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  • Within this loaf of delicious banana bread, there's butter and eggs and vanilla, bananas

  • maybe all the way from Guatemala, and a lot of sugar -- but there's also energy.

  • Energy is one of those things that's so basic and important to our lives and how the

  • world functions it's kind of hard to define.

  • But at its most simple, energy is the ability to do work.

  • So like a few bites will (hopefully) give me the fuel to record this episode.

  • Food energy is just one type of energy, but it's incredibly important and necessary

  • for humans to exist.

  • And that can create some tricky issues.

  • Like as the world's population keeps growing, we have to figure out how to provide enough

  • food and water for everyone and still support a sustainable environment.

  • That problem might set your geography senses tingling, because we can explore it through

  • human-environment interactions.

  • We might only be about halfway through our physical geography journey, but this is one

  • of those times when the line between physical and human geography doesn't really exist.

  • Some of the most critical issues we face as a society -- like climate change, eradicating

  • diseases, or making sure everyone has food -- require knowing about Earth's physical

  • and human systems and the interdependency of living things and physical environments.

  • I'm Alizé Carrère, and this is Crash Course Geography.

  • INTRO

  • People need a lot of energy throughout their lives, especially the food energy we get from

  • the banana bread (and other stuff) we eat to power our bodies.

  • And to understand how we get the food energy we need, we have to first understand how energy

  • gets to the Earth.

  • Once solar energy leaves the Sun and travels to Earth it can't be returned, so we say

  • energy flows in one direction.

  • Food energy is created when plants turn that solar energy into chemical energy.

  • Using photosynthesis plants combine sunlight, carbon dioxide, and water to make carbohydrates

  • -- which are little packets of food energy!

  • A food chain describes how energy makes its way through ecosystems, or communities of

  • living and nonliving things.

  • It's basically a list of who eats who.

  • Let's go to the Thought Bubble.

  • In a simple food chain, lets say a cow grazes on some grass.

  • Then a tiger comes along and attacks and eats the cow.

  • When the tiger dies, bacteria breaks down its body, returning it to the soil, where

  • it provides nutrients for plants -- like the grass.

  • But food chains are rarely simple.

  • Cows like grass, but they'll also munch on corn stalks and hay.

  • And tigers will eat other animals too.

  • So lots of food chains intertwine within different ecosystems and form food webs.

  • To organize the chaos, we can group organisms into categories called trophic levels.

  • The first trophic level is the producers that make their own food, like the grass that uses

  • solar energy to photosynthesize.

  • In the second trophic level, the producers are eaten by a primary consumer, like the cow.

  • Then there are secondary consumers who eat the primary consumers, like a tiger who eats the cow.

  • And there can be tertiary consumers, who eat the secondary consumers.

  • The highest trophic level of a food web is usually the apex predator, who doesn't get eaten.

  • In this little food chain, it's the tiger, our secondary consumer, and we only have three

  • trophic levels.

  • Each time we move up a trophic level, only 10% of the energy is passed on.

  • So the cow only gets 10% of the energy the grass absorbed from the Sun.

  • And the tiger only gets 10% of that 10%.

  • That means that each trophic level gets smaller and smaller.

  • So we might have a ton of grass, a lot of cows, but only a few apex predator tigers

  • at the top.

  • And lastly, sitting at the edges are the decomposers, the clean up crew who break down dead plants

  • and animals like our tiger into energy and nutrients that mix into the soil for plants

  • to absorb, starting the chain all over again.

  • Thanks, Thought Bubble!

  • The logic of passing on less energy to higher trophic levels applies to humans and our resources too.

  • If we add more people or consume more food, that's going to influence the trophic levels

  • below us.

  • In fact, we can predict our impact on the environment with a formula that uses population

  • size, how affluent a society is -- which is usually measured by how much it consumes -- and

  • how much access to technology it has, which can be both positive and negative.

  • The world's population has been rapidly increasing since the industrial revolution

  • in the 18th and 19th centuries.

  • With new manufacturing processes and machines, we could grow and create more food, and then

  • feed more people.

  • And in 2020, we officially reached 7.8 billion people on the planet.

  • As we keep adding more and more people to the world, we have to start thinking about

  • our planet's carrying capacity, which is the maximum population an environment can

  • support long term with a given set of natural resources.

  • So there are two types of overpopulation to consider if we're deciding if the Earth

  • will run out of resources.

  • People overpopulation is when there are a lot of people so a lot of resources are used.

  • This can be how poorer countries might run out of resources, because even though consumption

  • per person and technology's influence is lower, the high population size means a big

  • impact on the environment.

  • On the other hand, consumption overpopulation is when there are fewer people, but each individual

  • person uses a large quantity of natural resources.

  • This is usually how richer countries might run out of resources.

  • In both cases, we have to take a hard look at where we're getting our energy -- especially

  • our food energy.

  • How much energy we use depends on where we are in the food chain because as we climb

  • to higher trophic levels, it takes more total energy to generate the food that fills our stomachs.

  • If we look across the world, some people depend on traditional practices to get food energy,

  • and eat more grain, more seasonal foods, and larger amounts of fresh, homegrown, and unbranded foods.

  • They eat a lot of producers, so less energy is lost between trophic levels before making

  • it to their stomachs.

  • As incomes rise, though, people generally go through a nutrition transition, or a change

  • in food habits and culture because they have more wealth.

  • In richer countries, food is generally more homogenized, highly processed, and tends to

  • be meat-heavy.

  • They're eating more primary and secondary consumers, and it takes more energy to feed

  • all those trophic levels.

  • Like as China has risen economically, the people have moved away from a traditional

  • rice based diet to eating more meat, particularly beef.

  • But every person doesn't live their life exactly the same way, so we're going to use average

  • numbers to discuss energy consumption here.

  • Some people are eating more meat and some people are eating less!

  • In 2018, each person ate an average of just under 80 kilograms of meat in a year, and

  • with 1.35 billion people in China, that's more than 108 billion kilograms of meat per year.

  • Many other countries out-eat China per person, like an average American eats 120 kilograms

  • of meat per year.

  • That's like one person needing 1350 kilos of grain a year to survive, because that's

  • how much it takes to feed that amount of meat.

  • But if we hop down to a lower level on the food chain and ate grain instead of meat,

  • those 1350 kilos of grain could feed 22 people for a year.

  • This is why you might've heard about vegetarian and vegan diets being more environmentally friendly.

  • They take fewer resources and less energy to feed you.

  • So to put it all into perspective: eating a hamburger or something processed like banana

  • bread takes more energy than just eating a banana.

  • And that's only part of the picturewe also have to think about how that food is

  • grown and gets to us.

  • For example, since I live in the United States and we import bananas, a more energy-saving

  • choice might be to eat cornbread from corn grown in Iowa -- or just eat the oranges grown

  • in my backyard!

  • Urbanization and industrialization change how we produce our food, and how much energy

  • that takes.

  • We can't just look at food chains, because most of our food energy comes from a combination

  • of solar energy to help plants grow plus whatever work and fuel we put into agriculture practices.

  • For example, animal husbandry is a branch of agriculture focused on raising livestock,

  • and requires land for grazing and fresh water.

  • For thousands of years, we've raised animals like llamas in the Andes, yaks, goats, and

  • sheep in the Himalayas, reindeer in the Arctic Circle, and camels in Mongolia and in the Sahara.

  • And humans met those animal husbandry requirements through transhumance, or moving herds between

  • pastures with the change of seasons to help ecosystems stay productive.

  • Indigenous communities especially have farmed in ways that have left plenty of energy for

  • local ecosystems.

  • But as our societies have industrialized, farms have become large users of fossil fuel

  • -- from using equipment to plant and harvest crops, to transportation to deliver the food

  • to urban areas.

  • This is one spot where that technology piece of the formula can factor in.

  • As demand for meat has increased, we've also created factory farms dedicated to producing

  • meat, which require even more energy because all those animals need food to eat and water

  • to drink.

  • So there are farms that grow crops just to feed animals on other farms, like in the Corn

  • Belt in the middle of the US.

  • Instead of using the solar energy captured by these crops to directly feed people, it

  • goes to the next trophic level to fatten up cattle and hogs.

  • The Corn Belt is also a Pork Belt and a Beef Belt.

  • So we're devoting a ton of land, jobs, and industrial processes to keep our spot high

  • up on the food chain.

  • And as the world population keeps growing, managing the amount of resources we have -- especially

  • food energy -- is an increasingly urgent problem.

  • With 7.8 billion people on Earth we are changing the flow of energy through our ecosystems,

  • and those changes are tied to a cascade of environmental and social problems.

  • To find solutions, as geographers we examine how local choices intersect with larger scale outcomes.

  • On the population side, we can help feed growing populations by understanding where food is

  • produced and how it's distributed.

  • Locally, strong distribution networks, with access to affordable healthy foods, are critical

  • to making sure everyone has enough food.

  • Regionally and globally, we can study the economic incentives that allow food to easily

  • flow to some places and not others, or systems that break down local food networks to create

  • global ones -- like how affluence is tied to eating more meat.

  • To reduce our consumption impact, knowing our foodshed, or the area that feeds us, is critical.

  • We can limit how much meat we eat or try to eat locally grown foods.

  • And these local actions can impact ecosystems and food economies around the world as demands change.

  • Maintaining energy flows and finding a way to feed everyone on the planet is not going

  • to have a quick solution.

  • But as we all work together to keep moving forward, thinking carefully about what we