Feeding the additional population threatened by El Nino

Before checking sources

Matt's first pass

This was a difficult one to formulate. First I tried to estimate how many calories should count as acute food insecurity and how many of those calories might be supplemented by aid food. I settled on a per-person supplement of about 1,250 calories daily, about half an average adult's required intake.

For mass and volume, I guessed that would equate to about half a kilogram of staple food per person.

people needing additional support ~= 4.9 x 10^7
food supplement ~= 0.5 kg/person/day

daily food mass ~= 4.9 x 10^7 x 0.5
                ~= 2.5 x 10^7 kg/day

weekly food mass ~= 2.5 x 10^7 x 7
                 ~= 1.8 x 10^8 kg/week

I guessed that grain food has a density of about 700 kg/m3, low enough that it would float but still quite dense. That means weekly volume would be:

weekly volume ~= 1.8 x 10^8 kg / 700 kg/m3
              ~= 2.6 x 10^5 m3/week

Then I assumed both ships and cargo trucks would be required. For total distance, I took half the circumference of Earth, about 19,000 km, and guessed the average food-aid trip might be 10% of that, or about 1,900 km. I split that into roughly 1,800 km by ship and 100 km by truck.

I assumed a ship could hold 100 food-aid cargo containers, and each cargo container might average about 16 m3 of food aid. That made me estimate about 1,600 containers each week, and I wrote down 160 ships. I assumed a large cargo truck could hold about 50 m3, which gave about 5,000 cargo trucks.

For transportation cost, I estimated roughly $330,000 per week for the truck portion and $420,000 for the ocean portion, or about $750,000 per week to move the food. This did not include the cost of the food itself.

For current production, I guessed staple grains account for about 60% of all calories consumed worldwide. For 8 billion people, that means we are currently growing enough grain calories to support the full caloric needs of about 5 billion people. If we need to increase capacity to support half the caloric needs of about 50 million people, I estimated that at about 0.5% of current grain production worldwide.

Post-check reflection

Matt's reflection

Looks like I pretty much nailed my mass and volume estimates for supplementary food aid for that group. I was also very close on the global annual grain production percentage.

I way underestimated how much a shipping vessel could carry, so my count of shipments necessary was way high, and my truck count was also a bit low, though not by several orders of magnitude. I should have been estimating according to mass carried rather than volume. Those seem like important pegs to keep track of: about 30,000 to 75,000 metric tons on a ship, and about 20 to 25 tons on a cargo truck. I bet that will come up again.

I was also way under on the ocean freight estimate. Another great peg is about $40 per metric ton for a long-range shipping cost. Ultimately, my calculation put me just under $1 million per week, and the revised calculation is closer to $7 or $8 million. Technically that is a success for Fermi, but I could have gotten closer with some better starting assumptions.

While 0.3% of current grain production seems like a tiny relative amount, that corresponds to a lot of extra production capacity being activated. My understanding is that there is not a lot of arable land available to expand food production into, especially if climate change is affecting what land can be productively cultivated. We would be more reliant on deploying more productive strategies rather than just using more land. Either way, this is no minor undertaking. I think this is an especially important news item, and one that appears even more important after running these numbers.