Kai Ryssdal: If you want to date the global environmental movement, the one event that got the whole planet thinking about sustainability in all its forms -- climate change, hunger, poverty and pollution -- you'd probably have to go with the Rio Earth Summit 20 years ago.
There's another meeting down there this week, which has kind of been lost in the global economic mess. But the issues raised at Rio in 1992 have been engrained in a whole generation that's grown up with them.
From the Marketplace Sustainability Desk, Eve Troeh reports.
Eve Troeh: At the first Rio Earth Summit, 20 years ago, a 12-year-old girl from Vancouver stood before the general assembly of the United Nations in a floral print dress.
Severn Suzuki: To come 5,000 miles to tell you adults you must change your ways.
Her name was Severn Suzuki. Archived video shows diplomats riveted, some dabbing at tears.
Suzuki: I am fighting for my future. Losing my future is not like losing an election, or a few points on the stock market. I am here to speak for all generations to come.
And the world seemed to listen. Most countries, including the U.S., signed a set of goals that said, basically, let's grow the world's economy in a way that doesn't hurt the poor or the planet.
Keya Chatterjee was a teenager when Severn gave that stirring speech. Environmentalism was big in the '90s with kids like her.
Keya Chatterjee: I remember I had a little pin-up of a definition of the term "recyclosis," the guilt you feel when you don't recycle something, and I had it hanging in my locker.
There was even a new restaurant chain, the Rainforest Café. There's still one at the MGM Grand in Las Vegas, full of fake waterfalls, robot butterflies, and...
Tracy Tree: Hello kids, my name is Tracy Tree.
Yes, those Raging Thunder Buffalo Wings come with a side of education.
Tree: Hold up the paper towels and imagine it's a tree. Now we can understand why it's so important to reuse, reduce and recycle.
If that '90s-style environmentalism sounds naïve, Keya Chatterjee says it should. She, by the way, grew up to be director of international climate policy for the World Wildlife Fund.
Chatterjee: Twenty years ago, we knew what the problems were, but we didn't know the complexity of the solutions, and Rio was the start of all of that.
The start of carbon trading and electric cars and green building -- the brass tacks of the big problems.
Just across the street from the Vegas Rainforest Cafe, the MGM's Aria hotel is a great example. To get a green building certification for the 4,000-room resort, the company had to track thousands of tiny details. Cindy Ortega heads energy and environmental services for MGM.
Cindy Ortega: Finishings and carpets and veneers that are all environmentally correct. You can't have one wall that is wrong.
But no talking tree with green tips here. Guests check in largely unaware of MGM's efforts.
Ortega: And that's OK, because they're here to have a good time.
I asked Ortega who is leading the charge, if not the young, hip customers.
Ortega: The driving is coming from the top.
Older senior executives, Ortega says, not from younger employees.
That fits with the findings of Jean Twenge, a psychologist who wrote the book, "Generation Me."
She says there's been a false assumption that millennials -- people born roughly between the late 1970s and early '90s -- care more deeply about the environment than others.
Jean Twenge: My co-authors and I were quite surprised to see that there was a generational decline.
Sample question from their survey?
Twenge: How much of an effort do you make to conserve energy and protect the environment? And more baby boomers compared to millennials said they did a lot of those things. And many more millennials said they did absolutely nothing.
That doesn't mean this generation won't take up the mantle of solving environmental problems, she says. But we can't assume they already care.
Keya Chatterjee with the World Wildlife Fund points to one major factor that didn't exist 20 years ago: The Internet. It allows millennials who already care to amplify their message.
Chatterjee: We'll be having big social media movements to push President Obama to go to this meeting and join other heads of state there.
Activism by Twitter hashtag and Facebook "like" button.
There's another young voice on the ground in Rio this year. Britany Trilford is a bright teenager from New Zealand. She got invited because of a speech that she recorded alone, at her computer, and posted on YouTube.
Brittany Trilford: You and your governments have promised to reduce poverty and sustain our environment. I want a future where leaders will stop talking and start acting.
So far, she has 20,000 hits, and she opened the Rio 2012 summit today.
I'm Eve Troeh for Marketplace.