It's an honor to address this group of distinguished faculty, proud parents, supportive family members and friends.

We're gathered here in this idyllic location to celebrate the accomplishments of these young adults as they successfully complete one great challenge and prepare for others to come.

So please join me in congratulating Green Mountain College's (GMC) Class of 2017.

I'm especially honored to be giving the commencement speech at Green Mountain College for at least two reasons.

First of all, this is my home—broadly speaking.

I grew up in the foothills of the Green Mountains. Well, those of us in the slightly less "green" state of Massachusetts call them the Berkshires—but it is the same mountain range, the same magical small corner of the world.

Growing up in the town of Amherst, Massachusetts 100 miles southeast of here, I gained an appreciation for the wonder of nature hiking those mountains, wading in those streams, bicycling up and down those same hills.

I was an avid cyclist—though I didn't rack up the 4,000 miles a year that your president does.

Really? 4,000 miles a year President Allen?? [looking at him]

Have you tallied the carbon footprint of all of that respiration? I did (the nerd in me couldn't possibly resist). It's 95 entire kilograms of CO2 equivalent.

I hope that's been accounted for in GMC's carbon footprint estimates.

But let me get back on message…

The other reason I am so delighted to be here has to do with what Green Mountain College represents. Even the name of the college seems to speak unapologetically to its vision and its mission.

And GMC proudly advertises itself as "First in Sustainability."

Now talk is cheap of course. But GMC—and its students and graduates—haven't just talked the talk. They've walked the walk.

In this year's graduating class, for example, is a young woman named Keeley Titus. Keeley resided on the "sustainability floor" of her residence hall, which is built around locally raised food.

I have to say, I just love this story.

Keeley bottle-fed from birth two Nigerian dwarf goats named Margaret and Rose who reside at the college's farm. She's fed them 4 times a day. They are now old enough that Keely can produce fresh milk and cheese from them.

Keeley came to GMC because she wasn't interested in conventional programs focusing on big ag. She wanted to learn how to replicate sustainable food systems at the smaller mid-scale.

As Keeley notes, "I think that's the way we're moving as a country."

I think she's right. But only because of the efforts by her and other young leaders who are driven by the vision of a sustainable future—a vision undoubtedly nurtured by their experiences here at GMC.

For over two decades, this college has demonstrated an unmatched commitment to environmental, social and economic sustainability.

Amazingly, with an enrollment of only about 800 students (for the record—that's roughly the same size as my high school), the college offers majors in Environmental Studies, Renewable Energy & Ecological Design, Wilderness & Outdoor Therapy, Sustainable Agriculture & Food Production, Animal Conservation & Care and numerous minor options in the environmental and sustainability space. Students can also design their own majors.

But even more impressive is the way the college integrates the theme of environmental sustainability throughout students' educational experience via its unique Environmental Liberal Arts curriculum.

Students of all majors learn about the importance of social and ecological sustainability through coursework that stresses critical thinking, analysis and written expression.

And outside of class, the learning continues in the form of outings and field trips, and service learning projects.

This integrated focus creates a shared sense of purpose—because here, the environment is 100 percent relevant to every field.

The Association for the Advancement of Sustainability in Higher Education awarded Green Mountain College the Campus Sustainability Leadership Award in 2007 for—and I quote:

"Commitment to environmental sustainability in its governance and administration, curriculum and research, operations, campus culture, and community outreach."

Green Mountain was named an EPA Energy Star Showcase Campus.

That GMC has received such accolades is not incidental.

Let me stress, once again, that GMC walks the walk. It recognizes:

1. Little Things Add Up! Like the recent campus-wide retrofitting of light fixtures and students have installed a wind turbine to power the campus green house and solar panel on the roof of the student center.

2. Student Engagement is Critical: Through the Student Campus Greening Fund (SCGF) every GMC student contributes $30 from the college activities fee. Students design projects and submit proposals. Awards are based on a student vote. SCGF money has been used to install bike racks, purchase recycling bins, use bio-diesel in campus maintenance equipment and upgrade the alternative energy systems that power the farm greenhouse.

3. We Need to Think Big: Seven years ago, GMC opened a new combined heat and power biomass plant costing $5.8m.

4. Commitments Must be Actionable: In 2011, GMC became climate neutral. Only the second college in the nation to achieve this goal, and the first to do so through a significant reduction in on-site emissions achieved through efficiency, adoption of clean energy, and purchase of quantifiable local carbon offsets.

5. Peer Pressure Works: GMC's achievement of carbon neutrality in 2011 was followed by Colby College of Maine in 2013, and late last year, close-by Middlebury College.

In the end, though, it really comes down to the people. GMC's faculty are of course top notch and include leading thinkers, educators and practitioners in the sustainability space.

But it's truly the students who make GMC so special.

In recent years, GMC students have done internships with the Boston Aquarium, the Nature Conservancy, the United Nations, the Office of U.S. Senator Bernie Sanders.

They've done internships with Green Mountain Power and Duke Energy. Yes—sometimes change can come from within.

And so many of GMCs graduates are now working productively in the area of environmental sustainability.

Take for example Joe Bossen, class of 2008. As a student, he experimented with small community-based coop. After graduation he founded a company called "Vermont Bean Crafters"—as Joe puts it "joyfully serving the tastiest in local, organic and plant-based food."

Joe was named Vermont Young Entrepreneur of the Year by the Vermont Small Business Association in 2014.

Some of us grew up being told it's not easy being green.

But Joe is shining example that, with a bit of creativity, you can excel in both business and sustainability in today's world.

Or take Allan Coutinho—one of last year's graduates. Allan is a Brazilian native who was attracted by GMC's mission of social and environmental sustainability. He crafted a self-designed major that merged his interests in education and sustainable development. And he was the head of GMC's award-winning delegation to the UN's Model United Nations program.

He is now pursuing graduate studies at Harvard. He has said he doesn't think another school would have given him so many opportunities. And I suspect he's right about that.

Here are what a few other GMC graduates are doing today:

Kim Barrett—class of 2014, director of Kehoe Green Mountain Conservation Camp in Vermont.

Tori Knoss—class of 2012, naturalist, Pacific Whale Foundation, Maui, Hawaii.

Cory Cheever—class of 2008, environmental educator, Vermont Institute of Natural Science.

Keith Drinkwine—class of 2010, assistant director of Camps, Parks, & Forest, N.Y. State Dept. of Environmental Conservation.

Mindy Blank—class of 2010, adjunct professor of Environmental Studies at GMC. She participated in the history-making COP21 climate meeting in Paris in December 2015. She has also worked for the International Energy Agency helping countries accelerate the deployment of renewable energy.

The list goes on. And an impressive list it is.

At a time when our environment is most imperiled, your work—class of 2017—is more important than ever.

Now, let me regale you with a story about my own college experience.

In 1984, after graduating from Amherst High School, I headed off to Berkeley.

To demonstrate against the policies of Ronald Reagan, you ask?

To participate in sit-ins protesting Apartheid in South Africa, you ask?

Alas, no, I didn't go to protest or demonstrate.

I went there to study applied math and physics among some of the world's leading experts.

And ironically, it was that path turned out to be the one that would lead me toward confrontation and battle.

I would go on to study theoretical physics in graduate school and to move into the then-burgeoning field of climate research.

My path of discovery would ultimately lead to me to publish the now iconic "Hockey Stick" curve in the late 1990s.

The curve tells an unmistakable story, namely that the current warming spike is unprecedented as far back as we can go. Our continued burning of fossil fuels is the culprit.

And fossil fuel interests and front groups and politicians doing their bidding attacked it—and me.

Despite the numerous independent confirmations of my findings by the U.S. National Academy of Sciences and dozens of other assessments, the effort to discredit this research—and to discredit me personally—has continued.

I was initially reluctant about being at the center of the fractious societal debate over human-caused climate change.

But I have ultimately come to embrace that role. I have become convinced that there is no more noble pursuit we can engage in than to seek to insure that policy is informed by an objective assessment of scientific evidence.

That evidence now shows us that we face a stark choice, between a future with a little more climate change that we will still have to adapt to and cope with, and one with catastrophic climate change that will threaten the future of life as we know it.

And so here we are, at a crossroads.

Let me be blunt.

Never before have we witnessed science under the kind of assault it is being subject to right now in this country.

Nor have we witnessed an assault on the environment like the one we are witnessing in the current political atmosphere.

I will borrow and adapt—for our current time and place—the words of Martin Niemöller, a prominent Protestant pastor who emerged as an outspoken public foe of Adolf Hitler and spent the last seven years of Nazi rule in concentration camps:

First they came for the immigrants and I did not speak out—

Because I was not an immigrant.

Then they came for the scientists, and I did not speak out—

Because I was not a scientist.

Then they came for the environmentalists, and I did not speak out—

Because I was not an environmentalist.

Then they came for me—and there was no one left to speak for me.

Friends, let this not be our legacy.

Those of us who care about science and the role that science plays in our larger public discourse and those who care about environmental stewardship and a sustainable path forward must now make our voices heard.

Become involved. They are so many ways to speak out and to influence the dialogue. So many ways we can engage constructively with governmental, civic and corporate institutions in the realms of education, public policy and industry.

Past GMC graduates have gone on to become community planners, environmental lawyers, and directors of nonprofit organizations. Many now work for state and federal agencies or educational institutions.

My good friend Bill Nye, whom I marched with in Washington DC a few weeks ago at the March for Science, often ends his lectures with the exhortation "Change the World!"

Let me go just a bit further: Let me ask each of you to change the world for the better.

I am confident you will.

Godspeed to you all.