With the world on edge due to war, political chaos, and climate change, scientists are starting to plan for worst-case scenarios. One of those scenarios is a global disaster that blocks sunlight and cools the planet, like a nuclear war or a supervolcano eruption. This would make farming extremely difficult and cause major food shortages. So, what should we grow to survive?

A new study published in the journal PLOS One has some answers. Researchers looked at how to feed people in a midsize city using local farming, both during normal times and during a possible nuclear winter. Their goal was to find crops that give the most calories and protein using the least amount of land.

What to grow in normal conditions



If the weather and sunlight stay normal, the best crop to grow is peas. Peas are full of protein and don’t need a lot of space. According to the study, peas can feed a person for a whole year using just over 3,000 square feet of land. That’s far less than crops like cabbage or carrots, which need almost three times more space.


Boyd, one of the authors, said, "Peas are a high protein food. They grow well in urban agriculture environments. If you want to feed someone, growing peas minimizes the amount of land you need to feed that person."

Inside a city, people could grow peas in front yards, backyards, parks, and other green spaces. But even with all that, the city in the study (Palmerston North, New Zealand) could only feed about 20% of its population using just city land.

To feed everyone, the researchers say we’d also need farmland right outside the city. There, potatoes are the best choice during normal times. They grow well, fill you up, and don’t take up much room.


What to grow in a nuclear winter

If the sun is blocked and the planet cools down, the crops we grow must survive frost and low light. In that case, peas wouldn’t work well — they’re not frost-resistant.


Instead, the best crops to grow inside the city are a mix of spinach, sugar beets, wheat, and carrots. These can still grow in colder, darker conditions. But because of the tough weather, crop yields would drop, and city-grown food could feed only about 16% of the population.

Outside the city, the most efficient crop combo is 97% wheat and 3% carrots. Wheat grows in the cold and provides lots of calories, while carrots add nutrition and are also fairly frost-hardy.

Farming fuel and facing challenges


The study also looked at how to power farm machines in a post-disaster world. The answer: grow canola on extra land to turn into biodiesel. This way, tractors and tools can still be used even if fossil fuels aren’t available.

However, the scientists warned that real-life farming in a disaster wouldn’t be easy. Soil quality, broken water systems, and other problems could affect how much food we could actually grow. But this research is a useful starting point — and a reminder that smart planning now could save lives later.