Climate and Seasons — What the Weather Allows and Forbids

Why It Matters

Think about what it would be like to live before there was any such thing as air conditioning, central heating, or refrigeration. The weather outside was not an inconvenience — it was the entire rhythm of your life. If it was too hot, you could not work. If it was too cold, your crops died and you starved. If the rain came at the wrong time or not at all, your whole family might be hungry by winter. If the summers were long and mild, everyone was healthier and there was surplus food, and maybe there was a wedding and a festival. Weather was not something that happened to you. Weather was what told you what you could do.

For all of history, climate has decided what crops were even possible in a given place. Rice needs a lot of warmth and a lot of water, so it became the main crop in southern China, southeast Asia, and parts of India — places with monsoon rains and hot summers. Wheat is tougher and more flexible, so it spread across Europe, the Middle East, and North America — the temperate zones with moderate rain. Corn (or maize) was first grown in Mexico and Central America, in places with warm dry growing seasons. Potatoes came from the cold high mountains of Peru, where almost nothing else would grow. Each of these crops shaped the civilization that depended on it. Rice-eating cultures have different habits, different festivals, different foods, different farming methods than wheat-eating cultures. The crop comes from the climate, and the culture comes from the crop.

Climate also decided where diseases could spread. Warm, wet places often had more dangerous diseases — malaria, yellow fever, parasites — because the insects that carried them could thrive there. This is one reason why civilizations in the tropics often faced harder challenges than civilizations in temperate zones. It was not that the people were different. It was that the climate carried different enemies.

Here is the part people usually miss. Climate has not always been the same. Over thousands of years, the earth has gotten warmer and cooler many times. Sometimes the changes were small, but even small changes wiped out civilizations. A few degrees of cooling could mean that the growing season is a week too short, and the harvest fails. A few years of failed harvests could mean widespread hunger, and then migration, and then war. Some of the greatest mysteries of history — why did the Indus Valley civilization disappear? why did the Mayan cities empty? — are now being answered partly by climate: the rain patterns changed, and the civilizations could not survive the change.

When you learn about a place in history, you should always ask what the climate was like. You should ask what the growing season was. You should ask how reliable the rain was. These are not boring details. These are the first questions a historian has to answer before anything else makes sense.

Pattern

The Year Without a Harvest

There is a story, told differently in many parts of the world, about a year when the sun hid and the crops failed. The year was 1816 — not ancient history at all. This happened to people your great-great-great-great-grandparents might have known. It is called, in the history books, 'the year without a summer.'

What happened was this. A huge volcano on the other side of the world, called Mount Tambora, exploded in 1815. The explosion was so massive that it threw enormous amounts of ash and dust into the high sky. The ash spread across the entire globe, carried by winds that circle the earth at high altitudes. By the next summer, 1816, so much ash was blocking the sunlight that temperatures dropped everywhere. In places as far from the volcano as the United States and Europe, the weather in June and July was like late autumn. Frost killed crops in Vermont in June. Snow fell in New England in July. In Switzerland, families starved because the potatoes and wheat failed. In China, rice paddies froze and failed. In Ireland and Wales, there was widespread hunger.

The people experiencing this had no idea what had happened. They had not heard of the volcano — news traveled slowly, and few people outside of Indonesia knew Tambora had even erupted. All they knew was that the summer was wrong, the crops were dying, and they were going to be hungry. Some of them thought the world was ending. Many started migrating, looking for any place where food still grew. Some died.

And then there are the smaller, quieter effects. A young novelist named Mary Shelley was on vacation in Switzerland that summer, and because the weather was too cold to go outside, she spent her days indoors telling stories. One of the stories she made up became the novel Frankenstein. That book — written because of a climate disaster on the other side of the world — would shape science fiction for the next two hundred years.

A young painter named Caspar David Friedrich looked at the strange, ash-filled sunsets that year and painted them in colors so haunting that art historians still study them. The volcanic dust had turned the sky a deep red-orange, and people everywhere noticed. In England, J.M.W. Turner painted skies that same year that are now famous for their apocalyptic colors.

Farther east, in what is now India and Bangladesh, the strange weather messed with the monsoon rains. The monsoon is the massive annual rainfall that southeast Asia depends on for its rice crop. In 1816, the monsoon came strangely. In the years after, new strains of disease — especially cholera — spread in ways that had not happened before. The climate shift killed tens of thousands of people in ways that seemed mysterious at the time but that modern scientists can now link back to the volcano.

Think about this carefully. One mountain, half a world away, changed the weather of the entire earth for a year. And because of that, entire harvests failed, people migrated, died, ate differently, painted differently, and wrote different books. History was rerouted by the weather.

This was one volcano, one year. Now imagine what happens over many centuries when the climate slowly warms or slowly cools. Imagine what happens when the rains come a little later every year for a hundred years. Whole civilizations shift. Some rise because the new climate is better for them. Others die because the old climate was the only thing keeping them alive.

The weather is not a backdrop. It is one of the main characters in every story history has to tell.

Vocabulary

climate

The usual weather pattern of a place over many years — how hot or cold it gets, how much rain falls, how long the seasons are. Climate is different from 'weather,' which is what the sky is doing on a single day.

growing season

The time of year when crops can grow — long enough to plant, grow, and harvest before the weather turns too cold or too hot. A long growing season means bigger harvests. A short growing season means food is scarce.

monsoon

A seasonal wind system that brings heavy rain to parts of southern and southeastern Asia every year. Monsoon rains are the reason rice can be grown in huge quantities in those regions.

famine

A severe shortage of food across a whole area, usually caused when harvests fail. Famines have killed more people in history than most wars.

harvest

The time when crops are collected from the fields. A good harvest means food for the year. A failed harvest means hunger and often death.

tropical

Describing the warm, wet regions near the equator. Tropical climates support rapid plant growth and many different kinds of life, but they also support many diseases.

Guided Teaching

The simplest way to understand climate's role in history is this: climate decides what year looks like. And the year, repeated over many years, is what a civilization is built on.

Start with a farmer, anywhere in history. The farmer has a calendar — not a paper calendar, but a knowledge of when to do things. When to plant the first seeds. When to water. When to expect rain. When to harvest. When to store food for winter. When to butcher animals. When nothing grows at all and the family eats from what was stored. Every decision in the farmer's year is set by the climate. Shift the climate — make winters longer, or summers drier — and every decision on the calendar has to change.

Different climates produced different crops, and different crops produced different civilizations. Consider the two biggest crops of the ancient world: wheat and rice.

Wheat grows in temperate zones with moderate rainfall. It needs a cool growing season and a dry time for harvesting. It does not take much water. One family can farm wheat fairly independently on a patch of land. Wheat is also easy to store — you can keep it dry for years. This is part of why wheat-growing civilizations (like much of ancient Mesopotamia, Europe, and North America) developed traditions of individual family farms, stored wealth in granaries, and often had strong trade networks — because wheat travels well.

Rice, by contrast, needs enormous amounts of water. It grows in flooded fields called paddies. Building and maintaining rice paddies requires massive cooperation — you need whole villages to dig and maintain irrigation channels, and rice harvesting is backbreaking work that is usually done in groups. This is part of why rice-growing civilizations (much of China, southeast Asia, and parts of India) developed deeply communal village traditions, powerful centralized governments that managed water, and a different kind of culture than wheat civilizations.

The crop did not happen to match the culture. The climate forced the crop, and the crop forced the culture.

Now add one more thing: climate change. Most people think climate change is a modern problem, but the climate has changed many times in human history, and the changes have caused civilizations to rise and fall. A period called the Medieval Warm Period (roughly 950 to 1250 CE) allowed Vikings to farm in Greenland — a place far too cold to farm today. When the climate cooled again during what is called the Little Ice Age (roughly 1300 to 1850 CE), the Vikings in Greenland died out, and harvests failed across Europe, and peasants rebelled, and kingdoms struggled. The Mayan cities of Central America may have collapsed partly because of a long drought that made farming impossible in what had been productive land.

Whenever you hear about a civilization that rose or fell, one of the first questions to ask is: was there a climate change at that time? You would be surprised how often the answer is yes, and how often the climate change is the missing piece of the story. The human choices matter enormously, but the climate sets the stage on which those choices have to be made.

And the lesson underneath all of this: the weather is not a small thing. It is not background. For most of human history, the weather was the most important question in everyone's mind, every day. That is still true for most farmers in the world today. When we forget how powerful the weather is, we are forgetting what kind of animals we really are.

For Discussion

1. 1.Why do you think rice-growing and wheat-growing civilizations ended up with such different cultures?
2. 2.What would change about your life if you lived somewhere with no reliable winter heating or summer cooling — just what the land gave you?
3. 3.In the story of 1816, what was the connection between the volcano and the novel Frankenstein?
4. 4.Why is a 'failed harvest' such a serious problem in a pre-modern society? What happens next?
5. 5.Can you think of a place today that depends heavily on the weather? (Hint: think about food, but also think about tourism, energy, water.)
6. 6.What do you think happened to the people who lived in the Mayan cities when the long drought came?
7. 7.Is the climate a more powerful force in history, or are human decisions more powerful? Or is that the wrong question?

Practice

Track a Climate Story

1. 1.Pick any major historical period you are curious about — ancient Rome, medieval Europe, the American colonies, anything.
2. 2.Look up what the climate was like during that period. Was it warmer or colder than today? Was there more or less rain?
3. 3.Try to find one example of how the climate affected the people in that period. Did a drought cause a migration? Did a warm period allow a new crop to grow? Did a cold snap cause a famine?
4. 4.Write a short paragraph explaining what you found.
5. 5.Finally, think about your own area. What crops grow there today? What would change if the climate got a few degrees hotter? Cooler? Wetter? Drier? Would your area still be able to support the same kind of life it does now?

Memory Questions

1. 1.What does 'climate' mean? How is it different from 'weather'?
2. 2.Why did rice-growing civilizations end up different from wheat-growing civilizations?
3. 3.What happened in 1816, and what caused it?
4. 4.What is a 'growing season,' and why does its length matter so much?
5. 5.What is a 'famine,' and why have famines been more deadly than most wars?
6. 6.Give one example of a historical civilization that was affected by a climate change.