Growing up in Denver, I didn’t think about sustainability – at least not in the way we think about it today.

I never heard about “sustainable development goals.” I didn’t know what “the three-legged stool” referred to. I didn’t think about balancing the needs of the present with the needs of the future.

Life was simple. Water came from the tap. Food came from the grocery store. Travel was by car, or if you couldn’t afford a car, by bus.

I didn’t think about sustainability. But I did notice things.

I noticed the brown cloud of air pollution that hung over our city, especially in the winter. We had creeks and the South Platte River nearby, but people ignored them. Dumpsters were filled with trash, and litter blew around all over the place.

Denver had trees and parks, but they weren’t spread evenly around town. The rich parts of the city had more and the poor parts had less. I knew that there were polluted areas in the city. They always seemed to be in the poor neighborhoods. My family was not rich, so there were limits on where we could afford to live.

I loved living in a place where lofty mountains and picturesque plains were nearby. I loved the western spirit in Denver, where people depended on each other and so cooperated with each other. I grew to love the place, but I knew it could be better. I wanted to be part of making it better.

From an early age I was interested in becoming a part of my city. At the time, I didn’t realize that would mean one day becoming the Mayor of Denver – but I knew I would play an active role in public service. As a teen I was active in my school’s leadership, which would eventually lead me to an internship in the Mayor’s Office. I began to see possibilities.

I learned the intricacies of public policy early on. At the age of 27 I became the youngest executive director of a major city’s office of the National Urban League. A few years later, I was elected to Denver City Council, where I served for eight years, including time as Council President.

It was during this time that I learned about the importance of public health and sustainability. I began to understand what initiatives and actions would help us to further invest in the city, and what it truly meant to balance the needs of the present with the needs of the future.

I was elected to be the Mayor in the middle of 2011. By then I had definitely heard of sustainability. My predecessor, John Hickenlooper, had opened a conversation with our residents about it. He formed Greenprint Denver, our city’s first sustainability program. Greenprint drafted the city’s first sustainability goals and plan. It drafted the city’s first climate action plan.

Things were changing outside of city government as well. Thanks to the passage of the federal Clean Air Act, the brown cloud that hung over Denver was gone most of the time. The city had begun to rediscover its waterways; people were looking to the South Platte instead of ignoring it. The river was cleaner, thanks to the Clean Water act. And we were paying attention to our contaminated areas, thanks to the federal Superfund law. We were cleaning the dumps up.

The other thing that was changing, was our climate. It was hotter in Denver more often. The droughts were worse, and more frequent. The storms were worse too. And those changes hurt the most vulnerable among us the most. People without air conditioning suffered the most during our hot spells. People who lived in flood-prone areas suffered the most from the storms.

It was amazing to me that the climate itself could change visibly in a single lifetime – my own.

When I came in as Mayor I knew that Greenprint, as valuable as it had been in starting the sustainability conversation, wasn’t going to be enough. We needed to do two things.

First, we needed to achieve changes at scale – move big numbers in a way that would make a difference. Second, we needed to get all oars in the water. We needed to make sustainability the core business value of every agency of city government, regardless of what service it performed.

Scale meant being selective about what we worked on. It’s tempting as Mayor to make a splashy announcement or conduct a high-visibility event – pass out cloth grocery bags at a supermarket, or change light bulbs in someone’s home. Those actions are nice, but they don’t move big numbers. I wanted changes that were big and long-lasting.

I also knew that I had to get everyone in city government involved in sustainability. I didn’t want sustainability delegated to a small office somewhere in the bureaucracy while everyone else was doing business as usual. It had to become a part of the city culture – if not every agency’s instinct, then at least every agency’s habit.

We have term limits in Denver. Mayors come and mayors go, but the civil service work force goes on and on. Sustainability can’t just be the issue of the month. It has to become a permanent practice, an integral part of the fabric of our community and its government.

So I made some changes. I replaced Greenprint with an Office of Sustainability. I created the position of Chief Sustainability Officer. I made that position cabinet level, so its holder could deal with department heads as peers. And I gave the Chief Sustainability Officer a simple agenda: Scale, and Everybody Plays.

Early on we set new sustainability goals. We organized the goals around basic resources – the resources that are the foundation of every city’s economy and quality of life, things like water, energy, food, mobility and housing. I wanted to ensure that those basic resources would be available and affordable to everyone in my city, both today and tomorrow. We would do that through a combination of conservation, innovation, and cessation of reliance on non-renewable resources.

We got everybody involved by keeping the Office of Sustainability small. It has just three people, one of the smallest such offices in any major city in the U.S. I didn’t want the Office of Sustainability to be a green island, doing interesting projects on its own but not involving others. I wanted it to provide top-level policy guidance while leaving the implementation details to our city departments.

While our sustainability office is small, our sustainability efforts are big, because they live throughout our municipal government.

Another element of my sustainability program was a recognition that Denver couldn’t do it alone. Yes, we had to set a good example. We had to push ourselves. But pushing ourselves by itself would not resolve our challenges. Denver could shut down every smokestack, eliminate every tailpipe – we could all just stop exhaling – and rapid climate change would keep on going. As 700,000 people in a world of seven billion we are just too small to make global changes on our own.

We needed allies. We needed to set a good example ourselves, but we also needed to join forces with many other cities to do the same.

Other cities were the obvious partners. It was during my administration that the world crossed a threshold, where, for the first time in history, more people lived in cities than lived outside of them. Cities were going to be the key, and they had to move forward together.

We’ve set many good examples during my Administration. I’m particularly proud of a collection of actions we took in 2016 to address energy and climate at scale.

First, we adopted the 2015 version of the International Energy Conservation Code. Doing so increased the projected energy efficiency of new buildings and major renovations by more than 25 percent over the previous code.

Next, we adopted a graywater ordinance that allows people to direct waste water from sinks and showers in their homes into toilets and irrigation. This had the potential to allow major new reductions in usage of potable water.

We also created a Property-Assessed Clean Energy program for commercial buildings – sometimes known as C-PACE. This provided a new financing mechanism to make it easier and more affordable for commercial buildings to upgrade with energy efficiency improvements.

Finally, we enacted an ordinance that requires all buildings of 25,000 or more square feet to record their energy usage and report in publicly in a format that allows for comparison of energy performance among such buildings. We also created a web site – – where anyone can see the performance of each such building and compare buildings to each other. In the short time since we passed the ordinance thousands have visited to site to check performance; many building owners have been looking at their competitors. Such peer-to-peer competition will spur energy efficiency upgrades.

It was a big year and we are already reaping the benefits of those at-scale changes.

We use our own success to spur on other cities. We work closely through organizations like the U.S. Conference of Mayors, the Urban Sustainability Directors Network, and ICLEI Local Governments for Sustainability, to compare notes, learn from each other, push each other and join together to influence policy at the national level.

Speaking of the national level, I came into office during the first term of President Barack Obama. His administration provided a strong federal partner for our efforts. We lost that partner when President Obama was replaced by President Donald Trump. However, thanks to our growing alliance with cities around the world we were not left to cope on our own. Through the collective action of these cities working together we continue to make progress in avoiding the worst effects of rapid climate change.

I am now approaching the end of my second term as Mayor, but I am excited about getting the opportunity to continue my work in sustainability.

Adolescent me may not have paid much attention to sustainability, but it has my attention now.

I am proud of what we’ve accomplished so far by emphasizing scale, getting all city agencies involved, and working with many other cities to magnify our efforts. I am optimistic that we will in fact succeed in ensuring that our basic resources are available and affordable to all of our resident both today and tomorrow.


Michael B. Hancock

American businessman, author and politician, serving as the 45th and current mayor of Denver, Colorado. He was sworn in on July 18, 2012, and was easily reelected with no significant opposition in 2015....

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