Teacher: Good morning class. Today we are remembering what life was like in the days of Barack Hussein Obama, the first African American president of the United States. As you all know, President Obama did many things to distinguish himself as one of the greatest presidents our country has ever known.

Back in 2009, the country was in a fast downward spiral of financial disaster; but Obama and his cabinet -- against all odds -- implemented a plan that reorganized the way banks and public corporations did business. He made them accountable not only to the shareholders and government, but also to the environment and to the well-being of the workers. There were a couple of very dark years for a lot of people, but a second Great Depression was averted.

It was under President Obama's leadership that this country was ushered into the era of peace and prosperity that we've experienced since then. Some argue that he saved the world from impending ecological collapse by appointing key agricultural and scientific people that made critical recommendations.

A hundred years ago, you may find this hard to believe, but the entire world was behaving in a way that made scientists of the time wonder aloud whether humans are actually a rational species. Some of the most brilliant scientists of the day argued that without changes in policy, the world was doomed to biblical-style plagues, floods, famines, food and water wars, and other catastrophes -- all of human origin. Even so, entire industries lined up to condemn these scientists -- there was actually a debate about whether global warming was a problem.

[Gasps and murmuring of incredulity from the students.]

I know, we see it all clearly now. But back then, people were used to just taking whatever they wanted of natural resources, not believing that there could ever be consequences. They thought there was no end to the oil in the ground, fresh air or water, trees, or even animals. They believed they could do whatever they wanted, and so they did.

It's impressive to think about how the transformation occurred, though. Take for instance how people used to eat. Back in the day, people used to eat animals as part of nearly every meal. No kidding.

But then in late 2006, United Nations scientists argued that eating meat was "one of the top two or three most significant contributors to the most serious environmental problems, at every scale from local to global," singling out meat consumption as a top cause of everything from desertification to loss of biodiversity to global warming. In fact, it was the business of raising animals for food that caused more global warming gases -- carbon dioxide, methane and nitrous oxide -- than all the various forms of transportation put together.

So even though driving those millions of big cars and flying old-fashioned planes powered by oil were polluting the environment and warming the planet at breakneck speed, animal agriculture was an even bigger problem.

It seemed that no one listened, though, as 10 billion land animals and tens of billions of fish continued to be killed and eaten by humans every year in the United States alone.

Student: Ten billion animals and all those fish were slaughtered a year? For people to eat?

Teacher: Oh yes. People in the United States ate on average about 100 kilograms of animal flesh per person per year; of course back then the U.S. measured weight in something called pounds -- so it was an average of about 220 pounds. They ate huge chunks of cows -- their rumps, shoulders and from around their ribs -- and drank their milk. They even ate the cow's babies -- called veal -- because they liked the taste of tender flesh. They dined on chickens more than anything, eating their breasts, legs and wings. And people ate their eggs, too!