now and in a catastrophe are also important future projects.