Obesity, Global Warming, and Future Famines
March 9, 2023
by William P. Meyers

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Good News and Bad News

The good news is that so many Americans are obese that in the event of a substantial crop failure, we might be able to muddle through to the next harvest without anyone starving. The bad news is that crop failures are almost certain to become more common, and at some point not everyone in the United States will be able to get a fair amount of calories. That is, substantial numbers of people will die of starvation.

I am going to show this by walking through quite a mass of numbers. These numbers indicate that our agricultural sector can easily support an even larger human population, if everything stays the same. The problem is that everything is not going to stay the same. America has seen bad harvests for certain crops or certain regions many times in its history. In 2021 and 2022 we had regional crop failures for wheat and cotton. We have had peanut failures and corn failures and all sorts of failures of minor vegetable and fruit crops. But as the globe warms we are certain to see hotter summers and, in particular, larger and nastier heat domes. With a large enough heat dome at the wrong time of year there could be a major reduction in the amount of food, as measured in calories, available per person. There is really no limit to how bad this could become over the years. As a comparison, for 2022-23 Argentina has had its soybean crop estimate reduced from 51 million tons to 37 million tons, a reduction of 27.5%. Since Argentina is a major food exporter, no one in Argentina is likely to starve this year. If the U.S. has a bad year, but the global market is good, we'll just buy what we need and let the less affluent nations manage their calories. But if the world market is thin and we have a really bad year, or even worse a sequence of bad years, then . . . well, lets count some calories.

How many calories per day, on average, does a person need? It varies by factors like size, weight, and level of physical activity. It also depends on how you define "need." Throw two men of the same height into cells and refuse to feed either. If one is obese and you come back a month later, he will be mad, but alive. If one is a what is called a healthy weight, in thirty days he will probably be dead. But aside from having fat to burn off, an obese person needs more calories per day, to stay at a constant weight, than a thin person does (assuming equal amounts of physical activity).

You can see estimated calorie requirements for different types of people (sex, height, weight, activity levels) with this Calorie Calculator for maintaining weight. I will come back to this when I get to the famine part of the essay, but for now I will just prep you with two examples, showing how different requirements can be for maintaining weight. A 50 year old, 5'4", 120 lb. female, who is somewhat active needs 1,650 calories per day to maintain her weight. A 50 year old, 5'10", 300 lb. male, who is somewhat active requires 2,750 calories. The difference in 1,100 calories or 67%.

Diets vary, so for purposes of calculation I will focus on America's two big calorie producing crops: corn and wheat. Soy and potatoes are also relatively large calorie crops, but soybeans are mainly fed to animals and potatoes are far less significant than wheat and corn. One ounce of whole wheat flour has (typically) 96 calories. There are sixty pounds in a typical bushel, so there are 92,140 calories in a bushel of wheat. The 2022/23 U.S. harvest was 1.65 billion bushels. Divide that by 334 million Americans and you get 4.94 bushels per person per year, or 455 thousand calories per person per year. Per day per person it is 550. [I used a spreadsheet, which allowed me to look at more scenarios than I am presenting here.]

Following the same path with our largest crop, corn, which has 119 calories per ounce, you end up with almost 12,000 calories per person per day. Soybeans add another 4,200 calories per day. So we should be awash in calories. Divided up evenly, American farms produce about 17,428 calories per human per day. It is a wonder that only 33% of adult Americans are obese (and another 34% are overweight). I will use a round number, 2,000 calories per day, as an average of what people need (that is more than a 5'4", 120 pound female needs to stay at weight, but less than a 5'10" 160 pound male needs to stay at weight). Mostly tall people need more calories than short people, but other variables apply.

The calories must go somewhere, and indeed far less calories are actually available to we humans. Despite our penchant for nachos, Americans do not eat very much corn, not directly. Yes, I can see all you vegetarian and especially vegan students waving your hands, shouting "I know, I know." Most of the corn is used to feed animals including meat and laying chickens, milk and beef cows, and pigs. Some of that in turn supplies calories to humans, but for now I will treat them as waste. Considerable corn is also used for producing fuel alcohol and other non-food products. Fairly large quantities of corn and wheat are exported. Apparently only about 13% of the corn, and almost no soy, is produced for direct human consumption. Some wheat also is used to feed animals, but more is exported, so less than half goes to direct human consumption in the U.S. On top of, or leftover after, is the enormous waste due to spoilage and people buying food, eating only part, and then throwing the remainder away.

Applying these reductions, I found corn, wheat and soy contributed 2,434 possible calories per U.S. human per day. More than should be needing even without adding in every calorie from apples to zebra meat. So what if crops get knocked back a bit by global warming? We should be fine.

The real future pathway is complicated. In the event of shortages we could cut off exports, but then other nations might cut off imports when we need them. The corn that goes to ethanol could be turned to grits and corn flour, but it is generally not considered fit for human consumption. We eat different varieties of corn than those used for animal feed and ethanol. Aside from grumbling about how bad the new, government-issued corn chips taste, we would need a new year and vast quantities of human-food-corn seed to make up the deficit. Seed companies would have to redirect their efforts, which could take a year or more. Major wheat crop failures would have worse impacts than corn failures. Typically, animal feed acres of corn would need to be converted to additional wheat acres, something that again takes at least a year.

How bad would it need to get for us to go into a calorie deficit? I think 1,500 calories per day is a good number to start with. An unhappy number for those not used to it, but well above famine level. In addition to the 22% loss needed to get from the 2,434 calories currently available to the 2,000 real-need level, that would be a 25% reduction from 2,000 calories. About the reduction Argentina saw this year. How likely is that?

The United States has many corn and wheat growing regions. The top 10 wheat states in order are (usually): Kansas, North Dakota, Washington State, Montana, Oklahoma, Idaho, Colorado, Minnesota, Texas, and Oregon. But Kansas and North Dakota produce near half our wheat. We have a recent example from Washington State of the magnitude of crop damage when global warming causes a heat dome event. In 2021 the Washington wheat harvest was just 87.2 million bushels. In a more normal year, 2022, the harvest was 144 million bushels. So we have just seen a 39% reduction is a major wheat harvesting area due to a single global-warming event.

Suppose there is a heat dome large enough, or moving between, Kansas and North Dakota at the right time to produce a 40% reduction in the wheat crops of those states. Suddenly, even if we refuse to export wheat, even if none is use for animal feed, the US daily calorie availability per person from wheat drops to about 700 calories. Starvation calories, which will lead to death if not increased, are 600 per day. But what about corn and everything else?

The leading corn producing states are: Iowa, Illinois, Nebraska, Minnesota, Indiana, South Dakota, Kansas, Ohio, Wisconsin, and Missouri. Take out a map if you are not familiar with the midwest. If Kansas and North Dakota are damaged by a heat dome, chances are Iowa, Illinois, Nebraska, and South Dakota will be too. True, that is a massive heat dome. Or it could be three heat domes, one when the plants are young in one region, once during pollination in a second region, and one that prevents grains from filling out in a third.

Actual probabilities of such a disaster are hard to calculate. We are likely to see increasing frequency of regional poor to bad harvests as time goes on. When The Big One hits, the one that means that the U.S. is in its first famine since the Civil War, no one can predict with any certainty. But since global carbon dioxide levels are continuing to increase, since the poles are melting, I can say that The Big One will be here sometime, and perhaps sooner than anyone (except me and a few other analysts and alarmists) think. Throw in some other factors, like pesticide-resistant weeds, insects, and pathogens, and the likelihood increases.

How might rationing work in America? Giving everyone the same calories per day might seem fair, but given the different needs of a tall and a short person, some allowance might be made for that. In a truly dire situation, should obese people get the same number of calories as those who are already perilously thin? My thought is that obese people should get a ration of minimal calories, say 300 per day, until they are back to the normal weight range. But what will likely happen in the U.S. is the upper middle class and rich will be able to buy the calories they need. The poor will get what they need from the government, at least in the Blue states. It is the lower-income workers who will be left to fight over the scraps.